FOCUS ARTICLE Application of Principles of Evidence-Based ... · mal or systematic approaches. The informal approach is used by traditional narrative reviews. ... frequently used

FOCUS ARTICLE

Application of Principles of Evidence-Based Medicine toOcclusal Treatment for Temporomandibular Disorders:Are There Lessons to Be Learned?

The term evidence-based medicine (EBM) refers to the sys-tematic, explicit, and judicious use of best evidence inpatient care. In practice, EBM means the integration of

individual clinical expertise with the best available evidence, mod-erated by patient circumstances and preferences.1,2 The goal isobvious: EBM aims to improve patient care. The efficacy and cost-effectiveness of health services are also in the best interest ofpatients, as well as insurance companies, governments, and otherscontrolling payment plans.3

Heli Forssell, DDS, PhDSenior LecturerDepartment of Oral Diseases/Pain

ClinicTurku University Central HospitalTurku, Finland

Eija Kalso, MD, PhDAssociate ProfessorPain ClinicDepartment of Anesthesia and

Intensive Care MedicineHelsinki University Central HospitalHelsinki, Finland

Correspondence to:Dr Heli ForssellDepartment of Oral Diseases/Pain

ClinicLemminkäisenkatu 2Fin-20520 TurkuFinlandFax: +358-2-3338248E-mail: [email protected]

Journal of Orofacial Pain 9

Critical evaluation of treatment methods has become an importantpart of health care and will certainly have a major influence ondecisions about acceptable treatment methods in the future.Evidence-based medicine (EBM) means the systematic, explicit,and judicious implementation of the best evidence in patient care.The most reliable sources of evidence are high-quality systematicreviews and randomized controlled trials (RCTs). A systematicEBM approach could be particularly useful in the treatment oftemporomandibular disorders (TMD), where controversial andconflicting ideas about management are common. In this field, con-cerns about the lack of evidence are often expressed. This articleaims to elucidate and discuss the application of EBM to the treat-ment of TMD, using the most controversial treatments (ie, occlusaltreatments) as an example. By applying the principles of EBM toTMD treatments, we wish to highlight some of the importantissues that form the basis for high-quality care in this field. A sys-tematic review of occlusal treatments (occlusal splints and occlusaladjustment) updated to January 2003 revealed 16 RCTs of occlusalsplints and 4 of occlusal adjustment. The overall quality of the tri-als was fairly low. Recently, however, some high-quality RCTs ofocclusal splints have been published. The most obvious method-ologic shortcomings in published trials included problems in defin-ing the patient population, inadequacies in performing randomiza-tion and blinding, problems in defining the therapies orappropriate control treatments, short follow-ups, and problems inmonitoring patient compliance. Occlusal splint studies yieldedequivocal results. Even in the most studied area, stabilizationsplints for myofascial face pain, the results do not justify definiteconclusions about the efficacy of splint therapy. Their clinical effec-tiveness to relieve pain also seems modest when compared withpain treatment methods in general. None of the occlusal adjust-ment studies provided evidence supporting the use of this treatmentmethod. The clinical implications of the findings and future per-spectives are discussed. J OROFAC PAIN 2004;18:9–22.

Key words: dentistry, evidence-based medicine, occlusal adjustment, occlusal splints, randomized controlledtrials, temporomandibular disorders

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10 Volume 18, Number 1, 2004

Critical evaluation of treatment methods hasbecome an important part of health care and willcertainly have a major influence on decisionsabout acceptable treatment methods in the future.The positive effects of the practice of EBM canalready be seen in many areas, such as pain treat-ment in general.4 We believe that a systematicimplementation of EBM could be particularly use-ful in the field of temporomandibular disorders(TMD), where a wide range of controversial andconflicting ideas concerning management existsand where concerns about lack of evidence are fre-quently expressed.5–7

The present article aims to elucidate and discussthe application of EBM in the most controversialtreatment methods of TMD: occlusal treatments.By doing so, we hope to highlight some of theimportant issues bearing on improvements in thescientific standards of the treatment of TMD.

About EBM

The importance of developing an evidence-basedapproach to clinical care and treatment is empha-sized frequently.8,9 Traditionally, treatment plansin clinical practice have been based on a mixtureof knowledge gained through training, practicetraditions, and subjective perception of clinicalexperiences. This can result in highly varying treat-ments for the same condition, as well as ineffec-tive, expensive, and sometimes even harmful inter-ventions.3,10 EBM aims to move beyond anecdotalclinical experience by bridging the gap betweenresearch and the practice of medicine and den-tistry. The aim is to use an intervention that is asaccurate, safe, and effective as possible.11 Themost reliable sources of evidence are high-qualitysystematic reviews and large randomized con-trolled trials (RCTs)4 (Fig 1).

Why RCTs?

Uncontrolled clinical studies and case series can givepreliminary evidence of the benefit of a treatment.However, the extent to which patient outcomesreflect nonspecific effects, the natural history of adisease, regression to the mean, or specific effects oftreatment is unclear in the absence of RCTs.12–14

Nonspecific or placebo effects, such as physicianattention and patient expectations, influencepatients to report improvement. Many pain condi-tions can have a favorable natural history, and theymay resolve on their own irrespective of treatment.Patients with pain problems often have fluctuatingsymptoms, and they seek treatment when symptomsare at their worst. The tendency of extreme symp-toms to return toward the individual’s more typicalstate is known as regression to the mean.12 All theseeffects can be substantial and explain many of thebenefits attributed to treatment.

The RCT has become the gold standard for theassessment of treatment efficacy because of itspotential ability to control bias.15 Bias can be min-imized by randomization, blinding, description ofdropouts, and the use of appropriate controlgroups. Random allocation of treatments is of cru-cial importance. If trials are not randomized, esti-mates of treatment effect may be exaggerated byup to 40%.16

In practice, the quality and validity of publishedRCTs can show considerable variation.17 Differenttypes of quality and validity scales can be used toassess these.18–21 Rigorous studies should be givenmore weight, whereas flawed RCTs do not neces-sarily offer advantages over nonrandomized orcohort studies. Recently, consolidated standardsfor reporting trials have been published to improvethe quality of reporting of RCTs.22

Why Systematic Reviews?

Research evidence can be reviewed by either infor-mal or systematic approaches. The informalapproach is used by traditional narrative reviews.In these, the reviewers do not follow formal strate-gies to identify, extract, and summarize theresearch evidence.19 They can easily be biased andpresent a “personal estimate” of the evidence bythe reviewer.17 Systematic reviews try to overcomethe limitations of narrative reviews and be as objec-tive and transparent as possible.19 For a systematicreview to be scientifically sound, reviewers mustclearly describe the research question, the criteriafor inclusion or exclusion of the primary studies,the techniques to assess the methodologic quality of

I. Strong evidence from at least 1 systematic review ofmultiple well-designed RCTs

II. Strong evidence from at least 1 properly designedRCT of appropriate size

III. Evidence from well-designed trials without randomiza-tion, single group pre-post headwork, cohort, timeseries, or matched case-control studies

IV. Evidence from well-designed nonexperimental studiesfrom more than 1 center or research group

V. Opinions of respected authorities, based on clinicalevidence, descriptive studies, or reports of expertcommittees

Fig 1 Type and strength of efficacy evidence (McQuayand Moore4).

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the studies included, and the methods used toextract and synthesize the results of the primary tri-als on which the conclusions are based.23 It is oftennot possible or sensible to combine (pool) data; thisresults in a qualitative rather than a quantitativesystematic review (meta-analysis).17 Systematicreviews offer obvious advantages over traditionalreviews for the synthesis of the available evidence.19

However, one of the greatest benefits of systematicreviews is the lessons they teach about trialmethodology. They provide a means for qualitycontrol over clinical trials and help clinicians todevelop and apply better research methodology andto produce more reliable evidence.17

EBM: One Part of Scientific Work

EBM should be seen as one part of scientific work.Its foundation is in the knowledge achievedthrough epidemiologic studies and through basicscience and experimental studies. This knowledgeis used to guide the questions asked in clinicalpatient care and tested in RCTs. The informationobtained through EBM can, on the other hand,feed basic science, experimental, and epidemio-logic studies (Fig 2).

EBM and Pain Treatment

Because of the subjective character of pain and thesignificant placebo effect of pain treatments, theneed to pay attention to trial design was emphasizedmuch earlier in pain research than in other areas ofmedicine. Up to 1994 there were more than 14,000published RCTs of pain relief.4 Most of these RCTsexamined the pharmacotherapy of acute andchronic pain, where rigorous trial methodology iseasiest to follow. Many other pain treatment meth-ods have been tested in RCTs. In many cases,appropriate controls and problems with blindingmay make these trials more challenging to perform.

Many statistical methods, such as odds ratiosand relative risk, have been used to report treat-ment effects. The most “user-friendly” is the num-ber needed to treat (NNT). It tells how manypatients need to be treated with a particular treat-ment for 1 patient to achieve at least a 50% reduc-tion in pain beyond what would have beenachieved with a placebo. The following formula isused to calculate the NNT:

NNT = 1/(Aimproved/Atotal) – (Cimproved/Ctotal)

where A stands for active treatment and C for con-trol treatment (placebo). NNT can be used to com-

pare the relative effectiveness of different treat-ments across different studies, given that the treat-ment effect has been measured with the same out-come measures against the same comparator.24

Several meta-analyses have used this criterion fora range of treatments in pain. According to these,the best NNTs for at least 50% pain relief for anal-gesics in postoperative pain are about 2. NNTs forantidepressants in the treatment of neuropathicpain vary from 2.3 to 3.4. In general, NNTs of 2 to4 indicate that a treatment is effective.24

TMD: Musculoskeletal Pain Conditions

The term temporomandibular disorders refers to asubclassification of musculoskeletal disordersaffecting the masticatory muscles and/or the tem-poromandibular joint (TMJ). The most commonpresenting symptom is pain, which is usually aggra-vated by chewing or other jaw functions.6 A sepa-ration of masticatory muscle pain disorders fromTMJ disorders is currently advocated. The mostfrequently used classification subdivides TMD intomuscle (myofascial) pain, internal derangements ofthe joint, and degenerative joint diseases.25

Although the myalgia subtype is the most prevalentform, it is very usual for TMD patients to receive acombined diagnosis, with both muscle and jointproblems. Masticatory muscle pain seems to partlyoverlap with other pain conditions, such as tension-type headache, neck pain, and fibromyalgia.26

The etiology and the pathophysiologic mecha-nisms of TMD, like those of other musculoskeletalpain problems, are so far poorly understood.7,27,28

Earlier etiologic concepts based on a single factor,eg, prematurities in the occlusion, have lost scientificand clinical credibility.27 According to the prevailingmultifactorial etiologic concept, many initiating, pre-disposing, and perpetuating biomechanical, neuro-

Epidemiologic studies

EBM

Experimental clincal studies

Basic science

RCT

Fig 2 Algorithm showing how different methods ofresearch complement each other.

