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Biomaterials for promotingperiodontal regeneration inhuman intrabony defects: asystematic reviewANTON SCULEAN*, DIMITRIS NIKOLIDAKIS*, GEORGE NIKOU, ALEKSANDAR
IVANOVIC, IAIN L. C. CHAPPLE & ANDREAS STAVROPOULOS
Themain goals of periodontal treatment are the elimi-nation of infection and the resolution of chronicinflammation in order to arrest disease progressionand prevent its recurrence. This is manifested clini-cally by an absence of bleeding on probing and thepresence of shallow probing pocket depths (≤4 mm)(15, 47). In contrast, the persistence of residual perio-dontal pockets of >5 mm following completion ofactive periodontal therapy is associated with anincreased risk for disease progression (i.e. further lossof attachment) and tooth loss, irrespective of the pres-ence or absence of bleeding on probing (15, 47).Increased probing depths following treatment areoften related to the presence of intrabony (angular)periodontal defects, a feature of periodontitis and, inturn, intrabony defects have been shown to worsenthe long-term prognosis for teeth (62). The rationalebehind the treatment of intrabony defects is thereforeto reduce residual probing depths to improve toothprognosis. During the last three decades, varioustreatment approaches involving nonsurgical tech-niques, as well as conservative, resective and regener-ative surgical techniques, have been employed for thetreatment of intrabony defects and have achieved var-iable success (12, 16, 17, 37, 45, 59, 65, 69, 74, 82, 88,97, 98).
Clinical studies have provided evidence indicatingthat conventional periodontal surgery, comprisingvarious types of access flaps and/or resective tech-niques, may result in probing depth reduction, hard
tissue fill or even the elimination of the intrabonycomponent (37, 62, 65). However, residual pocketsoften persist following nonsurgical periodontaltherapy or the use of access flaps, and resectivetechniques are associated with substantial loss ofattachment and increases in soft-tissue recession(37, 62, 65, 69). Furthermore, despite the fact thatsuch techniques may improve clinical outcomes,healing is predominantly characterized by repair(i.e. formation of a long junctional epithelium) andno, or very limited, regeneration (i.e. formation ofroot cementum with functionally oriented insertingperiodontal ligament fibers connected to new alveo-lar bone) (14).
Thus, the optimal outcome of periodontal treat-ment is considered as the absence of bleeding onprobing, the presence of shallow pockets associa-ted with periodontal regeneration and limited/nosoft-tissue recession. Since the early 1970s, aplethora of different surgical techniques, oftenincluding implantation of various types of bonegrafts and/or substitutes, root surface deminera-lization, guided tissue regeneration, growth anddifferentiation factors, enamel matrix proteins orvarious combinations thereof, have beenemployed, aiming to achieve predictable periodon-tal regeneration (16, 17, 38, 45, 52, 74, 99). Sys-tematic reviews of clinical trials have shown thatsome of these materials, when used in conjunctionwith surgical approaches designed to facilitatemaximal preservation of soft and hard tissues,may indeed result in superior clinical outcomes interms of probing depth reduction, clinical attach-*Equal contribution.
Printed in Singapore. All rights reserved PERIODONTOLOGY 2000
ment gain and hard tissue fill when comparedwith access flaps alone (38). Moreover, numerousstudies have shown that the results obtained canbe sustained long term, up to 15 years, providedthat optimal plaque control and maintenance areevident (17, 74, 77, 82, 89, 98).
A recent systematic review has analyzed theregenerative potential of various available tech-niques and materials, either alone or in differentcombinations, for the treatment of periodontal in-trabony defects, as assessed in pre-clinical in vivostudies that provide histological evidence (36). Therewas substantial heterogeneity in the studies with
Table 1. Search terms used to identify the relevantstudies
Search terms
(“periodontal defect” OR “periodontal lesion” OR“periodontal osseous defect” OR “intraosseous defect”OR “intra-osseous defect” OR “intrabony defect” OR“intra-bony defect” OR “infrabony defect” OR“infra-bony defect” OR “angular defect” OR“bony defect” OR “osseous defect” OR “crater”)
AND
(“guided tissue regeneration” OR “GTR” OR “membrane”OR “barrier” OR “periodontal regeneration” OR “bonegraft” OR “bone replacement graft” OR “bone substitute”OR “osseous graft” OR “bone transplantation” OR “boneregeneration” OR “bone matrix” OR “autograft” OR“autogenous bone graft” OR “allogenic bone graft” OR“allograft” OR “freeze dried bone allograft” OR“demineralized freeze-dried bone allograft” OR“decalcified freeze-dried bone allograft” OR “bovinebone” OR “xenograft” OR “xenogenic graft” OR “syntheticgraft” OR “alloplastic graft” OR “alloplastic material” OR“polymer” OR “ceramic graft” OR “bioactive ceramicgraft” OR “bioglass” OR “biomaterial” OR “bioceramic”OR “hydroxyapatite” OR “calcium phosphate” OR“tricalcium phosphate” OR “beta-tricalcium phosphate”OR “tricalcium phosphate” OR “ceramic” OR “calciumcarbonate” OR “calcium sulfate” OR “Plaster of Paris” OR“Emdogain” OR “EMD” OR “enamel matrix derivative”OR “biomimetic substances” OR “growth factors” OR“graft” OR “grafting” OR “regenerative material”)
AND
(“human study” OR “clinical study” OR “patient” OR“human” OR “case” OR “report”)
AND
(“histological study” OR “histology” OR“histomorphometrical study” OR “histomorphometry”OR “electron microscopy study” OR “biopsy” OR “blocksection” OR “histological evaluation’ OR“histomorphometrical evaluation”)
Potentially relevant publications identified from electronic and hand searching (n = 184)
Potentially relevant publications retrieved for further evaluation (n = 84)
Publications included in the present systematic review (n = 58)
Publications excluded on basis of abstract evaluation (n = 100) (Inter-reader agreement k = 0.98)
Publications excluded on basis of full text evaluation (n = 26) (Inter-reader agreement k = 0.97)
Fig. 1. Flow chart of the screened relevant publications.
Table 2. Studies excluded (n = 26)
Authors (year) (ref. no.) Reason for exclusion
Bosshardt et al. (2005) (3) Short healing
Sculean et al. (2003) (76) Repeated data
Sculean et al. (2003) (81) Unrelated data
Sculean et al. (2002) (85) Unrelated data
Sculean et al. (2001) (75) Unrelated data
Heijl (1997) (32) Unrelated data
Reynolds & Bowers (1996) (67) Repeated data
Guillemin et al. (1993) (29) Unrelated data
Stahl & Froum (1991) (92) Unrelated data
Galgut et al. (1990) (26) Unrelated data
Wachtel et al. (1990) (104) Language
Saffar et al. (1990) (72) Unrelated data
Bowers et al. (1989) (6) Unrelated data
Issahakian et al. (1989) (35) Language
Mattout et al. (1988) (46) Unrelated data
Ganeles et al. (1986) (27) Unrelated data
Sapkos (1986) (73) Unrelated data
Bowers et al. (1986) (8) Unrelated data
Stahl & Froum (1986) (91) Unrelated data
Baldock et al. (1985) (2) Unrelated data
R€uhling & Plagman (2001) (71) Language
Kenney et al. (1986) (39) Unrelated data
Dragoo & Kaldahl (1983) (18) Language
Busschop & De Boever (1983) (9) Unrelated data
Froum et al. (1982) (24) Unrelated data
Hiatt et al. (1978) (33) Mixed data
Periodontal regeneration in intrabony defects
183
Table 3. The 58 human histologic studies included for analysis, categorized into seven biomaterial groups (note thatsome studies are cited in more than one group)
Biomaterial group and author (year) (reference) Biomaterials
Autogenous bone grafts (10 studies)
Zubery et al. (1993) (109) Autograft
Stahl et al. (1983) (95) Autograft
Froum et al. (1983) (25) Autograft
Evans (1981) (20) Autograft
Listgarten & Rosenberg (1979) (42) Autograft
Moskow et al. (1979) (53) Autograft
Hawley & Miller (1975) (31) Autograft
Dragoo & Sullivan (1973) (19) Autograft
Nabers (1972) (55) Autograft
Ross & Cohen (1968) (70) Autograft
Allogeneic bone grafts (7 studies)
Koylass et al. (2012) (41) Mineralized human cancellous bone allograft
Mellonig (2006) (49) Decalcified freeze-dried bone allograft or allogenicdemineralized bone matrix
Froum (1996) (23) Freeze-dried bone allograft
Bowers et al. (1991) (4) Decalcified freeze-dried bone allograft
Bowers et al. (1989) (6) Decalcified freeze-dried bone allograft
Stahl et al. (1983) (95) Decalcified freeze-dried bone allograft
Listgarten & Rosenberg (1979) (42) Decalcified freeze-dried bone allograft
Xenogeneic bone grafts (5 studies)
Hartman et al. (2004) (30) Bovine-derived xenograft
Sculean et al. (2003) (84) Bovine-derived xenograft
Nevins et al. (2003) (57) Bovine-derived xenograft
Camelo et al. (1998) (11) Bovine-derived xenograft
Louise et al. (1992) (43) Coralline
Alloplastic bone grafts (10 studies)
Horv�ath et al. (2013) (34) Hydroxyapatite
Mellonig et al. (2010) (51) Calcium phosphate
Stavropoulos et al. (2010) (100) Beta-tricalcium phosphate
Sculean et al. (2005) (86) Bioglass
Nevins et al. (2000) (58) Bioglass
Froum (1996) (23) HTR
Stahl et al. (1990) (93) HTR
Carranza et al. (1987) (13) Hydroxyapatite
Stahl & Froum (1987) (94) Hydroxyapatite
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184
Table 3. (Continued)
Biomaterial group and author (year) (reference) Biomaterials
Froum & Stahl (1987) (22) Tricalcium phosphate
Barriers (9 studies)
Windisch et al. (2002) (106) Guided tissue regeneration
Sculean et al. (1999) (79) Guided tissue regeneration
Sculean et al. (1999) (80) Guided tissue regeneration
Windisch et al. (1999) (105) Guided tissue regeneration
Parodi et al. (1997) (63) Guided tissue regeneration
Stahl et al. (1990) (93) Guided tissue regeneration
Gottlow et al. (1986) (28) Guided tissue regeneration
Nyman et al. (1982) (60) Guided tissue regeneration
Feingold et al. (1977) (21) Guided tissue regeneration
respect to species (i.e. dog or monkey), study design(i.e. parallel, split-mouth or mixed), materialsutilized (i.e. resorbable and nonresorbable mem-branes, different types of bone grafts/bone substi-tutes, biologics and various combinations thereof),defect and tooth type, selected outcome measuresand healing periods employed. Overall, the resultsdemonstrated that flap surgery, in conjunction withmost of the biomaterials evaluated, either alone orin various combinations, promoted periodontalregeneration to a greater extent than did flap sur-gery without biomaterials. Nevertheless, despitethese positive observations in animal models andthe successful outcomes reported for many of theavailable regenerative techniques and materials inpatients, the extent to which clinical improvementsreflect histologically proven periodontal regenera-tion remains to be determined. This paper presentsa systematic summary of the available histologicalevidence on the effects of reconstructive periodontalsurgery to enhance periodontal wound healing/regeneration in human intrabony defects.
