periodontology 2000, vol. 22, 2000, 104–132 copyright ... intrabony gtr.pdf · the biological...

Periodontology 2000, Vol. 22, 2000, 104–132 Copyright C Munksgaard 2000Printed in Denmark ¡ All rights reserved

PERIODONTOLOGY 2000ISSN 0906-6713

Focus on intrabony defects:guided tissue regenerationPIERPAOLO CORTELLINI & MAURIZIO S. TONETTI

The American Academy of Periodontology has de-fined regeneration as the reproduction or reconstitu-tion of a lost or injured part to restore the architec-ture and function of the lost or injured tissues. Peri-odontal regeneration is defined as regeneration ofthe tooth-supporting tissues including cementum,periodontal ligament and alveolar bone (41).

Melcher (61) suggested that the cells that repopu-late the root surface after periodontal surgery deter-mine the nature of the attachment that will form.Following flap elevation, the instrumented root sur-face can be repopulated by epithelial cells, gingivalconnective tissue cells, bone cells and periodontalligament cells. Under normal healing conditions,epithelial cells rapidly migrate in an apical directionto reach the most apical portion of the instrumen-tation, forming a long junctional epithelium (10, 14,57, 72) and preventing the formation of a newattachment.

The aim of regenerative procedures is to displacethe epithelial attachment at a more coronal positionthan before treatment, allowing cells from peri-odontal ligament and bone to repopulate the rootsurface and to form a new periodontal attachment(49, 50, 62, 72).

The biological concept of guidedtissue regeneration

Guided tissue regeneration with barrier membraneshas been demonstrated to be effective in preventingepithelial and gingival connective tissue cells frommigrating into the blood clot about the instru-mented root surface (44, 45, 71, 73). A physical bar-rier (membrane) is placed to cover the area in whichthe regenerative process is to take place. The barrieris properly shaped and positioned to form a spacearound the bony defect and the root surface. In thespace under the barrier, cells from periodontal liga-

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ment and bone colonize the blood clot, expressingtheir potential for regeneration. Cementum, peri-odontal ligament and alveolar bone are expected toform.

Clinical and histological outcomes

The clinical methods to evaluate the outcomes of aregenerative therapy include assessment of peri-odontal probing (pocket depth and clinical attach-ment levels) and bone levels (re-entry procedures,bone sounding and radiographs) (41). Histologicalevaluation, however, remains the only reliablemethod of determining the nature of the attachmentapparatus resulting from regenerative procedures.Several studies in animals (3, 4, 12, 13, 15, 43, 44, 71)and some human biopsy material (8, 20, 32, 45, 73,80, 81) have documented that guided tissue re-generation is capable of promoting new attachmentformation.

The overall treatment rationale of applying guidedtissue regeneration in deep intrabony defects comesfrom the need to increase the periodontal support inteeth severely compromised by periodontal disease.The clinical goals of the use of regenerative pro-cedures are improvements in the local anatomy and/or the functioning and prognosis of teeth. The majorbenefits the patient can expect from guided tissueregeneration treatment are improved masticatoryfunction, comfort and prognosis of the involvedteeth, with minor detriment to the aesthetic appear-ance. The primary outcomes in the treatment of in-trabony defects are (i) increase in functional toothsupport (clinical attachment and bone levels); (ii) re-duction in pocket depth; and (iii) minimal gingivalrecession. Since human biopsy material is very dif-ficult to obtain, for ethical reasons, the cited out-comes should be interpreted as evidence of im-proved healing response in the lack of histologicalevidence (56).

Focus on intrabony defects: guided tissue regeneration

Clinical evidence

The year 1982 was the starting-point of guided tissueregeneration (73). Following the first case publishedby Sture Nyman, other authors (7, 22, 45, 76) re-ported encouraging results in independent caseseries. That evidence, in fact, demonstrated that ap-plying guided tissue regeneration to deep intrabonydefects could promote significant clinical improve-ments in terms of clinical attachment and bonegains and reducing pocket depth. These pioneeringexperiences have opened the road to a new era ofexcitement in the periodontal field. The original ex-citement, however, was soon followed by a great dealof frustration, since clinicians found it very difficultto predictably duplicate the clinical outcomes re-ported in the cited studies in daily practice. The ap-plication of the biological concept of guided tissueregeneration appeared to be very difficult andaffected by many different unknown variables.

The turning point in the guided tissue regenera-tion arena was the year 1993, when the clinical out-comes of a group of 40 intrabony defects treatedwith non-resorbable expanded polytetrafluoroethy-lene membranes were analyzed with a multivariatestatistical approach with the aim of isolating the rel-evant variables that could influence the healing re-sponse and the final clinical outcomes of guidedtissue regeneration (23, 31, 32, 85, 89). The resultsfrom the cited studies demonstrated that the vari-ability in clinical outcomes was affected by patient-,defect- and procedure-associated factors. Under-standing the factors determining the clinical out-comes rendered their control, at least in part, poss-ible, allowing remarkable improvements in their ex-tent and predictability (Fig. 1).

At the end of 1997, 35 scientific investigations hadbeen published and reported 943 intrabony defectstreated with guided tissue regeneration (Table 1) (1,5–7, 9, 11, 16–19, 21, 24, 26, 27, 29–31, 33, 38, 39, 46,48, 51–53, 55, 59, 63, 67, 74, 75, 77, 84, 88). Thesestudies have addressed the issue of the evaluation ofthe extent and predictability of the clinical outcomesfollowing application of guided tissue regeneration.The weighted mean of the reported results indicatesgains in clinical attachment of 3.86∫1.69 mm andresidual probing pocket depths of 3.35∫1.19 mm.

Different types of nonresorbable and resorbablebarrier membranes have been used in the citedstudies. Guided tissue regeneration treatment of 351defects (20 studies) with nonresorbable barriermembranes resulted in clinical attachment levelgains of 3.7∫1.8 mm; this was similar to the results

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Fig. 1. Plot of some of the clinical studies on guided tissueregeneration published between 1988 and 1998. The dots(red for nonresorbable barriers and blue for resorbablebarriers) indicate the average probing attachment level(PAL) gain reported by each author. The yellow line, con-necting some of the studies published by the group ofCortellini, Pini Prato & Tonetti, shows the improvementsobtained by these clinicians through time in terms ofprobing attachment level gains. Such improvements wereachieved by controlling the critical factors involved in theguided tissue regeneration procedure.

obtained treating 592 intrabony defects (17 studies)with bioresorbable barrier membranes (3.6∫1.5mm).

The reported outcomes indicate that the appli-cation of nonresorbable or bioresorbable barriermembranes consistently and predictably results inclinical improvements in intrabony defects. The ef-ficacy of guided tissue regeneration treatment ofinfrabony defects has been evaluated in 11 ran-domized controlled clinical trials in which guidedtissue regeneration has been directly compared withaccess flap surgery (Table 2) (1, 18, 19, 27, 33, 52, 53,59, 74, 75, 84). A total of 213 defects treated withaccess flap and 243 defects treated with guidedtissue regeneration were included in these studies.Ten of the 11 investigations concluded that guidedtissue regeneration resulted in statistically and clin-ically significant greater probing attachment levelgains when compared to the access flap. The onlyinvestigation reporting no significant differences be-tween guided tissue regeneration and access flapsurgery was carried out in only 9 pairs of defectslocated on maxillary premolars; in this study the in-trabony component of the defects was shallow and10 of the 18 defects had a furcation involvement (74).The weighted mean of the evidence reported in the11 studies listed in Table 2 indicated that the gain ofclinical attachment in sites treated with guidedtissue regeneration was 3.4∫1.8 mm (95% confi-

Cortellini & Tonetti

Table 1. Clinical studies on guided tissue regeneration with nonresorbable and bioresorbable barriermembranes

Probing Probing pocketAuthors Type of barrier n attachment gain SD depth at 1 year SD

Becker et al. (7) Expanded polytetrafluoroethylene 9 4.5 1.7 3.2 1

Chung et al. (18) Collagen 10 0.6 0.6

Handelsman et al. (48) Expanded polytetrafluoroethylene 9 4 1.4 3.9 1.4

Quteish et al. (75) Collagen 26 3 1.5 2.19 0.44

Selvig et al. (77) Expanded polytetrafluoroethylene 26 0.8 1.3 5.4

Proestakis et al. (74) Expanded polytetrafluoroethylene 9 1.2 1.3 3.5 0.88

Kersten et al. (51) Expanded polytetrafluoroethylene 13 1 1.1 5.1 0.9

Becker et al. (5) Expanded polytetrafluoroethylene 32 4.5 3.88 0.26

Cortellini et al. (20) Expanded polytetrafluoroethylene 40 4.1 2.5 2 0.6

Falk et al. (38) Polymer 25 4.5 1.6 3 1.1

Laurell et al. (55) Polymer 47 4.9 2.4 3 1.4

Cortellini et al. (21) Rubber dam 5 4 0.7 2.4 0.5

Cortellini et al. (27) Expanded polytetrafluoroethylene 15 4.1 1.9 2.7 1Titanium-reinforced expanded 15 5.3 2.2 2.1 0.5

polytetrafluoroethylene

Al-Arrayed et al. (1) Collagen 19 3.9 2.5

Cortellini et al. (24) Expanded polytetrafluoroethylene 14 5 2.1 2.6 0.9Expanded polytetrafluoroethylene 14 3.7 2.1 3.2 1.8

Mattson et al. (59) Collagen 13 2.5 1.5 3.6 0.6Collagen 9 2.4 2.1 4 1.1

Cortellini et al. (26) Expanded polytetrafluoroethylene 11 4.5 3.3 1.7Expanded polytetrafluoroethylene 11 3.3 1.9 1.9