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muscular, and psychosocial factors are involved.27

Intensive research on the pathophysiology underly-ing joint and muscle pain has characterized the lastdecade of the TMD field. Understanding of the me-chanisms has increased, along with advances in theunderstanding of pain mechanisms in general.29–31

Today, new treatment strategies are expected toarise from basic research rather than from clarifica-tion of etiologic concepts.28,30,32

TMD are considered the most common cause ofnondental pain in the orofacial region. These condi-tions affect about 10% of women and 6% of men inany given year, giving a rough estimate of 450 millionadults afflicted worldwide.26 Annually, 1% to 3% ofpeople seek professional help for the symptoms, thusmaking TMD a significant health care problem.

Although they are prevalent disorders, TMD seemto have a favorable course.6,33–35 Longitudinal epi-demiologic findings indicate substantial fluctuation ofsymptoms and signs. Progression to severe pain anddysfunction is very rare.36 A minority, usually fewerthan 20%, have either continued or increased pain.

Chronic TMD pain is similar to many othercommon pain problems, such as low back painand headache, in terms of levels of pain intensityand interference and psychologic and psychosocialprofiles.37,38 Psychologic factors are also seen asthe most important risk factors for chronicity.26,39

Along with this, comprehensive diagnostic systemsincorporating psychosocial, behavioral, and physi-cal components of the TMD problem have becomewidely accepted.40,41

TMD Controversies

Treatment goals for patients with TMD includepain alleviation, decreased loading of the mastica-tory system, and restored function.33 The methodsused to achieve these goals can be highly variable,such as patient education and self-care, exercises,physical therapy, relaxation, biofeedback, cogni-tive-behavioral interventions, occlusal splints,occlusal adjustment, occlusal rehabilitation,orthodontics, pharmacotherapy including intra-articular injections, and TMJ surgery. All treat-ment approaches claim success, and the majorityof patients are reported to improve.33,34 It is wellrecognized, however, that we lack prospectivestudies that use appropriate outcome measures andcontrols to validate the results.6,7,42

Different treatments and the rationales behindthem constitute one of the most controversial areasin the field of TMD. Perhaps the most conflictingof these is the role of occlusal factors.6,43–47

The interest in occlusal and other structural fac-tors was started by Costen’s hypothesis about theimportance of these as etiologic factors in TMD.48

Although the original hypothesis was later refuted,the occlusal-structural model of TMD causationhas been extremely popular among dentists fordecades. Along with the belief that unfavorableocclusal contacts can lead to neuromuscular dis-turbances and pain and dysfunction, occlusal treat-ments such as occlusal adjustment of the naturaldentition or occlusal splints were recommendedand widely used.44 However, there is no universalagreement about which type of occlusal interfer-ences are considered detrimental to function orabout the best way to perform occlusal adjust-ment.43,47 No consensus has been reached aboutthe design and occlusal scheme of the splints orabout whether the mechanism of action is relatedto occlusal or other factors.34,49,50

In recent years, the etiologic significance ofocclusal factors has been increasingly questioned.Based on epidemiologic data and systematic stud-ies, the relationship between these and TMD isconsidered weak or nonexistent.33,34,42,47,51,52 Inline with this, the strategy of occlusal treatmentshas been increasingly criticized.34,45,53–55 In partic-ular, the use of irreversible forms of occlusal treat-ments (such as occlusal adjustment) has been dis-couraged in recent guidelines and textbooks onTMD.6,33,34,56

However, all in the field do not agree.43,46,57,58

According to the most frequently presented argu-ment, the current empirical evidence is not soundenough to justify the rejection of the hypothesisabout the etiologic importance of occlusal factorsbecause of methodologic problems in the stud-ies.43,58 Furthermore, Kirveskari et al59 showed inan RCT, in which young subjects underwentocclusal adjustment or mock adjustment over aperiod of 4 years, that the elimination of the pre-sumed structural risk by real adjustment signifi-cantly decreased the incidence of TMD. With theseresults, they suggested that the discussion aboutocclusal factors and TMD should continue.

Despite the uncertainties in the field of TMD,some general guidelines are offered for managementtoday. It is argued that TMD as a variant of muscu-loskeletal disorders should be considered as disor-ders that can be managed rather than cured.7,34,56,60

Practice guidelines recommend reversible treat-ments, which should be tailored to individual symp-toms and patient characteristics.6,7,33,39,41 A unifyingconsensus seems to prevail as regards 1 importantpoint in TMD therapy. Expert panels, new text-books, and new curricula for TMD education all

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emphasize that the treatments used should be evi-dence-based.3,6,11,33,53,61 To avoid pure lip servicehere, the next logical question is: What is evidence-based treatment of TMD?

TMD and EBM

The actual starting point for discussion about TMDand evidence-based treatment was the reportdescribing the epidemiology of research for TMDby Antczak-Bouckoms.5 It was compiled to evaluatein broad terms the strength of evidence regardingTMD therapy. In this systematic search of literaturepublished between 1980 and 1992, more than4,000 references to TMD were found. Of these,about 1,200 examined therapy. Forty-one percentof the 1,200 references were classified as reviews,and only about 15% were clinical studies. Less than5% (n = 51) were RCTs. The findings indicated thatvirtually all the evidence regarding therapy forTMD was likely to be subject to considerable bias.Concerns about the state of science in the field wereexpressed, and the importance of basing patient caredecisions on evidence was emphasized. Later, thesame concerns were expressed by many experts inthe field.14,28,44,53,62–64

Despite the great interest in EBM and its possi-bilities to improve the treatment of TMD prob-lems, systematic searches for evidence have beenrare. Only a few systematic reviews of TMD treat-ments have been published.65–70 In addition, in arecent systematic review of pharmacotherapy offacial pain, studies concerning drugs used to treatTMD pain were also analyzed.71 The scarcity ofsystematic reviews at this point is somewhat sur-prising, given the important role they are thoughtto have in trying to create a comprehensive andunbiased picture about a particular clinical area.19

Systematic Review of RCTs of Occlusal Treatments

In the field of TMD, the question about evidence isespecially intriguing when considering controver-sial, albeit widely used, methods such as occlusaltreatments. To find out whether studies are inagreement with current clinical practices, wedecided to conduct a systematic review of all rele-vant RCTs of occlusal treatments for TMD symp-toms.67 The review gave a qualitative overview ofthe evidence on these treatment methods. A quan-titative review (ie, systematic pooling of results)was not possible because of the heterogeneity of

the data. The research question, the search strategyto locate the studies, the criteria for inclusion andexclusion of primary studies, the techniques usedto assess the methodologic quality of the studiesincluded, and the methods used to extract and syn-thesize the results of the primary studies were care-fully described to allow critical appraisal.

The objective of our systematic review was toevaluate the effectiveness of occlusal treatments (ie,occlusal splints and occlusal adjustment) for thesymptoms of TMD. A study was included in thereview if it was a randomized comparison ofocclusal splint therapy or occlusal adjustment withplacebo, no treatment, or some other interventionused to treat TMD symptoms in patients whosought treatment for these symptoms.

The search strategy for identification of studiesincluded different database searches (MEDLINE,EMBASE, Cochrane, DARE) of literature pub-lished between 1966 and March 1999. This wascomplemented by extensive hand searching.

Each trial was read independently by theauthors and scored with the use of the qualityscale presented by Antczak et al,18 with minormodifications. The scale evaluates both the qualityof the study protocol and the presentation andanalysis of the data. The scale assigns an arbitrar-ily defined set of weights to a list of items, thepresence and correctness of which are assumed toreflect the quality of the research. If a study fulfillsall the requirements, a score of 1.00 is given. Thespecific items and weight given to each of them arepresented in Table 1.

In the review, a positive result was defined as astatistically significant difference, as reported bythe authors, between occlusal splint therapy/occlusal adjustment and a control, in pain inten-sity, overall success rating, or any other outcomemeasure used in the studies. Finally, we reachedconsensus about the overall outcome of each trialand put emphasis on the results of the latest fol-low-up.

Twenty-eight RCTs of occlusal treatments werefound. Eighteen studies met the inclusion crite-ria72–91 (Table 2). Fourteen of the RCTs examinedsplint therapy and 4 examined occlusal adjust-ment. One study compared occlusal splint therapyto several types of control treatments.73

Based on simple vote counting, we summarizedthat splint therapy was found to be superior to 3control treatments and comparable to 12 controltreatments. Furthermore, splints were superior to apassive control in 4 studies and comparable to it inanother 4 (Table 2). Occlusal adjustment wasfound to be equivalent to control treatment in 2

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studies and inferior to control treatment in 1study. It was equivalent to a passive control in 1study (Table 2).