Methods
Development of a protocol
A protocol covering all aspects of the systematicreview methodology was developed before startingthe review. The protocol included: the definition of afocused question; a defined search strategy; studyinclusion criteria; the determination of outcomemeasures; screening methods, data extraction andanalysis; and data synthesis.
Defining the focused question
The focused question was defined as: ‘What is theregenerative effect obtained by using several
biomaterials as adjuncts to surgery in the treatmentof periodontal intrabony defects as evaluated inhuman histological studies?’
Search strategy
The literature was searched for articles published upto and including June 2014 using the MEDLINE data-base. Combinations of search terms were employedto identify appropriate studies (Table 1). Referencelists of review articles were also scanned manually. Inaddition, the reference lists of articles selected forinclusion in the present review were screened.Finally, a hand search of the Journal of DentalResearch, the Journal of Clinical Periodontology, theJournal of Periodontology, the Journal of PeriodontalResearch and The International Journal of Periodon-tics and Restorative Dentistry was performed.
Criteria for study selection and inclusion
The study selection was limited to human histologicalstudies evaluating the effect of nonsurgical or surgicaltreatment, with or without the adjunctive use ofpotentially regenerative materials (i.e. barrier mem-branes, grafting materials, growth factors/proteinsand combinations thereof), for the treatment of peri-odontal intrabony defects. A time limitation of a mini-mum of 6 weeks for the postoperative evaluationperiod was applied. Only studies published in Englishwere considered.
Outcome measure determination
The primary outcome of interest was the formation ofperiodontal tissues following the use of regenerativematerials, as evaluated histologically/histomorpho-metrically. The development of periodontal ligament,cementum and bone, given as linear measurements(in mm) or as a percentage of the instrumented root
Table 3. (Continued)
Biomaterial group and author (year) (reference) Biomaterials
HTR (synthetic bone polymer combining polymethylmethacralate (polyhydroxyethylmethacralate and calcium.
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Table 4. Histologic results of human periodontal defects treated using autogenous bone grafts (10 studies)
Study: authors(year) (ref. no.)
No. ofpatientsNo. ofdefects
Defect typeDefect depth
Healing timeGraft type
Healing type Histological results
Ross & Cohen(1968) (70)
11
1-3 osseous walls6 mm
8 monthsMandibleAlveolar crest
Regeneration Notch was placed at the mostapical extent of the defect. Newcellular cementum, new boneformation and new periodontalligament fibers running parallel to thetooth were present. Bone formationand fibrous tissue around autograftparticles that were under remodeling.Complete defect resolution wasreported
Nabers et al.(1972) (55)
11
3 osseous walls–
57 months–
Regeneration The termination of the root planingwas used as mark. New cellularcementum, new bone formation andnew periodontal ligament fibers werepresent. The graft was fully replaced.Complete defect resolution wasreported
Dragoo & Sullivan(1973) (19)
412
1-2 osseous walls1.4 mm
2–8 monthsIliac crestCancellous
Regeneration One notch at the level of alveolar crestwas placed. New cellular cementum, newbone formation and new periodontalligament fibers running oblique tothe tooth were present. Autograftparticles were not fully replaced.Complete defect resolution wasreported
Hawley & Miller(1975) (31)
11
3 osseous walls–
28 monthsMaxillaAlveolar crest
Regeneration The termination of the root planingwas used as mark. New cellularcementum, bone formation and newfibers of oblique orientation wereobserved. Partial defect resolution wasreported
Moskow et al.(1979) (53)
11
1-3 osseouswalls–
28 weeksMandibleAlveolar crest
Long junctionalepithelium
Osseous repair
No notches were placed. Epitheliumdowngrowth and encapsulated graftparticles by connective tissue andepithelium were noticed. Activeosteogenesis opposite to tooth surfacewas seen. Complete defect resolutionwas reported
Listgarten &Rosenberg(1979) (42)
66
1-3 osseous walls3–7 mm
6–12 monthsAlveolar crestCancellous
Long junctionalepithelium
Regeneration
Notch was placed at the bottom of thedefect. Epithelium downgrowth andencapsulated graft particles byepithelium (exfoliation) werenoticed. Signs of new cementumand bone formation were seen.Partial defect resolution was reported
Evans (1981) (20) 11
2-3 osseous walls–
24 monthsAlveolar crestCoagulum
Regeneration Notch at the level of alveolar crest wasused. Fully regeneration of periodontaltissues was noticed. The graft was fullyreplaced. Complete defect resolutionwas reported
Periodontal regeneration in intrabony defects
187
length (%), were analyzed. Postsurgical alterations inthe periodontal defect size, based upon histomorpho-metric measurements, were also considered. Whenspecific data were reported, defect resolution and fillwere calculated. The nature of healing associatedwith defect resolution was recorded (i.e. completeregeneration, long junctional epithelium, connectivetissue attachment, connective tissue adhesion orosseous repair).
Screening method
The titles and abstracts of the selected studies wereindependently screened by two reviewers (D.N. andG.N.). The screening of titles and abstracts was basedon the following question: ‘Was the study conductedin humans and did it present histological treatmentoutcomes in periodontal intrabony lesions followingthe use of regenerative biomaterials, at least 6 weekspostoperatively?’ The full text of each article wasobtained if the response was ‘yes’ or ‘uncertain’ to thescreening question. Disagreement regarding inclusionwas resolved by discussion between authors. The levelof agreement between reviewers was determinedby kappa scores. The authors of the studies werecontacted to provide missing data where this wasnecessary and feasible.
Data extraction and analysis
Data were extracted on the following: the generalcharacteristics (authors and year of publication);study characteristics (number of patients and defects,tooth type, defect characteristics, intervention strate-gies, evaluation period and outcome measures);methodological characteristics (study design andmethodological quality); and conclusions. There wassubstantial heterogeneity in the data collectedregarding study design, defect type, materials used,evaluation methods, outcome measures and obser-vation periods. Additionally, most of the studies hadeither a split-mouth or a mixed design and did notprovide data on intra-individual variance. Weightedmean differences could not be calculated, and con-sequently it was not possible to perform a quantita-tive data synthesis leading to a meta-analysis.Therefore, the mean and standard deviation, the95% confidence intervals and the statistical signifi-cance were determined and extracted from thereviewed articles. These data were summarized inseparate tables based upon the various types ofbiomaterials/interventions employed. Furthermore,the results of the studies that used similar outcomemeasurements were combined and the data arepresented graphically.
Table 4. (Continued)
Study: authors(year) (ref. no.)
No. ofpatientsNo. ofdefects
Defect typeDefect depth
Healing timeGraft type
Healing type Histological results
Froum et al.(1983) (25)
13
2-3 osseous walls2–5 mm
24 weeksAlveolarOsseousCoagulum
Long junctionalepithelium
Regeneration
Two notches at the level of alveolar crestand the base of the defect were placed.Citric acid was applied on the teeth.Long junctional epithelium coronallyand regeneration of periodontal tissuesapically were noticed. Encapsulatedgraft particles were seen.Partial defect resolution was reported
No notches were placed. Citric acid wasapplied on the teeth. Long junctionalepithelium coronally and regenerationof periodontal tissues apically wereobserved. Limited osteogenesis of thegraft particles was seen. Partial defectresolution was reported
Zubery et al.(1993) (109)
11
1-3 osseous walls5 mm
8 monthsMaxillaryOsseousSwaged graft
Long junctionalepithelium
Connectivetissue adhesion
Osseous repair
No notches were placed. Tetracycline wasapplied on the tooth surface. Longjunctional epithelium coronally,connective tissue adhesion apicallyand osteogenesis were found.Encapsulated graft particles wereobserved.Partial defect resolution was reported
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188
Results
Data extraction after literature searching
The MEDLINE literature search resulted in 162 poten-tially relevant publications (Fig. 1). After the firstselection step, based upon the title and abstract ofthe collected studies, 62 articles were included for fur-ther analysis (inter-reader agreement k = 0.98). Handsearching identified a further 22 articles that wereadded at this stage, resulting in a total of 84 selectedstudies. Finally, based upon text screening, 26 articleswere excluded (the reasons for exclusion are pre-sented in Table 2), and 58 publications, completelyfulfilling the inclusion criteria, were selected for thereview (inter-reader agreement k = 0.97). These arepresented in Table 3 and grouped according to rele-vant biomaterial/intervention.