Mellado et al. (63) Expanded polytetrafluoroethylene 11 2 0.9

Chen et al. (16) Collagen 10 2 0.4 4.2 0.4

Cortellini et al. (33) Expanded polytetrafluoroethylene 12 5.2 1.4 2.9 0.9Polymer 12 4.6 1.2 3.3 0.9

Tonetti et al. (88) Expanded polytetrafluoroethylene 23 5.3 1.7 2.7

Becker et al. (6) Polymer 30 2.9 2 3.6 1.3

Kim et al. (53) Expanded polytetrafluoroethylene 19 4 2.1 3.2 1.1

Gouldin et al. (46) Expanded polytetrafluoroethylene 25 2.2 1.4 3.5 1.3

Murphy (67) Expanded polytetrafluoroethylene 12 4.7 1.4 2.9 0.8

Cortellini et al. (29) Polymer 10 4.5 0.9 3.1 0.7

Falk et al. (39) Polymer 203 4.8 1.5 3.4 1.6

Caffesse et al. (11) Polymer 6 2.3 2 3.8 1.2Expanded polytetrafluoroethylene 6 3 1.2 3.7 1.2

Kilic et al. (52) Expanded polytetrafluoroethylene 10 3.7 2 3.1 1.4

Benque’ et al. (9) Collagen 52 3.6 2.2 3.9 1.7

Christgau et al. (7) Expanded polytetrafluoroethylene 10 4.3 1.2 3.6 1.1Polymer 10 4.9 1 3.9 1.1

Cortellini et al. (30) Polymer 18 4.9 1.8 3.6 1.2

Tonetti et al. (84) Polymer 69 3 1.6 4.3 1.3

Cortellini et al. (19) Polymer 23 3 1.7 3 0.9

Weighted mean 943 3.86 1.69 3.35 1.19

dence interval 3.0–3.7 mm), while the access flap re-sulted in a mean gain of 1.8∫1.4 mm (95% confi-dence interval 1.5–2.1 mm). The analysis of the re-ported clinical outcomes strongly suggests an addedbenefit deriving from the placement of barrier mem-

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branes after elevation of an access flap. This im-pression is reinforced by the lack of overlap observedin the 95% confidence intervals.

The data reported in some of the studies summar-ized in Table 1 (651 defects in 17 investigations (9,


Table 2. Controlled clinical trials comparing guided tissue regeneration procedure with access flap pro-cedures

Guided tissuen (guided regeneration Flap probingtissue probing attachment attachment

Authors Type of membrane regeneration) gain∫SD (mm) n (flap) gain∫SD (mm)

Chung et al. (18) Collagen 10 0.6∫0.6 10 ª0.7∫0.9

Quteish & Dolby (75) Collagen 26 3.0∫1.5 26 1.8∫0.9

Proestakis et al. (74) Expanded polytetrafluoroethylene 9 1.2∫2.0 9 0.6∫1.0

Al-Arrayed et al. (1) Collagen 14 3.9 14 2.7

Mattson et al. (59) Collagen 9 2.4∫2.1 9 0.4∫2.1

Cortellini et al. (27)* Expanded polytetrafluoroethylene 15 4.1∫1.9 15 2.5∫0.8

Cortellini et al. (27) Titanium-reinforced expanded 15 5.3∫2.2 – –polytetrafluoroethylene

Cortellini et al. (33)* Expanded polytetrafluoroethylene 12 5.2∫1.4 12 2.3∫0.8

Cortellini et al. (33) Polymer 12 4.6∫1.2 – –

Kim (53) Expanded polytetrafluoroethylene 19 4.0∫2.1 18 2.0∫1.7

Kilic (52) Expanded polytetrafluoroethylene 10 3.7∫2.0 10 2.1∫2.0

Tonetti (84) Polymer 69 3.0∫1.6 67 2.2∫1.5

Cortellini (19) Polymer 23 3.0∫1.7 23 1.6∫1.8

Weighted mean 243 3.4∫1.8 213 1.8∫1.4

* Three-arm studies. Comparisons were made among two different barrier membranes and access flap.

17–19, 27, 29–31, 33, 38, 39, 48, 55, 59, 75, 84, 88)allowed a further analysis to address the issue of pre-dictability of obtaining relevant amounts of attach-ment level gains in intrabony defects. The frequencydistribution of clinical attachment level changes at 1year has been evaluated subdividing the data in 5classes of probing attachment level changes: loss ofattachment, gain of 0–1 mm, gain of 2–3 mm, gainof 4–5 mm and gain of 6 mm or more. Only 2.7% of651 treated cases lost attachment, while gains of lessthan 2 mm were observed in 11% of the cases. Mostof the sites gained considerable attachment. In fact,gains of 2–3 mm were observed in 24.8% of the cases,gains of 4–5 mm in 41.3%, and gains of 6 mm ormore in 21.2% of defects. These encouraging datademonstrate that guided tissue regeneration is notonly efficacious, but also predictable.

Five investigations reported changes in bonelevels (7, 32, 48, 51, 78). Bone gains ranged from 1.1mm to 4.3 mm and seemed to correlate well withthe gains in clinical attachment. The existence of acorrelation between gains in clinical attachment andgains in bone levels in intrabony defects was demon-strated in an investigation by Tonetti et al. (89). Inthis study, the expected position of the bone 1 yearafter guided tissue regeneration was consistentlyfound to be located 1.5 mm apical to the position ofthe clinical attachment.

Reduction of pocket depths is one of the critical

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endpoints of most periodontal procedures, includingguided tissue regeneration. An important parameterto evaluate the successful outcomes of guided tissueregeneration, therefore, is the depth of the residualpockets. In most of the studies listed in Table 1, shal-low pockets were consistently measured at 1 year.The weighted mean of residual pocket depths was3.3∫1.2 mm, with a 95% confidence interval rangingfrom 3.2 to 3.5 mm. It is interesting to note that deepresidual pockets (greater than 5 mm) were observedin only two studies, which reportedly resulted inminimal amounts of attachment and bone gains (51,78).

Factors affecting the clinicaloutcomes

The primary factors affecting the clinical outcomesof periodontal surgery have been classified by Korn-man in this volume as: 1) bacterial contamination,2) innate wound-healing potential, 3) local sitecharacteristics and 4) surgical procedure. These fac-tors have been summarized in an influence diagramto illustrate how various factors influence regenera-tion.

The information used to build the influence dia-gram primarily derive from studies in which multi-variate approaches have been employed to identify


factors associated with the observed clinical out-comes (58, 85–87). These studies have evaluatedthree types of possible sources of variability: (i) thepatient; (ii) the morphology of the defect; (iii) theguided tissue regeneration procedure and the heal-ing period.

The patient

Physiological, environmental, behavioral and gen-etic patient factors may affect the healing outcomeof guided tissue regeneration procedures. So far, ahighly significant environmental exposure, cigarettesmoking, has been associated with reduced out-comes (86). The ability to maintain high levels ofplaque control has also been associated with im-proved outcomes (23, 28, 86, 87). Since these factorscan be controlled through behavioral interventions,clinicians should discuss with the patient the oppor-tunity to further improve hygiene and discontinuethe smoking habit. Another important variable as-sociated with guided tissue regeneration outcomesis the level of residual periodontal infection in thedentition, evaluated clinically as the percentage ofsites with bleeding on probing, or microbiologicallyas the persistence of periodontal pathogens aftercompletion of initial therapy (58, 85). A clinical im-plication of such observation is to defer guidedtissue regeneration procedures until the periodontalinfection is adequately controlled. Despite the lackof direct evidence, other factors, such as diabetes,intraoral accessibility and stressful life events,should be kept in mind in patient selection.

The defect

Defect morphology plays a major role in the healingresponse of guided tissue regeneration therapy in in-trabony defects. It has been demonstrated thatgreater amounts of clinical attachment and bone canbe gained in deeper defects (42, 85, 87). Defectsdeeper than 3 mm have been found to result consist-ently in greater probing attachment gains than de-fects of 3 mm or less (19). The potential for regenera-tion, however, has been reported to be similar indeep and shallow defects. In fact, in the cited study(19) similar results were observed in shallow anddeep defects, when probing attachment gains wereexpressed as a percentage of the baseline intrabonycomponent of the defects. Another importantmorphological characteristic is the width of the in-trabony component of the defect, measured as theangle that the bony wall of the defect forms with the

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long axis of the root (82). Wider defects have beenassociated with reduced amounts of probing attach-ment level gain and bone fill at 1 year (85). In a re-cent study on 242 intrabony defects, defects with aradiographic defect angle of 25æ or less gained con-sistently more attachment (1.5 mm on average) thandefects of 37æ or more (35).

Two investigations failed to demonstrate a sig-nificant association between the number of residualbony walls and the clinical outcomes (85, 87). In onestudy, clinical improvements were associated withthe depth of the three-wall intrabony component ofthe defect (78). All investigations agree on the lackof significance of defect circumference and/or num-ber of tooth surfaces involved (78, 85, 87). In a study,gingival thickness of less than 1 mm was associatedwith higher prevalence and severity of flap dehis-cence over the membrane (2).

Based on this evidence and the treatment objec-tives, deep and narrow defects are the ones that maybenefit most from guided tissue regeneration treat-ment. It is also desirable to surgically manipulatethick tissues for membrane coverage and thus re-duce the occurrence of flap dehiscence.

The guided tissue regeneration procedure andthe healing period

Evidence from 2 randomized, controlled clinical tri-als indicates that the choice among different guidedtissue regeneration strategies affects the expectedoutcomes resulting in significantly greater improve-ments in clinical attachment levels (24, 27, 87). Dif-ferent membranes, i.e. resorbable vs. non-resorbableor self-supporting membranes, possess differentabilities to create and maintain the necessary spacefor regeneration. Different surgical approaches to ac-cess the interdental spaces, to preserve tissues andto protect the area of regeneration, are associatedwith different outcomes.

