The International Journal of Periodontics & Restorative Dentistry 233
Treatment of Class II Furcations with Autogenous Bone Grafts and e-PTFE Membranes
Marcelo C Camelo* This Study reports the clinical results Marc L Neuins, D/WD, MMSc* of the treatment of 28 consecutive Myron Nevins, DDS** Class II furcation defects with tetra- cycline root conditioning, autoge- nous bone grafts, and expanded This article reports a successful clinical regimen of treatment for the Class il furca- polytetrafluoroethylenc (e-PTFE) tion defect. Twenty-eight patients with molar teeth demonstrating Class It furca- tions were treated with regenerative therapy with the goal of regenerating lost membranes. The authors were dir- interradicutar periodontium. The treatment selected included scaling and root ected toward this therapeutic regi- planing, surgical flap design that would enable the flap to completely cover the men after analyzing previous publi- surgical site, complete enucleation of granulation tissue, tstracycline root condi- cations that addressed regenerative tioning, a particulate autogenous bone graft, and an expandecJ polytetrafluo- efforts when encountering Class II roethylene (e-PTFEj membrane. Of the twenty-eight consecutive patients treated,and III furcation invasion in mandibu- twenty-five demonstrated no postoperative clinical evidence of furcation inva- lar and maxillary molar teeth. sion, for a success rate of 39%. Eleven sites were reopened 3 to 9 months post- surgical and presented complete furcation fill with a hard, bone-lii
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included coronally advanced flaps results compared to other available The e-PTFE barrier membranes with or without citric acid root con- regenerative regimens for treating (3Í/WL Gore) with or without tita- ditioning,^'^ bone autografts,' bone Class II furcation defects. This study nium reinforcement were placed allografts,'' freeze-dned bone allo- was designed to investigate whether over the bone grafts and stabilized grafts,^* alloplasts,'' nonresorbable the combined treatment with tetra- with stainless steel pins and sutures barrier membranes,^"^^ resorbable cycline root conditioning, autoge- as indicated in each case. Soft tissues barrier membranes,^''''' and combi- nous bone grafts, and e-PTFE mem- were sutured tension free with Gore- nation procedures of bone allografts branes IS predictable to treat Class II Tex (3ÍAA/L Gore) or silk sutures to with barrier membranes.'^"^'• furcation defects. This study reports achieve primary closure over the Schallhorn and McClain^^ on 28 consecutive furcation defects grafts and membranes. treated 62 Class II and III furcations treated in this way. Surgical dressing was placed with e-PTFE barrier membranes over the surgical site for 1 to 3 alone or in combination with com- weeks. Patients were examined posite bone grafts with or without Method and materials every 2 to 4 days for the first 2 weeks citric acid root conditioning. Ofthe and then weekly for the next 8 46 furcation defeas, 33 (72%) receiv- Twenty-eight patients having mod- weeks. The surgical sites were ing combined treatment had com- erate to advanced periodontitis in- swabbed with chlorhexidine diglu- plete furcation fill, while 5 of 16 cluding one Class II furcation defect conate 0.12%, and supragingival membrane-only sites (31%) had consented to participate in this plaque was removed at each post- complete furcation fill. Their 5-year study. The protocol included presur- operative visit, with the sutures re- data were reported for 38 of 46 gical treatment with extensive oral moved between 7 and 21 days. Pa- graft- and membrane-treated furca- hygiene instruction, scaling and root tients were instructed to rinse with tion sites and all 16 membrane-only planing, and preoperative recording 0.12% chlorhexidine digluconate 2 furcation sites.