On the basis of our analysis, we concluded thatRCTs seem to suggest that the use of occlusalsplints may be of some benefit in the treatment ofTMD, but the evidence is scarce. On the otherhand, the few available studies do not provide evi-dence for the use of occlusal adjustment.

To update the information of the review, a litera-ture search using the same search strategy as that inthe published review was undertaken to cover thetime interval from March 1999 to January 2003.The search provided 5 new RCTs of occlusal treat-ments for TMD.92–96 Kuttila et al94 studied the effi-cacy of an occlusal splint in a nonpatient popula-tion with secondary otalgia and TMD, andtherefore the study did not meet our inclusion crite-ria. The trial by Minakuchi et al92 was excludedfrom further analysis because patients were treatedwith other forms of therapy in addition to splint

therapy, which precluded the assessment of theeffects of occlusal splint therapy. The studies byRaphael and Marbach93 and Ekberg et al96 met ourinclusion criteria and are included in the followingevaluation (Table 2). The study by Raphael at al95

was excluded, because it reported results of a groupof patients that was part of the material presentedin their earlier study.93

In the RCT by Raphael and Marbach,93 63women meeting criteria for the myofascial subtypeof TMD25 were assigned to use either a flat-plane,hard acrylic splint or a palatal splint at night for 6weeks. At the end of the study period, the groupswere compared for pain, number of painful mus-cles, functional complaints, and psychologic mea-sures (mood and depression). The treatment groupsdiffered significantly after 6 weeks on only 1 of the3 self-reported pain severity measures. The authorsconcluded that active splints were of modest valuefor patients with myofascial pain, but according toour estimate about the overall outcome of the resultof the trial, there were no significant differencesbetween the groups. Post hoc comparisons of studysubjects with local versus widespread pain93 indi-cated that patients with local pain who received theactive splint experienced more improvement thanthe other patient groups.

In the study by Ekberg et al,96 60 patients suffer-ing from myofascial pain were randomized to astabilization splint or a palatal splint. The studydesign was similar to an earlier trial by the sameauthors.86 After 10 weeks of treatment, there weresignificant differences between the groups in favorof the use of stabilization splints for the improve-ment of overall subjective symptoms, the preva-lence of daily or constant pain, and the number ofpainful muscles. The overall result of the studywas considered positive.

Occlusal Treatment Studies and EBM Rules: What Makes a Good RCT?

As discussed earlier, the methodologic quality ofthe trial dictates the credibility of the results. In thefollowing, some of the most important method-ologic aspects concerning the study protocol of agood RCT will be discussed. We assessed theseunder the headings of the quality scoring system byAntczak et al18 (items marked with an asterisk inTable 1). The evaluation is based on the RCTs ana-lyzed in our review, and it complements theremarks in the discussion section of our systematicreview.67 We focused particularly on the lessonsthat could be learned for future studies in this field.

Table 1 Quality of Study Protocol, DataAnalysis, and Presentation According to theQuality Scale of Antczak et al18

Items evaluated Potential score

Selection description* 3No. of patients seen and reasons for rejections 3Definition of therapeutic regimen* 3Follow-up schedule* 3Test of adherence to treatment* 3Blinding randomization* 10Patient blind to treatment* 8Observer blind to treatment* 8Observer blind to results* 4Testing randomization* 3Testing blinding* 3Stopping rules 3Prior estimate of sample size* 3Error measurements 3Dates of the study 2Results of randomization* 2Major endpoints 4Post beta estimate† 3Confidence limits 3Repeat measures 2Timing of events 4Regression/correlation analysis 2Statistical analysis 4Withdrawals* 4Handling withdrawals 4Side effects discussion 3

*Discussed further in text.†An estimate of the probability of Type II error.

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Table 2 Details of RCTs on Use of Occlusal Splints and Occlusal Adjustment for Treatment of TMD

Study Treatments Outcome measures Score Overall efficacy*

Occlusal splintsDahlström et al72 Stabilization splint; biofeedback Subjective rating of symptoms; 0.32 � BL

Helkimo Clinical Index = Control treatmentBrooke and Stenn73 Stabilization splint; ultrasound; Successful outcome = symptom- 0.22 � 1 control treatment

relaxation training + biofeedback; free or only minor/a few symptoms = 2 control treatmentsrelaxation training

Lundh et al74 Stabilization splint; anterior Reciprocal clicking; 0.39 = Control treatmentrepositioning splint; control group tenderness to muscle palpation = Passive control

Rubinoff et al75 Stabilization splint; palatal splint Pain diary; success rating; 0.60 � BLjoint sounds; palpation score = Control treatment

(placebo?)Lundh et al76 Stabilization splint; occlusal Pain VAS; clicking; 0.44 = Control treatment

onlays; control group tenderness to palpation (� Control treatment regarding clinical signs)= Passive control

Monteiro and Clark77 Stabilization splint; movement TMD questionnaire 0.12 = Control treatmentfeedback

Johansson et al78 Stabilization splint; acupuncture; Pain VAS; improvement of 0.44 � BLcontrol group subjective symptoms; = Control treatment

Helkimo Clinical Index � Passive controlList et al79 Stabilization splint; acupuncture; Pain VAS; subjective improvement; 0.47 � BL(List and Helkimo80) waiting list control Helkimo Anamnestic Index; Helkimo = Control treatment

Clinical Index; activity of daily living � Passive controlLundh et al81 Stabilization splint; control group Overall treatment results; 0.24 = Passive control

79 clinical variablesTurk et al82 Stabilization splint; biofeedback/ Pain severity scale; Muscle Pain 0.42 � BL

stress management; waiting list Palpation Index; depression scales = Control treatmentcontrol � Passive control

Dao et al83 Stabilization splint; stabilization Pain VAS; pain unpleasantness VAS; 0.78 � BLsplint (4 � 30 min = passive quality of life = Control treatment control); palatal splint (placebo?)

= Passive controlLinde et al84 Stabilization splint; TENS Positive responders; frequency 0.44 = Control treatment

of complaints; severity of complaints;symptom questionnaire; pain registration

Wright et al85 Soft splint; palliative treatment Symptom Severity Index; 0.62 � BL(= self care); control group pressure algometer score; � Control treatment

maximum pain-free opening � Passive controlEkberg et al86 Stabilization splint; palatal splint Pain VAS; verbal pain rating; frequency 0.71 � BL

of pain; overall change in subjective � Control treatmentsymptoms; tenderness to palpation of TMJ; Helkimo Clinical Index

Raphael Stabilization splint; palatal splint Pain VAS; no. of painful muscles; 0.62 � BLand Marbach93 functional complaints; average = Control treatment

mood scale; SCL-90 depression scale (placebo?)Ekberg et al96 Stabilization splint; palatal splint Pain VAS; verbal pain rating; frequency 0.71 � BL

of pain; improvement of overall subjective � Control treatmentsymptoms; no. of painful muscles; (placebo?)Helkimo Clinical Index

Occlusal adjustmentWerndahl et al87 Occlusal adjusment; muscle Subjective improvement 0.24 = Control treatment

exerciseWenneberg et al88 Occlusal adjustment; different Subjective dysfunction score 0.40 � BL

stomatognathic treatment methods Clinical dysfunction score � Control treatmentVallon et al89 Occlusal adjustment; control group Pain VAS; overall changes in severity; 0.57 � BL(Vallon et al90) clinical signs = Passive controlTsolka et al91 Occlusal adjustment; mock Prevalence of symptoms; Helkimo 0.36 = Control treatment

occlusal adjustment Anamnestic Index; Helkimo Clinical Index (placebo)

*Reviewers’ overall conclusion of efficacy when emphasis was put on results at the longest follow-up of each study. � results significantly better than; =results comparable to; � results significantly worse than.Control treatment = any active control treatment; passive control = control group without any treatment or waiting list control, or stabilization splint used only 4� 30 minutes (Dao et al83). BL = baseline; TENS = transcutaneous electrical nerve stimulation; pain VAS = pain visual analog scale; SCL-90 = symptomchecklist 1990.

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Selection Description

A detailed description of criteria for inclusion andexclusion is a minimum requirement for an RCT.15

Except for a few studies,77,81,91 most RCTs pro-vided this information. The actual definitions ofthe patient samples varied, however. In 7 studies(including all studies of occlusal adjustment), thestudy population was described to consist of TMD(or alike) patients, and patients with muscle painand different types of joint problems were placedinto a single group. However, the distinct clinicalentities that constitute TMD are likely to exhibitdifferences in treatment responses. Trials usingmore detailed case definitions would probably bemore sensitive and give more clinically usefulinformation. The Research Diagnostic Criteria forTMD (RDC/TMD) provide a systematic methodof classifying the major subtypes of TMD along aphysical disease axis (Axis I) through a standard-ized clinical examination.25 In addition, theRDC/TMD allow classification of the subject’spsychosocial status (Axis II) based on standardizedpsychometric instruments and include self-reportsof pain intensity and pain-related disability. So far,this instrument has been used in only 1 RCT ofocclusal treatments.93 Its use in future trials wouldoffer several advantages, including a common setof methods and terms and increased sensitivity tocomplex cases.7

TMD patients can also differ in terms ofchronicity of their TMD pain, psychologic charac-teristics, and the presence or absence ofwidespread pain or concomitant bruxism. Possibledifferences in treatment responses based on thesedistinctions have so far not been tested in RCTs onocclusal treatments, except for spread of pain andseverity of bruxism in the most recent trial.93,95

Given the differing pathophysiologic mechanismsof acute and chronic pain, pain duration shouldreceive more attention in future trials.