In particular, membrane exposure is a major com-plication of guided tissue regeneration with a preva-lence in the 70% to 80% range (7, 22, 31, 36, 37, 65,78). Membrane exposure has been reported to behighly reduced (range 40 to 5%) with the use of ac-cess flaps specifically designed to preserve the inter-dental tissues (25, 29, 30, 67, 84). This is a relevantissue, since membranes exposed to the oral environ-ment have been shown to be contaminated by bac-teria (36, 37, 47, 58, 64, 68–70, 77, 79, 83). Severalindependent studies have associated contaminationof both non-resorbable and resorbable membraneswith reduced amounts of probing attachment gains


Fig. 2. Conventional technique. Man- Fig. 3. Conventional technique. After Fig. 4. Conventional technique. Atdibular right cuspid: the preoperative flap elevation a 7-mm two- and three- week 2, the nonresorbable barrierpocket depth was 5 mm and the prob- wall defect was exposed. The total membrane was partially exposed anding attachment level 11 mm. depth of the defect measured 12 mm. thus contaminated.

Fig. 5. Conventional technique. The re- Fig. 6. Conventional technique. The re- Fig. 7. Conventional technique. At 1generated tissue appeared inflamed at generated tissue was not properly pro- year, the residual pocket depth was 4membrane removal. tected in the interproximal area. mm. A gain of 3 mm of clinical attach-

ment and a substantial increase of thegingival recession were measured.

(36, 37, 69, 70, 77). Antimicrobial prophylaxis of ex-posed membranes has been shown to be effective inreducing the bacterial load but ineffective in pre-venting biofilm formation (40, 69). This evidence

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suggests the importance of keeping the membranessubmerged to obtain optimal results. Further, reduc-tion of bacterial load by an appropriate anti-microbial approach may reduce the negative effects


Fig. 8. Conventional technique. Baseline radiograph.

Fig. 9. Conventional technique. One-year radiograph.

associated with membrane contamination. Thechoice of the surgical approach and of a specific typeof barrier membrane is therefore a critical clinicaldecision. Finally, operator skill may influence theclinical outcomes (84). Different ability in tissuemanagement, membrane manipulation, attention toblood supply, suturing technique and other factorsmay play a major role in a difficult procedure suchas guided tissue regeneration. Other components ofoperator skill may relate to the individual skills in

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patient and site selection and postoperative man-agement.

The guided tissue regenerationprocedures

Various surgical approaches and suturing techniqueshave been proposed in the literature. Cliniciansshould incorporate in their clinical armamentariumall the possible alternatives to optimize the pro-cedure.

Conventional approach

The conventional approach consists of a flap ap-proach (access flap or modified Widman flap) notspecifically designed for use with barrier membranes(7, 22, 31, 48). Full-thickness flaps are elevated to tryto preserve the marginal and the interdental tissuesto the maximum possible extent. Vertical releasingincisions are performed as needed to increase defectaccessibility. Periosteal incisions are normally per-formed to allow coronal displacement of the flap andto improve the ability to cover the membrane. Mat-tress and passing sutures are placed in the inter-proximal spaces in order to attempt primary closureof the interdental tissues over the membranes (Fig.2–9).

This approach normally does not allow a com-plete preservation of the interdental papilla, there-fore rendering very difficult the primary closure ofthe interdental tissues over the membrane. Majorcomplications are gingival dehiscence and mem-brane exposure.

Modified papilla preservation technique

The rationale for developing this technique was toachieve and maintain primary closure of the flap inthe interdental space over the membrane (Fig. 10–15). Access to the interproximal defect consists of ahorizontal incision traced in the buccal keratinizedgingiva at the base of the papilla, connected withmesiodistal buccal intrasulcular incisions. After elev-ation of a full-thickness buccal flap, the residual in-terproximal tissues are dissected from the neigh-boring teeth and the underlying bone and elevatedtowards the palatal aspect. A full-thickness palatalflap, including the interdental papilla, is elevatedand the interproximal defect exposed. Following de-bridement of the defect, the buccal flap is mobilizedwith vertical and periosteal incisions, when needed.


Fig. 13. Modified papilla preservation technique. The in-Fig. 10. Modified papilla preservation technique. Access toterproximal defect after debridement.the defect was gained with a buccal horizontal incision at

the base of the papilla.

Fig. 14. Modified papilla preservation technique. A ti-Fig. 11. Modified papilla preservation technique. A buccaltanium-reinforced barrier membrane was positioned nearfull-thickness flap was elevated. The defect-associated pa-to the cementoenamel junction.pilla is still in place.

Fig. 12. Modified papilla preservation technique. The pa- Fig. 15. Modified papilla preservation technique. Primarypilla was elevated along with the full-thickness palatal closure of the interdental space was ensured with a hori-flap. zontal internal crossed mattress suture to relieve the ten-

sion of the flaps and a second suture to close the interden-tal papilla.

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Fig. 16, 17. Modified papilla preservation technique.Drawing of the horizontal internal crossed mattress su-ture. The suture runs under the flaps, hanging on top ofthe titanium reinforcement of the membrane. The buccalflap is coronally displaced.

This technique was originally designed for use incombination with self-supporting barrier mem-branes (25). In fact, the suturing technique requires asupportive (or supported) membrane to be effective(Fig. 16, 17). To obtain primary closure of the inter-dental space over the membrane, a first suture (hori-zontal internal crossed mattress suture) is placed be-neath the mucoperiosteal flaps between the base ofthe palatal papilla and the buccal flap. The interproxi-mal portion of this suture hangs on top of the mem-brane allowing the coronal displacement of the buc-cal flap. This suture relieves all the tension of the flaps.To ensure passive primary closure of the interdentaltissues over the membrane, a second suture (a verticalinternal mattress suture) is placed between the buccalaspect of the interproximal papilla (that is, the mostcoronal portion of the palatal flap that includes theinterdental papilla) and the most coronal portion ofthe buccal flap. This suture is free of tension.

An alternative type of suture to close the interden-tal tissues has been proposed by Laurell (54). Thismodified internal mattress suture (Fig. 18, 19) startsfrom the external surface of the buccal flap, crossesthe interdental area and passes through the lingual

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flap at the base of the papilla. The suture runs backthrough the external surface of the lingual flap andthe internal surface of the buccal flap, about 3 mmapart from the first two bites. Finally, the suture ispassed through the interproximal area above thepapillary tissues, passed through the loop of the su-ture on the lingual side and brought back to the buc-cal side, where it is tied. This suture is very effectivein ensuring stability and primary closure of theinterdental tissues.

In a randomized controlled clinical study of 45 pa-tients (27), significantly greater amounts of probingattachment were gained with the modified papillapreservation technique (5.3∫2.2 mm), in compari-son with either conventional guided tissue regenera-tion (4.1∫1.9 mm) or access flap surgery (2.5∫0.8mm), demonstrating that a modified surgical ap-proach can result in improved clinical outcomes.The sites accessed with the modified papilla preser-vation technique showed primary closure of the flapin all but one case, and no gingival dehiscence untilmembrane removal, in 73% of the cases (Fig. 20–40).

This surgical approach has been also attempted incombination with non-supported bioresorbable bar-rier membranes (29), with positive results. Clinical

Fig. 18, 19. A modification of the suture described in Fig.15 and 16, described by L. Laurell. This suture ensuresalso an external stabilization to the interproximal tissues.


Fig. 20. Modified papilla preservation technique. A 10 mm Fig. 23. Modified papilla preservation technique. Primarypocket on the mesial surface of the upper left central in- closure of the interdental tissues was achieved over thecisor. membrane.

Fig 24. Modified papilla preservation technique. PrimaryFig. 21. Modified papilla preservation technique. After de-closure was maintained at week 5. The gingiva wasbridement a one- and three-wall combination intrabonyhealthy.defect was evident.

Fig. 25. Modified papilla preservation technique. AfterFig. 22. Modified papilla preservation technique. A ti-membrane removal a mature, rich in collagen and un-tanium-reinforced barrier membrane was positioned atinflamed tissue was evident.the level of the cementoenamel junction.

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Fig. 26. Modified papilla preservation technique. The re-generated tissue was properly protected with the gingivalflaps.

attachment level gains at 1 year were 4.5∫0.9 mm. Inall the cases primary closure of the flap was achieved,and about 80% of the sites maintained primary clo-sure over time (Fig. 41–48). It should be emphasized,however, that the horizontal internal crossed mattresssuture most probably caused an apical displacementof the interproximal portion of the membrane, there-by reducing the space for regeneration.

The surgical access of the interproximal spacewith the modified papilla preservation technique is

Fig. 28. Modified papilla preservation Fig. 29. Modified papilla preservation Fig. 30. Modified papilla preservationtechnique. Baseline radiograph. technique. One-year radiograph show- technique. Upper right cuspid: the in-

ing almost complete resolution of the trabony defect is 14 mm deep.defect.

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Fig. 27. Modified papilla preservation technique. At 1 year,no recession of the interdental tissues was observed. Thepocket depth was reduced to 3 mm with a gain of attach-ment of 7 mm.

technically very demanding, but it has been reportedto be very effective and applicable in wide interden-tal spaces (wider than 2 mm at interdental tissuelevel), especially in the anterior dentition. In prop-erly selected cases, large amounts of attachmentgain and consistent reduction of pocket depths as-sociated with no or minimal recession of the inter-dental papilla are consistently expected. It is, there-fore, especially indicated in cases in which aestheticsis particularly important.


