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Guided Tissue Regeneration With a Bioabsorbable Polylactic Acid Membrane in Gingival Recessions. A Histometric Study in DogsMarcio Z. Casati,* Enilson A. Sallum,† Raul G. Caffesse,† Francisco H. Nociti Jr.,* Antonio Wilson Sallum,* and Sergio L. da Silva Pereira*

Background: The goal of this investigation was to histologi-cally and histometrically evaluate the healing process of gingi-val recessions treated by guided tissue regeneration with bioab-sorbable polylactic acid membranes (GTR group) and tocompare it to that obtained with coronally positioned flaps (CPFgroup).

Methods: Gingival recessions were surgically created on thebuccal aspect of the upper cuspids of 5 mongrel dogs. Thedefects (5×7 mm) were exposed to plaque accumulation for 3months. The contralateral defects were then randomly assignedto each group. After 3 months of healing, the dogs were sacri-ficed and the blocks were processed. The histometric parame-ters evaluated included length of sulcular and junctional epithe-lium, connective tissue adaptation, new cementum, new bone,and defect coverage.

Results: The extension of the epithelium was 1.9 ± 0.8 mmfor the GTR-group and 3.0 ± 0.9 mm for the CPF-group (P =0.16). The connective tissue adaptation was 0.1 ± 0.1 and 0.8± 0.5 mm in the GTR group and CPF group, respectively (P =0.051). The new cementum was 3.8 ± 1.5 mm and 2.4 ± 0.3mm in the GTR group and CPF group, respectively (P = 0.16).Bone formation was 1.1 ± 0.5 mm in the GTR group and 1.4 ±0.2 mm in the CPF group (P = 0.53). Histologically, the defectcoverage observed was similar, 90.5% and 91.9% for the GTRgroup and the CPF group, respectively. No statistical differencesin any of the parameters could be detected.

Conclusions: Within the limits of this study, it can be con-cluded that both procedures resulted in a favorable healingresponse with no significant difference between the treatments.J Periodontol 2000;71:238-248.

KEY WORDSGingival recession/surgery; gingival recession/therapy;guided tissue regeneration; comparison studies; animalstudies; membranes/artificial; membranes/barrier; polylactic acid/therapeutic use.

* Department of Prosthodontics and Periodontics, Division of Periodontics, School ofDentistry at Piracicaba, UNICAMP, São Paulo, Brazil.

† Department of Stomatology, Division of Periodontics, Dental Branch, University of Texas,Houston, TX.

The ultimate goal of periodontaltherapy includes not only the arrestof progressive periodontal disease

but also the restitution of those parts ofthe supporting apparatus which havebeen destroyed by disease.1 Anotherimportant consideration is esthetics.2

Buccal gingival recessions in the ante-rior region represent one of the mostimportant challenges for periodontists. Avariety of surgical procedures have beendescribed to achieve soft tissue cover-age of exposed root surfaces such as:laterally positioned flap3 coronally posi-tioned flap,4 the free gingival graft,5,6

subepithelial connective tissue graft witha coronally positioned flap,7 and guidedtissue regeneration (GTR).8-11

It is generally accepted that mucogin-gival surgery results in root coveragewithout significant enhancement of theattachment apparatus. It has beendemonstrated that recessions treated withpedicle flaps heal with a long junctionalepithelium between the root surface andthe covering tissue in both animals12,13

and humans.14,15 Regeneration has beenobserved only in the most apical portionof the lesion.13,16

Gottlow et al., using the coronallypositioned flap with and without citricacid conditioning to treat gingival reces-sions in beagle dogs, observed a lengthof newly formed cementum of 2.2 ± 1.2mm on the citric acid treated roots and

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2.1 ± 0.8 mm on the non-citric acid controls. Theauthors pointed to the possibility of an increased periodduring which the periodontal ligament cells can formnew attachment provided by the coronal displacementof the flap and the corresponding increase in the dis-tance that epithelial cells need to migrate.17

GTR has proven to favor new attachment formationon recessions in animals8,16,18 and humans19 and couldbe the treatment of choice when the success of thetreatment includes not only the esthetic but also thefunctional and histologic outcomes.20