Definition of Therapeutic Regimen

The description of therapeutic procedures must besufficiently detailed to allow comparison withother studies. This was usually accomplished in theRCTs of occlusal splints. In most studies, a flat-plane, hard acrylic splint adjusted to even outocclusal contacts and provide canine guidance wasused. The issue seems to be much more compli-cated for occlusal adjustment procedures. The pro-cedures performed varied from elimination ofgross interferences to meticulous occlusal equili-bration procedures consisting of four 60-minute

treatment sessions.87,88 Experts should agree aboutthe way to perform the procedure so that credibleRCTs on the subject may be instituted.43,55

Selection of the control treatment or condition isa complicated matter,62,97 and ideal ways to han-dle this, especially in splint studies, have perhapsnot yet been established.62 Waiting list controls areused in some studies, but they do not rule out theplacebo effect and can in fact include negativeeffects while reducing the expectation-fulfillmentcontamination.62,97,98 The use of a placebo controlgroup can balance the nonspecific effects in thetreatment group and allow for independent assess-ment of the real treatment effect. The use of thepalatal (nonoccluding) splint as a placebo condi-tion in splint studies99 can, however, result inunintended active treatment components, eg, byincreasing cognitive awareness of oral habits49,50

or changing muscle function.100 They can thusovercontrol for the active ingredient of stabiliza-tion splint therapy.14,62,63

An obvious problem with the use of active con-trol treatments in RCTs of occlusal treatments isthat the efficacy of most of them is not known.While many RCTs indicated that occlusal splintswere as effective as the control treatment, itremains unclear whether treatments were indistin-guishable from each other because they wereequally effective or because they were equally inef-fective. For the time being, only placebo controlsor inactive (waiting list) controls are justified.

Follow-up Schedule

Trials should be sensitive to the long-term out-comes. This was demonstrated clearly in our sys-tematic review, where studies with longer follow-ups generally did not show favorable treatmentresults, despite good short-term results in some ofthem.82,89,90

Test of Adherence to Treatment

Future splint studies should pay attention to moni-toring patient compliance with given instructionsabout splint use. In the published studies, this wasassessed only seldom.82,83,93 The same applies tothe use of concomitant treatments. Only 3 RCTsclearly stated that no other pain treatments wereallowed or performed during the trials,83,84,86 orthat the study groups did not differ on the use ofcointerventions.93 Two RCTs did not report ondropouts or loss to follow-up.73,77 The number ofdropouts in the RCTs was usually fewer than10%, which is considered acceptable.18 Systematic

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reporting of protocol violations in RCTs allowsmore precise estimates of bias and of the generaliz-ability of the findings.101

Randomization

Detailed instructions about acceptable ways toperform randomization are provided in severaltextbooks.8,15 Randomization should be concealedso that it eliminates any influence of the investiga-tors on the allocation of the interventions.Properly performed randomization is consideredcrucially important in trial design.102 Trials thatuse inadequate or unclear allocation concealmenttend to overestimate the effect of treatment andcan yield up to 40% larger estimates of effect incomparison to studies that use adequate allocationconcealment.16 Surprisingly, the procedure of ran-domization was described in only 2 studies.86,96

Although randomization eliminates systematicbias, it does not necessarily produce perfectly bal-anced study groups with respect to prognostic fac-tors. This was the case in 3 studies, where randomassignment had failed to equate the study groupswith respect to pretreatment symptoms.75,79,91 Theunbalanced randomization was not taken into con-sideration in 2 of them during the analysis ofdata.75,91 Furthermore, 3 studies did not report theresults of randomization.73,77,81

Blinding

Nine RCTs used blinding (single- or double-blindprocedures), and the rest were open studies.Unfortunately, the fulfillment of the blinding proce-dures was not mentioned in any of the studies.Open trials always involve a risk of bias. This is aconcern, especially in studies that use subjectivemeasurements, such as pain scores, as outcomemeasures.4,103 Double-blinding may not always bepossible, but there should never be objections toblinding the investigator who assesses the treatmentresults.15,103 However, the importance of blindingas a source of bias is considered somewhat lessimportant than that of adequate allocation conceal-ment. The lack of double blinding is reported tooverestimate treatment effects by roughly 17%.16

Prior Estimate of Sample Size

The number of patients per study group was lessthan 15 in 7 of the RCTs. Reliable findings areconsidered unlikely in trials with inadequate groupsizes.104 Group sizes that are large enough to pro-duce statistical significance should be chosen

through power calculations. For pain studies, theusual size is 30 to 40 patients for a 30% differencebetween active treatment and placebo to becomeapparent.4 Power and sample size calculations forclinical trials of myofascial pain of the jaw musclesare described by Dao et al.105

While the size of the sample population dependsin part on the outcome measures of the study,60 theprimary outcome measure should be chosen at theoutset of the study. Furthermore, the determinationof the primary outcome measure beforehand is ingeneral considered an important part of good trialmethodology.22 So far the methods to measuretreatment success have varied, and for many out-comes used, there is no evidence about their relia-bility and validity.60,106 The use of standardizedoutcome measures and reporting of data wouldenable pooling and comparison of different studies.

Most of the RCTs published after 1990 usedvisual analog scales (VAS) to measure pain. VAS arein general widely used in all types of pain studies4

and have been shown to be a valid tool.107 As a gen-eral rule, it is required that treatments improve out-comes that are important to patients.108 The use ofpain relief as the primary outcome measure in trialson TMD treatment makes sense, since pain is thecardinal symptom of TMD and the main reason toseek treatment.105,109 Secondary outcomes shouldalso take into account the multidimensional natureof TMD as a pain problem, and cost-effectiveness ofthe methods should be evaluated. Possible adverseeffects connected with occlusal treatments have sofar received very little attention.76,84,85,88 All theseoutcomes are essential for clinicians and patients tomake informed treatment decisions where the prob-ability of benefit is weighed against the costs andpossible adverse effects.

Is There Evidence of Efficacy forOcclusal Treatments?

The process of drawing conclusions about the effi-cacy of a particular treatment on the basis of theresults of a qualitative systematic review is noteasy. As described earlier, simple vote counting ofthe results of the RCTs of occlusal splints thatwere included in our systematic review yieldedequivocal findings, and we were not able to drawfirm conclusions. On the basis of our analysis,however, we did suggest that the use of occlusalsplints might be beneficial. Unfortunately, theresults of the 2 newest studies could not give thefinal answer on the efficacy of splint therapy. Inthe following, the process of analyzing the results

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that led us to these conclusions is described inmore detail.

A simple vote-counting procedure, in which thenumber of negative studies versus the number ofpositive studies is counted, ignores the possibilitythat this estimate may be invalid, eg, qualitativelyweak studies may be given the same weight ashigh-quality studies. Previous studies have indi-cated that trials with lower quality may be morelikely to report positive results.17 Thus, the qualityscores can be of assistance when drawing conclu-sions. No such trend, however, was found con-cerning studies included in our systematic review.

Obviously, studies with adequate/good qualityshould be given more weight.17 If an arbitrary cut-off point of 0.50 for the quality score18 is used, weare left with 5 stabilization splint stud-ies75,83,86,93,96 and 1 soft splint study.85 The out-comes of the stabilization splint studies indicatedthat stabilization splint therapy is either statisti-cally superior to palatal splint therapy86,96 or thatit is equivalent to palatal splint therapy.75,83,93 Themethodologically strongest studies came to differ-ent conclusions.83,86,96 These studies differed fromeach other in the use of outcome measures and theanalysis of the results. Dao et al83 presented con-tinuous data on pain intensity and unpleasantnessand quality of life. The overall pattern of groupdifferences was analyzed from baseline through the8 weeks of follow-up to assess the effects of thetreatment over time. This type of measurementbest reflects the true changes in symptoms. Ekberget al86,96 used a different set of outcomes, and instatistical testing, time-by-time comparisons ofdichotomous variables at baseline and end of thestudy were made. Some of the comparisons yieldedstatistically significant differences between thestudy groups.

In 4 of these RCTs the patients suffered mainlyfrom a myofascial type of TMD pain,75,83,93,96 andin 1 study the patients suffered mainly joint pain.86

Thus we conclude that even in the most studiedarea—stabilization splint therapy for myofascialface pain—the results do not justify definitive con-clusions about the efficacy of this therapy.

So far, we have discussed the statistical efficacyof splint therapy. What could be the clinicalimportance of the results presented? We can try toestimate this in several ways. First, a closer look atthe changes in pain intensity over time in the stud-ies by Dao et al83 and Raphael and Marbach93

indicates that the actual differences in VAS painintensities between stabilization splints and palatalsplints were marginal—about 1 or less on a 10-unit scale. In pain treatment studies, the NNT

value is often used to give an impression about theclinical efficacy of the treatment methods, asdescribed earlier. Unfortunately, most of the RCTson occlusal splints did not provide data that madethe calculation of these values possible. To give anexample of the use of NNT in TMD splint studies,the NNT for 50% reduction of worst pain withstabilization splint versus palatal splint was calcu-lated for the studies by Ekberg et al,86,96 whoreported the most positive outcomes among thehigh-quality studies. The calculated NNT valueswere 6 for TMD patients suffering from jointpain86 and 4.3 for patients with TMD of mainlymyogenous origin.96 Thus, about 4 to 6 patientsare needed for 1 more patient to receive a 50%reduction in worst pain with a stabilization splintcompared to a palatal splint. Thus, compared withpain treatment methods in general, the therapeuticvalue of splints seems only modest, and the differ-ences between stabilization splints and palatalsplints seem to be clinically unimportant. The pos-sibility that palatal splints pose active treatmentingredients, as discussed earlier, needs to be takeninto account here. It might be interesting to notethat the best NNT values for more than 50% painrelief in TMD for drugs versus placebo were calcu-lated to be 2.7 and 3.5.71

None of the 4 RCTs of occlusal adjustment pro-vided evidence for the use of this treatmentmethod. The performed RCTs were mainly of lowquality, and only the study by Vallon et al89,90 hada quality score over 0.50. In that study, occlusaladjustment was compared to passive control(counseling only). Despite some short-term bene-fits, occlusal adjustment had little or no effect inthe long-term perspective.

