Condylar remodeling accompanying splint therapy: a …tmjsleepapneatherapy.com/articles/Condylar remodeling...Condylar remodeling accompanying splint therapy: a cone-beam computerized

Vol. 114 No. 2 August 2012

Condylar remodeling accompanying splint therapy: a cone-beamcomputerized tomography study of patients withtemporomandibular joint disk displacementMu-Qing Liu,a,b,c Hui-Min Chen, DDS,a,c Adrian U. Jin Yap, PhD, MSc, BDS, GradDipPsychotherapy, FAMS,d,e,f

and Kai-Yuan Fu, DDS, PhD,a,b,c Beijing, China, and SingaporePEKING UNIVERSITY SCHOOL AND HOSPITAL OF STOMATOLOGY AND NATIONAL ENGINEERING LABORATORY FORDIGITAL AND MATERIAL TECHNOLOGY OF STOMATOLOGY; RAFFLES HOSPITAL, NATIONAL UNIVERSITY OF SINGAPORE;AND SIM UNIVERSITY

Objective. The aim of this study was to evaluate osseous changes accompanying anterior repositioning splint (ARS) therapy inpatients with temporomandibular joint disk displacement.Study Design. Cone-beam computerized tomography (CBCT) data of 36 patients with intermittent or permanent closed-lockwere used; 23 patients with permanent closed-lock had their displaced disks physically reduced by mandibular manipulationbefore ARS therapy. CBCT was performed before and �6 months after ARS therapy. The presence and location of “doublecontour” images suggesting condylar bone remodeling were statistically analyzed.Results. The “double contour” images after ARS therapy were observed in �80% of patients, more frequently in joints withsigns of displaced disks. The “double contour” appeared more often on the posterior bevel as well as the medial and middlepart of condyles (P � .01).Conclusions. ARS therapy can facilitate regenerative remodeling of condyles. CBCT is a useful tool for monitoring osseous

Temporomandibular joint (TMJ) disk displacement isthe most common type of TMJ arthropathy. It is char-acterized by several stages of clinical dysfunction aris-ing from deviant relationship of the articular disk tocondyle. Although different displacements have beendescribed, the usual direction is in an anterior direction.Disk displacement can be subdivided into disk dis-placement with reduction (DDwR) and disk displace-ment without reduction (DDwoR). In the latter (alsoreferred to as “TMJ closed-lock”), the misaligned disk-condyle relationship is maintained during translation.When acute, DDwoR is usually associated with suddentrismus, pain, and functional disability. As the condi-tion becomes chronic, mandibular range of motion mayapproach normal and pain becomes markedly reduced

Supported by Capital Medical Development Research Foundation(2009-3037).aCenter for TMD and Orofacial Pain, Peking University.bDepartment of Oral and Maxillofacial Radiology, School and Hos-pital of Stomatology, Peking University.cNational Engineering Laboratory for Digital and Material Technol-ogy of Stomatology.dRaffles Dental, Raffles Hospital.eDepartment of Restorative Dentistry, Faculty of Dentistry, NationalUniversity of Singapore.fSchool of Science and Technology, SIM University.Received for publication Jan 1, 2012; returned for revision Feb 27,2012; accepted for publication Mar 4, 2012.© 2012 Mosby, Inc. All rights reserved.2212-4403/$ - see front matter

or absent. Patients with advanced DDwR may experi-ence intermittent closed-lock, restricted motion, andpainful function before progression to acute DDwoR.Anterior repositioning splint (ARS) therapy has beenshown to be effective for the management of TMJDDwR.1,2 In acute DDwoR, the TMJ closed-lock mustbe physically reduced by jaw manipulation before theuse of ARS.3-5 Yano et al. found that ARS therapy notonly repositions displaced articular disks but also leadsto condylar bone remodeling that is manifested as a“double contour” on magnetic resonance imaging(MRI) of the condylar heads.6