Fig. 31. Modified papilla preservation Fig. 32. Modified papilla preservation Fig. 33. Modified papilla preservationtechnique. Two membranes were su- technique. Baseline radiograph, show- technique. One-year radiograph: thetured together to cover all the apicoco- ing radiolucency up to the apex of the intrabony defect was almost com-ronal extension of the defect. tooth. pletely resolved.

Simplified papilla preservation flap

To overcome some of the technical problems en-countered with the modified papilla preservationtechnique, including difficult application in narrowinterdental spaces and in posterior areas and a su-turing technique not appropriate for use with non-supportive barriers, a different approach, the simpli-fied papilla preservation flap (Fig. 49–58), was subse-quently developed (30).

This different and simplified approach to theinterdental papilla includes a first incision across the

Fig. 34. Modified papilla preservation technique. Upperright central incisor: the intrabony defect is deeper than15 mm. Total bone loss is greater than 20 mm.

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defect associated papilla, starting from the gingivalmargin at the buccal-line angle of the involved toothto reach the mid-interproximal portion of the papillaunder the contact point of the adjacent tooth. Thisoblique incision is carried out keeping the blade par-allel to the long axis of the teeth to avoid excessivethinning of the remaining interdental tissues. Thefirst oblique interdental incision is continued intra-sulcularly in the buccal aspect of the teeth neigh-boring the defect. After elevation of a full-thicknessbuccal flap, the remaining tissues of the papilla arecarefully dissected from the neighboring teeth and

Fig. 35. Modified papilla preservation technique. Lingualview showing the severity and extension of the bone de-struction.


Fig. 36, 37. Modified papilla preservation technique. A ti-tanium-reinforced barrier membrane positioned to iso-late the defect (buccal and lingual view).

Fig. 38. Modified papilla preservation technique. One-yearre-entry surgery. The distance from the cementoenameljunction and the bottom of the defect was 10 mm: thebone gain was greater than 10 mm.

the underlying bone crest. The interproximal papil-lary tissues at the defect site are gently elevatedalong with the lingual/palatal flap to fully expose theinterproximal defect. Following defect debridementand root planing, vertical releasing incisions and/orperiosteal incisions are performed, when needed, to

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improve the mobility of the buccal flap. After appli-cation of a barrier membrane, primary closure of theinterdental tissues above the membrane isattempted in the absence of tension, with the follow-ing sutures: 1) a first horizontal internal mattress su-ture (offset mattress suture) is positioned in the de-fect-associated interdental space running from thebase (near the mucogingival junction) of the kera-

Fig. 39. Modified papilla preservation technique. Baselineradiograph.

Fig. 40. Modified papilla preservation technique. One-yearradiograph. The defect was almost completely resolved.


Fig. 41. Modified papilla preservation technique with bio-resorbable membranes. Upper left central incisor at base-line.

Fig. 42. Modified papilla preservation technique with bio-resorbable membranes. A deep one-, two- and three- wallcombination defect was evident after debridement.

Fig. 43. Modified papilla preservation technique with bio-resorbable membranes. A bioresorbable barrier was posi-tioned.

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Fig. 44. Modified papilla preservation technique with bio-resorbable membranes. Primary closure of the interproxi-mal tissues was obtained over the bioresorbable mem-brane.

Fig. 45. Modified papilla preservation technique with bio-resorbable membranes. Primary closure was maintainedthrough time.

Fig. 46. Modified papilla preservation technique with bio-resorbable membranes. At one-year, the final fixed recon-struction was placed.


Fig. 47. Modified papilla preservation technique with bio-resorbable membranes. Baseline radiograph.

Fig. 48. Modified papilla preservation technique with bio-resorbable membranes. One-year radiograph.

tinized tissue at the mid-buccal aspect of the toothnot involved by the defect to a symmetrical locationat the base of the lingual/palatal flap. This suturerubs against the interproximal root surface, hangs onthe residual interproximal bone crest and is an-chored to the lingual/palatal flap. When tied, itallows the coronal positioning of the buccal flap. Arelevant notation is that this suture, laying on the

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Fig. 49. Simplified papilla preservation flap. Upper rightlateral incisor at baseline.

Fig. 50. Simplified papilla preservation flap. The pocketdepth and the attachment level were 9 mm and 11 mm,respectively.

Fig. 51. Simplified papilla preservation flap. The intrabonydefect was a deep one-wall defect with a shallow three-wall component at the bottom. Note the bone crest ad-jacent to the central incisor.


Fig. 52. Simplified papilla preservation flap. A bioresorb-able barrier membrane was positioned to cover the defect.

Fig. 53. Simplified papilla preservation flap. Primary clo-sure of the defect-associated interproximal space. Notethe offset suture positioned on the buccal side of the cen-tral incisor.

Fig. 54. Simplified papilla preservation flap. The treatedarea at 1 year. Probing depth is 2 mm.

interproximal bone crest, does not cause any com-pression at the mid-portion of the membrane, there-fore preventing its collapse into the defect. 2) The

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interdental tissues above the membrane are then su-tured to obtain primary closure with one of the fol-lowing approaches: a) one interrupted suture when-ever the interproximal space is narrow and the inter-dental tissues thin; b) two interrupted sutures, whenthe interproximal space is wider and the interdentaltissues thicker; c) an internal vertical/oblique mat-tress suture (25), when the interproximal space is

Fig. 55. Simplified papilla preservation flap. Baselineradiograph.

Fig. 56. Simplified papilla preservation flap. One-yearradiograph.


Fig. 57, 58. Simplified papilla preservation flap. Drawingrepresenting the ‘‘offset mattress suture’’. This suture rubsagainst the root surface of the tooth approximal to thedefect, hangs on the residual bone crest preventing theapical displacement of the resorbable barrier membrane.

wide and the interdental tissues thick. Special carehas to be paid to ensure that the first horizontal mat-tress suture would relieve all the tension of the flaps,and to obtain primary passive closure of the inter-dental tissues over the membrane with the last su-ture. When tension is observed, the sutures shouldbe removed and the primary passive closureattempted a second time.

This approach has been preliminarly tested in acase series of 18 deep intrabony defects in combi-nation with bioresorbable barrier membranes (30).The average clinical attachment level gain observedat 1 year was 4.9∫1.8. In all the cases it was possibleto obtain primary closure of the flap over the mem-brane, and 67% of the sites maintained primary clo-sure over time. The same approach was then testedin a multicenter controlled randomized clinical trialinvolving 11 clinicians from 7 different countries anda total of 136 defects (84). The average clinicalattachment gain observed at 1 year in the 69 defectstreated with the simplified papilla preservation flapand a resorbable barrier membrane was 3∫1.6 mm.More than 60% of the treated sites maintained pri-mary closure over time. It is important to underline

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that these results were obtained by different clini-cians treating different populations of patients anddefects including also narrow spaces and posteriorareas of the mouth.

Interdental tissue maintenance

Interproximal tissue maintenance is a techniqueproposed by Murphy (67) to be used in combinationwith nonresorbable barrier membranes and graftingmaterial. It involves the reflection of a triangularlyshaped palatal flap that remains contiguous with thebuccal portion of the flap. The triangularly shapedpalatal tissue is referred to as the papillary triangle.The isthmus of tissue that connects the papillary tri-angle with the buccal flap provides the primarycoverage for the interproximal guided tissue re-generation material during wound healing. The suc-cess of this technique depends upon the followingfactors: excellent preoperative tissue tone and ab-sence of local inflammation; the thickness of thepalatal tissue; the use of wide, inverse bevelled pala-tal incisions; a minimal interradicular width of 2 mmmeasured at the osseous crest; and atraumatic man-agement of the tissue intraoperatively.

The surgical procedure starts with initial buccalintrasulcular incisions extending one to two teeth oneither side of the defect. Vertical releasing incisionsare made to facilitate flap reflection. Full-thicknessflap reflection is made at the level of the mucogingi-val junction, except in the area adjacent the inter-proximal defect. No attempt is made to reflect theinterproximal tissue at this stage. Palatal incisionsare made that create the papillary triangle and thepalatal flap. Intrasulcular interproximal incisions aremade with great care not to sever the isthmus oftissue that connects the papillary triangle to the buc-cal flap. Full-thickness elevation of the papillary tri-angle is performed using small periosteal elevators.From the palatal aspect, the isthmus of interproxi-mal tissues is carefully released from the interproxi-mal alveolar defect using the back hand of a largesurgical curette. Before the papillary triangle is dis-placed under the contact point, the buccal flap isexamined for any adhesion to the alveolar crest inthe area of the defect. To facilitate coronal repo-sitioning of the flap and passive closure, the buccalflap is released from the periosteum with split thick-ness dissection. The defect is debrided thoroughly. Adecalcified freeze-dried allograft is placed into thedefect and over the alveolar crest in an attempt tomaintain space. The barrier is shaped and sized sothat it will remain passively in position over the de-


Fig. 59. The crestal incision. Maxillary right cuspid atbaseline. The defect was located on the distal aspect.

Fig. 60. The crestal incision. A crestal incision and distalvertical releasing incisions uncovered a one-, two- andthree-wall combination intrabony defect.

fect. No suturing of the barrier is performed. Thepapillary triangle is returned to its original positionby gently pushing the papillary triangle under thecontact area. The flaps are sutured using a modifiedvertical mattress suture. The suture first passesthrough the buccal flap and exits the tissue at theedge of the papillary triangle. The suture overlays themesial aspect of the papillary triangle, and theneedle is passed in a mesial to distal directionthrough the mesial portion of the palatal flap engag-ing the tip of the papillary triangle, and then ispassed through the distal portion of the palatal flap.The suture exits the palatal flap at this point and willoverlay the distal aspect of the papillary triangle. Thesuture is then passed under the contact area and tiedto the free end of the suture on the buccal flap. Theother areas of the flap are closed in a standard man-ner using interrupted sutures.