Clinical Implications and Future Perspectives

Does the widespread use of oral splints need to bere-evaluated because of the lack of clear evidenceof their efficacy? The same question has been pre-sented in other critical reviews about splint ther-apy, but the answers have varied. Marbach andRaphael63 suggested that appliances should not berecommended for musculoskeletal facial painbecause of a lack of evidence of their long-termefficacy. Dao and Lavigne50 and Feine et al60 hadanother view. Their arguments were based on afurther analysis of the results of the RCT by Daoet al,83 where additional data of perceived painrelief were added to compare these to true painrelief (efficacy).60 Patients who had worn either the

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stabilization splint or palatal splint reported signif-icantly more pain relief than those in the passivecontrol group. Because of the data to support theeffectiveness, though not the efficacy, of oralsplints they recommended that splints can be usedas an adjunct to pain management. Although finalanswers to the question about the efficacy of splinttherapy cannot be given at the moment, the lateststudies have provided some further support fortheir use. The recommendation may still remainvalid until the question is solved through newhigh-quality RCTs, or until evidence for othermore effective and less costly therapies hasappeared, as also suggested by Raphael et al.95

Since there is no evidence for the efficacy ofocclusal adjustment in TMD, its use cannot be rec-ommended. This conclusion is in line with thatmade in the recent reviews by Koh and Robinson70

and Tsukiyama et al55 and follows the recommen-dations made by several experts in the field.6,33,34,56

The small number and the poor quality of most ofthe published RCTs do not, however, allow definiteconclusions, because lack of evidence cannot beinterpreted as evidence of lack of effect. If the prin-ciples of EBM are to be followed, good-qualityRCTs are necessary to provide the answers and tosolve the discrepancy in opinions.

We have focused here on the occlusal methodsamong the many treatments for TMD. On thewhole, compared to the impression gained throughuncontrolled studies that reported high successrates, the role of occlusal treatments as a treatmentof choice for TMD problems changes radicallywhen it is evaluated critically with the rules ofEBM. It is clear that more research is neededbefore their final role in the treatment of TMD canbe understood.

The principles of evidence and the rules abouthow to perform a good RCT are the same for allmethods of treatment of TMD, and obviously allof them should be assessed with the same rigor asocclusal treatments. All relevant treatment meth-ods should be assessed and tested, including allthose that are widely used today. Effort shouldalso be focused on pharmacotherapy, which is anunderinvestigated area within the TMD field.

We firmly believe that acceptance of criteria forevidence-based clinical practices and a strongemphasis on performance of RCTs with good trialmethodology would help to clarify many uncer-tainties and controversial issues in the TMD field,as has been done in many other areas of medicine.It would be exciting to consider the consequencesof reversing the ratio between published reviewarticles and original RCTs on the treatment of

TMD during the next decade.5 One can only spec-ulate what difference it would make in our under-standing about the high-quality care of TMDpatients. However, EBM alone will not change theworld. Innovative basic science, experimental clini-cal studies, and epidemiologic studies form thebasis for the practice of EBM. The high standardof science in many areas of TMD studies shouldencourage all those who are working in the field touse the potential of EBM to move TMD treatmentto a new level of scientific rigor.

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98. Kalso E, Moore RA. Five easy pieces on evidence-basedmedicine (2). Eur J Pain 2000;4:321–324.

99. Greene CS, Laskin DM. Splint therapy for the myofascialpain-dysfunction (MPD) syndrome. A comparative study.J Am Dent Assoc 1971;84:624–628.

100. Minagi S, Okomoto M, Shimamura M, Sato T. Palatalplate of different designs for the suppression of massetermuscle activity during sleep. A challenge to the concept ofplacebo splint. J Oral Rehabil 2002;29:882–883.

101. Whitney CW, Dworkin SF. Practical implications of non-compliance in randomized clinical trials for temporo-mandibular disorders. J Orofac Pain 1997;11:130–138.

102. Schulz KF, Grimes DA. Allocation concealment in ran-domized trials: Defending against deciphering. Lancet2002;359:614–618.

103. Schulz KF, Grimes DA. Epidemiology series: Blinding inrandomized trials. Hiding who got what. Lancet 2002;359:696–700.

104. Moore RA, Gavaghan D, Tramer MR, Collins SL,McQuay HJ. Size is everything—Large amounts of infor-mation are needed to overcome random effects in esti-mating direction and magnitude of treatment effects. Pain1998;78:209–216.

105. Dao TTT, Lavigne GJ, Feine JS, Tanguay R, Lund JP.Power and sample size calculations for clinical trials ofmyofascial pain of jaw muscles. J Dent Res 1991;70:118–122.

106. Dworkin SF, LeResche L, DeRouen T. Reliability of clini-cal measurement in temporomandibular disorders. Clin JPain 1988;4:89–99.

107. Price DD, McGrath PA, Rafii A, Buckingham B. The vali-dation of visual analogue scales as ratio scale measuresfor chronic and experimental pain. Pain 1983;17:45–56.

108. Guyatt GH, Sackett DL, Cook DJ. Users’ guides to themedical literature. II. How to use an article about therapyor prevention. B. What are the results and will they helpme in caring for my patients? JAMA 1994;271:59–63.

109. Dworkin SF. Behavioral characteristics of chronic tem-poromandibular disorders: Diagnosis and assessment. In:Sessle BJ, Bryant PS, Dionne RA (eds). Progress in PainResearch and Management. Vol 4: Temporomandibulardisorders and related pain conditions. Seattle: IASP Press,1995:175–192.

Clark


The focus article1 performs an admirablereview of the literature on occlusal-basedtreatments for temporomandibular disor-

ders (TMD). The noteworthy accomplishment ofthis article is that the method used by the authorsto select only high-quality articles for review isfully described, logical, and appropriate.Specifically, they were looking for evidence-basedarticles that had reasonable quality with regard toexperimental design and objective research out-comes. Another noteworthy feature is that theauthors include good descriptions of how some ofthe control therapies, which are usually presumedto be nonactive therapies, might be able to pro-duce an active therapeutic result. For example,they note that palatal splints have been used as acontrol or nonactive treatment, but this methodmay instead be an active device that is fully able toinfluence and reduce jaw muscle hyperactivity. Thefinal positive comment is that these authors appro-priately discuss the limitations of any researchstudy in which subjects are not randomly assignedto a treatment procedure. The authors point outthat most prior studies claiming randomizationhave not adequately described the methods used.Inadequate randomization may result in inequalityand heterogeneity of the treatment groups. Theyalso appropriately point out that a potential con-founding factor in the attempt to find a suitabletreatment approach will be etiology of the disease.They note that, unfortunately, TMD are not cate-gorized by etiology, which is a substantial limita-tion. Moreover, current diagnostic systems, whichdepend on signs and symptoms and joint imaging,do not identify etiology.

The critical points about this review are that theauthors do not explain fully why they suggest that

patients with muscle problems should be separatedfrom those with temporomandibular joint (TMJ)problems in future research. While this recommen-dation has good face validity, it is not clear that thisdistinction is so easily made. For example, if all TMJclicking patients who have a predominantly muscu-lar pain disorder and just happen to have joint noisesare to be excluded, this specification process mighteliminate a large portion of the population. Anotherexample is that most muscle pain patients also havejoint tenderness; again, this would make the specifi-cation process intrusive and highly exclusive. Whilethis dilemma is solved by simply including allpatients and then sorting them out afterward to seeif any cluster of symptoms is unduly affected by thetherapy being tested, the problem here is that a cali-brated examination must be performed blind to sub-ject (control versus patient) and treatment time(before/during/after) status.

A second critical issue is the authors’ conclusionregarding the efficacy of occlusal treatment forTMD. While I agree and believe the literaturestrongly supports the concept that occlusal adjust-ment is not a logical therapeutic approach forchronic, spontaneous-onset TMD, this conclusionis not so clear for occlusal appliance therapy andTMD symptoms. Certainly occlusal applianceshave their limitations as an intervention, but theissue comes down to how occlusal appliances areused. If they are expected to cure TMD, then thedata suggest they have a weak efficacy at best. If,however, they are used as a management methodto protect teeth that are sore or worn, or to makea patient more aware of a destructive behavior,they have clear merit. In general, in considering thetreatment efficacy of occlusal appliances, the dis-cussion can be divided into 2 components: (1) Are

CRITICAL COMMENTARY 11APPLICATION OF PRINCIPLES OF EVIDENCE-BASED MEDICINE TOOCCLUSAL TREATMENTS FOR TEMPOROMANDIBULAR DISORDERS: ARE THERE LESSONS TO BE LEARNED?

Glenn Clark, DDS, MSDirectorCenter for Orofacial Pain and Oral MedicineProfessor of Diagnostic SciencesUSC School of Dentistry925 West 43th Street (Rm B-14)Los Angeles, California 90089E-mail: [email protected]

Clark/Klineberg


occlusal appliances a cure for the TMD problem?and (2) Are occlusal appliances a reasonablemethod of providing help and protection for someselective TMD patients? The authors do notaddress this distinction, and this is largely becauseprior research has not examined the utility of thesedevices as a therapeutic aid. A logical conclusionto reach for the efficacy of occlusal applianceswould be that as a bite guard that prevents abnor-mal tooth attrition and/or reduces individual toothloading, and sometimes changes clenching behav-iors, these devices have merit. It would be illogical

to suggest that these devices stop a strong, long-term sleep bruxism behavior, that they put a looseTMJ disc back in place, or that they resolvearthritic destruction of the TMJ.

References

1. Forssell H, Kalso E. Application of principles of evidence-based medicine to occlusal treatments for temporo-mandibular disorders: Are there lessons to be learned? JOrofac Pain 2004;18:9–22.