Data analysis of the regenerative effect ofeach biomaterial/intervention
Seven biomaterial/intervention types – autografts,allogenic bone, xenogeneic bone, alloplastic materi-als, barriers, growth factors and biological factors(and combinations thereof) – were reported. Auto-grafts are tissues transferred from one part of a
person’s body to another part of the same person;allogenic bone is bone harvested from geneticallydistinct individuals within the same species; xenoge-neic bone is that harvested from a species geneticallydifferent from humans; and alloplastic materials arebiological materials that are synthesized or chemi-cally processed.
The nature of healing in the treated defects follow-ing regenerative therapy was defined as follows: longjunctional epithelium (epithelial downgrowth cover-ing the treated tooth surface); connective tissueattachment (new cementum with inserting collagenfibers on the treated tooth surface but not connectedto new bone); connective tissue adhesion (connectivetissue contact to the root without apparent cemen-tum formation); regeneration (new cementum withinserting fibers functionally oriented and new bone);and osseous repair (bone formation opposite thetooth surface, leading to defect filling but withoutapparent periodontal ligament formation). Histologicdata were included in tables, reporting, for eachselected study, the following items: author name,publication date, number of patients, number ofdefects, number of osseous walls, defect depth,healing period, biomaterial type, healing type andhistological results (Tables 4–18). Additionally, histo-morphometric data were analyzed by reporting the
Table 5. Histomorphometric results of human periodontal defects treated using autogenous bone grafts
Study* Toothnotation
Defectdepth(mm)
Osseouswalls
Collagenfiberson toothsurface(mm)
Newcementum(mm)
New bone(mm)
Longjunctionalepithelium(mm)
Healing type
Dragoo & Sullivan(1973) (19)
4 teeth 1.4 1-2 3.1 3.1 2.1 1.3 Regeneration
1.4 1-2 3.1 3.1 2.1 1.3 Regeneration
1.4 1-2 3.1 3.1 2.1 1.3 Regeneration
1.4 1-2 3.1 3.1 2.1 1.3 Regeneration
Listgarten &Rosenberg(1979) (42)
Mesial 5.2 1 0 0 0.8 3.6 Long junctional epithelium
*Only 2 of the 10 studies given in Table 4 provided appropriate histomorphometric data, which are presented here.
Periodontal regeneration in intrabony defects
189
Table 6. Histologic results of human periodontal defects treated using allogeneic bone grafts (7 studies)
Study: authors(year) (ref. no.)
No. ofpatientsNo. ofdefects
Defect typeDefect depth
Healing timeGraft type
Healing type Histological results
Listgarten &Rosenberg(1979) (42)
66
1-3 osseous walls3–6.5 mm
6–12 months–
Long junctionalepithelium
Connective tissueattachment
Osseous repair
Notch was placed at thebottom of the defect.Epithelium downgrowth,new cementum and newbone formation werepresent. Graft particlesencapsulated byepithelium or connectivetissue were reported.Partial defect resolutionwas noticed
Stahl et al. (1983) (95) 11
2 osseous walls–
12 monthsDecalcifiedfreeze-driedbone allograft
Long junctionalepithelium
Regeneration
Notches at the gingivalmargin and the mostapical extent of calculus.Long junctionalepithelium was present.Apically, new cementum,new periodontal ligamentand limited osteogenesiswere noticed. Graftparticles encapsulated byepithelium were seen.Partial defect resolutionwas reported
Bowers et al.(1989) (5, 6)
1232
1-3 osseous walls6.9 mm
6 monthsDecalcifiedfreeze-driedbone allograft
Regeneration (68%)Connective tissueattachment
Long junctionalepithelium
Notches at the level ofalveolar crest and themost apical extent ofcalculus. New cellularcementum, parallel orperpendicular newperiodontal ligamentfibers and bone formationwere noticed. Graftparticles were not oftenobserved
Bowers et al.(1991) (4)
611
1-3 osseous walls5.3 mm
6 monthsDecalcifiedfreeze-driedbone allograft
Regeneration (95%)Long junctional epithelium
Notches at the level ofalveolar crest and themost apical extent ofcalculus. New cellularcementum, periodontalligament fibers and boneformation were observed
Froum (1996) (23) 13
Circumferential3–4 mm
30 monthsDecalcifiedfreeze-driedbone allograft
Long junctional epithelium Notches at the gingivalmargin and the mostapical extent of calculus.Long junctionalepithelium was present.No evidence of graftparticles and osteogenesis.Partial defect resolutionwas reported
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190
amount of new cementum and bone formation, andalso collagen fibers and junctional epithelium on thetooth surface, as linear measurements (in mm).
Regenerative effect of autogenous bone
Ten studies providing data on the effect of autoge-nous bone grafting in intrabony defects were identi-fied. Histologic and histomorphometric results ofthese studies are summarized in Tables 4 and 5,respectively. Five of the 10 studies reported completeregeneration of the periodontal tissues (i.e. the entiredefect) (19, 20, 31, 55, 70), three studies noticed a longjunctional epithelium (25, 42, 95) coronally and peri-odontal regeneration apically and two studiesobserved only long junctional epithelium and osseousrepair (53, 109). Autograft particles were not fullyreplaced in six studies and were encapsulated in boneor connective tissue in five studies depending uponthe healing observation period, graft source and typeof healing (Tables 4 and 5). Fifty percent of studiesrevealed complete defect resolution, and no remark-able inflammation was described. However, in fivestudies, root notches were not placed before treat-ment, and the absence of a fixed landmark may callinto question the results because the histologicalregion of interest was not necessarily identifiable(Tables 4 and 5). Only two of the 10 studies providedhistomorphometric data and included a total of 10defects; in 80% of the defects partial or complete
regeneration was observed. The mean defect depthwas 3.0 mm, and both cementum and bone forma-tion were 1.9 mm when calculated in a linear manner(along the tooth surface).
Regenerative effect of allogeneic bone
Seven studies providing data on the effect of alloge-neic bone grafting in intrabony defects were identi-fied. The histologic and histomorphometric results ofthese studies are summarized in Tables 6 and 7,respectively. Two studies reported almost completeperiodontal regeneration (4, 49); six studies observeda combination of long junctional epithelium and peri-odontal regeneration/connective tissue attachment(4–6, 41, 42, 95); and one study observed a reparativetype of healing characterized by long junctional epi-thelium (23). Two of the studies reported that graftparticles were not completely replaced and remainedencapsulated within connective tissue. No histologi-cal study to date has demonstrated or reportedcomplete defect resolution, but equally none hasreported any significant inflammation. Five studiesprovided histomorphometric data involving a total of31 defects; 70% of the defects demonstrated signs ofpartial periodontal regeneration but none reportedcomplete regeneration. The mean defect depth atsurgery was 6.0 mm, and cementum and bone forma-tion (given in linear measurements) of 1.3 and1.8 mm, respectively, were noted.
Table 6. (Continued)
Study: authors(year) (ref. no.)
No. ofpatientsNo. ofdefects
Defect typeDefect depth
Healing timeGraft type
Healing type Histological results
Mellonig (2006) (49) 33
2-3 osseous walls–
6 monthsAllogenicdemineralizedbone matrix
RegenerationConnective tissue adhesion
Notch at the most apicalextent of calculus.New cellular cementum,parallel or perpendicularnew periodontal ligamentfibers and bone formationwere noticed. Connectivetissue adherence, in onecase, was seen. Partialdefect resolutionwas reported
Notch at the apical extentof the calculus. Newcellular cementum,parallel or perpendicularnew periodontal ligamentfibers and bone formationwere noticed
Periodontal regeneration in intrabony defects
191
Regenerative effect of xenogeneic bone
At the time of writing, five studies had provided dataon the effect of xenogeneic bone grafting in intrabonydefects. The histologic and histomorphometric resultsof these studies are summarized in Tables 8 and 9,respectively. Of the five studies, three reportedperiodontal regeneration (11, 57, 84), one describedthe combination of long junctional epithelium andperiodontal regeneration/connective tissue attach-ment (30), and one, using coralline hydroxyapatite,
did not provide any information on the healing out-come (43). Graft particles were partially encapsulatedwithin connective tissue in two studies, and all stu-dies reported bone formation in contact with graftparticles. None of the studies described or reportedcomplete defect resolution, and no information on thedegree of inflammation was provided. Four studiesprovided histomorphometric data for a total of 11defects. Partial periodontal regeneration was observedin 73% of the defects, but none showed complete
Table 7. Histomorphometric results of human periodontal defects treated using allogeneic bone grafts
12x and 6x are given in italics because there were 12 and 6 defects, respectively. As the author reported mean values and not single values per defect, the mean valuecontributed in a 12-fold and 6-fold manner, respectively, to the final result.*Five of the 7 studies given in Table 6 provided appropriate histomorphometric data, which are presented here.