^° There was complete of the probing depth, attachment times per day for 8 weeks and re- furcation fill as determined by reen- levels, and the presence or absence sumed oral hygiene after the third try surgery for 66% ofthe graft-and- and classification of furcation in- postoperative week. Complete- membrane sites (38 of 46), while only volvement using the classification mouth prophylaxis and oral hygiene 12.5% (2 of 16) ofthe membrane- system of Hamp et al.^^ Full-thick- instruction were performed every 2 only sites had complete furcation fill. ness mucoperiosteal flaps with sul- months for the duration ofthe study. The combination-treatment sites cular incisions and vertical releases Clinical measurements were had a decrease in horizontal probing were designed to achieve primary performedforallcases8to 9 months depth of 4.0 mm, versus 2.0 mm for closure over the membrane and after the surgical procedure. Eleven membrane-only sites. Reentry after bone graft. Meticulous root prepa- patients consented to reentry surgi- 5 years demonstrated remarkable ration was performed, and the root cal procedures, and the defects were stability for the combined-treatment surface was treated with tetracycline classified as having either incom- cohort, with 6ó% complete furcation paste for 4 minutes. Prior to graft plete or complete bone fill. fill compared to the initial report of placement, all granulation tissue was 72%. The membrane-only sites co- removed from the defect and bleed- hort depreciated to 13% from the ini- ing was stimulated from the defect tial success rate of 31%. and from the periodontal ligament Autogenous bone grafts alone^^ space. Autogenous bone grafts were and combined treatment of allo- harvested from the maxillary tuber- genic bone grafts with barrier mem- osity or the mandibular retromolar have shown improved region and grafted into the defects.
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^^^^M Hf";Ml|-.;r.fTliniral paramotorc (mmf
Probinq depth Attachment level Patient Initial Postoperative Change Initial Postoperative Change Recession Failure
1 4.0 2.0 2.0 5.0 2.0 3.0 1.0 1 5.0 1.0 5.0 9.0 1.0 8.0 3.0 3 (case 4) 12.0 3.0 9.0 13.0 4.0 9.0 0.0 4 7.0 2.0 5.0 8.0 3.0 5.0 0.0 5 9.0 1.0 8.0 11.0 3.0 8.0 0.0 6 9.0 2.0 7.0 9.0 4.0 5.0 2.0 7 6.0 2.5 3.5 6.0 3.0 3.0 0.5 8 (case 3) 6.0 1.5 4.5 7.0 3.0 4.0 0.5 9 n.o 1.0 10.0 10.0 3.0 7.0 3.0 10 8.0 2.0 6.0 8.0 4.0 4.0 2.0 11 9.0 2.0 7.0 8.0 4.0 4.0 3.0 12 (case 2) 9.0 3.0 6.0 10.0 4.0 6.0 0.0 13 8.0 9.0 -1.0 9.0 10.0 -1.0 0.0 X 14 7.0 2.0 5.0 9.0 4.0 5.0 0.0 15 8.0 2.0 6.0 8.0 2.0 6.0 0.0 16 6.0 1.0 5.0 7.0 2.0 5.0 0.0 17 8.0 1.5 6.5 9.0 3.0 6.0 0.5 18 8.0 1.0 7.0 10.0 3.0 7.0 0.0 19 (easel) 11.0 4.0 7.0 11.0 5.0 6.0 1.0 20 9.0 2.0 7.0 10.0 3.0 7.0 0.0 21 8.0 8.0 0.0 n.o 11.0 0.0 0.0 X 22 7.0 8.0 -1.0 7.0 9.0 -2.0 1.0 X 23 14.0 3.0 11.0 14.0 5.0 9.0 2.0 24 6.0 2.0 4.0 7.0 3.0 4.0 0.0 25 12,0 4.0 8.0 12.0 5.0 7.0 1.0 26 10.0 2.0 8.0 10.0 4.0 6.0 2.0 27 9.0 3.0 6.0 10.0 5.0 5.0 1.0 28 8.0 4.0 4.0 8.0 4.0 4.0 0.0 Mean 8.39 2.84 5.55 9.14 4.14 5.00 0.84 Standard deviation 2.20 2.13 2.93 2.05 2.30 2.68 1.04
Results failures because of continued clini- attachment of 5.00 ± 2.68 mm, and cally detectable Class II furcations a mean recession of 0.84 ± 1.04 mm. Clinical results and no positive changes in clinical measurements. All successful cases Twenty-five of the twenty-eight cases presented with no clinically de- Reentry results were judged to be clinically suc- tectable furcations at the 8- to 9- cessful as evidenced by no longer month réévaluation, There were no Eleven patients had reentry surgery having clinically detectable furcation cases with intermediate results to evaluate bone fill of the furcation involvement, a significant decrease showing a change from a Class II to defects. All eleven cases showed in probing depth, and a significant a Class I furcation. There was a mean complete fill of the furcation defects gain in attachment level {Table 1). decrease in probing depth of 5.55 ± by hard, dense, bone-like tissue; four Three cases were classified as 2.93 mm, a mean increase in clinical of these cases are reported.