Histological studies in animals have been performedutilizing non-resorbable expanded polytetrafluoroeth-ylene (ePTFE) membranes. Gottlow et al. evaluated thetreatment of recession-type defects in the monkeymodel with ePTFE membranes. The amount of newattachment formation histologically observed was onthe average 74.3% of the defect height in the test teethand 36.9% in the controls (without membrane).8

Cortellini et al. demonstrated the possibility ofobtaining a new connective tissue attachment whenusing GTR and a fibrin-fibronectin system in surgicallyinduced buccal recessions in dogs. According to theauthors, the injection of the fibrin-fibronectin betweenthe membrane and the root surface could be helpfulin providing a stable and consistent clot, which stabi-lized the membrane and kept it apart from the rootsurface.16

Weng et al. compared the use of ePTFE membraneswith the free connective tissue graft in the treatmentof recession defects in maxillary canines of beagledogs. The evaluated parameters were coverage height,bone, cementum and connective tissue attachmentregeneration, length of the epithelium, resorption, andankylosis. The amount of new bone observed in theGTR group was more pronounced than in the con-nective tissue graft group, however, no statistical dif-ferences in any of the evaluated parameters could bedetected between the procedures.20

Evidence of periodontal regeneration in gingivalrecession-type defects treated with GTR in humanswas reported by Cortellini et al.19 with nonresorbablemembranes and by Vincenzi et al.21 with bioab-sorbable membranes. Cortellini et al. utilized a non-resorbable ePTFE membrane to treat an 8 mm deeprecession on a mandibular incisor. The tooth wasextracted along with marginal tissues 5 months afterthe removal of the membrane. Histologically, 3.66 mmof new connective tissue attachment (2.48 mm ofnewly formed cementum) and 1.84 mm of new bonewere observed. These results indicate that new con-nective tissue attachment can be established on ahuman root surface which had been exposed due to along-standing buccal recession.19

When using nonresorbable membranes, a secondoperation is necessary to remove the membrane, a

procedure which reduces the practicality of GTR dur-ing routine patient management. In addition, this sec-ond surgical procedure interferes with the healingprocess, reintroducing destructive and inflammatoryconditions in the regenerating periodontal areas; it maybe difficult to completely cover the newly formed tis-sue after the re-entry and patient morbidity mayincrease due to a second procedure.22 These prob-lems could be solved by using bioabsorbable barriersof different materials such as: collagen, polylactic acid,polyglycolic acid, or copolymers of the 2.23,24 Vincenziet al. provided histologic evidence of periodontal regen-eration in humans after treatment of a gingival reces-sion-type defect with a bioabsorbable membrane madeof a copolymer of a glycolide and lactide derived fromglycolic and lactic acids. After a 6-month healingperiod, a newly formed tissue composed of a coronalarea of connective tissue attachment and an apicalarea of bone, periodontal fibers, and cementum wasobserved.21

A bioresorbable matrix barrier‡ made of amorphouspolylactic acid (with a citric acid ester) in a specialdouble-layer is designed to promote integration of thedevice with the gingival connective tissue and preventor minimize the epithelial downgrowth along the bar-rier.18,25,26

Lundgren et al. evaluated 2 bioabsorbable barriers:a polylactic acid membrane‡ and a polyglactin 910membrane§ for the treatment of recession-type defectsin monkeys. A superior amount of new attachmentwas observed with the polylactic acid membrane, withless epithelial migration and less inflammation whencompared with the polyglactin 910 membrane. Thefavorable result obtained with the polylactic acid mem-brane was credited to the special double layer designwhich promoted the integration of the barrier with thesurrounding tissues.18 The potential for tissue inte-gration and new attachment formation after the use ofthis type of barrier‡ in dehiscence-type defects in dogswere reported in a previous histological study.27

The goal of this investigation is to histologically andhistometrically evaluate the healing process of surgi-cally created gingival recessions treated by guided tis-sue regeneration with polylactic acid membranes‡ orwith coronally positioned flaps.

MATERIALS AND METHODSFive adult female mongrel dogs were included in theexperiment (mean weight = 15 kg). This study wasapproved by the Institutional Committee of Researchwith Animals. The surgical procedures were performedunder general anesthesia with intravenous injection ofa 3% sodium pentobarbital solution (0.5 ml/kg). Gin-

‡ Guidor, Guidor AB, Novum, Huddinge, Sweden.§ Vicryl, Johnson & Johnson Consumer Products, Skillman, NJ.