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192
regeneration. The mean defect depth was 6.6 mm, andcementum and bone formation (expressed in linearmeasurements) were 2.4 and 2.3 mm, respectively.
Regenerative effect of alloplasticsubstitutes
Ten studies provided data on the effect of the implan-tation of alloplastic materials in intrabony defects.The histologic and histomorphometric results ofthese studies are summarized in Tables 10 and 11,respectively. The healing was predominantly charac-terized by a long junctional epithelium and connec-tive tissue encapsulation of the graft particles.Periodontal or cementum regeneration was usuallylimited to the apical parts of the defects (Fig. 2).Despite prolonged healing periods of 18–30 months,all studies reported the presence of biomaterial/graftparticles, which were surrounded by fibrous tissue.
Bone formation around graft particles was very limi-ted and only occasionally reported. No studiesreported complete defect resolution, and remarkablylittle inflammation was described. Additionally,notches were employed for reference in all studiesexcept one. Five studies provided histomorphometricdata on 23 defects. Partial periodontal regenerationwas observed in 34% of the defects, but none demon-strated complete regeneration. The mean defectdepth was >4 mm at baseline, with linear measure-ments of cementum and bone formation being 0.6and 0.4 mm, respectively.
Regenerative effect of guided tissueregeneration
We identified nine studies presenting data on theeffect of guided tissue regeneration in intrabonydefects, and the histologic and histomorphometeric
Table 8. Histologic results of human periodontal defects treated using xenogeneic bone grafts (5 studies)
Study: authors(year) (ref. no.)
No. ofpatientsNo. ofdefects
Defect typeDefect depth
Healing timeGraft type
Healing type Histological results
Hartman et al.(2004) (30)
25
1-2 osseous walls5–8 mm
6 monthsBone mineralmatrix
Long junctionalepithelium
Connectivetissueattachment
Regeneration
Notch was placed at the apical extent ofcalculus.
Root conditioning (tetracycline)was applied.
New cellular cementum was noticed.Encapsulated biomaterial particles and/orbone formation around biomaterialparticles was seen.
All types of healing were observed
Sculean et al.(2003) (84)
11
1-2 osseous walls–
6 monthsBone mineralmatrix
Regeneration Notches were placed at the most apicalextent of the defect and at the level ofthe alveolar crest.
New cellular cementum with insertingcollagen fibers was reported.
Bone formation around graft particleswas found
Nevins et al.(2003) (56)
22
2-3 osseous walls5–6 mm
9 monthsBone mineralmatrix
Regeneration Notch was placed at the apical extent ofcalculus.
Root conditioning (tetracycline) was applied.Bone formation around graft particleswas evident.
New cellular cementum was noticed
Camelo et al.(1998) (11)
22
3 osseous walls6 mm
6–9 monthsBone mineralmatrix
Regeneration No notches were placed.New cellular cementum was noticed.Encapsulated biomaterial particles and/orbone formation around biomaterialparticles was seen
Louise et al.(1992) (43)
44
2-3 osseous wallsModerate/severeintrabony defects
6–36 monthsCorallinehydroxyapatite
Not reported No notches were placed.New bone formation around biomaterialparticles was reported
Periodontal regeneration in intrabony defects
193
results of these studies are summarized in Tables 12and 13, respectively. Five of the nine studiesreported periodontal regeneration (63, 79, 80, 105,106) (Fig. 3), one described a combination of longjunctional epithelium formation and connective tis-sue attachment (93) and three provided evidence ofnew connective tissue attachment (21, 28, 60).Interestingly, all studies that employed collagen bar-riers reported periodontal regeneration, and no col-lagen barrier remnants were observed after5 months of healing. Two studies revealed completedefect resolution, but no data were reported oninflammatory reactions or infiltrates. Additionally,in two studies, notches were not placed. Eight stud-ies provided histomorphometric data encompassinga total of 20 defects. Seventy-five percent of thedefects showed either partial or complete periodon-tal regeneration. The mean defect depth was5.1 mm, with 2.6 and 1.7 mm of cementum andbone formation respectively (as expressed by linearmeasurements).
Regenerative effect of biological agents
Of the eight studies reporting data on the efficacy ofbiological factors in intrabony defects, all utilizedenamel matrix derivative (Tables 14 and 15). The his-
tologic and histomorphometric results of these stu-dies are summarized in Tables 14 and 15, respectively.All studies except one reported a healing character-ized predominantly by periodontal regeneration and/or connective tissue attachment (44, 48, 78, 80, 87,106, 108) (Fig. 4), while one study showed the forma-tion of a long junctional epithelium (64). No studiesreported complete defect resolution, and no remark-able inflammation was described. In all studies, refe-rence notches were placed on the root surfaces. Sixstudies provided histomorphometric data for a totalof 29 defects; in 45% of the defects, partial periodon-tal regeneration was observed. The mean defectdepth was 4.8 mm, and cementum and bone forma-tion (as expressed in linear measurements) were 1.3and 0.6 mm, respectively.
Regenerative effect of combinationtechniques
Twenty studies provided data on the effect of usinga combination of regenerative techniques. Thehistologic and histomorphometeric results of thesestudies are summarized in Tables 16 and 17, respec-tively. In most studies the healing was predominantlycharacterized by periodontal regeneration and/or for-mation of a connective tissue attachment. Formation
Table 9. Histomorphometric results of human periodontal defects treated using xenogeneic bone grafts
Long junctional epithelium with nosigns of regeneration was reported
Periodontal regeneration in intrabony defects
195
of long junctional epithelium was limited and gene-rated located to the most coronal part of the defect.The most frequently utilized graft material was ofbovine origin. Graft particles were present in all stu-dies, irrespective of the healing period (up to 5 years)employed, and were surrounded by either bone orfibrous tissue (Fig. 5). Bone formation around thegraft particles varied widely among the studies andwas related to the type of graft material used. Nostudy reported complete defect resolution, and noinflammation worthy of note was described. Addi-tionally, notches were used in all studies except four.Thirteen studies provided histomorphometric datafor a total of 74 defects. In 75% of the defects, partialperiodontal regeneration was observed. The meandefect depth was more than 6.1 mm at baseline, andformation of cementum and bone (analyzed by linearmeasures) was 1.9 mm for both parameters.
Data synthesis
In order to derive summary measures of the histologi-cal outcomes of studies employing the same methodsof evaluation and similar outcome measures, the datafrom these studies were collated and averaged andare illustrated in Table 18 and Figs 6 and 7. The meanvalues of periodontal regeneration, expressed as‘means of new cementum with inserting periodontalligament fibres’ and ‘new bone’, were calculated aslinear measurements based upon relevant data. Thelength of any new cementum layer, presented as apercentage of the defect depth for comparison, ran-ged from 15% to 63%. The linear length of new bonealso ranged from 13% to 63%. Additionally, the per-centage of treated defects demonstrating complete orpartial regeneration was estimated (Tables 4–17) andis presented in Fig. 7. Periodontal regeneration, in
Table 10. (Continued)
Study: authors(year) (ref. no.)
No. ofpatientsNo. ofdefects
Defect typeDefect depth
Healing timeGraft type
Healing type Histological results
Sculean et al.(2005) (86)
33
1-3 walls4–6 mm
6 monthsBioglass
Long junctionalepithelium
Regeneration
Notch was placed at the most apicalextent of calculus.
Epithelial downgrowth, connectivetissue encapsulation of the graftmaterial and limited regenerationat the most apical part of one defectwere reported
Stavropouloset al. (2010) (100)
55
1-2 osseous walls≥4 mm
6 monthsBeta-tricalciumphosphate
RegenerationConnective tissueadhesion
Notch was placed at the most apicalpart of the defect.
New cellular cementum withinserting, functionally orientedcollagen fibers were reported.
Connective tissue adhesion in threecases and new bone formation infour cases were noticed.
Graft particles were present,surrounded by fibrous tissue withperipheral bone formationoccasionally
Mellonig et al.(2010) (51)
44
Vertical osseousdefects>4 mm
6 monthsCalciumphosphatecement
Long junctionalepithelium
Notch was placed at the most apicalextent of calculus.
Poor wound healing was observed.Encapsulated graft particles with noregeneration were reported
Horvath et al.(2013) (34)
66
1-2 osseous walls3.5 mm
7 monthsNano-hydroxyapatite
Long junctionalepithelium
Notch at the base of the defect.No ankylosis or root resorption.Graft particles were surrounded byconnective tissue in two of sixspecimens.
Limited regeneration
HTR, synthetic bone polymer combining polymethylmethacralate, polyhydroxyethylmethacralate and calcium.
Sculean et al.
196
terms of the percentage of maximal potential treat-ment outcomes, ranged from 34% to 80%.
Discussion
The results of the present systematic review indicatethat periodontal regeneration in human intrabonydefects can be achieved to a variable extent using avariety of methods and materials. Periodontal regene-ration was observed after the use of a variety of bonegrafts and substitutes, guided tissue regeneration,biological factors and combinations thereof. Surpri-singly, the amount of periodontal regeneration (i.e.new cementum with inserting fibers functionally
oriented and new bone) was rather similar among thevarious treatments (the average values ranged from1.3 to 2.3 mm), except for alloplastic materials andbiological factors used as monotherapies, whichshowed limited amounts of periodontal regeneration(the average values were 0.4 and 0.6 mm, respec-tively), despite a large range (3.0–6.6 mm) in pretreat-ment intrabony defect depth. This finding appearsto contrast with observations made in clinical studieson regenerative periodontal therapy, in whichdeep defects showed more clinical attachment gainand radiographic bone fill compared with shallowdefects (18).