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Fig 1a Flap reflectron reveals a Class li Fig 1 b Ahe' meticulous degranuJatron of Fig 1c Aiirogenoiis bone is harvested bucea) furcalion on iJiJS maxillary left tirsl ihe defect and scaling and rool planing, a from the rnaxillary tuberosity and placed to moter. letracycline pasfe is applied to ihe root fill Ihe defect. surface and the defect for approiirnately 4
Fig Id (left) Titanium-reinforced Gore- Tex membrane is placed to cover the hone graft and stabilized with a bone-fiiotion screw and an e-PTFE suture.
Fig 1 e (nght) Bghr-month pos topera t;ve reeriíry surgery sfi o ws the stability ofthe autogenous bone graft. Note that the entire defect has been successfully filled.
Case reports planing, a tetracycline paste was healing was excellent, and the bar- applied to the root surface and the rier membrane was removed after 3 Case 1 defect for approximately 4 minutes months because of exposure. The (Fig 1 b). Autogenous bone was har- postoperative clinical evaluation Flap reflection for a maxillary leftfirst vested from the maxillary tuberosity revealed a probing depth of 4 mm, molar [Fig 1 a) revealed a Class II buc- and grafted into the defect (Fig 1 c]. an attachment level of 5 mm, and cal furcation invasion with an initial Atitanium-reinforccd Gore-Tex bar- recession of 1 mm. The 8-month probing depth of 11 mm and at- rier membrane was placed to cover postoperative reentry surgery tachment level of 11 mm (patient the bone graft and stabilized with a showed the stability of the autoge- 19). After meticulous degranulation bone-fixation screw and an e-PTFE nous bone graft with complete fill of of the defect and scaling and root suture (Fig Id). The postoperative the furcation defect [Fig 1 e).
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Fig 2a Preoperative radiograph demónstrales a penbdontaily com- Fig 2b Fuií-íhiclíness mucopenosteal flap is reflected, the second promised second molar that was deemed hopeless The first molar molar rs extracted, and ihe C'ass li furcation with a wraparound has CJass ii furcation invasion that extends to ihe mesial defect. defect on the lingua! aspect of the first molar is identified.
Fig 2c Seven teen-mo nth postoperative reentry surgery evi- Fig 2d Thprty-SFx-monlh postoperative radiograph is no longer dences complete bone fill of the furcation defect. suggestive of furcatron rnvoivement, evjdencing the stafailjty of the successful graft.
Case 2 from the second premolar to the defect (Fig 2b). The defect was second molar, and the second molar degranulated, and the root surfaces The mandibular right first molar pre- with radiographie bone loss beyond were meticulously scaled and sented a lingual Class II furcation the apex of the distal root was planed and then treated with a defect with an initial probing depth extracted (Fig 2a). The Class II fur- tetracycline paste for 4 minutes. of 9 mm and an attachment level of cation defect on the lingual aspect Autogenous bone was harvested 10 mm (patient 12). A full-thickness ofthe first molarwas associated with from the region ofthe second molar mucoperiosteal flap was reflected a distal wraparound intrabony with rongeurs, and the bone was
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Fig 3a Preoperatj've radiograph is suggestive of furcation Fig 3b Flap reflection reveals Class ¡I furcation involvement for involvement for the mandibular nght first rnoler the first molar, No!e that there is a biologic width problem that may have contributed to the etiology of the problem.