“Double contour” image was first mentioned by Hol-lender et al. in 1974.7,8 They observed a distinct “dou-ble contour” in the posterior and lateral-superior partsof the condylar head after oblique sliding osteotomy ofthe mandibular rami and condylar fracture. “Doublecontour” images were also observed after other man-dibular osteotomies,7,9-11 condylar fractures,8,12 splinttherapy,6,13 Herbst appliance therapy,14-17 occlusaltreatment,18 and other conditions19 and were attributedto adaptive bony remodeling of the condyles. “Double

Statement of Clinical Relevance

Our findings indicate that condylar bone is veryactive for remodeling, and cone-beam computerizedtomography (CT) can be used to detect very subtleosseous changes on the condyles.

259

change

ORAL AND MAXILLOFACIAL RADIOLOGY OOOO260 Liu et al. August 2012

contour” of the condyles has been observed with con-ventional radiography, computerized tomography (CT),and MRI.6-19

Conventional helical CT (HCT) was considered tobe the preferred imaging method for evaluating bonyconditions.20 It uses a fan-shaped x-ray beam rotat-ing in a helical mode around the patient. Data isacquired through parallel arrays of solid state detec-tors located at the gantry. The high equipment cost,large space required for operations, and high radia-tion dosage limits the use of HCT in dentistry. Cone-beam CT (CBCT) was developed as an alternative toHCT for dental and maxillofacial imaging. It uses acone-shaped x-ray beam that rotates around the pa-tient with the image being detected by a flat paneldetector. CBCT offers images of HCT quality, butthe scanners are smaller and cheaper. Scanning timeis also shorter and radiation dose lower. CBCT hasbeen recommended for TMJ evaluation and is thepreferred TMJ imaging method when bony condi-tions are involved.21,22 The use of CBCT for analyz-ing osseous condylar changes after splint therapy,however, has not been reported.

The aim of the present retrospective study was toevaluate osseous changes accompanying ARS therapyin patients with intermittent or permanent TMJ closed-lock with the use of CBCT.

MATERIALS AND METHODSCBCT imaging and clinical data of patients attendingour hospital from 2008 to 2011 for temporomandibulardisorders (TMD) were used for this retrospective study.The TMJ images were taken as part of the hospital’sstandard clinical protocol for patients seeking treatmentfor TMJ closed-lock. Data of all patients aged 13-31years diagnosed with DDwR with transient limitedopening and DDwoR with limited opening (based onthe Research Diagnostic Criteria for TMD [RDC/

Figure 1. Dividing lines for specifying location of condylar

TMD]23) of �3 months’ duration and managed with

ARS therapy were used. A total of 36 patients (6 maleand 30 female) with a mean age of 19.8 � 4.2 yearswere selected. Twenty-three patients with DDwoR withrestricted mouth opening had their TMJ closed-lockreduced by manual manipulation before ARS therapy.Lidocaine (2%) injection into the upper joint cavity wasadministered to facilitate joint maneuvering. The re-maining 13 patients with intermittent closed-lock wereroutinely prescribed ARS therapy. The splints werefabricated on the upper arch with the mandible guidedinto a protrusive position.4 Patients were instructed towear the ARS 24 hours a day for 3 months and toremove it only for oral hygiene procedures. After theinitial 3 months, patients were weaned off daytimewear and were required to wear their ARS only duringthe night while sleeping.

CBCT images were taken before and after �6months of ARS therapy, when patients were able tobite effectively into maximum intercuspation. Theaverage time to achieve the latter was 5.5 � 2.7months. The CBCT images of the bilateral TMJswere obtained with the use of a 3DX MultiimagemicroCT (J. Morita Corp., Kyoto, Japan) with a fieldof view of 29 � 38 mm at 76-80 kV, 4.2-6 mA. Thepatients were seated and asked to rest their heads in

s: A, sagittal plane; B, coronal plane.