Another interesting observation made in thisreview is that, in the majority of cases, the amount
Table 11. Histomorphometric results of human periodontal defects treated using alloplastic materials
Mean (in mm) >4 0.1 � 0.1 0.6 � 0.8 0.4 � 0.6 2.9 � 1.4 34% regeneration
*Five of the 10 studies given in Table 10 provided appropriate histomorphometric data, which are presented here.
Periodontal regeneration in intrabony defects
197
Table 12. Histologic results of human periodontal defects treated using guided tissue regeneration (9 studies)
Study: authors(year) (ref. no.)
No. ofpatientsNo. ofdefects
Defect typeDefect depth
Healing timeGraft type
Healing type Histological results
Feingold et al.(1977) (21)
414
1-2 wallsShallow broadcraters
12–28 weeksScleral barrier
Connectivetissue attachment
No notches were placed.Findings included new cementumat tooth nicks, dense connectivetissue formation, no evidence ofepithelial downgrowth orosteogenesis and complete repair
Nyman et al.(1982) (60)
11
1-3 walls2 mm
3 monthsTeflon barrier
Connectivetissue attachment
Notch at the level of alveolar crestwas placed.
New cementum and newinserting fibers, but no coronalbone overgrowth, were noticed.
Complete defect resolution wasreported
Gottlow et al.(1986) (28)
22
Extensive periodontaldestruction
3 monthsTeflon barrier
Connective tissueattachment
Root-planed surface served asreference mark.
New cementum and new fiberattachment were noticed.
No bone regrowth was reported
Stahl et al.(1990) (93)
22
1-2 walls4.5–5 mm
14–30 weeksTeflon barrier
Long junctionalepithelium
Connectivetissue attachment
Two notches at the gingival marginand at the most apical extent ofcalculus were placed.
Defect resolution was achievedby the combination of longjunctional epithelium and newattachment apically
Parodi et al.(1997) (63)
11
Circumferential3.5 mm
5 monthsCollagen barrier
Regeneration Two notches at the gingivalmargin and at the level of thealveolar crest were placed.
New cellular cementum, newperiodontal ligament fibersperpendicular to tooth and boneformation were reported.
No collagen traces were observedComplete defect resolution wasseen
Sculean et al.(1999) (79)
22
Circumferential 6 monthsCollagen barrier
Regeneration Two notches at the level of thealveolar crest and at the bottomof the defect were placed.
New cellular cementum, newperiodontal ligament fibersperpendicular to tooth and boneformation were reported
Sculean et al.(1999) (80)
77
Advanced angulardefects
6 monthsCollagen barrier
Regeneration Two notches at the level of thealveolar crest and at the mostapical extent of calculus or thebottom of the defect were placed.
New cellular cementum, newperiodontal ligament fibersperpendicular to tooth and boneformation were reported
Sculean et al.
198
of new cementum formation, in terms of height,was either larger than or equal to that of the newbone (83 and 46, respectively, of 198 histologicalcases). Also, the observation that a long junctionalepithelium was not necessarily formed in nonguidedtissue regeneration cases supports the notion thatnew connective tissue attachment formation maynot depend primarily on physical exclusion of epi-thelial downgrowth (e.g. the guided tissue regenera-tion principle) and that wound stability and spaceprovision are of paramount importance for unfol-ding the innate regenerative potential of the peri-odontium. It also supports the notion that bone isthe most ‘sensitive’ tissue within the periodontium,and that the majority of available bone grafts andsubstitute materials are merely osteocompatiblerather than osteoconductive, in the sense ofenhancing bone formation. Indeed, several preclini-cal in vivo experiments and human biopsies haveshown that bone-substitute materials may actuallydelay, rather than accelerate, bone formation whenspace provision is assured (2, 13, 102, 103). On theother hand, a recent pre-clinical in vivo study indi-cated that given enough time for tissue remodelingand maturation, even very large periodontal defectsgrafted with a bone substitute by guided tissueregeneration showed complete regeneration (36).Thus, the reduced amount of bone formationobserved in several biopsies may simply be theresult of a less-than-adequate healing time.
Amongst the criteria established by the AmericanAcademy of Periodontology at the World Workshopin Periodontics in 1996 to evaluate regenerativeperiodontal procedures, was the existence of human
histologic specimens, ideally obtained from rando-mized controlled trials and demonstrating the forma-tion of cementum, bone and periodontal ligamentcoronal to a notch in the root, in calculus or at thegingival margin. The present systematic review iden-tified only a single randomized controlled trial thatprovided human histologic data following regenera-tive treatment of intrabony defects with growth dif-ferentiation factor-5 coated onto beta-tricalciumphosphate particles (99), whereas the remainder ofthe reported studies utilized data obtained fromonly few patient case series. Theoretically, humanhistological data from randomized controlled trialsshould provide the most convincing evidence forthe potential of a procedure to facilitate periodontalregeneration; however, such studies are extremelydifficult and costly to conduct. Moreover, humanhistological studies may raise ethical concerns, giventhe need for biopsy in otherwise healthy/healing tis-sues and the fact that some form of patient com-pensation is provided, and this may be regarded as‘coercion’ to participate. Patients participate in suchstudies after receiving verbal and written informa-tion about the aims and procedures involved andthe consequences of those procedures, and afterhaving provided written informed consent. More-over, in most of the studies identified, ethicalapproval from the relevant authorities was obtained.In contrast to human studies, a large sector of soci-ety has difficulties understanding why it is moreethical to kill a dog or a monkey, animals unable toprovide informed consent before participating inthe ‘experiment’, to evaluate periodontal regenera-tion. Indeed, the core principle underpinning the
Table 12. (Continued)
Study: authors(year) (ref. no.)
No. ofpatientsNo. ofdefects
Defect typeDefect depth
Healing timeGraft type
Healing type Histological results
Windisch et al.(1999) (105)
11
Advanced angulardefect
6 monthsCollagen barrier
Regeneration Notch at the bottom of the defectwas placed.
New cellular cementum, newperiodontal ligament fibers andosteogenesis were reported
Windisch et al.(2002) (106)
44
1-3 walls3–7 mm
6 monthsCollagen barrier
Regeneration Two notches at the level of alveolarcrest and at the most apical extentof calculus or the bottom of thedefect were placed.
New cellular cementum, newperiodontal ligament fibersperpendicular to tooth and boneformation were reported
Periodontal regeneration in intrabony defects
199
difference between ‘experimentation’ and ‘research’is the importance of obtaining informed consent inthe latter, something missing in the former. No ani-mal models provide an anatomic and physiologicenvironment identical to that of the human, withvariations between species, including anatomy anddimensions of the teeth and alveolar processes,amount and character of the gingiva, local physio-logic environment, behavior, healing rate, as well assusceptibility to periodontitis. Therefore, translation
of results from animal ‘experiments’ to the humansituation is always problematic.
By contrast, it should be stressed that informationobtained from human histological case reports shouldnot be accepted without critical evaluation andappraisal, and the findings must always be interpretedwith care. When evaluating the outcome of regenera-tive procedures in human biopsies, one has to bear inmind the fact that the harvesting procedure itselfplays an important role in unbiased evaluation of the
Table 13. Histomorphometric results of human periodontal defects treated using guided tissue regeneration
Mean (in mm) – 5.1 � 2.5 – 3.1 � 2.1 2.6 � 1.6 1.7 � 1.3 – 75% regeneration
*Eight of the 9 studies given in Table 12 provided appropriate histomorphometric data, which are presented here.
Sculean et al.
200
results. Obviously, with the exception of the dexterityand experience of the operating surgeon, anatomic(the presence of neighboring teeth and a narrow vs. awide interproximal space), esthetic (anterior vs. pos-terior region) and prosthetic (need to extract vs. need
to preserve part of the tooth) concerns dictate thespatial origin and volume (i.e. the biopsy representsall or part of the original intrabony defect, includingthe defect bone wall) and the amount of harvestedperiodontal tissue available for evaluation.
Table 14. Histologic results of human periodontal infrabony defects treated using biological agents (8 studies)
Study: authors(year) (ref. no.)
No. ofpatientsNo.of defects
DefecttypeDefectdepth
Healing timeFactor type
Healing type Histological results
Sculean etal. (1999) (80)
77
––
6 monthsEnamelmatrixderivative
Long junctionalepithelium
Connective tissueattachment
Regeneration
Two notches at the most apical extent of the defector calculus and at the level of the alveolar crestwere placed.
Root surface conditioning(ethylenediaminetetraacetic acid) was applied.
New cellular cementum, new periodontalligament and new bone were observed
Mellonig (1999)(48)
11
3 walls5 mm
6 monthsEnamelmatrixderivative
Regeneration Notch at the most apical extent of calculus wasplaced.
Root surface conditioning(ethylenediaminetetraacetic acid) was applied.
New acellular cementum, new periodontalligament and new bone were observed
Yukna &Mellonig(2000) (108)
810
1-3 walls3–10 mm
6 monthsEnamelmatrixderivative
Long junctionalepithelium
Connective tissueattachment
Regeneration
Notches at the most apical extent of calculus, thedefect base and the level of alveolar crest wereplaced.