The author reports an average clinical attachmentlevel gain of 4.7∫1.4 mm after 1 year in a population

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of 12 defects. Primary closure was obtained in 95%of the cases. This technique can be applied only todefects located in the upper jaw, preferably bicus-pids, with an interdental space wide at least 2 mm.

The crestal incision

When a defect is located at a tooth side adjacent toan edentulous area (frequently occurring to abut-ment teeth), a crestal incision is performed to accessthe area (34, 88). The incision extends 2 to 3 mmfurther from the defect and can be associated withvertical releasing incisions. Full-thickness buccaland lingual flaps are elevated, the defect debridedand a membrane positioned. Membrane coverageand primary closure of the flap over the implantedmaterial is achieved with interrupted or mattress su-tures (Fig. 59–67).

Fig. 61. The crestal incision. Filling material was posi-tioned into the defect to support the bioresorbable barriermembrane.

Fig. 62. The crestal incision. A bioresorbable barrier waspositioned.


Fig. 63. The crestal incision. Primary closure was obtainedover the membrane.

Fig. 64. The crestal incision. The primary closure wasmaintained over time.

Fig. 65. The crestal incision. One-year clinical appearanceof the treated area.

Free gingival graft at membrane removal

The use of free gingival grafts has been proposed toafford better coverage and protection of the regener-

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ated interproximal tissues after membrane removal,when the occurrence of a dehiscence of the gingivalflap does not allow a primary coverage of the inter-dental area (24). The free gingival graft is positionedin the interdental space to cover the interproximalregenerated tissue (Fig. 68–76). The gingival graftconsists of an interproximal, saddle-shaped epi-thelial–connective tissue portion and two disepi-thelialized buccal and lingual portions. The buccaland lingual connective tissue portions of the grafts

Fig. 66. The crestal incision. Baseline radiograph.

Fig. 67. The crestal incision. One-year radiograph.


Fig. 68. Free gingival graft. Mandibular Fig. 69. Free gingival graft. The intra- Fig. 70. Free gingival graft. A nonre-right cuspid at baseline. The defect bony component of the three-wall de- sorbable barrier membrane was posi-was positioned on the distal side. fect was 5 mm. tioned.

Fig. 71. Free gingival graft. Exposure of Fig. 72. Free gingival graft. The regen- Fig. 73. Free gingival graft. A saddle-the barrier occurred at week 4. erated tissue at membrane removal shaped free gingival graft was posi-

(week 5) was slightly inflamed. tioned in the interproximal space toprotect the regenerated tissue.

extend 2 to 3 mm below the margin of the residualbuccal and lingual flaps. The graft has to be firmlystabilized with interrupted sutures placed betweenthe margins of the graft and the buccal and lingualmargins of the gingival flaps. Compressive suturesare also positioned to improve stability.

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A randomized controlled clinical trial (24) resultedin significantly greater probing attachment levelgains in the 14 sites where a free gingival graft waspositioned to cover the regenerated tissues, aftermembrane removal (5∫2.1 mm) compared with the14 sites where a conventional protection of the re-


Fig. 74. Free gingival graft. At 1 year, the probing depthwas 3 mm.

generated tissue was afforded with coronal posi-tioning of the gingival flap (3.7∫2.1 mm). In 12 ofthe 14 grafted sites the free gingival graft succeeded;in the other 2 it was lost.

Postoperative regime

The postoperative regime prescribed to patients isaimed at controlling wound infection or contami-nation as well as mechanical trauma to the treatedsites (27, 31, 39, 55, 84). It generally includes the pre-scription of systemic antibiotics (tetracycline oramoxicillin) in the immediate postoperative period(1 week), 0.2 or 0.12% chlorhexidine mouthrinsingtwo or three times per day and weekly professionaltooth cleaning until the membrane is in place. Pro-fessional tooth cleaning consists of supragingivalprophylaxis with a rubber cup and chlorhexidine gel.Patients are generally advised not to perform mech-anical oral hygiene and not to chew in the treatedarea. Nonresorbable membranes are removed 4 to 6weeks after placement, following elevation of partialthickness flaps. Patients are re-instructed to rinsetwo or three times per day with chlorhexidine, notto perform mechanical oral hygiene and not to chewin the treated area for 3 to 4 weeks. In this period,weekly professional control and prophylaxis are rec-ommended. When bioresorbable membrane areused, the period of tight infection control regime is

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extended for 6 to 8 weeks. After this period, patientsare re-instructed to gradually resume mechanicaloral hygiene, including interdental cleaning, and todiscontinue chlorhexidine. Patients are then enrolledin a periodontal care program on a monthly basisuntil 1 year. Probing or deep scaling in the treatedarea is generally avoided before the 1-year follow-upvisit.

Fig. 75. Free gingival graft. Baseline radiograph.

Fig. 76. Free gingival graft. One-year radiograph showingthe complete resolution of the defect.


Barrier membranes

Nonresorbable and bioresorbable barrier mem-branes are available. The main clinical differenceamong the two types is the need of a second surgeryto remove the nonresorbable barrier membranes.Among the latter, the expanded polytetrafluorethy-lene membranes are widely used and successfullytested in many clinical studies (Table 1). The ti-tanium-reinforced membrane is an evolution of theexpanded polytetrafluoroethylene barrier. The de-sign of this barrier enhances its ability to save spacefor regeneration and to support the gingival tissues.In recent years bioresorbable barrier membraneshave been introduced in guided tissue regenerationto avoid further surgery. Barrier membranes of colla-gen (Table 1) and of polylactic acid or copolymers ofpolylactic acid and polyglycolic acid (Table 1) havebeen evaluated in independent studies, with variousdegrees of clinical success. From a clinical stand-point, these membranes are generally easy to ma-nipulate and position about the defect, but have alimited ability to save room for regeneration and tosupport the gingival tissues.

A subset analysis performed on the studies listed intable 1 to compare the 351 sites treated with non-re-sorbable barriers and the 592 treated with bioresorb-able ones shows probing attachment gains of 3.7∫1.8mm (95% confidence interval 3.4 to 4.0 mm) for thenonresorbable group and probing attachment gainsof 3.6∫1.5 mm (95% confidence interval 3.4 to 3.8mm) for the bioresorbable one. When the bioresorb-able group is further subdivided into two subgroups,one for collagen material, the other for polymers, theweighted mean in terms of probing attachment gainis 3.0∫1.7 mm (95% confidence interval 2.5 to 3.5mm) for the 139 collagen-treated sites, and 4.1∫1.6(95% confidence interval 3.9 to 4.4 mm) for the 453sites treated with polymers. These data seem to indi-cate that similar outcomes can be expected usingnonresorbable and bioresorbable barriers. Among thebioresorbable membranes, however, better outcomesare to be expected using polymers.

Combination treatment

Schallhorn & McClain have suggested that a combi-nation therapy consisting of barrier membranes plusbone grafting may result in significant improvementsof expected outcomes (60, 76). Four studies (16, 52, 53,63), however, evaluating the added benefit of bone orbone substitutes used in combination with barrier

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membranes failed to demonstrate an additive effectof these adjunctive materials to barrier membranesalone in deep intrabony defects. On the other hand,negative effects of the employed materials have notbeen reported, indicating a possible use of these ma-terials in combination with barrier membranes withthe aim of providing better support to the flap and tosave room for regeneration (Fig. 59–67). The designand the sample size of the cited studies, however, doesnot allow any negative effect of the implanted ma-terials on the guided tissue regeneration process to beexcluded, thereby preventing definitive conclusions.

Complications

Complication of guided tissue regeneration pro-cedures are frequent and frequently associated withimpairment of the clinical outcomes. Membrane ex-posure has been reported in many investigations to bethe major complication with a prevalence in the rangeof 70 to 80% (7, 22, 31, 36, 37, 65, 78). Prevalence ofmembrane exposure has been highly reduced withthe use of access flaps (modified papilla preservationtechnique, interproximal tissue maintenance andsimplified papilla preservation flap) specifically de-signed to preserve the interdental tissues (25, 29, 30,67, 84). Control of membrane exposure is of great im-portance for the clinical outcomes, since in manystudies exposed membranes have been shown to becontaminated with bacteria (36, 37, 47, 58, 64, 68–70,77, 79, 83). Contamination of exposed nonresorbableand resorbable barrier membranes has been associ-ated with reduced probing attachment gains in intra-bony defects (36, 37, 69, 70, 77).

Other postoperative complications such as swell-ing, erythema, suppuration, sloughing or perforationof the flap, membrane exfoliation and postoperativepain have been reported in independent studies. Aninvestigation reported the prevalence of pain (16%of cases), suppuration (11%), swelling and sloughingof the marginal portion of the flap (7%) in the im-mediate postoperative period (65, 66). Postsurgicalpain can be easily controlled with administration ofpain-killers. The events connected with local bac-terial contamination are treated by enhancing theinfection control regime both at home and in thedental office. This is based on the use of chlorhex-idine rinses and gels, wiping devices such as softtoothbrushes and cotton pellets and frequent pro-fessional cleaning and prophylaxis. Perforation ofthe flap or severe exposure of the membrane couldrequire removal of the material.


Fig. 77. Decision tree 1: selection of patient, defect and objective of treatment.

Treatment strategies

Guided tissue regeneration in the year 2000 can nolonger be considered as a single treatment approach.In fact, today there is evidence to consider guidedtissue regeneration as a multifactorial treatment ap-proach comprising careful selection of patients and

Fig. 78. Decision tree 1, node 1: selection of patient.Source: modified from Cortellini & Bowers. Int J Peri-odontics Restorative Dent 1995. FMPS: full-mouth plaquescore. FMBS: full-mouth bleeding score.