Iven KlinebergProfessor of ProsthodonticsHead, Jaw Function and Oro-facial Pain

Research UnitFaculty of DentistryUniversity of Sydney, AustraliaFax: +61-2-9845-7192E-mail: [email protected]

The authors of the focus article1 are to becommended for their commitment to theprinciples of evidence-based medicine

(EBM) with their critical appraisal of the evidencelinking occlusion and temporomandibular disor-ders (TMD).

EBM is succinctly defined by the authors as the“systematic, explicit, and judicious use of best evi-dence in patient care.” However, a more completeexplanation of EBM2 includes a combination of(1) the application of the best available clinicalresearch evidence with (2) the clinical experienceand expertise of the clinician (3) in addressing thepatient’s specific concerns.

Recognition of the application of EBM for den-tistry is as crucial for the clinical practice of den-tistry as it is for medicine. The presence of 2 dentaljournals that are wholly committed to the promo-tion of an evidence-based approach—The Journalof Evidence-Based Dentistry and The Journal ofEvidence-Based Practice—attests to this, as does

the emergence of texts that provide evidence-basedcritiques of dentistry3 and orofacial pain.4 Giventhat this has been an emerging requirement fordentistry for more than a decade,5,6 the term evi-dence-based dentistry or the more generic term evi-dence-based practice (EBP) is more appropriate.

TMD and the Biologic Basis of Dentistry

A critical rethinking of the management of TMDin clinical practice is crucial to the continuingemergence of dentistry as a biologic discipline. Thereputation of dentistry depends on the provision ofa service for patients that recognizes contemporarytreatment methods and acknowledges developingclinical research evidence to support “mainstream”dental practice. A fundamental change in the man-agement of TMD is needed to continue the evolu-tion from dentistry’s mechanical traditions and theanecdotal evidence or clinical opinion (the “expert

Klineberg


view”) that continues to guide much of TMDmanagement,7 and the authors recognize this need.The concerns for TMD diagnosis and managementwere comprehensively documented by theNational Institutes of Health Technology Confer-ence Statement on management of TMD,8 whichhas become the benchmark statement on TMDand is acknowledged in this article.

Quality of Clinical Research

The authors emphasize the hierarchy of clinicalresearch evidence, led by randomized controlledtrials (RCTs) and systematic reviews. This is not todeny the role of case reports and case series9 as ameans of reporting new disease entities or innova-tive clinical treatment methods. However, furtherprogress in the particular condition or treatmentrequires appropriate follow-up study.

The authors recognize the RCT as the gold stan-dard for assessment of efficacy of treatment.Where trials are not randomized, the treatmenteffect may be significantly enhanced (“up to40%”). It is also a concern that the quality ofstudy design, even for RCTs, is not standardized;this undermines validity by inadequate conceal-ment in management of bias.5,10 Inconsistent qual-ity of data from varying research methodologiescompromises the quality of meta-analyses and sys-tematic reviews and creates a major problem forassessment of TMD research.11 Dao et al12 pro-vided explicit recommendations for power andsample size in clinical trials. It is hoped that thisadvice will be applied to future clinical trials inaddressing the requirements for study design.

TMD and Musculoskeletal Pain

The focus article clearly describes TMD controver-sies and recognizes that varied treatment methodsreport success and patient improvement, but thatprospective studies are needed with standardizedoutcome measures for study and control groups.The article focuses on the role of occlusal factorsin TMD. The authors identify Costen’s syndrome,which drew attention to an occlusal etiology. Thereasoning behind the preoccupation with theocclusion in dentistry is not surprising, sincerestoration of the occlusion continues to be amainstream need in dental practice.

This focus in traditional dental curricula anddental practice with restoration of the occlusion,

supported by the mechanical nature of much ofwhat is needed in restorative and prosthodontictreatment, has not surprisingly led to a transfer ofthis approach to management of TMD. This doesnot excuse the reluctance of some clinicians tomove away from these mechanical associations.The authors emphasize that the relationshipbetween occlusion and TMD is “weak or nonexis-tent” and that management therapies should bereversible according to each patient’s needs.

Efficacy of Occlusal Treatments

Evidence-based treatment for TMD is consideredin detail in the article, which recognizes the vary-ing quality of clinical trials of TMD therapy, not-ing that fewer than 5% were RCTs. The problemis compounded by the poor quality of most RCTs.Notwithstanding these difficulties, the authorshave completed a systematic review of RCTs andalso have outlined appropriate methodologicaspects to be incorporated into future RCTs.

The authors conclude that, based on the avail-able evidence, occlusal adjustment is, at best, nobetter than control treatment and that occlusalsplint therapy may be of benefit in management ofTMD. They have acknowledged the difficulty incomparing studies because of their heterogeneity indesign, outcome measures, and study duration.

The authors also conclude that definitive statisti-cal results concerning the efficacy of stabilizationsplints for myofascial pain could not be justified.The clinical importance of studies on stabilizingocclusal splints is considered on the basis of thenumber needed to treat (NNT), eg, for a 50%reduction in worst pain experience comparing“active” and “passive” splints. The NNT was calcu-lated from the studies of Ekberg et al13,14 as 6 forjoint pain and 4.3 for muscle pain. This result sug-gests a modest therapeutic value and is onlymarginally different from the comparisons of VASscores by Dao et al15 and Raphael and Marbach,16

which described minimal outcome differences. Theauthors support the conclusion that, since the datamodestly support the effectiveness but not the effi-cacy of stabilization splints, they should be seenonly as an adjunct to orofacial pain management.

The authors also conclude that RCTs thatreported on occlusal adjustment could not be scru-tinized following EBP principles because of theirlow quality. On the basis of published research,there is no evidence to justify the use of occlusaladjustment.

Klineberg


Ethics in Clinical Research

In critically reviewing the literature on TMD, theauthors struggle with the heterogeneity of studydesign, a preponderance of poor-quality studies(including RCTs), and an acknowledgment thatthe data was in general confusing. We could ask,where have the ethics of clinical research gone, andhow has a commitment to professional ideals forquality let us down so badly? The answer is com-plex and has many facets. Of importance are limi-tations in research training and in research as adesirable and necessary component of the educa-tional process; an obvious limitation in necessaryfunding; and the continuing preoccupation of uni-versities to, not unreasonably, require publicationsas an indicator of scholarship.

There needs to be a rethinking of these prioritiesas a general requirement for dentistry. Morespecifically, the research process needs to be recon-sidered. Emanuel et al17 defined ethical require-ments for clinical research, which are listed belowand might form a useful starting point in thereassessment of study design.

1. The research must be of value in enhancingknowledge of health issues.

2. The research must be methodologically rigorous.3. The subjects selected must be representative of

the population and selected objectively.4. There must be a favorable risk-benefit ratio.5. There must be independent review of the

research proposed.6. Informed consent is essential.

Equally important, Benatar and Singer18 havedefined a “standard of care” for research subjects,which also ought to be acknowledged.

Conclusions

The authors of the focus article have applied theprinciples of EBP in their assessment of the role ofocclusal therapy in management of TMD. Theirconclusions are a sobering reminder of the needfor careful planning of clinical study design toensure that quality clinical trials allow the pro-posed outcomes. This baseline information isessential to ensure that the dental research commu-nity addresses the need for directing TMD man-agement in practice by focusing on an evidence-based approach. EBP needs to become thecornerstone of clinical decision-making, and dentalcurricula need to emphasize these principles.

In addition to the evidence presented by theauthors, it is appropriate to acknowledge the following:

1. As with all chronic conditions, TMD showregression to the mean.19 This contributes to theexacerbations and remissions described by TMDpatients and other musculoskeletal pain patients.

2. Placebo effects are an important and positivecomponent of clinical treatment and research.20

Placebo effects influence outcomes for any treat-ment and together with regression to the meanare responsible for successful outcomes that maybe attributed to treatment effect. This needs tobe addressed for pain treatment by appropri-ately designed RCTs.

3. Visual analog scales need to be correctly appliedin pain studies for description of both the inten-sity and affective dimensions of the pain experi-ence.21

4. Finally, colleagues wishing to maintain the linkwith the occlusion for all components of clinicaldentistry should not feel disenfranchised, sincethe following identify a significant role for theteeth and the occlusion in dental practice: (1) determination of occlusal vertical dimension(OVD), lower face height, esthetics of individualteeth and tooth arch arrangement, and posturaljaw position through the role of OVD on physi-ologic jaw muscle length; (2) influencing psy-chosocial factors of facial profile, orofacial com-fort for biting, psychosocial well-being, and therelationship between completeness of the dentalstatus and body self-image; and (3) functionalcomponents of masticatory efficiency, mastica-tion and swallowing, and speech.

It is clear that even without a role in TMD etiol-ogy, the occlusion retains an important role inmost aspects of dental practice.

References

1. Forssell H, Kalso E. Application of principles of evidence-based medicine to occlusal TMD treatments: Are therelessons to be learned? J Orofac Pain 2004;18:9–22.

2. Sackett DL, Rosenberg WMC, Gray JAM, Hayes RB,Richardson WS. Evidence based medicine: What it is andwhat it isn’t. It’s about integrating individual clinical expertiseand the best external evidence. Br Med J 1996;312:71–72.

3. Walther W, Micheelis W (eds). Evidence-Based Dentistry.Cologne, Germany: Deutscher Zahnärzte Verlag DÄV-Hanser, 2000.

4. Zakrzewska JM, Harrison SD (eds). Pain Research andClinical Management. Vol 14: Assessment and manage-ment of orofacial pain. Amsterdam: Elsevier Science,2002.

Klineberg/Nilner


5. Antczak AA, Tang J, Chalmers TC. Quality assessment ofrandomised control trials in dental research. I. Methods. JPeriodontal Res 1986;21:305–314.

6. Antczak AA, Tang J, Chalmers TC. Quality assessment ofrandomised control trials in dental research. II. Results. JPeriodontal Res 1986;21:315–321.