Fig 3c One-yeae reentry shows a completely inlegra ted grafl fill- ing the furcation defect.
placed in the lingual defect on the revealed probing depth of 3 mm, Case 3 first molar The bone graft was then attachment gam of 6 mm, and covered with a titanium-reinforced recession of 0 mm. The 17-month A mandibular right first molar had an Gore-Tex membrane, and the soft postoperative reentry surgery evi- initial probing depth of 6 mm, tissues were sutured to obtain pri- denced complete bone fill of the attachment level of 7 mm, and the mary closure over the surgical site. furcation defect with a bone-like preoperative radiograph suggested The postoperative healing was ex- substance (Fig 2c). The 36-month furcation invasion (Fig 3a) {patient cellent, and the membrane was postoperative radiograph no longer 8). Flap reflection confirmed a Class removed after 2 months because of suggested furcation invasion and II furcation involvement for this exposure at the gingival margin. The offered evidence of the stability of tooth, which had a biologic width postoperative clinical evaluation the successful treatment (Fig 2d), problem because of a composite
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F¡g 4a Preoperatrue radiograph evi- Fig 4c Eight-month reentry surgery aftei dences an intcabony defect for the second treatment with autogenous bone graft and molar associated with the distal furcation. Gore-Tex membrane shoivs complete bone fill ol the furcation defect. Fig 4b (right! There is a preoperarrve 12- mm probing depth on the distal surface ol the maxillary righf second molar. Flap reflection evidences the extensive bone loss on the distai surface ofthe second molar witfi a Class II furcation
restoration encroaching upon the graft filling the furcation defect (Fig debridement of the defect and root furcation entrance (Fig 3b). Prior to 3c). The 40-month postoperative preparation including scaling and placing an autogenous bone graft radiographie and clinical examina- root planing and treatment with and an e-PTFE (Gore-Tex) mem- tions suggested complete resolution tetracycline paste for 4 minutes. brane, the defect was completely ofthefurcation defect on this molar. Autogenous bone was harvested debrided by scaling and root plan- from the tuberosity, grafted to the ing, the restoration was reshaped to defect site, and covered with a Gore- remove excess restorative material Case 4 Tex membrane. The flap design from the furcation entrance and root allowed for primary closure over the trunk, and tetracycline root condi- There was a preoperative 12-mm graft and membrane to be easily tioning was performed for 4 min- probing depth and an attachment achieved. The postoperative clinical utes. The postoperative healing was level of 13 mm on the distal surface evaluation revealed a probing depth uneventful, and the membrane was of the maxillary right second molar of 3 mm, an attachment gain of 9 removed after 2 months because of (Fig 4a) (patient 3). Flap reflection mm, and recession of 0 mm. The 8- exposure at the gingival margin. The evidenced extensive bone loss on month reentry surgery showed com- postoperative clinical evaluation the distal surface of the second plete bone fill ofthe furcation defect revealed a probing depth of 1.5 mm, molar, with a Class II furcation inva- (Fig 4c). The 2.5-year postoperative attachment gain of 4 mm, and reces- sion (Fig 4b). This furcation defect radiograph suggested regenerated sion of 0.5 mm. The 1-year reentry received the same care as the above- bone on the distal surface ofthe sec- showed a completely integrated described cases, with meticulous ond molar.