Table I. Results of ARS therapy in the DDwR group(n � 13)

Successful

Unsuccessful

Recurrence Progression to DDwoR

8 4 1

Table II. Results of ARS therapy in the DDwoR group(n � 23)

Successful

Unsuccessful

Presence of some signs/symptoms Recurrence

16 5 2

the center of the proprietary headrest. Their heads

OOOO ORIGINAL ARTICLEVolume 114, Number 2 Liu et al. 261

were then positioned with the Frankfurt plane paral-lel to the floor. The patients were then instructed tobite their teeth into intercuspal position. The centerbeam was lined up with the sagittal plane and the seatposition adjusted so that the lateral crossed cursorwas targeted at the condyle. The scanned data wasautomatically exported to the 3DX software. Imageswere reconstructed and multiple images of axial,coronal and sagittal planes of the joints at 1.0-mmslice intervals/thickness were created and stored.Pre- and posttreatment images of each patient wereexamined for “double contour” images, which were

Figure 2. “Double contour” images (arrows) found in the (toDDwoR: A, before treatment; B, after ARS therapy.

defined as periosteal reaction–like double images on

the cortical surface of the condylar head.6 The pres-ence and location of the double contour images weredocumented by 2 independent oral radiologists. Incases of disagreement, a final recording was obtainedby consensus.

Images in the sagittal and coronal planes werefurther divided and explored to determine the spe-cific locations of osseous change. Sagittal images ofthe condyle were divided into anterior and posteriorsegments, taking the highest point of transverse ridgeof condyle as the dividing line (Figure 1, A). Coronalimages were divided equally into medial, middle,

ttom) axial, coronal, and sagittal planes, from a patient with

and lateral segments (Figure 1, B). Patients were

ORAL AND MAXILLOFACIAL RADIOLOGY OOOO262 Liu et al. August 2012

subsequently reviewed on a 6-monthly basis, andARS therapy was considered to be successful if signsand symptoms of TMJ closed-lock, including re-stricted mouth opening, uncorrected jaw deviation,pain, and dysfunction, ceased after splint wear. Re-sults were analyzed with the use of Pearson �2 test ata significance level of .05 using SPSS version 13.0.

RESULTSARS therapy was deemed to be successful in 16 of the23 patients with DDwoR and in 8 of the 13 withDDwR. The overall treatment success rate was 67%

Figure 3. “Double contour” image observed in only 1 planebefore treatment; B, after ARS therapy.

(Tables I and II). Osteoarthritic changes were detected

in 5 joints of 4 patients, and no “double contours” of thecondyle head were observed before treatment in all ofthe patients. After ARS therapy, “double contour” im-ages were present in �80% of patients (29 out of 36;Figures 2-4). The “double contours” were observed in atotal of 43 joints in these 29 patients. “Double contour”images were observed in both joints with and withoutsigns of displaced disks. The prevalence in joints withsigns of displaced disks was higher than those without,but not statistically significantly (Table III). In the 39joints with displaced disks, no significant difference inthe prevalence of “double contour” images was ob-

in sagittal image, bottom), from a patient with DDwoR: A,

served between DDwoR and DDwR (Table IV).

nt wit

OOOO ORIGINAL ARTICLEVolume 114, Number 2 Liu et al. 263

When the specific location of osseous change wasanalyzed, “double contours” appeared more often sig-nificantly on the posterior bevel (sagittal plane) as wellas the medial and middle part (coronal plane) of con-

Figure 4. No “double contour” image observed, from a patie

Table III. Frequency of “double contour” images injoints with and without signs of displaced disks (n �72)

Presence Absence Total

With signs of displaced disks 27 12 39Without signs of displaced disks 16 17 33

P � .074.

dyles (Tables V and VI).

DISCUSSIONThe presence of “double contour” images after splinttherapy occurred frequently and was confirmed in 3dimensions with the use of CBCT. Careful exploration

h DDwR: A, before treatment; B, after ARS therapy.