7. Greene CC. The etiology of temporomandibular disorders:Implications for treatment. J Orofac Pain 2001;15:93–105.

8. Management of temporomandibular disorders. NIHTechnology Assessment Conference Statement. J Am DentAssoc 1996;127:1595–1603.

9. Vandenbrouke JP. In defense of case reports and caseseries. Ann Intern Med 2001;134:330–334.

10. Schulz KF, Clamers I, Hayes RJ, Altman DG. Empiricalevidence of bias. Dimensions of methodological qualityassociated with estimates of treatment effects in controlledtrials. JAMA 1995;273:408–412.

11. Antczak-Bouckoms AA. Epidemiology of research fortemporomandibular disorders. J Orofac Pain 1995;9:226–234.

12. Dao TTT, Lavigne GJ, Feine JS, Tanguay R, Lund JP.Power and sample size calculations for clinical trials ofjaw muscles. J Dent Res 1991;70:118–122.


14. Ekberg EC, Vallon D, Nilner M. The efficacy of appliancetherapy in patients with temporomandibular disorders ofmainly myogenous origin. A randomised, controlled,short-term trial. J Orofac Pain 2003;17:133–139.



17. Emanuel EJ, Wendler D, Grady C. What makes clinicalresearch ethical? JAMA 2000;283:2701–2711.

18. Benatar SR, Singer PA. A new look at internationalresearch ethics. Br Med J 2000;321:824–826.

19. Whitney CW, Von Korff M. Regression to the mean intreated versus untreated chronic pain. Pain 1992;50:281–285.

20. Turner J, Deyo RA, Loeser J, Von Korff M, Fordyce W.The importance of placebo effects in pain treatment andresearch. JAMA 1994;271:1609–1614.

21. Price DD, McGrath PA, Rafii A, Buckingham B. The vali-dation of visual analogue scales as ratio scale measures forchronic and experimental pain. Pain 1983;17:45–56.


Maria Nilner, DDS, Odont DrProfessorDepartment of Stomatognathic PhysiologyFaculty of OdontologyMalmö UniversitySE-205 06 Malmö, SwedenFax: +46-40-6658420E-mail: [email protected]

The authors of the focus article1 state that evi-dence-based medicine (EBM) is “the system-atic, explicit, and judicious use of best evi-

dence in patient care.” They state that in practice,“EBM means the integration of individual clinicalexpertise with the best available evidence, moder-ated by patient circumstances and preferences.”The authors express an intention to elucidate anddiscuss the application of EBM in the most contro-versial treatment methods for temporomandibular

disorders (TMD), ie, occlusal treatments, includingocclusal adjustment and splint therapy. To be ableto treat patients according to the rules of EBM, atreating dentist must have knowledge about the sci-entific standards of treatments for TMD. Today, itis obvious for dentists claiming to be lifelong learn-ers that there are lessons to be learned when apply-ing principles of EBM to occlusal TMD treatments.The article is thereby an important paper, whichthe authors also underscore.

Nilner


Clinicians like to believe that what they aredoing for their patients is for the patients’ owngood. There are, however, instances when clinicalintervention has been more detrimental than bene-ficial, for example, when patients with periodontalproblems were subjected to uncomfortable surgerywith exposed bone, which resulted in a loss ofperiodontal support. These results were presentedin a meta-analysis.2 Other treatment methods thathave been questioned are extraction of asymp-tomatic third molars on a massive scale.3 Theseexamples clearly show the importance of EBM.

Many clinicians encounter patients who requesta treatment that they have read about in the news-paper or sensational press. Still, the patients havethe right to expect a high standard of care from thedentist. Achieving these standards forces dentists toengage themselves in lifelong learning. Since largenumbers of research articles in the area of dentistryare published every year in over 500 journalsrelated to dentistry, it is easy to understand that itis impossible for the clinicians to be up to date inall areas of dentistry. Moreover, if clinicians studyarticles on TMD treatment, they are seldom edu-cated in research methodology and are thereforeunable to be sufficiently critical of the publisheddata. High-quality review articles are for that rea-son of the utmost importance for the treating clini-cian. This cannot be overstated, but it also puts agreat responsibility on the authors of review arti-cles, as the responsibility of the reviewers is to dis-cuss all the evidence available at the time.

In 1999 the authors of this high-quality system-atic review presented a systematic review ofocclusal treatment for patients suffering fromTMD.4 In that review article, it was concludedthat “the use of occlusal splints may be of somebenefit in the treatment of TMD” but that “theevidence for the use of occlusal adjustment is lack-ing.” These statements present a clear picture ofthe available evidence. It was also expressed thatthere is an obvious need for well-designed con-trolled trials to analyze current clinical practices.The call for well-designed controlled studies hasbeen heard, and in this new review article, another2 articles on splint therapy are included,5,6 but noadditional studies on occlusal adjustment as atreatment modality in the management of patientssuffering from TMD have been published. It seemsthat the status of occlusal adjustment as a mode oftreatment in patients suffering from TMD hasbeen settled according to the well-written reviewarticle by De Boever et al.7

Regarding splint therapy, Raphael and Marbach5

concluded that patients with myofascial face pain

with only local pain experience pain reduction whentreated with oral splints, compared to patients withwidespread pain. The conclusion in the 2003 studyby Ekberg et al6 was that the stabilization appliancewas more effective in alleviating symptoms andsigns in patients with TMD of mainly myogenousorigin than a control, nonocclusal appliance. Thestabilization appliance was therefore recommendedfor the therapy of these patients. Only patients withlocalized pain were included in that study. In thesection “Clinical Implications and FuturePerspectives” of the focus article, it is stated that“although final answers to the question about theefficacy of splint therapy cannot be given at themoment, the latest studies have provided some fur-ther support for their use. The recommendationmay still remain valid until the question is solvedthrough new high-quality randomized controlledtrials” (RCTs). It is not difficult to agree with thisstatement, but surprisingly, another conclusion isexpressed in the abstract: “Occlusal splint studiesyielded equivocal results. … the results do not jus-tify definite conclusions about the efficacy of splinttherapy. Their clinical effectiveness to relieve painalso seems modest when compared with pain treat-ment methods in general.”

Under the heading “Systematic Review of RCTsof Occlusal Treatments,” another objective for thefocus article is expressed, ie, to evaluate the effec-tiveness of occlusal treatments for the symptoms ofTMD. To be able to do so, long-term follow-upstudies must be available. The continuation of 1RCT acknowledged in the present article as well asin the earlier review4 (on both occasions rated witha score of 0.71) has been published as a long-termfollow-up study at both 6 and 12 months thatfocused on the alleviation of signs and symptoms.8

This study lends further support to stabilizationappliance therapy but unfortunately, since it waspublished in 2002, is not included in the focus arti-cle. The conclusion about splint therapy and itseffectiveness in the abstract of the focus articlewould probably have been expressed in anotherway if the above-mentioned study had beenincluded. A long-term follow-up study of an RCT ofpain treatment8 cannot, because of ethical aspects,keep the groups intact. Still, these kinds of studiesare of the utmost importance in our ability to judgethe effectiveness of stabilization splint therapy.

In the cited article by Antczak et al,9 the thera-peutic procedure is discussed and it is stated that theprocedure must be described in sufficient detail toallow a comparison with other studies. The authorsof the focus article seem to have accomplished thecomparisons. However, important discussions are

Nilner


missing. The studies that evaluated treatment withstabilization splints and that had the highest scores(above 0.5) include different treatment regimens(Table 1). In the studies by Rubinoff et al10 and Daoet al,11 the splints in the active treatment groupswere worn day and night, and in the other studiesthey were worn only at night. Additional treatmentswere also performed. The different ways of wearingthe splints, as well as the additional treatments,probably created different therapies, which surpris-ingly was ignored in Forssell and Kalso’s compari-son. What these differences mean we do not know.However, studies examining the raising of bites withthe help of splints have found new resting positionsfor the mandible12 after splint insertion. Anotheraspect of using the splint day and night is that ofcomfort. It is not difficult to imagine a patient’sreluctance to comply fully. No study has proventhat the wearing of a splint night and day is themost effective in the treatment of TMD. Differencesin ways of recruiting patients, numbers of patients,diagnoses, and information given to the patients areimportant parameters to take into account whenevaluating the results of treatment (see Table 1 fordifferences between the highly scored studies).

The focus article’s section “Is There Evidence ofEfficacy for Occlusal Treatments?” includesimportant discussions about drawing conclusionsregarding the efficacy of a particular treatment.

Referring to Antczak et al,9 the authors decided toset a cutoff point of 0.5 for the quality score,which removed 14 of 20 studies from considera-tion. Of the 6 remaining studies, 5 evaluated treat-ment with stabilization splints and 1 assessedtreatment with the soft splint. It soon becomesobvious how difficult it is to devise a good methodfor scoring quality, as the method used could haveincluded studies that did not have, eg, selectiondescription, blinding, or description of with-drawals but still had a score above 0.5. A call forother and new tools for evaluation of the qualityof a study seems appropriate. In the excellent arti-cle by Kalso et al14 it is stated that high qualitydoes not necessarily mean that a trial of adequatedesign can answer the question posed, and there-fore the issue of validity must be discussed. Toassess validity, 2 of the most important inclusioncriteria are suggested to be adequate: baseline painintensity and adequate number of patients in eachgroup. According to the importance of these crite-ria, Table 1 was created to get an overview of thestrength in the studies regarding these and otherimportant parameters.