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Discussion trimmed from the surgical flap that is apically positioned at a distance from The goal of definitive furcation treat- the bony defect to allow the blood ment is to achieve complete resolu- clot to organize unencumbered by tion of the defect to improve plaque the gingival epithelium. This con- removal. However, a Class II furcation cept was then reintroduced by that is unsuccessfully treated will con- Nyman et af in 1982 and Gottlow tinue to be a maintenance problem. et aP° in 1986 as an integral factor in Therefore, treatments that offer the guided tissue regeneration (GTR). potential for complete resolution of The limits of GTR for treating the furcation defect are preferred. maxillary Class II or II! furcations have Lynch^" evaluated the possible demonstrated that maxillary inter- parameters of success of a peri- proximal Class II furcations respond odontal regenerative activity. His less favorably than buccal Class II conclusion that the most important furcations to treatment with GTR, criterion is human biopsy is validated with no improvement over open de- by significant consensus meet- bridement alone for mesial and dis- ings.^^^' Recognizing the obvious tal sites.^''^^ Maxillary Class III furca- limitations of procuring this level of tions treated with GTR do not evidence, we offer the treatment of respond more favorably than open 28 consecutive defects and the sur- debridement alone. gical reopening of 11 cases as an al- Selecting biomaterials and treat- ternative. ment methodology for periodontal Periodontics continues to seek a regeneration should be an evidence- predictable and successful method based decision. Unfortunately, meth- to achieve periodontal regeneration. ods and materials that have not been Autogenous bone grafts have been histologically proven to achieve peri- shown to have a substantial biologic odontal regeneration are available potential to achieve periodontal and have been advocated. regeneration, as evidenced by his- The coronally advanced flap tologie biopsy analysis evidencing with or without citric acid root con- new cementum, alveolar bone, and ditioning is one method suggested periodontal ligament.' The role of to achieve periodontal regeneration ban"ier membranes is multifactorial, when treating Class II furcation inva- providing stability to the blood clot sion.^ A longitudinal clinical trial in- and excluding the gingival epithe- cluding 22 buccal mandibular molar lium and corium, and allowing the Class II furcations reported closure of progenitor cells from the bone and the defects with bone fill following periodontal ligament to populate the coronally advanced flap proce- the surgical wound. The principle of dure.^^ However, the 5-year report epithelial exclusion in periodontal showed instability of the results, with regeneration was first reported by 12 of 16 sites exhibiting recurrent Prichard^^ as the "intrabony tech- Class II furcation invasion. Other ma- nique," in which the epithelium is terials, such as freeze-dried bone
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grafts, have been validated through both presurgically and postsurgically. multicenter clinical trials and have The patients were instructed to rinse been shown to consistently induce with chlorhexidine digluconate for periodontal regeneration in intra- 8 weeks postoperative, and oral bony defects.^•^'' However, it is note- hygiene techniques were reviewed worthy that clinical results in Class II at each follow-up visit. At these vis- furcations have consistently shown its, supragingival plaque removal improvement without complete res- was performed at the surgical site olution ofthe defects, thus the need and the site was swabbed with chlor- for human histologie data. hexidine digluconate. The combination treatment of a This study used autogenous bone graft and membrane appears bone grafts combined with barrier to outperform bone grafts alone or membranes to achieve bone regen- membranes alone in comparative eration in Class II furcation defects. studies.""