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gival recessions were surgically created on the vestibu-lar aspect of the maxillary canines: 2 vertical incisionsseparated by a distance of 5 mm were made from thegingival margin and extending 7 mm apically. Theseincisions were connected apically by a horizontal inci-sion and coronally by an intrasulcular incision (Fig.1). The gingival tissue limited by the incisions (5 × 7mm) was removed using a periosteal elevator. Theexposed bone was removed by hand instruments andthe root surface instrumented to remove the cemen-tum. A coronal notch was placed on the root surfaceat the level of the cemento-enamel junction (Fig. 2).The created defects were exposed for a period of 3months to plaque accumulation (Fig. 3). Inflamed softtissue bordering 2 defects tended to grow in and coverthe denuded areas. It was removed by a gingivectomy2 months before treatment in order to ensure plaqueaccumulation on the exposed root surfaces. After 3months of plaque accumulation, scaling and root plan-ing were performed. A regimen of daily brushing andtopical application of 0.1 % chlorhexidine gluconatewas instituted for 15 days prior to the surgical proce-dures. Each of the contralateral defects in each ani-mal was randomly assigned to one of the followingtreatments:

Guided tissue regeneration (GTR group) with theresorbable polylactic acid membrane. Two oblique inci-sions connected by an intrasulcular incision were exe-cuted. A trapezoidal mucoperiosteal flap was raised to

the mucogingival junction. After this point, a split thick-ness flap was extended apically, releasing the tensionand favoring the coronal positioning of the flap (Fig.4). The root surface was instrumented with curets andan apical notch was placed at the level of the alveo-lar crest as a landmark for the histologic measure-ments. The resorbable polylactic acid membrane wasadapted to cover the defect and sutured with the pre-positioned ligatures around the tooth (Fig. 5). The flapwas coronally positioned to cover the membrane andsutured with an ePTFE suture. A single intramuscularinjection of penicillin (1.5 ml − 150,000 IU) was admin-istered after the surgeries.

In the coronally positioned flap (CPF group), thedefects were treated with the same procedure exceptfor the placement of the membrane (Fig. 6).

Each animal received the 2 treatments in a split-mouth design. The postoperative plaque control wasperformed by irrigation with a solution of 1% chlorhex-idine gluconate every other day. After 3 months, theanimals were sacrificed with an overdose of sodiumpentobarbital 3%. The jaws were dissected and theblocks containing the experimental specimens wereobtained. The blocks were fixed in a 10% neutral for-malin solution for 1 week. They were decalcified in asolution of equal parts of 50% formic acid and 20%sodium citrate for 3 months. The decalcified speci-mens were washed in running water, dehydrated andembedded in paraffin. Bucco-lingual sections of 7 µm

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Figure 1.Tissue to be removed limited by the incisions.

Figure 2.Soft and hard tissue removed. Coronal notchplaced at the cemento-enamel junction.

Figure 3.Created defect after 3 months of plaqueaccumulation.

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were obtained. They were stained with hematoxylinand eosin and with Masson’s trichrome.

Eight sections representing the midbuccal portionof each defect were selected for the histometric pro-cedures. The following distances were measured(Fig. 7):

Total epithelium (sulcular and junctional epithe-lium): from the gingival margin to the apical border ofthe junctional epithelium.

Epithelium on the root: from the coronal notch tothe apical border of the junctional epithelium, mea-sured when the gingival margin was coronal to thecoronal notch. If gingival recession was present, thevalue of the total epithelium was entered.

Connective tissue (without cementum): from theapical border of the junctional epithelium to the coro-nal end of new cementum.

New cementum: from the apical notch to the mostcoronal part of new cementum.

New bone: from the apical notch to the most coro-nal part of new bone.

Gingival position: from the gingival margin to thecoronal notch. Positive values were assigned when thegingival margin was positioned coronally to the coro-nal notch and negative values were assigned when thegingival margin was positioned apically to the coronalnotch.

Gingival recession: from the gingival margin to thecoronal notch in the sites where the gingival marginwas located apically to the coronal notch. Negativevalues were assigned. If the gingival margin waslocated at the level of the coronal notch or coronal tothis notch, a “0” value was applied.

Defect extension: from the apical notch to the coro-nal notch.