Root surface conditioning (citric acid) was applied.New cellular or accelular cementum, newperiodontal ligament and new bone were observed
Sculean etal. (2000) (78)
22
1-2 walls–
6 monthsEnamelmatrixderivative
Connective tissueattachment
Regeneration
Notches at the most apical extent of defect and atthe level of alveolar crest were placed.
Root surface conditioning(ethylenediaminetetraacetic acid) was applied.
New cellular or accelular cementum, newperiodontal ligament and new bone were observed
Parodi etal. (2000) (64)
22
1-2 walls–
6–9 monthsEnamelmatrixderivative
Long junctionalepithelium
Notch at the most apical extent of defect was placed.Root surface conditioning(ethylenediaminetetraacetic acid) was applied.
No regeneration was reported
Windisch et al.(2002) (106)
66
1-2 walls3–8 mm
6 monthsEnamelmatrixderivative
Long junctionalepithelium
Connective tissueattachment
Regeneration
Notches at the most apical extent of defect orcalculus and at the level of alveolar crest wereplaced.
Root surface conditioning(ethylenediaminetetraacetic acid) was applied.
New cementum, new periodontal ligament andnew bone were observed
Sculean et al.(2003) (87)
1010
––
6 monthsEnamelmatrixderivative
Long junctionalepithelium
Connective tissueattachment
Regeneration
Notch at the most coronal level of gingival was placed.Root surface conditioning(ethylenediaminetetraacetic acid) was applied.
Reparative cementum was reported
Majzoub et al.(2005) (44)
11
1-3 walls8.5 mm
9 monthsEnamelmatrixderivative
Regeneration Notch at the most apical extent of calculus was placed.Orthophosphoric acid as root conditioner wasapplied.
New cellular cementum, new periodontal ligamentand new bone were observed
Periodontal regeneration in intrabony defects
201
Table 15. Histomorphometric results of human periodontal infrabony defects treated using biological agents
An important parameter that may introduce biasduring the histological evaluation, and that needsconsideration for a balanced interpretation of thehealing outcome, and/or fair comparisonsbetween treatment modalities, relates to the varia-tion in morphological characteristics and dimen-sions of naturally developing periodontal defects.For instance, healing of deep three-walled intrabonylesions and deep dehiscence or gingival recessiondefects appears to be greatly influenced by vascularand cellular resources from the periodontal liga-ment, alveolar bone and gingiva circumscribing thedefect (Fig. 8). In contrast, it is obvious that the dis-tribution and contribution of tissue resources is dra-matically altered and reduced in two- and one-walled intrabony defects, Class II and III furcations,and horizontal bone defects. Such an assumption issupported by observations made in an experimentalstudy in dogs, using box-type intrabony defects,in which larger amounts of periodontal regenera-tion were observed as the number of bone wallsincreased (40).
Indeed, defect dimensions appear to be animportant factor in predicting healing outcomes inthe clinical situation, following both conventionalsurgical therapy, in which wide defects respondedwith less bone gain compared with narrow defects(101), as well as following periodontal regenerativesurgery, in which better clinical outcomes (i.e. lar-ger clinical attachment level gain and bone fill) areachieved in deep, narrow intrabony defects com-pared with wide, shallow defects (16). Regenerationin shallow defects may be antagonized to a greaterextent by microbial factors or epithelial down-growth than regeneration in deep defects. Never-theless, it should also be recognized that thenumber of bone walls present preoperatively doesnot appear to influence the treatment outcomes, interms of clinical measurements, following conven-tional (66) or regenerative (97, 98, 102, 103) peri-
odontal surgery. Finally, irrespective of the type ofperiodontal defect, the amount and character ofresidual gingiva is critical for achieving passive flapadaptation and wound closure for primary inten-tion healing. For example, in one clinical study itwas observed that sites with a tissue thickness buc-cally of ≤1 mm presented statistically significantgreater recession, 6 months after regenerative treat-ment, than sites with tissues thicker than 1 mm (1).Indeed, the need for full soft-tissue coverage of awound to a level above the cemento–enamel junc-tion following regenerative surgery is often over-looked, largely because of failure to regeneratethose soft tissues at the same time as the hard-tis-sue regenerative surgery.
Taking into consideration the above limitations,when evaluating the outcomes of regenerative pro-cedures in human biopsies, one has to bear in mindthe fact that large amounts of regeneration may notnecessarily arise as a result of the strong biologicpotential of a technique or material but rather mayreflect biases arising from the method of biopsyharvesting or histological evaluation. For example,sections representing areas close to the originalbone walls of an intrabony defect would probablydemonstrate a better regenerative response thanmore peripheral (i.e. furthest from the bone wall)sections (Fig. 9). This is exemplified by the observa-tions of Paolantonio et al. (61), who took a corebiopsy from the interdental area of a site treated8 months earlier with a deproteinized bovine bonesubstitute and a collagen membrane and found thatsome periodontal regeneration had occurred in thevicinity of the pre-existing lingual alveolar plateonly, and that the majority of the defect space wasoccupied by deproteinized bovine bone particlesembedded in connective tissue.
In contrast, a lack of periodontal regeneration maysimilarly not necessarily indicate absence of the bio-logical potential of a technique or material, but may
Mean (in mm) – 4.8 � 2.4 – 2.5 � 1.6 1.3 � 1.5 0.6 � 1.0 – 45% regeneration
*Six of the 8 studies given in Table 14 provided appropriate histomorphometric data, which are presented here.
Periodontal regeneration in intrabony defects
203
Tab
le16
.Histologicresu
ltsofh
uman
periodontald
efects
trea
tedusingco
mbinationtech
niques
(20studies)
Study:
authors
(yea
r)(ref.
no.)
No.o
fpatients
No.o
fdefects
Defecttype
Defectdep
thHea
lingtime
Biomaterials
Hea
lingtype
Histologica
lresults
Moskow
&Lu
barr(198
3)(54)
1 1Exten
sive
periodontald
efects
9wee
ksAutograft+
hyd
roxyap
atite
Eve
ntfulh
ealin
gNonotches
wereplaced.E
nca
psu
latedhyd
roxyap
atiteparticles
inco
nnective
tissuean
dac
tive
osteo
genesisonly
onau
tograft
particles
wereobserved
Bowerset
al.
(198
5)(7)
2 61-3osseo
uswalls
5–10
mm
6months
Decalcified
free
ze-dried
boneallograft+barrier
Longjunctional
epithelium
Reg
eneration
Notches
atthemost
apical
extentofthedefectan
dat
theleve
lofthealve
olarcrestwereplaced.F
ourdefects
showed
sign
sof
rege
nerationan
dtw
odefects
showed
longjunctional
epithelium.
Graftparticles
wereinco
rporatedin
new
boneorsu
rrounded
byco
nnective
tissue
Stah
l&Froum
(199
1)(90)
2 41-2osseo
uswalls
Dee
pintrab
ony
defects
5–6wee
ksDecalcified
free
ze-dried
bone
allograft+barrier
Longjunctional
epithelium
Reg
eneration
Notches
atthegingiva
lmarginan
dthemost
apical
extentof
calculuswereplaced.T
hreedefects
showed
limited
sign
sof
cemen
toge
nesis,o
steo
genesisan
dfunctionally
inserted
fibers.
Onedefectexhibited
longjunctional
epithelium
Bowerset
al.
(199
1)(4)
6 141-3osseo
uswalls
7mm
6months
Decalcified
free
ze-dried
bone
allograft+osteo
genin
Longjunctional
epithelium
Reg
eneration
Twonotches
atthealve
olarcrestan
dat
themost
apical
extentof
calculuswereplaced.N
ewcellu
larcemen
tum,n
ewperiodontal
ligam
entfibersan
dosteo
genesisin
78%
oftheca
ses
Cam
ello
etal.
(199
8)(11)
2 22-3osseo
uswalls
7mm
7–9months
Bovinederived
xenograft+barrier
Reg
eneration
Nonotches
wereplaced.R
egen
erationofp
eriodontaltissu
eswas
reported
.Graftparticles
wereinco
rporatedin
new
boneorwere
surrounded
byco
nnective
tissueco
ronally.Colla
genmem
brane
was
partially
resorbed
Mellonig
(200
0)(50)
4 41-3osseo
uswalls
6–10
mm
4–6months
Bovine-derived
xenograft+barrier
Longjunctional
epithelium
Reg
eneration
Notchat
theap
ical
extentofc
alcu
luswas
placed.Inthreeca
ses,
new
cellu
larcemen
tum,n
ewperiodontalligam
entfibers
perpen
dicularorparalleltothetooth
surfac
ean
dosteo
genesis
withgraftparticles
inco
rporatedin
new
bone
werereported
.In
oneca
se,longjunctional
epithelium
withen
capsu
lated
biomaterialp
articles
was
seen
Cam
ello
etal.
(200
1)(10)
3 33osseo
uswalls
6–7mm
9months
Autograft+
bovine-derived
xenograft+barrier
Reg
eneration
Notchat
thebaseofthedefectwas
placed.R
ootsu
rfac
eco
nditioning(tetracycline)
was
used.N
ewcellu
larcemen
tum,
new
periodontalligam
entfibersan
dosteo
genesiswerereported
.Graftparticles
wereinco
rporatedin
new
bone
Pao
lantonio
etal.(20
01)
(61)
1 41osseo
uswall
Intrab
onydefects
8months
Bovine-derived
xenograft+barrier
Reg
eneration
Nonotchwas
placed.N
ewcemen
tum,n
ewperiodontalligam
ent
fibersan
dosteo
genesiswithgraftparticles
surrounded
by
den
seco
nnective
tissueornew
bonewereobserved
Sculean et al.