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defects, different surgical techniques, various typesof membranes and adjunctive materials and manysuturing approaches. All the cited components couldbe variously combined to build up different treat-ment strategies loaded with different degrees oftechnical difficulties. Various combinations of fac-tors are expected to produce different clinical results.

The treatment philosophy proposed in this chap-ter is based on selecting the combination of factorsable to guarantee the maximum degree of predict-

Fig. 79. Decision tree 1, node 2: selection of defect. Source:modified from Cortellini & Bowers. Int J Periodontics Re-storative Dent 1995.


Fig. 80. Decision tree 2: non-aesthetically sensitive sites. modified papilla preservation technique. ITM: interproxi-The objective of treatment is to increase the periodontal mal tissue maintenance. SPPF: simplified papilla preser-support and decrease the probing pocket depth. MPPT: vation flap. e-PTFE: expanded polytetrafluoroethylene.

ability with the minimal degree of technical diffi-culty, to reach the desirable objective of the treat-ment.

With this in mind, three operative decision trees,based on a stepwise approach with subsequent de-cision nodes, have been built up to assist cliniciansin the process of selecting the proper treatmentstrategy in different clinical cases. A first decisiontree (decision tree 1) will help clinicians in selectingpatients, defects and setting the objectives of treat-ment. Then, two different trees, one for non-aesthet-ically sensitive sites (decision tree 2) and the otherfor aesthetically sensitive sites (decision tree 3), willhelp clinicians in selecting the treatment strategy.

The starting-point of the decision process is theselection of the patient (decision tree 1, node 1; seeparagraph ‘‘the patient’’). According to the evidence,patients with less than 15% of sites presenting withplaque and residual infection, nonsmokers, with ahigh degree of compliance, and systemically healthyare the best candidates for guided tissue regenera-tion.

The second step is the selection of the defect (de-

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cision tree 1, node 2; see paragraph ‘‘the defect’’).Defects presenting with a radiographic angle of 25æor less, an intrabony component deeper than 3 mmand gingival tissues at least 1 mm thick have thegreatest chances to result in consistent amounts ofclinical attachment and bone gains, irrespective ofthe number of residual bony walls. The thickness ofthe gingival tissues, if unfavorable, can be improvedwith mucogingival surgery.

The third step sets the objectives of the treatment(decision tree 1, node 3). The primary outcomes anddesirable clinical results of the regenerative treat-ment of intrabony defects are (i) gain of clinicalattachment and bone, (ii) fill of the intrabony com-ponent of the defect, (iii) reduction of pocket depthand (iv) minimal gingival recession. In some in-stances, however, such as in non-aesthetically sensi-tive sites, a partial result could be the desirable ob-jective of treatment if combined with a more simpleand less invasive approach. The main objective oftreatment will be the gain of periodontal supportand the reduction of pocket depth, with a minor in-terest for the complete resolution of the defect and


Fig. 81. Decision tree 3: aesthetically sensitive sites. The vation technique. ITM: interproximal tissue maintenance.objective of treatment is to completely resolve the defect SPPF: simplified papilla preservation flap. e-PTFE: ex-and minimize recession. MPPT: modified papilla preser- panded polytetrafluoroethylene.

the amount of gingival recession. In aestheticallysensitive sites, on the contrary, it is desirable to max-imize the clinical result. The objective of treatmentis to gain periodontal support and reduce pocketdepth associated with full resolution of the intrabonycomponent of the defect and minimal or no gingivalrecession. In the first case (non-aesthetically sensi-tive sites), less invasive and easier techniques, eventhough less efficacious, may be chosen, whereas inthe second case the most effective procedures andcombination of materials will be included in thetreatment strategy, even if associated with greattechnical difficulty.

Once the objectives of treatment have been set,the next steps are the selection of (i) the surgical ac-cess of the interproximal defect-associated papilla,(ii) the type of membrane and the possible use offilling materials, (iii) the suturing approach to obtainprimary closure of the flap, and (iv) the modality ofprotection of the regenerated tissues at the time ofnonresorbable membrane removal. All these de-cisions are based on anatomical considerations.

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Non-aesthetically sensitive sites (decision tree 2)

The interdental space can be accessed (node 1) witha modified papilla preservation technique (25) whenthe interdental space is wider than 2 mm at softtissue level. A possible alternative is the interdentaltissue maintenance (67), applicable only on upperpremolars. When the interdental width is 2 mm orless, the treatment of choice is a simplified papillapreservation flap (30).

Selection of the barrier membrane (node 2) isbased mainly on the anatomy of the intrabony de-fect. Wide defects (ample radiographic angle) and/or nonsupportive anatomy (one- and two-wall con-figurations) require the use of stiff membranes or thecombined use of supportive or filling materials.Among the different commercial proposals, nonre-sorbable barrier membranes are stiffer than biore-sorbable ones and therefore are the first choice. Theuse of bioresorbable membranes, which render theprocedure easier and less invasive for the patient (1surgery only), could be associated with the use of


fillers to avoid its collapse. The ideal material for usein combination with membranes, however, is farfrom being established. Narrow and/or supportivedefects (3 wall configurations) indicate the use of bi-oresorbable barrier membranes.

The suturing approach (node 3) will be chosen ac-cording to the defect anatomy and the type of mem-brane or combination material used in the givencase. In every instance, however, a combination of 2sutures, one to relieve the tension, the other to closethe flap, are strongly suggested. When a supportivedefect or a supported membrane is the case, sutureof the interdental space can be attempted with aninternal horizontal crossed mattress suture (25) torelieve the tension. If a non-supported membrane ora non-supportive defect is the case, an offset internalmattress suture (30) will be chosen, to limit the api-cal displacement of the barrier and the consequentreduction of the space for regeneration. Primary clo-sure of the interdental space will be attempted inboth the instances with a single passing suture whenthe papilla is very narrow; with two parallel passingsutures when the papilla is wider; or with a mattresssuture (54) to get the best apposition of the flapedges.

When nonresorbable barrier membranes are used,the regenerated tissue needs to be protected at thetime of membrane removal (node 4). If the gingivahas not been impaired by a dehiscence, a replace-ment flap is the first choice. In case of gingival dehis-cence, the use of a saddle-shaped free gingival graftwill allow proper protection of the delicate regener-ated tissues (24).

Aesthetically sensitive sites (decision tree 3)

When the interdental space is wider than 2 mm, itcan be accessed (node 1) with a modified papillapreservation technique (25) or with the interdentaltissue maintenance (67) on upper premolars only.When the interdental width is 2 mm or less, thetreatment of choice is a simplified papilla preser-vation flap (30).

For the selection of the barrier membrane (node2) it is important to consider not only the intrabonycomponent of the defect, but also the suprabonycomponent. When the defect has a consistent supra-bony component, the material of choice is a ti-tanium-reinforced expanded polytetrafluoroethy-lene membrane that can properly support the softtissues, limiting the gingival recession and, thereby,preventing aesthetic damages. In fact, the use of ti-tanium-reinforced expanded polytetrafluoroethy-

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lene membranes has been reported to result in clin-ical attachment level gains in the supracrestal por-tion of the defects (27). When the defect is purelyintrabony, if it is a wide (ample radiographic angle)and/or a nonsupportive defect (one- and two-wallconfigurations), a titanium-reinforced expanded po-lytetrafluoroethylene membrane is again the firstchoice. When the defect is narrow and/or has a sup-portive anatomy (three-wall configurations), biore-sorbable membranes, eventually associated withsupportive materials (bone or bone substitutes), canbe successfully applied.

The suturing approach (node 3) will be chosen ac-cording to the defect anatomy and the type of mem-brane or combination material used in a given case.A combination of two sutures, one to relieve the ten-sion, the other to close the flap are mandatory. Asupportive defect (three-wall defect), a self-support-ing membrane (titanium-reinforced expanded poly-tetrafluoroethylene membrane) or a supportedmembrane (combination therapy) requires suturingthe interdental space with an internal horizontalcrossed mattress suture (25) to relieve the tension. Ifa nonsupported membrane (bioresorbable material)or a nonsupportive defect (one- or two-wall defect)is the case, an offset internal mattress suture (30) willbe chosen. Primary closure of the interdental spacewill be attempted in both the instances with a singlepassing suture when the papilla is very narrow; withtwo parallel passing sutures when the papilla iswider; with an internal mattress suture or with aninternal mattress suture (54) to get the best appo-sition of the flap edges.

When nonresorbable barrier membranes are usedat the time of membrane removal (node 4), the re-generated tissues can be protected with a replace-ment flap in case of gingival integrity or with asaddle-shaped free gingival graft in case of gingivaldehiscence (24).

Conclusions

Evidence demonstrates a clear benefit from the useof barrier membranes in the treatment of intrabonydefects. The clinical outcomes, in terms of gain ofperiodontal support, pocket depth reduction andminimal recession of the gingival margin, are influ-enced by a series of factors that can be controlled, atleast in part. Control of these factors is of paramountimportance to enhance the predictability of guidedtissue regeneration treatment. Clinicians shouldcarefully select patients and defects, set the objec-


tives of treatment and then design the surgical strat-egy. Several surgical alternatives and different ma-terials can be variously combined to optimize thetreatment strategy. The decision-making processshould be undertaken while keeping in mind theratio between the difficulties of the selected pro-cedures and the expected outcomes. A good balancebetween these two components will be the key tosuccess.

References

1. Al-Arrayed F, Adam S, Moran J, Dowell P. Clinical trial ofcross-linked human type I collagen as a barrier material insurgical periodontal treatment. J Clin Periodontol 1995: 22:371–379.