The measurements were performed using a micro-scope� with a 2.5/.10 objective associated with a videocamera¶/computer/software.#

The mean value for each parameter was obtainedfor the site. The mean values for the groups were deter-mined by using the values from the 5 dogs. The datawere analyzed using paired t test (n = 5).

RESULTSClinical ObservationsClinically, the healing response was favorable for bothtechniques with no suppuration or abscess formation.In the GTR group, membrane exposure was observedin 2 of the 5 treated sites, ranging from 1 to 2 mm,but no complications other than a slight inflammationwere associated with these sites. The defect coverage

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Figure 4.Trapezoidal mucoperiosteal flap raised to themucogingival junction.A split thickness flapwas extended apically.

Figure 5.Bioabsorbable polylactic acid membraneadapted to cover the defect and sutured withthe pre-positioned ligatures around the tooth.

Figure 6.Coronally positioned flap.

� Diastar, Cambridge Instruments, Buffalo, NY.¶ DXC-107 A/107 AP, – Sony Electronics, Inc., Japan# Jandel Scientific, San Rafael, CA.

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was clinically similar for the 2 tested techniques (Figs.8 and 9).

Histologic ObservationsThe CPF group showed the development of a longjunctional epithelium (Figs. 10 and 11). A continuouslayer of new cementum with inserting collagen fibershad formed in the specimens of both groups extend-ing coronally to a varying degree. However, in theGTR group (Figs. 12, 13, and 14), the coronal exten-sion of the new cementum was considerable in thematerial from 3 of the 5 dogs (approximately twicethat observed in the CPF group). In the remaining 2dogs, the extension of new cementum was apparentlysimilar beween the groups. The dentin surface under-neath the new cementum presented irregularities orsurface resorption. Root resorption was frequently asso-ciated with the areas located between the apical ter-mination of the junctional epithelium and the coronalborder of new cementum (Fig. 15). Connective tissuewith collagen fibers running parallel to the root sur-face was also observed in these areas. The areas of

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Figure 7.Histometric parameters evaluated: 1: total epithelium; 2: epitheliumon the root; 3: connective tissue adaptation; 4: new cementum; 5:new bone; 6: gingival position; 7: gingival recession; and 8: defectextension.

Figure 8.Area treated by coronally positioned flapalone after 3 months of healing.

Figure 9.Area treated by GTR with the bioabsorbablemembrane after 3 months of healing.

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connective tissue adjacent to the root without cemen-tum formation were more frequent in the CPF group.Bone formation was limited to the apical area and wassimilar for the 2 groups (Figs. 10 and 12). Ankylosiswas observed in only one specimen in the CPF group.The general design of the barrier was recognizable inthe GTR group specimens. Penetration of the connec-tive tissue from the flap into the perforations of theexternal layer prevented epithelial downgrowth alongthe device (Fig. 16)

Histometric MeasurementsThe histometric results are shown in Table 1. No sta-tistical differences were found between the 2 testedtechniques in any of the evaluated parameters. Theresults from the various histometric measurements;

i.e., the length of the epithelium on the root, connec-tive tissue adaptation, new cementum, and gingivalrecession expressed as the percent of the distancebetween the coronal and the apical notch are pre-sented in Figure 17.

DISCUSSIONFew histological studies have examined the quality ofthe healing after root coverage8,12,13,16,17,20 and thoseusing GTR were performed with non-resorbable ePTFEmembranes.16,20

A bioabsorbable membrane offers the possibility ofperforming a single-step GTR as a root coverage pro-cedure. The elimination of the second procedure formembrane removal prevents the risks of mechanicaltrauma to the newly developed tissues in the initialphase of healing. Therefore, the present investigationwas designed to evaluate the healing response of gin-gival recessions treated by guided tissue regenerationwith a bioabsorbable membrane and with a conventionalmucogingival procedure (coronally positioned flap).

Figure 10.Site treated by coronally positioned flap alone.A long junctionalepithelium can be observed in the coronal half of the defect.Periodontal regeneration is restricted to the apical portion (bar =1 mm; original magnification ×12.5; Masson’s trichrome).

Figure 11.Higher magnification of the coronal portion of the tooth shown inFigure 10. Detail of the long junctional epithelium (bar = 0.2 mm,original magnification ×40; Masson’s trichrome).