Table IV. Prevalence of “double contour” images be-tween DDwR and DDwoR in joints with signs of dis-placed disks (n � 39)

Presence Absence Total

DDwR 10 6 16DDwoR 17 6 23

P � .498.

of CBCT images in all 3 planes (especially the coronal

ORAL AND MAXILLOFACIAL RADIOLOGY OOOO264 Liu et al. August 2012

and sagittal) is therefore necessary. In the present study,the “double contours” appeared more often on the pos-terior bevel (sagittal plane) as well as the medial andmiddle part (coronal planes) of condyles. The “doublecontour” images are considered to be the result ofadaptive bone remodeling arising from change ofstresses in the articular space.7-9,14,16,19 After insertionof an ARS, the condyles were moved downwards andforwards, increasing both posterior and medial jointspaces.

Suei et al. validated histologically the existence of“double contour” formation in the human mandiblecondyle.19 Because no cartilage layer was found on thecondylar surface, they suggested that the “double con-tour” formation was due to periosteal bone formation.Paulsen, however, suggested that the “double contours”on the posterior part of condyles and ramus were theresult of endochondral and periosteal ossification re-spectively.16 Similar condylar remodeling was also ob-served in rats with mandibular protrusion by means offixed bite-jumping devices.24 The deposition of boneoccurred at the posterior and superior surfaces of con-dyles but not on the anterior surfaces. They reportedthat forward mandibular positioning improved the pro-liferation of mesenchymal cells in the condylar carti-lage of rats, especially in the posterior surface.24 Man-dibular repositioning was hypothesized to enhancesignaling of growth factors, such as parathyroid hor-mone–related protein, insulin-like growth factor, fibro-blast growth factors, and vascular endothelial growthfactor, which elicited a cascade of molecular responsesstimulating chondrogenesis and osteogenesis.25

Yano et al. found that disks of all joints showing“double contours” after ARS therapy were displacedanteriorly before treatment.6 In the present study, “dou-ble contours” were also more frequently observed injoints with signs of displaced disks than those without,

Table V. Specific location of condyles showing “dou-ble contour” images on coronal sections (n � 43 joints)

Location Presence Absence

Medial part 34* 9Middle part 40† 3Lateral part 22 21

*P � .01; †P � .001 (compared with lateral part).

Table VI. Specific location of condyles showing “dou-ble contour” images on sagittal sections (n � 43 joints)

Location Presence Absence

Anterior part 2 41Posterior part 43 0

P � .001.

but not statistically significantly (P � .074). Disk im-

provement may facilitate bone remodeling, but changeof stresses in the articular space by ARS-producedcondylar movement is a key contributing factor. Al-though permanent “recapturing” of the disk with ARStherapy is still controversial,26,27 its effectiveness inreducing painful symptoms associated with DDwoR isnot. However, we reduced the displaced disks by man-ual manipulation before ARS therapy for the patientswith DDwoR and attained high treatment success ratein this study.

The downward and forward mandibular positioningwith an ARS prevents the condyle from articulatingwith the vascularized and well innervated retrodiscaltissues in the posterior attachment. Over time, the ret-rodiscal tissues undergo adaptive and reparativechanges.28 When patients are weaned off their ARS, thecondyles move posteriorly into the fossa to function onthe adapted retrodiscal tissues with the disks probablystill displaced to various degrees. Condylar function onthe adapted retrodiscal tissues may also reduce jointloading and stresses, facilitating bone remodeling thatis evidenced by “double contour” images. No signifi-cant difference in the prevalence of “double contour”images was observed between DDwoR and DDwR.Our findings corroborated those of Yano et al.,6 whoalso reported that the formation of “double contours” inMRI was not associated with the type of disk displace-ment before treatment. ARS therapy is therefore helpfulfor facilitating regenerative condylar remodeling in pa-tients with DDwoR and DDwR.