^' The advantage of es- Twenty-five ofthe twenty-eight cases tablishing initial blood clot stabiliza- werejudged to be clinically success- tion with a bone graft and mem- ful as evidenced by no longer having brane is that it is less likely to have clinically detectable furcation inva- dead space under the membrane. sion, a significant decrease in prob- Both the mechanical handling prop- ing depth, and a significant gain in erties and the biologic potential of attachment level. There was a mean graft materials must be considered. decrease in probing depth of 5.55 ± Autogenous bone has demon- 2.93 mm, a mean increase in clinical strated ease of handling and bio- attachment of 5.00 ± 2.68 mm, and logic potential. The membrane a mean recession of 0.84 ± 1.04 mm. should be made stable and passive Three cases were classified as fail- using sutures and/or screws as ures because of continued clinically needed to avoid micromovements detectable Class 11 furcations and no that might interfere with the regen- positive changes in clinical measure- erative wound healing. ments. All successful cases presented Eleven of the patients agreed with no clinically detectable furca- to reentry surgery 9 months after the tions at the 8- to 9-month réévalua- first surgical procedure, and all of tion. There were no cases with inter- these cases demonstrated complete mediate results demonstrating a hard tissue furcation fill. There is no changefrom a Class II to a Class I fur- reason to believe that the other cation. The results of this study are cases that were equally successful unique in the level of success clinically would not show similar achieved and in the fact that for the results if they were reentered. There successful cases [89%) the furcation were no smokers enrolled in this problem was completely resolved. study, as smoking has been shown to have adverse effects on both bone grafts^^ and GTR.^* Plaque control was maintained at an optimal level
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References 10. Becker W, Becker BE, Berg L, Prichard J, Caffesse R, Rosenberg E. New attach- 1. Schallhorn RG, HiattWH, Boyce W, Iliac ment after treatment with root isolation transplants in periodontal therapy. J procedures: Report for treated Class III Periodontol 1970;41:556-5ea. and Class II furcations and vertical osseous defects. Int J Periodontics 2. Gantes 6G, Martin M, Garrett S, Egelberg Restorative Dent 1988;8(3):9-23, JH. Treatment of periodontal furcation defects. (ll¡. ßone regeneration in man- 11. Lekovic V, Kenney EB, Kovacevic <, dibular Class II defects. J Clin Periodontol Carranza FA. Evaluation of guided tissue 1988,15 232-239. regeneration in Class II furcation defects. A clinical re-entry study. J Periodontol 3. Garrett S, Martin M, Egelberg J, Treat- 1989:60:694-698. ment of penodontal furcation defects. Coronslly positioned flaps versus dura 12. Caffesse RG, Smith BA, Duff B, Momson mater membranes in Class II defects. J EC, Merrill D, BeckerW. Class II furcations Clm Periodontol 1990;17:179-185. treated with guided tissue regeneration in humans: Case reports. J Periodontol 4. SchallhornRG, HiattWH. Humanallografts 1993,64:925-933. of iliac cancellous bone and marrow in 13 Mellon ig JT, Seamons BC, Gray JL, Towie periodontai defects: Clinical observations. HJ, Clinical evaluation of guided tissue JPenodontol 1972:43.67-31. regeneration in the treatment of grade II 5. Mellonig JT, Bowers GM, Bright RW, niolar furcation invasions. Int J Lawrence JJ Clinical evaluation of freeze- Periodontics Restorative Dent 1990;10 dried bone allografts in periodontal 255-271. osseous defects. J Periodontol 1976;47: 125-131 14. Caton J, Greenstein G, Zappa U. Synthetic bioabsorbable barrier for regeneration in 6 Sepe WW, Bowers GM, Lawrence JJ, human pcnodontal defects. J Periodontol Friedlander GE, Kock RW. Clinical evalu- 1994:65:1037-1045. ation of freeze-dried bone allografts m 15. Wang HL, O'Neal RB, Thomas CL, ShyrY, periodontal osseous defects: Part II. J McNeil RL Evaluation of an absorbable Periodontol 197B;48:9-14. collagen membrane in treating Class {I 7. Kenney EB, Lekovic V, Elbaz JJ, Kovacvic furcs-uon defects J Periodontol 1994:65: K, Carranza FA Jr, Takei HH. The use of 1029-1036. porous hydroxy I apatite implants in pe.i- odontal defects. II. Treatment of Class II 16. Poison AM, Garrett S, Stoller NH, Greenstein G, Poison AP, Harrold CQ, furcation lesions in lower molars. J Laster L Guided tissue regeneration in Periodontol 1988;59:67-72. human furcation defects using a bio- 8. Pontoriero R, Nyman S, Lindhe J, degradable barrier A multi-center feasi- Rosenberg E, Sanavi F Guided tissue re- bility study. J Periodontol 1995:66: generation 'n the treatment of furcation 377-385 defects in man. J Clin Periodontol 1987; 17. [_aurell L, Falk H, Cornell J, Johard G, 14.Ó18-620. Gottlow J. Clinical use oía bioresorbable 9. Pontoriero R, Lindhe J, Nyman S, Karring matrix barnerin guided tissue regenera- T, Rosenberg E, Sanavi F. Guided tissue tion therapy. Case series. J Penodontol regeneration in degree II furcation- 1994:65:967-975 involved mandibular molars. A clinical study. J Clin Periodontol 1933;15: 18. Schallhorn RG, McClain PK. Combined 247-254. osseous composite grafting, root condi- tioning, and guided tissue regeneration. Int J Periodontics Restorative Dent 1988: 8(41:9-31.