2. Anderegg C, Martin S, Gray J, Mellonig JT, Gher ME. Clinicalevaluation of the use of decalcified freeze-dried bone allo-graft with guided tissue regeneration in the treatment ofmolar furcation invasions. J Periodontol 1991: 62: 264–268.

3. Aukhil I, Pettersson E, Suggs C. Guided tissue regeneration.An experimental procedure in beagle dogs. J Periodontol1986: 57: 727–734.

4. Aukhil I, Simpson DM, Schaberg TV. An experimental studyof new attachment procedure in beagle dogs. J PeriodontalRes 1983: 18: 643–654.

5. Becker W, Becker BE. Treatment of mandibular 3-wall in-trabony defects by flap debridement and expanded polyte-trafluoroethylene barrier membranes. Long term evalu-ation of 32 treated patients. J Periodontol 1993: 64: 1138–1144.

6. Becker W, Becker BE, Mellonig J, Caffesse RG, Warrer K,Caton JG, Reid T. A prospective multicenter study evalu-ating periodontal regeneration for class II furcation in-vasions and intrabony defects after treatment with a bioab-sorbable barrier membrane: 1-year results. J Periodontol1996: 67: 641–649.

7. Becker W, Becker BE, Berg L, Prichard J, Caffesse R, Rosen-berg E. New attachment after treatment with root isolationprocedures: report for treated class III and class II fur-cations and vertical osseous defects. Int J Periodontics Re-storative Dent 1988: 8: 8–23.

8. Becker W, Becker BE, Prichard JF, Caffesse R, Rosenberg E,Gian-Grasso J. Root isolation for new attachment pro-cedures. A surgical and suturing method: three case re-ports. J Periodontol 1987: 58: 819–826.

9. Benque’ E, Zahedi S, Brocard D, Oscaby F, Justumus P, Bru-nel G. Guided tissue regeneration using a collagen mem-brane in chronic adult and rapidly progressive peri-odontitis patients in the treatment of 3-wall intrabony de-fects. J Clin Periodontol 1997: 24: 544–549.

10. Bowers GM, Chadroff B, Carnevale R, Mellonig J, Corio R,Emerson J, Stevens M, Romberg E. Histologic evaluation ofnew attachment apparatus formation in humans. I. J Peri-odontol 1989: 60: 664–674.

11. Caffesse R, Mota L, Quinones C, Morrison EC. Clinicalcomparison of resorbable and non-resorbable barriers forguided tissue regeneration. J Clin Periodontol 1997: 24:747–752.

12. Caffesse RG, Nasjleti CE, Morrison EC, Sanchez R. Guided

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tissue regeneration: comparison of bioabsorbable and non-bioabsorbable membranes. Histologic and histometricstudy in dogs. J Periodontol 1994: 65: 583–591.

13. Caffesse RG, Smith BA, Castelli WA, Nasjleti CE. Newattachment achieved by guided tissue regeneration inbeagle dogs. J Periodontol 1988: 59: 589–594.

14. Caton J, Nyman S, Zander H. Histometric evaluation ofperiodontal surgery. II. Connective tissue attachment levelsafter four regenerative procedures. J Clin Periodontol 1980:7: 224–231.

15. Caton J, Wagener C, Polson A, Nyman S, Frantz B, Bouws-ma O, Blieden T. Guided tissue regeneration in inter-proxymal defects in the monkey. Int J Periodontics Restora-tive Dent 1992: 12: 266–277.

16. Chen CC, Wang HL, Smith F, Glickman GM, Shyr Y, O’NealRB. Evaluation of a collagen membrane with and withoutbone grafts in treating periodontal intrabony defects. J Peri-odontol 1995: 66: 838–847.

17. Christgau M, Schamlz G, Wenzel A, Hiller KA. Periodontalregeneration of intrabony defects with resorbable and non-resorbable membranes: 30-month results. J Clin Peri-odontol 1997: 24: 17–27.

18. Chung KM, Salkin LM, Stein MD, Freedman AL. Clinicalevaluation of a biodegradable collagen membrane inguided tissue regeneration. J Periodontol 1990: 61: 732–736.

19. Cortellini P, Carnevale G, Sanz M, Tonetti MS. Treatment ofdeep and shallow intrabony defects. A multicenter ran-domized controlled clinical trial. J Clin Periodontol 1998:25: 981–987.

20. Cortellini P, Clauser C, Pini Prato G. Histologic assessmentof new attachment following the treatment of a humanbuccal recession by means of a guided tissue regenerationprocedure. J Periodontol 1993: 64: 387–391.

21. Cortellini P, Pini-Prato G. Guided tissue regeneration witha rubber dam: a five case report. Int J Periodontics Restora-tive Dent 1994: 14: 9–15.

22. Cortellini P, Pini-Prato G, Baldi C, Clauser C. Guided tissueregeneration with different materials. Int J Periodontics Re-storative Dent 1990: 10: 137–151.

23. Cortellini P, Pini-Prato G, Tonetti M. Periodontal regenera-tion of human infrabony defects. V. Effect of oral hygieneon long term stability. J Clin Periodontol 1994: 21: 606–610.

24. Cortellini P, Pini-Prato G, Tonetti M. Interproxymal free gin-gival grafts after membrane removal in GTR treatment ofinfrabony defects. A controlled clinical trial indicating im-proved outcomes. J Periodontol 1995: 66: 488–493.

25. Cortellini P, Pini-Prato G, Tonetti M. The modified papillapreservation technique. A new surgical approach for inter-proxymal regenerative procedures. J Periodontol 1995: 66:261–266.

26. Cortellini P, Pini-Prato G, Tonetti M. No detrimental effectof fibrin glue on the regeneration of infrabony defects. Acontrolled clinical trial. J Clin Periodontol 1995: 22: 697–702.

27. Cortellini P, Pini-Prato G, Tonetti M. Periodontal regenera-tion of human infrabony defects with titanium reinforcedmembranes. A controlled clinical trial. J Periodontol 1995:66: 797–803.

28. Cortellini P, Pini-Prato G, Tonetti M. Long term stability ofclinical attachment following guided tissue regenerationand conventional therapy. J Clin Periodontol 1996: 23: 106–111.

29. Cortellini P, Pini-Prato G, Tonetti M. The modified papilla


preservation technique with bioresorbable barrier mem-branes in the treatment of intrabony defects. Case reports.Int J Periodontics Restorative Dent 1996: 16: 547–559.

30. Cortellini P, Pini-Prato G, Tonetti M. The simplified papillapreservation flap. A novel surgical approach for the man-agement of soft tissues in regenerative procedures. Int JPeriodontics Restorative Dent (in press).

31. Cortellini P, Pini-Prato GP, Tonetti MS. Periodontal re-generation of human infrabony defects. I. Clinical meas-ures. J Periodontol 1993: 64: 254–260.

32. Cortellini P, Pini-Prato GP, Tonetti MS. Periodontal re-generation of human infrabony defects. II. Reentry pro-cedures and bone measures. J Periodontol 1993: 64: 261–268.

33. Cortellini P, Prato GPP, Tonetti MS. Periodontal regenera-tion of human intrabony defects with bioresorbable mem-branes. A controlled clinical trial. J Periodontol 1996: 67:217–223.

34. Cortellini P, Stalpers G, Pini Prato G, Tonetti MS. Long-termclinical outcomes of abutments treated with guided tissueregeneration. J Prosthet Dent 1999: 81: 305–311.

35. Cortellini P, Tonetti M. Radiographic defect angle influ-ences the outcomes of GTR therapy in intrabony defects.77th General Session of the IADR, Vancouver, Canada,March 10–13, 1999.

36. DeSanctis M, Clauser C, Zucchelli G. Bacterial colonizationof resorbable barrier materials and periodontal regenera-tion. J Periodontol 1996: 67: 1193–1200.

37. DeSanctis M, Zucchelli G, Clauser C. Bacterial colonizationof barrier material and periodontal regeneration. J ClinPeriodontol 1996: 23: 1039–1046.

38. Falk H, Fornell J, Teiwik A. Periodontal regeneration usinga bioresorbable GTR device. J Swed Dent Assoc 1993: 85:673–681.

39. Falk H, Laurell L, Ravald N, Teiwik A, Persson R. Guidedtissue regeneration therapy of 203 consecutively treated in-trabony defects using a bioabsorbable matrix barrier. Clin-ical and radiographic findings. J Periodontol 1997: 68: 571–581.

40. Frandsen EV, Sander L, Arnbjerg D, Theilade E. Effect oflocal metronidazole application on periodontal healing fol-lowing guided tissue regeneration. Microbiological find-ings. J Periodontol 1994: 65: 921–928.

41. Garret S. Periodontal regeneration around natural teeth. In:Genco R, ed. World Workshop in Periodontics. Lansdowne,VA: American Academy of Periodontology, 1996: 621–666.

42. Garrett S, Loos B, Chamberlain D, Egelberg J. Treatment ofintraosseous periodontal defects with a combined therapyof citric acid conditioning, bone grafting, and placement ofcollagenous membranes. J Clin Periodontol 1988: 15: 383–389.

43. Gottlow J, Laurell L, Lundgren D, Mathisen T, Nyman S,Rylander H, Bogentoft C. Periodontal tissue responses toa new bioresorbable guided tissue regeneration device: alongitudinal study in monkeys. Int J Periodontics Restora-tive Dent 1994: 14: 436–449.

44. Gottlow J, Nyman S, Karring T, Lindhe J. New attachmentformation as the result of controlled tissue regeneration. JClin Periodontol 1984: 11: 494–503.

45. Gottlow J, Nyman S, Lindhe J, Karring T, Wennstrom J. Newattachment formation in the human periodontium byguided tissue regeneration. Case reports. J Clin Periodontol1986: 13: 604–616.