Although no “double contour” image was observedin all patients before ARS therapy, “double contour”–like structures had been previously reported in MRI ofchildren aged 9-14 years. These “double contour”–likestructures, however, disappeared as the children devel-oped.29,30 The presence of “double contours” afterHerbst appliance therapy disappeared after a fewmonths in children and adolescents but tended to persistin adults.15 Follow-up of the present cohort of patientsis warranted to determine longer-term changes of the“double contour” images. In view of its increasingavailability, lower radiation dosage and diagnostic re-liability, CBCT is becoming the imaging technique ofchoice for evaluating and monitoring osseous changesin the TMJs.

REFERENCES1. Kurita H, Kurashina K, Baba H, Ohtsuka A, Kotani A, Kopp S.

Evaluation of disk capture with a splint repositioning appliance:clinical and critical assessment with MR imaging. Oral Surg OralMed Oral Pathol Oral Radiol Endod 1998;85:377-80.

2. Gökalp H, Türkkahraman H. Changes in position of the tem-poromandibular joint disc and condyle after disc repositioningappliance therapy: a functional examination and magnetic reso-nance imaging study. Angle Orthod 2000;70:400-8.

3. Mongini F, Ibertis F, Manfredi A. Long-term results in patients

OOOO ORIGINAL ARTICLEVolume 114, Number 2 Liu et al. 265

with disk displacement without reduction treated conservatively.Cranio 1996;14:301-5.

4. Fu K, Zhang H, Ma X, Zhang Z, Zhao Y. [Manipulation aided byjoint cavity extension followed by occlusal splint for treatment ofacute anterior disk displacement without reduction]. ZhonghuaKou Qiang Yi Xue Za Zhi 2002;37:36-8. Chinese.

5. Chiba M, Echigo S. Longitudinal MRI follow-up of temporo-mandibular joint internal derangement with closed lock aftersuccessful disk reduction with mandibular manipulation. Den-tomaxillofac Radiol 2005;34:106-11.

6. Yano K, Nishikawa K, Sano T, Okano T. Relationship betweenappearance of a double contour on the mandibular condyle andthe change in articular disc position after splint therapy. OralSurg Oral Med Oral Pathol Oral Radiol Endod 2009;108:e30-4.

7. Hollender L, Ridell A. Radiography of the temporomandibularjoint after oblique sliding osteotomy of the mandibular rami.Scand J Dent Res 1974;82:466-9.

8. Hollender L, Lindahl L. Radiographic study of articular remod-eling in the temporomandibular joint after condylar fractures.Scand J Dent Res 1974;82:462-5.

9. Edlund J, Hansson T, Petersson A, Willmar K. Sagittal splittingof the mandibular ramus. Electromyography and radiologic fol-low-up study of temporomandibular joint function in 44 patients.Scand J Plast Reconstr Surg 1979;13:437-43.

10. Hall HD, Navarro EZ, Gibbs SJ. Prospective study of modifiedcondylotomy for treatment of nonreducing disk displacement.Oral Surg Oral Med Oral Pathol Oral Radiol Endod2000;89:147-58.

11. Katsumata A, Nojiri M, Fujishita M, Ariji Y, Ariji E, LanglaisRP. Condylar head remodeling following mandibular setbackosteotomy for prognathism: a comparative study of differentimaging modalities. Oral Surg Oral Med Oral Pathol Oral RadiolEndod 2006;101:505-14.

12. Lindahl L, Hollender L. Condylar fractures of the mandible. II. Aradiographic study of remodeling processes in the temporoman-dibular joint. Int J Oral Surg 1977;6:153-65.

13. Uematsu H, Ichida T, Masumi S, Morimoto Y, Tanaka T, KonooT, Yamaguchi K. Diagnostic image analyses of activator treatedtemporomandibular joint in growth and maturing stages. Cranio2002;20:254-63.

14. Paulsen HU, Karle A, Bakke M, Herskind A. CT-scanning andradiographic analysis of temporomandibular joints and cephalo-metric analysis in a case of Herbst treatment in late puberty. EurJ Orthod 1995;17:165-75.