204
Tab
le16
.(Con
tinued
)
Study:
authors
(yea
r)(ref.
no.)
No.o
fpatients
No.o
fdefects
Defecttype
Defectdep
thHea
lingtime
Biomaterials
Hea
lingtype
Histologica
lresults
Nev
inset
al.
(200
3)(56)
2 21-3osseo
uswalls
4–7mm
9months
Bovine-derived
xenograft+barrier
Longjunctional
epithelium
Reg
eneration
Notchat
themost
apical
extentofc
alcu
luswas
placed.R
oot
surfac
eco
nditioning(tetracycline)
was
applie
d.N
ewcellu
lar
cemen
tum,n
ewattach
men
tap
paratusan
dboneform
ation
wereobvious.Biomaterialp
articles
weresu
rrounded
by
den
seco
nnective
tissueornew
bone
Sculean
etal.
(200
3)(84)
2 21-2osseo
uswalls
6months
Bovine-derived
xenograft+en
amel
matrixderivative
Reg
eneration
Notches
atthemost
apical
extentofd
efectan
dat
theleve
lof
alve
olarcrestwereplaced.N
ewcellu
lar-ac
ellularcemen
tum
withinserting
colla
genfibersan
dboneform
ationaround
biomaterialp
articles
werenoticed
Yunka
etal.
(200
2)(107
)1 1
1-2osseo
uswalls
4mm
6months
Bovine-derived
xenograft+
Pep
Gen
-P-15
Reg
eneration
Notchat
themostap
ical
extentofc
alcu
luswas
placed.R
ootsu
rface
conditioning(citricacid)was
applie
d.N
ewcellu
larcemen
tum,
new
periodon
talligam
entfibersan
dgraftparticles
surrou
nded
bynew
bon
ewereob
served
Nev
inset
al.
(200
3)(57)
6 6Interproximal
intrab
onydefects
9months
Decalcified
free
ze-dried
bone
allograft+
platelet-derived
growth
factor-BB
Longjunctional
epithelium
Reg
eneration
Notchat
themostap
ical
extentofc
alcu
luswas
placed.R
ootsu
rface
conditioning(tetracycline)
was
applie
d.F
ourdefects
exhibited
rege
neration
Hartm
anet
al.
(200
4)(30)
1 21osseo
uswall
5–6mm
6months
Bovine-derived
xenograft+barrier
Longjunctional
epithelium
Notchat
theap
ical
extentofc
alcu
luswas
placed.R
ootsu
rfac
eco
nditioning(tetracycline)
was
used.E
nca
psu
latedbiomaterial
particles
andlongjunctional
epithelium
wereobserved
Sculean
etal.
(200
4)(83)
8 81-2osseo
uswalls
3–6mm
6months
Bovine-derived
xenograft+barrier
Longjunctional
epithelium
Reg
eneration
Notchat
thebottom
ofthedefectwas
placed.N
ewcellu
lar
cemen
tum,n
ewperiodontalligam
entfibersan
dgraftparticles
surrounded
bynew
bonewereseen
.Nomem
braneremnan
tswerereported
.Longjunctional
epithelium
was
observed
inone
case
Sculean
etal.
(200
5)(86)
3 31-2osseo
uswalls
4–6mm
6months
Enam
elmatrix
derivative+
bioglass
Reg
eneration
Notchat
themost
apical
extentofc
alcu
luswas
placed.
Reg
enerationoftheperiodontaltissu
eswas
noticed.G
raft
particles
werepresentsu
rrounded
by
bone-lik
etissue,
indicatingongo
ingmineralization
Ridgw
ayet
al.
(200
8)(68)
8 8Dee
pintrab
ony
defects
6months
Beta-tricalcium
phosp
hate+platelet-
derived
growth
factor
Longjunctional
epithelium
Connective
tissue
attach
men
tReg
eneration
Notchat
themost
apical
extentofc
alcu
luswas
placed.
Reg
enerationoftheperiodontaltissu
eswas
noticed.G
raft
particles
wereen
capsu
latedin
connective
tissue.
Minim
alosseo
genesisin
contact
withgraftwas
seen
Periodontal regeneration in intrabony defects
205
Tab
le16
.(C
ontinued
)
Study:
authors
(yea
r)(ref.
no.)
No.o
fpatients
No.o
fdefects
Defecttype
Defectdep
thHea
lingtime
Biomaterials
Hea
lingtype
Histologica
lresults
Sculean
etal.
(200
8)(88)
1 11-2osseo
uswalls
Dee
pintrab
ony
defects
5ye
ars
Enam
elmatrix
derivative+bovine-
derived
xenograft
Reg
eneration
Nonotchwas
placed.G
raftparticles
werepresentinco
rporated
into
bone.
New
cemen
tum
andperiodontalligam
entwere
opposite
toxenograft.Partial
defectresolutionwas
reported
Sculean
etal.
(200
8)(77)
9 91-2osseo
uswalls
3–7mm
9months
Enam
elmatrix
derivative+
bicalcium
phosp
hate
Longjunctional
epithelium
Connective
tissueattach
men
tReg
eneration
Notchat
themost
apical
extentofc
alcu
lusorthedefect
bottom
wereplaced.N
ewac
ellular/cellu
larcemen
tum,n
ewinsertingfibersan
den
capsu
latedgraftparticles
wereseen
.Minim
alnew
boneform
ationwas
reported
Stav
ropoulos
etal.
(201
1)(99)
5 51-2osseo
uswalls
≥3mm
6months
Bovine-derived
xenograft+barrier
(bovinepericardium)
Longjunctional
epithelium
Connective
tissueattach
men
tTwonotch
eswereplaced:o
neat
thepostsurgical
levelo
fthegingival
marginan
don
eat
theap
ical
extentof
root
planingor
calculus.
Graftparticles
mostlyem
bed
ded
inco
nnective
tissue.An
amorphou
s,mineralized
,cellulartissuein
contact
withbon
egraft.Nonew
bon
eform
ation.N
oresorption
oran
kylosis
Stav
ropoulos
etal.
(201
1)(96)
10 101-2osseo
uswalls
6.7mm
6months
Recombinan
thuman
growth/d
ifferentiation
factor5+
beta-
tricalcium
phosp
hate
Longjunctional
epithelium
Reg
eneration
Twonotch
eswereplaced:o
neat
thepostsurgical
levelo
fthegingival
marginan
don
eat
theap
ical
extentof
root
planing.Cem
entum,
bon
ean
dperiodon
talligam
entregeneration.N
oan
kylosis,
noroot
resorption
.Beta-tricalcium
phosphateparticles
were
occasion
allyob
served
surrou
nded
byco
nnective
tissuewith
sign
sof
inflam
mationor
foreignbod
yreaction
Sculean et al.
206
Tab
le17
.Histomorphometricresu
ltsofh
uman
periodontald
efects
trea
tedusingco
mbinationtech
niques
Study*
Tooth
notation
Defectdep
th(m
m)
Osseo
uswalls
Collag
enfiberson
tooth
surfac
e(m
m)
New
cemen
tum
(mm)
New
bone
(mm)
Junctional
epithelium
(mm)
Hea
lingtype
Bowers
etal.(19
85)(7)
13mesial
81-2
0.0
0.0
0.0
–Lo
ngjunctional
epithelium
25mesial
53
0.2
1.7
2.3
–Reg
eneration
35mesial
92
1.5
0.2
1.2
–Reg
eneration
35distal
72
0.0
0.0
2.7
–Lo
ngjunctional
epithelium
33distal
101
0.8
1.0
2.3
–Reg
eneration
34mesial
72
1.5
1.2
3.3
–Reg
eneration
Bowers
etal.(19
91)(4)
14x
6.6
1-3
0.3
2.4
2.7
–Reg
eneration
Cam
ello
etal.(19
98)(11)
43distal
73
–7.0
5.3
–Reg
eneration
13distal
72
–7.6
4.5
–Reg
eneration
Cam
ello
etal.(20
01)(10)
44distal
73
–5.3
4.7
–Reg
eneration
44distal
63
–3.9
3.8
–Reg
eneration
44distal
63
–4.5
4.8
–Reg
eneration
Nev
ins
etal.(20
03)(56)
23mesial
71-2-3
–2.2
3.0
–Lo
ngjunctional
epithelium,
rege
neration
25mesial
41-2-3
–1.9
3.1
–Lo
ngjunctional
epithelium,
rege
neration
Sculean
etal.(20
03)(84)
15–
1-2
–2.2
0.5
–Reg
eneration
16–
1-2
–1.9
1.8
–Reg
eneration
Hartm
anet
al.(20
04)(30)
12mesial
61
00
01.9
Longjunctional
epithelium
22mesial
51
00
03.5
Longjunctional
epithelium
Periodontal regeneration in intrabony defects
207
Tab
le17
.(Con
tinued
)
Study*
Tooth
notation
Defectdep
th(m
m)
Osseo
uswalls
Collag
enfiberson
tooth
surfac
e(m
m)
New
cemen
tum
(mm)
New
bone
(mm)
Junctional
epithelium
(mm)
Hea
lingtype
Sculean
etal.(20
04)(83)
26mesial
61
–2.5
2.8
–Reg
eneration
27distal
51-2
–2.9
3.0
–Reg
eneration
26distal
41-2
–3.8
3.8
–Reg
eneration
37distal
62
–2.8
3.4
–Reg
eneration
16distal
41-2
–0
0–
Longjunctional
epithelium
26distal
42
–2.4
1.6
–Reg
eneration
16mesial
31-2
–1.5
0.5
–Reg
eneration
16distal
51-2
–2.2
1.0
–Reg
eneration
Sculean
etal.(20
05)(86)
364
1-2
–1.6
1.4
–Reg
eneration
475
1-2
–1.5
1.4
–Reg
eneration
466
1-2
–2.9
2.8
–Reg
eneration
Ridgw
ayet
al.(20
08)(68)
12mesial
––
00
03.5
Longjunctional
epithelium
33distal
––
1.3
14.9
2.6
Reg
eneration
13distal
––
1.6
1.8
0.8
2.1
Reg
eneration
13mesial
––
1.1
1.6
5.4
2.3
Reg
eneration
36distal
––
11.9
1.4
0.6
Reg
eneration
35mesial
––
00.9
1.3
1.2
Reg
eneration
35distal
––
0.7
0.9
1.6
1.3
Reg
eneration
25distal
––
0.3
0.7
0.4
-0.3
Reg
eneration
Sculean
etal.(20
08)(88)
117
––
00
–Lo
ngjunctional
epithelium
124
––
0.4
0–
Connective
tissueattach
men
t
323
––
1.3
0.2
–Reg
eneration
116
––
1.1
0.5
–Reg
eneration
265
––
00
–Lo
ngjunctional
epithelium
415
––
0.6
0–
Connective
tissueattach
men
t
216
––
00
–Lo
ngjunctional
epithelium
415
––
0.7
0–
Connective
tissueattach
men
t
255
––
2.1
0.7
–Reg
eneration
Sculean et al.