131

46. Gouldin A, Fayad S, Mellonig J. Evaluation of guided tissueregeneration in interproximal defects. II. Membrane andbone versus membrane alone. J Clin Periodontol 1996: 23:485–491.

47. Grevstad H, Leknes K. Ultrastructure of plaque associatedwith polytetrafluoroethylene (PTFE) membranes used forguided tissue regeneration. J Clin Periodontol 1993: 20:193–198.

48. Handelsman M, Davarpanah M, Celletti R. Guided tissueregeneration with and without citric acid treatment in ver-tical osseous defects. Int J Periodontics Restorative Dent1991: 11: 351–363.

49. Karring T, Isidor F, Nyman S, Lindhe J. New attachmentformation on teeth with a reduced but healthy periodontalligament. J Clin Periodontol 1985: 12: 51–60.

50. Karring T, Nyman S, Lindhe J. Healing following implan-tation of periodontitis affected roots into bone tissue. J ClinPeriodontol 1980: 7: 96–105.

51. Kersten B, Chamberlain A, Khorsandl S, Wikesjo UM, SelvigKA, Nilveus RE. Healing of the intrabony periodontal lesionfollowing root conditioning with citric acid and wound clo-sure including an expanded PTFE membrane. J Periodontol1992: 63: 876–882.

52. Kilic A, Efeoglu E, Yilmaz S. Guided tissue regeneration inconjunction with hydroxyapatite-collagen grafts for intra-bony defects. A clinical and radiological evaluation. J ClinPeriodontol 1997: 24: 372–383.

53. Kim C, Choi E, Cho K, Chai JK, Wikesjo UM. Periodontalrepair in intrabony defects treated with a calcium carbon-ate implant and guided tissue regeneration. J Periodontol1996: 67: 1301–1306.

54. Laurell L. Guided tissue regeneration in clinical studies: areview. In: Hugoson A, Lundgren D, Lindgren B, ed. Guidedperiodontal tissue regeneration. Jonkoping, Sweden, Insti-tute for Postgraduate Dental Education, 1995: 68–90.

55. Laurell L, Falk H, Fornell J, Johard G, Gottlow J. Clinical useof a bioresorbable matrix barrier in guided tissue regenera-tion therapy. Case series. J Periodontol 1994: 65: 967–975.

56. Lindhe J, Echeverria J. Consensus report of session II. In:Lang N, Karring T, ed. Proceedings on the 1st Europeanworkshop on periodontology. London: Quintessence Pub-lishing Co., 1994: 210–214.

57. Lindhe J, Nyman S, Karring T. Connective tissue attach-ment as related to presence or absence of alveolar bone. JClin Periodontol 1984: 11: 33–40.

58. Machtei E, Cho M, Dunford R, Norderyd J, Zambon JJ, Gen-co RJ. Clinical, microbiological, and histological factorswhich influence the success of regenerative periodontaltherapy. J Periodontol 1994: 65: 154–161.

59. Mattson J, McLey L, Jabro M. Treatment of intrabony de-fects with collagen membrane barriers. Case reports. J Peri-odontol 1995: 66: 635–645.

60. McClain P, Shallhorn R. Long term assessment of combinedosseous composite grafting, root conditioning and guidedtissue regeneration. Int J Periodontics Restorative Dent1993: 13: 9–27.

61. Melcher AH. On the repair potential of periodontal tissues.J Periodontol 1976: 47: 256–260.

62. Melcher AH, McCulloch CA, Cheong T, Nemeth E, Shiga A.Cells from bone synthetize cementum-like and bone-liketissues in vitro and may migrate into periodontal ligamentin vivo. J Periodontal Res 1987: 22: 246–247.

63. Mellado JR, Salkin LM, Freedman AL, Stein MD. A com-


parative study of e-PTFE periodontal membranes with andwithout decalcified freeze dried bone allografts for the re-generation of interproximal intraosseous defects. J Peri-odontol 1995: 66: 751–755.

64. Mombelli A, Lang N, Nyman S. Isolation of periodontalspecies after guided tissue regeneration. J Periodontol1993: 64: 1171–1175.

65. Murphy K. Post-operative healing complications associatedwith Gore-Tex periodontal material. 1. Incidence and char-acterization. Int J Periodontics Restorative Dent 1995: 15:363–375.

66. Murphy K. Post-operative healing complications associatedwith Gore-Tex periodontal material. 2. Effect of compli-cations on regeneration. Int J Periodontics Restorative Dent1995: 15: 549–561.

67. Murphy K. Interproximal tissue maintenance in GTR pro-cedures: description of a surgical technique and 1 year re-entry results. Int J Periodontics Restorative Dent 1996: 16:463–477.

68. Novaes AB Jr, Gutierrez FG, Francischetto IF, Novaes AB.Bacterial colonization of the external and internal sulci andof cellulose membranes at time of retrieval. J Periodontol1995: 66: 864–869.

69. Nowzari H, Matian F, Slots J. Periodontal pathogens on po-lytetrafluoroethylene membrane for guided tissue re-generation inhibit healing. J Clin Periodontol 1995: 22: 469–474.

70. Nowzari H, Slots J. Microorganisms in polytetrafluoroethy-lene barrier membranes for guided tissue regeneration. JClin Periodontol 1994: 21: 203–210.

71. Nyman S, Gottlow J, Karring T, Lindhe J. The regenerativepotential of the periodontal ligament. An experimentalstudy in the monkey. J Clin Periodontol 1982: 9: 257–265.

72. Nyman S, Karring T, Lindhe J, Planten S. Healing followingimplantation of periodontitis-affected roots into gingivalconnective tissue. J Clin Periodontol 1980: 7: 394–401.

73. Nyman S, Lindhe J, Karring T, Rylander H. New attachmentfollowing surgical treatment of human periodontal disease.J Clin Periodontol 1982: 9: 290–296.

74. Proestakis G, Bratthall G, Soderholm G, Kullendorff B,Grondahl K, Rohlin M, Attstrom R. Guided tissue regenera-tion in the treatment of infrabony defects on maxillary pre-molars. A pilot study. J Clin Periodontol 1992: 19: 766–773.

75. Quteish D, Dolby A. The use of irradiated-crosslinked hu-man collagen membrane in guided tissue regeneration. JClin Periodontol 1992: 19: 476–484.

76. Schallhorn RG, McClain PK. Combined osseous compositegrafting, root conditioning, and guided tissue regeneration.Int J Periodontics Restorative Dent 1988: 4: 9–31.

77. Selvig KA, Kersten BG, Chamberlain AD, Wikesjo UM, Nil-veus RE. Regenerative surgery of intrabony periodontal de-

132

fects using e-PTFE barrier membranes. Scanning electronmicroscopic evaluation of retrieved membranes vs. clinicalhealing. J Periodontol 1992: 63: 974–978.

78. Selvig K, Kersten B, Wikesjo U. Surgical treatment of intra-bony periodontal defects using expanded polytetrafluoro-ethylene barrier membranes: influence of defect configur-ation on healing response. J Periodontol 1993: 64: 730–733.

79. Selvig KA, Nilveus RE, Fitzmorris L, Kersten B, KharsandiSS. Scanning electron microscopic observations of cellpopulations and bacterial contamination of membranesused for guided periodontal tissue regeneration in humans.J Periodontol 1990: 61: 515–520.

80. Stahl S, Froum S. Healing of human suprabony lesionstreated with guided tissue regeneration and coronally an-chored flaps. J Clin Periodontol 1991: 18: 69–74.

81. Stahl S, Froum S, Tarnow D. Human histologic responses toguided tissue regenerative techniques in intrabony lesions.Case reports in nine sites. J Clin Periodontol 1990: 17: 191–198.

82. Steffensen B, Weber HP. Relationship between the radiolo-gic periodontal defect angle and healing after treatment. JPeriodontol 1989: 60: 248–254.

83. Tempro P, Nalbandian J. Colonization of retrieved polyte-trafluoroethylene membranes: morphological and micro-biological observations. J Periodontol 1993: 64: 162–168.

84. Tonetti MS, Cortellini P, Suvan JE, Adriaens P, Baldi C, Dub-ravec D, Fonzar A, Fourmousis I, Magnani C, Muller-Cam-panile V, Patroni S, Sanz M, Vangsted T, Zabalegui I, PiniPrato G, Lang NP. Generalizability of the added benefits ofguided tissue regeneration in the treatment of deep intra-bony defects. Evaluation in a multi-center randomizedcontrolled clinical trial. J Periodontol 1998: 69: 1183–1192.

85. Tonetti M, Pini-Prato G, Cortellini P. Periodontal regenera-tion of human infrabony defects. IV. Determinants of thehealing response. J Periodontol 1993: 64: 934–940.

86. Tonetti M, Pini-Prato G, Cortellini P. Effect of cigarettesmoking on periodontal healing following GTR ininfrabony defects. A preliminary retrospective study. J ClinPeriodontol 1995: 22: 229–234.

87. Tonetti M, Pini-Prato G, Cortellini P. Factors affecting thehealing response of intrabony defects following guidedtissue regeneration and access flap surgery. J Clin Peri-odontol 1996: 23: 548–556.

88. Tonetti M, Pini-Prato G, Stalpers G, Cortellini P. Guidedtissue regeneration of deep intrabony defects in strategic-ally important prosthetic abutments. Int J Periodontics Re-storative Dent 1996: 16: 379–387.

89. Tonetti MS, Pini-Prato GP, Williams RC, Cortellini P. Peri-odontal regeneration of human infrabony defects. III. Diag-nostic strategies to detect bone gain. J Periodontol 1993:64: 269–277.

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