To answer a question proposed15 to the readerof systematic reviews: Were differences in individ-ual study results explained adequately? I wouldsay no! First of all, 3 different treatments wereevaluated: (1) stabilization splint used 24 hours a

Table 1 Studies of Stabilization Splints (with a Quality Score ≥ 0.5 as a Measure of Adequate/Good Quality) ThatAre the Basis for the Conclusions in the Focus Article

PainSampling of No. of (acute/ Pain Use of Additional tx

Studies patients patients Diagnosis chronic) rating splint during trial

Rubinoff et al10 Recruitment through 28 total; 13 tx Myofascial pain Unknown Daily pain (scale 0–5) 24 h* Moist heata newspaper notice 15 control dysfunction CS 3.6 ± 0.78 home exercise

NS 2.1 ± 0.9Dao et al11 Recruitment through 60 total; 22 tx, Myofascial pain Chronic VAS (1–10); 3.5 at Tx and AC: —

announcement 20 AC, 19 PC rest; 4.0 postexercise; 24 h*; PC:quality of life 30 min/visit

Ekberg et al8,13 Patients referred to 60 total; 30 tx, TMD of arthro- Chronic Verbal scale: At night — a specialist clinic 30 control genous origin 93% moderate to

very severe; VAS (0–100):worst pain � 70

Raphael and Referrals and recruit- 63 total; 32 tx, Myofascial pain Chronic VAS (0–10): At night Soft diet, moistMarbach5 ment of referrals 31 control and widespread mean pain level heat, massage,

pain 4.5 ± 1.8 exercise, NSAIDsEkberg et al6 Patients referred to 60 total; 30 tx, TMD of Chronic Verbal scale: At night —

a specialist clinic 30 control myogenous origin 97% moderate tovery severe; VAS (1–100):worst pain � 70

*Except for cleaning and meals.CS = conventional splint; NS = nonoccluding splint; tx = active treatment; AC = active control; PC = passive control; NSAIDs = nonsteroidal anti-inflammatory drugs.

Nilner


day, (2) stabilization splint used only at night, and(3) soft splint. The number of patients in 4 of thestudies with stabilization splints is adequate; thepatients, however, were recruited in differentways, which probably cannot be neglected in theevaluation of treatment outcome. Patients referredto a specialist clinic because of TMD problems areprobably quite different from patients recruitedthrough announcements. To be able to judge theefficacy and effectiveness of treatment, theseparameters are of great importance.

Number needed to treat (NNT) was calculatedfor a 50% reduction of worst pain in 2 RCTs.6,13

Since these trials did not include continuous mea-surements of visual analog scale scores, NNT ofthe change in pain according to the verbal scalewould be of more interest. If patients whoreported that they got better, got much better, orwere symptom-free in both studies are considered,NNT values of 2.36 and 313 will result, which arewell in accordance with the pain relief seen in drugstudies.16

In conclusion, I agree with the authors of thefocus article that EBM is an important part ofhealth care and will have a major influence ondecisions about acceptable treatment methods inthe future. I think, however, that a review mustclearly express the type and strength of the evi-dence of efficacy of the treatment evaluated, inaccordance with the principles of EBM. After myanalysis of quality and validity of the RCTs, I sug-gest the following about occlusal treatments forTMD, in accordance with the guidelines ofMcQuay and Moore17:

• Treatment of patients suffering from TMD ofmainly myogenous origin by means of occlusaladjustment alone must be regarded as ineffectiveat evidence level II.

• The treatment with stabilization splints used atnight for patients suffering from TMD of botharthrogenous and myogenous origin seemsappropriate, at evidence level II.

• A stabilization splint used day and night is notmore effective than a control splint in patientssuffering from myofascial pain, at evidence levelII.

• The level of evidence for the use of a soft splintin the treatment of patients with masticatorymuscle pain is III, as the number of patients inthe single available study18 is too small.

• There is a need for an ongoing discussion aboutthe tools for evaluating both the quality and thevalidity of RCTs and review articles.

References

1. Forssell H, Kalso E. Application of principles of evidence-based medicine to occlusal TMD treatments: Are therelessons to be learned? J Orofac Pain 2004;18:9–22.

2. Antczak-Bouckoms A, Joshipura K, Burdick E, TullochJFC. Meta-analysis of surgical versus nonsurgical methodsof treatment for periodontal disease. J Clin Periodontol1993;20:259–268.

3. Song F, Landes DP, Glenny A-M, Sheldon TA. Proph-ylactic removal of impact third molars: An assessment ofpublished reviews. Br Dent J 1997;182:339–346.

4. Forssell H, Kalso E, Koskela P, Vehmanen R, Alanen P.Occlusal treatments in temporomandibular disorders: Aqualitative systematic review of randomised controlled tri-als. Pain 1999;83:549–560.


6. Ekberg EC, Vallon D, Nilner M. The efficacy of appliancetherapy in patients with temporomandibular disorders ofmainly myogenous origin: A randomized, controlled,short-term trial. J Orofac Pain 2003;17:133–139.

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Forssell/Kalso


We thank Drs Clark,1 Klineberg,2 andNilner3 for their criticism and valuablecomments on our article on the evi-

dence-based management of temporomandibulardisorders (TMD). The commentaries raise impor-tant new issues on this topic, such as DrKlineberg’s discussion on research ethics. All 3authorities seem to agree on the main issue of ourfocus article, ie, the importance of evidence-basedknowledge in the TMD field. If experts in differentparts of the world recognize the importance ofhigh-quality clinical studies of TMD, we canexpect the future to bring new evidence to guidethe decisions of clinicians who treat TMD patients.In the following, we will briefly comment on someof the main issues raised in the commentaries.

Dr Clark and Dr Klineberg address the hetero-geneity of TMD problems and discuss how thisshould be handled in treatment studies. We sug-gested that future studies should define the diagno-sis more clearly (eg, joint or muscle pain) ratherthan lumping everything under the term TMD. Itis obvious that at least acute joint pain and musclepain have different pathophysiologic mechanisms,and presumably, they respond differently to treat-ments. The best way to handle this problem wouldbe to use the Research Diagnostic Criteria forTMD,4 which allow a patient to receive multiplediagnoses on the somatic axis.

Results from long-term follow-up studies areindeed important, as mentioned by Dr Nilner. Shepaid attention to one recently published long-termfollow-up of a randomized controlled trial (RCT)that lent support to the effectiveness of stabiliza-tion appliance therapy.5 The long-term follow-upresults of both this study and 4 others mentionedin our previous systematic review6 had to beexcluded from the efficacy analysis because of ran-domization violations.

Despite the many difficulties discussed in ourtext, we wanted to follow the rules of evidence-based medicine (EBM) and base our conclusionsabout the efficacy of occlusal treatments on theevidence provided by the RCTs. Unlike Dr Nilner,we found it impossible to draw definite conclu-sions about the evidence-based efficacy of stabi-

lization appliances. When 2 high-quality studies7,8

show different results, we have to conclude thatthe issue remains unsettled.

Dr Clark’s conclusions about the efficacy ofocclusal appliances—that they prevent abnormaltooth attrition and/or reduce individual toothloading and sometimes change clenching behav-iors—cannot be substantiated by published evi-dence. None of the RCTs on splint therapy usedtooth attrition or clenching behaviors as outcomemeasures.

What endpoints should be used to calculatenumber needed to treat (NNT)? We used theexample of a 50% reduction in pain intensity,rather than the outcomes suggested by Dr Nilner,as this outcome has been used in the vast majorityof published studies in pain medicine. The use ofthe same endpoint enables comparisons acrossstudies and between different treatments.However, any NNT based on small patient popu-lations (fewer than 500) should be treated withcaution.9

Finally, we fully agree with Dr Klineberg’s state-ment that EBM should be implemented by consid-ering the best available research evidence, alongwith the clinical experience of the clinician and,most importantly, the individual patient’s needs.The main criticism toward EBM seems to be basedon the fear that EBM as such would dictate howclinicians should treat their patients. It is impor-tant to understand that EBM is a good tool to beused to guide decisions when delivering optimalclinical care to the patients. Research-based evi-dence will be vital for the reputation of any area ofclinical practice, as stated by Dr Klineberg.

References

1. Clark G. Critical commentary 1. Application of principlesof evidence-based medicine to occlusal TMD treatments:Are there lessons to be learned? J Orofac Pain 2004;18:23–24.

2. Klineberg I. Critical commentary 2. Application of princi-ples of evidence-based medicine to occlusal TMD treat-ments: Are there lessons to be learned? J Orofac Pain2004;18:24–27.

AUTHORS’ RESPONSE TO CRITICAL COMMENTARIES

Heli Forssell, DDS, PhD Eija Kalso, MD, PhD

Forssell/Kalso


3. Nilner M. Critical commentary 3. Application of princi-ples of evidence-based medicine to occlusal TMD treat-ments: Are there lessons to be learned? J Orofac Pain2004;18:27–30.

4. Dworkin SF, LeResche L. Research Diagnostic Criteria forTemporomandibular Disorders: Review, Criteria, Exami-nations and Specifications, Critique. J CraniomandibDisord Facial Oral Pain 1992;6:301–355.

5. Ekberg EC, Nilner M. A 6- and 12-month follow-up ofappliance therapy in TMD patients: A follow-up of a con-trolled trial. Int J Prosthodont 2002;15:564–570.

6. Forssell H, Kalso E, Koskela P, Vehmanen R, Puukka P,Alanen P. Occlusal treatments in temporomandibular dis-orders: A qualitative systematic review of randomizedcontrolled trials. Pain 1999;83:549–560.


8. Ekberg EC, Vallon D, Nilner M. The efficacy of appliancetherapy in patients with temporomandibular disorders ofmainly myogenous origin. A randomized, controlled,short-term trial. J Orofac Pain 2003;17:133–139.

9. Moore RA, Gavaghan D, Tramer MR, Collins SL,McQuay HJ. Size is everything—Large amounts of infor-mation are needed to overcome random effects in estimat-ing direction and magnitude of treatment effects. Pain1998;78:209–216.

FOCUS ARTICLE Application of Principles of Evidence-Based ... · mal or systematic approaches. The informal approach is used by traditional narrative reviews. ... frequently used

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