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19. Anderegg C, Martin S, Gray J, Mellonig 29. Nyman S,UndheJ,KarringT,RylanderH. J, Gher M. Clinical evaluation of the use New attachment following surgical treat- ofdecalcitiedfreeze-driedboneallograft ment of human penodcntal disease. J with guided tissue regeneration in the Clin Penodontol 1982:9:290-296. treatment of molar furcation invasions. J 30 GottlowJ, Nyman S, UindheJ, KarringT, Periodontol 1991 ,ó2 264-268. Wennstrom J. New attachment forma- 20. McCain PK, Schallhorn RG. Long-term tion in the human periodontium by guid- assessment of combined osseous com- ed tissue regeneration. Case reports. J posite grafting, root conditioning, and Clin Periodontol 1986; 13:604-616. guided tissue regeneration Int J 31. Pontoriero R, Lindhe J. Guided tissue Periodontics Restorative Dent 1993,13- regeneration in the treatment of degree 9-27. II furcations in maxillary molars. J Clin 21. Guiilemin MR, Mellonig JT, Brunsvold Periodontol 1995:22:756-763. MA. Healing of penodontal defects treat- 32. Pontonero R, Lindhe J. Guided tissue ed by decalcified freeze-dried bone allo- regeneration in the treatment of degree grafts in combination with ePTFE mem- III furcation defects in maxillary molars. J branes. 1. Clinical and scanning electron Clin Periadontol 1995;22:31O-812. microscopic analysis. J Clin Penodontol 1993:20-528-536. 33. Haney JM, Leknes KN, Wikesjö UME, Recurrence of mandibular molar furca- 22. Kaldahl WB, Kalkwarf KL, Patil KD, Molvar tion defects following citric acid root treat- MP, Dyer JK, Long-term evaluation of ment and coronally advanced flap pro- periodontal therapy: I. Response to 4 cedures. Int J Periodontics iiestorative therapeutic modalities. J Periodontol Dent 1997:17 529-535 199ó;ó7:93-lu2. 34. Bowers GM, Chadroff S, Carnevale R. 23. Hamp SE, Nyman S, Lindhe J Mellonig J, Corio R, Emerson J, et al, Periodontal treatrnent of multirooted Histologie evaluation of a new attach- teeth. Results after 5 years J Clin ment apparatus formation in humans. Periodontoi1975;2:126-135. Partlll.J Periodontol 1989:60:683^93.
24. Lynch SE. Methods for the evaluation of 35. Rosen PS, Marks MH, Reynolds MA. regenerative procedures, J Periodontol Influence of smoking on long-teim clini- 1992,63:1085-1092. cal results of intrabony defects treated 25. Hancock EB Regenerative procedures with regenerative therapy J Penodontol In: Nevins M, Becker B, Komman K(eds) 1996:67:1159-1163. Proceedings of the World Workshop in 36. Tonetti MS, Pini Prato G, Cortellini F. Clinical Periodontics. Chicago: American Effect of cigarette smoking on periodon- Academy of Periodontology, 1989:1-26 tal healing following GTR in intrabony 26. Machtei EE, Schallhorn RG. Successful defects. A preliminary retrospective study. regeneration of mandibular Class II fur- J Clin Periodontol 1995:22:229-234. cation defects: An evidence-based treat- ment approach. Int J Periodontics Restorative Dent 1995,15:147-167, 27. Garrett S. Periodontal regeneration around natural teeth. Ann Periodontol 1996:1:621^666 28. Prichard J. The infrabony technique as a predictable procedure. J Periodontol 1957:28:202-216.
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