15. Ruf S, Pancherz H. Temporomandibular joint remodeling inadolescents and young adults during Herbst treatment: a prospec-tive longitudinal magnetic resonance imaging and cephalometricradiographic investigation. Am J Orthod Dentofacial Orthop1999;115:607-18.

16. Paulsen HU. Morphological changes of the TMJ condyles of 100patients treated with the Herbst appliance in the period of pubertyto adulthood: a long-term radiographic study. Eur J Orthod1997;19:657-68.

17. Paulsen HU, Karle A. Computer tomographic and radiographic

with occlusal asymmetry, treated with the Herbst appliance. EurJ Orthod 2000;22:649-56.

18. Lundh H, Westesson PL. Long-term follow-up after occlusaltreatment to correct abnormal temporomandibular joint disk po-sition. Oral Surg Oral Med Oral Pathol 1989;67:2-10.

19. Suei Y, Tanimoto K, Ogawa I, Wada T. Formation of doublecontour in the human mandibular condyle. A case report. OralSurg Oral Med Oral Pathol 1994;77:327-30.

20. Larheim TA. Current trends in temporomandibular joint imag-ing. Oral Surg Oral Med Oral Pathol Oral Radiol Endod1995;80:555-76.

21. Honda K, Larheim TA, Maruhashi K, Matsumoto K, Iwai K.Osseous abnormalities of the mandibular condyle: diagnosticreliability of cone beam computed tomography compared withhelical computed tomography based on an autopsy material.Dentomaxillofac Radiol 2006;35:152-7.

22. Tsilakis K, Syriopoulos K, Stamatakis HC. Radiographic exam-ination of the temporomandibular joint using cone beam com-puted tomography. Dentomaxillofac Radiol 2004;33:196-201.

23. Anderson GC, Gonzalez YM, Ohrbach R, Truelove EL, Som-mers E, Look JO, Schiffman EL. The research diagnostic criteriafor temporomandibular. Disorders: VI: future directions. J Oro-fac Pain 2010;24:79-88.

24. Xiong H, Hägg U, Tang GH, Rabie AB, Robinson W. The effectof continuous bite-jumping in adult rats: a morphological study.Angle Orthod 2004;74:86-92.

25. Shen G, Darendeliler MA. The adaptive remodeling of condylarcartilage—a transition from chondrogenesis to osteogenesis. JDent Res 2005;84:691-9.

26. Choi BH, Yoo JH, Lee WY. Comparison of magnetic resonanceimaging before and after nonsurgical treatment of closed lock.Oral Surg Oral Med Oral Pathol 1994;78:301-5.

27. Chen CW, Boulton JL, Gage JP. Effects of splint therapy in TMJdysfunction: a study using magnetic resonance imaging. AustDent J 1995;40:71-8.

28. Pereira FJ, Lundh H, Eriksson L, Westesson PL. Microscopicchanges in the retrodiscal tissues of painful temporomandibularjoints. J Oral Maxillofac Surg 1996;54:461-8, 469.

29. Morimoto Y, Tominaga K, Konoo T, Tanaka T, Ohba T. Detec-tion and significance of the characteristic magnetic resonancesignals of mandibular condyles in children. Oral Surg Oral MedOral Pathol Oral Radiol Endod 2004;97:269-75.

30. Morimoto Y, Tominaga K, Konoo T, Tanaka T, Yamaguchi K,Fukuda J, Ohba T. Alternation of the magnetic resonance signalscharacteristic of mandibular condyles during growth. Oral SurgOral Med Oral Pathol Oral Radiol Endod 2004;98:348-54.

Reprint requests:

Prof. Kai-Yuan FuCenter for TMD and Orofacial Pain andDepartment of Oral and Maxillofacial RadiologySchool and Hospital of StomatologyPeking UniversityBeijing 100081 China