208
Tab
le17
.(Con
tinued
)
Study*
Tooth
notation
Defectdep
th(m
m)
Osseo
uswalls
Collag
enfiberson
tooth
surfac
e(m
m)
New
cemen
tum
(mm)
New
bone
(mm)
Junctional
epithelium
(mm)
Hea
lingtype
Stav
ropoulos
etal.(20
11)(99)
–≥3
1-2
–0.1
0–
Connective
tissueattach
men
t
–≥3
1-2
–2.1
0–
Connective
tissueattach
men
t
–≥3
1-2
–0
0–
Longjunctional
epithelium
–≥3
1-2
–1.0
0–
Connective
tissueattach
men
t
–≥3
1-2
–0.9
0–
Connective
tissueattach
men
t
Stav
ropoulos
etal.(20
11)(96)
357
1-2
–2.98
3.79
2.84
Reg
eneration
365
1-2
–1.45
2.77
2.60
Reg
eneration
114
1-2
–2.91
2.53
3.48
Reg
eneration
345
1-2
–0.95
2.17
2.78
Reg
eneration
124
1-2
–4.99
5.02
2.05
Reg
eneration
2311
1-2
–1.81
1.88
0Reg
eneration
217
1-2
–1.80
1.03
3.94
Reg
eneration
2311
1-2
–0
03.35
Longjunctional
epithelium
214
1-2
Excluded
459
1-2
–2.52
0.48
1.42
Reg
eneration
Mea
n(inmm)
6.1�
1.7
1-3
0.5�
0.5
1.9�
1.5
1.9�
1.6
2.1�
1.2
75%
rege
neration
14xisgive
nin
italicsbecau
setherewere14
defects
andtheau
thorofthestudyga
vemea
nva
lues
andnosingleva
lues
per
defect.Thus,themea
nva
lueco
ntributedin
a14
-fold
man
ner
tothefinal
resu
lt.
*Thirteen
ofthe20
studiesgive
nin
Tab
le16
provided
appropriatehistomorphom
etricdata,
whicharepresentedhere.
Periodontal regeneration in intrabony defects
209
Tab
le18
.Histomorphometricresu
ltsofh
uman
periodontald
efects
trea
tedfollo
winguse
ofsev
eral
biomaterials
Defectdep
th(m
m)
Osseo
us
walls(n)
Collag
enfibers
ontooth
surfac
e(m
m)
New
cemen
tum
(mm)
New
bone
(mm)
Longjunctional
epithelium
(mm)
Hea
lingtype
%Reg
eneration
Autografts
3.0�
2.1
1-3
2.1�
1.5
1.9�
1.5
1.9�
1.0
2.3�
1.0
Reg
eneration,longjunctional
epithelium
80
Allo
grafts
6.0�
1.1
1-3
0.5�
0.9
1.3�
0.7
1.8�
0.9
1.4�
0.9
Reg
eneration,c
onnective
tissueattach
men
t,longjunctional
epithelium,o
sseo
usrepair
70
Xen
ografts
6.6�
0.9
1-3
1.4�
1.2
2.4�
1.9
2.3�
1.8
1.2�
0.6
Reg
eneration,c
onnective
tissueattach
men
t,longjunctional
epithelium
70
Allo
plastic
>4
1-3
0.1�
0.1
0.6�
0.8
0.4�
0.6
2.9�
1.4
Reg
eneration,c
onnective
tissueattach
men
t,longjunctional
epithelium
34
Barriers
5.1�
2.5
1-3
3.1�
2.1
2.6�
1.6
1.7�
1.3
–Reg
eneration,c
onnective
tissueattach
men
t,longjunctional
epithelium
75
Biologicac
tive
factors
4.8�
2.4
1-3
2.5�
1.6
1.3�
1.5
0.6�
1.0
–Reg
eneration,c
onnective
tissueattach
men
t,longjunctional
epithelium
45
Combinations
6.1�
1.7
1-3
0.5�
0.5
1.9�
1.5
1.9�
1.6
2.1�
1.2
Reg
eneration,c
onnective
tissueattach
men
t,longjunctional
epithelium
75
Fig. 2. Healing of an intrabony defect following graftingwith an alloplastic material (e.g. Bioglass). The healing ischaracterized by formation of a long junctional epithelium(between the two red arrowheads). Formation of a newcementum is limited to the most apical part of the defect(the green arrow indicates the most coronal extent of newcementum).
Fig. 3. Periodontal regeneration following treatment withguided tissue regeneration. Formation of new cementum(green arrowheads) and new bone (blue stars) are clearlyvisible coronally to the most apical part of the defect indi-cated by the apical notch.
Sculean et al.
210
derive from technical problems arising during har-vesting and/or processing of the biopsy. For exam-ple, because of the anatomic nuances discussedearlier, or perhaps for accidental reasons, the biopsymay not comprise a complete or representative por-tion (i.e. root, periodontal ligament or bone) of theoriginal defect or the newly regenerated tissues.Moreover, the teeth included in such analyses areusually deemed to have a hopeless prognosis,amongst other reasons, because of advanced peri-
odontitis, and thus the regenerative potential at suchsites may be extremely limited and/or exhausted.Moreover, teeth showing an especially favorable out-come following periodontal regenerative proceduresare frequently not harvested for obvious ethical rea-sons. Thus, limited, or lack of, periodontal regenera-tion may simply be a result of the evaluation of‘hopeless’ cases. Nevertheless, in several of the stu-dies discussed in the present review, the teeth
Fig. 4. Healing following treatment with enamel matrixderivative, demonstrating periodontal regeneration. Newcementum (green arrowheads) and new bone (blue star)have formed coronally to the most apical part of the defectindicated by the notch.
Fig. 5. Healing following treatment with a bovine-derivedxenogeneic bone grafts and guided tissue regeneration.New cementum (green arrowheads) and remnants of thegraft material (blue and green stars) can be distinguished.New bone (yellow arrowheads) has formed around some ofthe graft particles, whereas some other particles (greenstars) are surrounded by connective tissue.
0 20 40 60 80 100
Autografts
Allografts
Xenografts
Alloplastic
Barriers
Biologic active factors
CombinationsREG (%)
NB/DD(%)
NC/DD(%)
Fig. 6. Diagram illustrating percent-ages of treated defects with histologi-cal evidence of regeneration (REG%), and amount of cementum (NC/DD%) and bone (NB/DD%) forma-tion presented as percentage ofdefect depth.
211
included, despite advanced disease, were describedas having a reasonable potential for regenerationowing to the presence of a deep intrabony compo-nent and the one- or two-bone wall (or combinationthereof) configuration.
In summary, it is important to recognize that,despite the limitations and challenges in both techni-cal and ethical histological studies of periodontalregeneration in humans, there is strong proof-of-principle evidence for partially successful regenera-tive outcomes, although these remain inconsistentand somewhat unpredictable.
Conclusion
The histological evaluation of human specimens inthe study of periodontal regeneration is fraught withchallenges of a technical nature, as are those associ-ated with data interpretation. Nevertheless, humanhistology provides important information on the bio-logical potential of various regenerative protocols andbiomaterials, which is vital to advancing this field ofresearch and clinical practice. As the outcomes ofsuch studies can be influenced by various factorsoutlined in this review, the information obtainedfrom such studies needs to be carefully interpreted inthe light of the evidence available from pre-clinicaland clinical studies, designed to serve as ‘proof-of-principle’ studies.
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A B C D
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A B C D
Fig. 9. Sections (dotted red line) representing areas closeto the original bone walls (pink line) of the inrabony defect(A and C), would probably demonstrate a better regenera-tive response than those representing the mid-portion ofthe defect (B). Such a problem does not exist with horizon-tal defects (D).
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