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Cortellini et al. reported significantly more new con-nective tissue attachment obtained with GTR (21.20%)than with a lateral pedicle flap (0.60%) in the treatmentof surgically created gingival recessions in dogs, aftera healing period of 50 days.16 However, in the presentinvestigation, no statistically significant difference couldbe observed in the amount of new connective tissueattachment (new cementum) achieved with GTR andwith a coronally positioned flap (3.87 ± 1.59 mm and2.45 ± 0.35, respectively). Some methodological dif-ferences between the studies should be stressed tounderstand the difficulty in comparing the results. Theprevious study used a different type of membrane(non-resorbable) associated with a fibrin-fibronectinseal and a laterally positioned flap to cover an initiallyv-shape defect. In the present investigation, the shapeof the defect was rectangular which could influencethe migration of periodontal ligament cells from thelateral borders of the defect. The coronally positioned

flap used in this study could have improved thechances for new attachment formation in the controlareas by increasing the distance that epithelial cellshad to migrate and providing more time for new attach-ment formation by the periodontal ligament cells.17

Furthermore, it needs to be emphasized that the nvalue used for statistical analysis was significantlydifferent between these two studies. While in the pres-ent study the animal was used as the statistical unit(n = 5), Cortellini et al.16 used histological readings(n = 24 to 40) for the statistical analysis with one dogper time period (15, 30, and 50 days).

In the GTR group, new cementum was observed on61% of the defect extension and on 36.8% in the CPFgroup. Similar results were reported by Gottlow et al.8

using recession-type defects in monkeys (74.3% forGTR and 36.9% without membranes) and by Weng etal.20 in the defects treated by GTR in dogs (60.7%)using the gingival margin as the coronal reference

Figure 12.Site treated by GTR with bioabsorbable membrane.The membranestructure can be easily identified.The epithelium is confined to thecoronal portion of the defect. New connective tissue attachmentextends to the coronal notch. New bone is observed in the apicalarea (bar = 1 mm; original magnification ×12.5; Masson’strichrome).

Figure 13.Higher magnification of the coronal part of the tooth shown inFigure 12. Detail of the epithelium restricted to the coronal notcharea. Proliferation of new cementum and the coronal portion of themembrane can be observed (bar = 0.2 mm; original magnification×40; hematoxilin and eosin).

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point. Weng et al.20 could not find a statistically sig-nificant difference in the new attachment formationafter GTR and a conventional mucogingival surgery(free connective tissue graft), which is in accordancewith the results of the present investigation.

A long junctional epithelium is generally theexpected healing pattern after conventional mucogin-gival surgery.12,13 However, it seems that some degreeof regeneration can be achieved with the conventionaltechniques.17,20,28 The length of sulcular and junc-tional epithelium observed was 1.96 ± 0.81 mm and3.05 ± 0.97 mm for the GTR group and CPF group,respectively. The percentage of epithelium reported byGottlow et al.17 using the coronally positioned flap in

the treatment of localized gingival recessions in dogswas 38.5% (in the non-acid treated group) which iscomparable to the results observed for the coronallypositioned flap in the present investigation (42%). Wenget al.20 reported an epithelial length of 2.97 ± 0.54mm for the GTR group and 4.14 ± 1.29 mm for theconnective tissue graft group with approximately 1 mmless epithelium in the GTR group compared with themucogingival surgery. A difference of similar magni-tude was observed between the 2 techniques tested inthis study.

The connective tissue attachment without cemen-tum formation almost reached a statistically signifi-cant difference between the tested groups, with agreater value for the CPF group. The coronal dis-placement of the flap and an extension of the distancewhich epithelial cells have to cover may have enhanced

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Figure 14.Higher magnification of the apical part of the tooth shown in Figure12. New cementum extends coronally. New bone in the apicalnotch area and the membrane structure surrounded by non-infiltrated connective tissue fibers can be seen (bar = 0.2 mm;original magnification ×40; hematoxylin and eosin).

Figure 15.Root resorption in an area coronal to the apical notch, close to thetermination of the junctional epithelium in a tooth treated bycoronally positioned flap (bar = 0.1 mm; original magnification×100; hematoxylin and eosin).

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both the chance for new attachment but also the riskfor root resorption.17 This seems to be important inthe CPF group because of the lack of the protectiveeffect provided by the membrane interposed betweenthe root surface and the connective tissue of the flap.The achievement of new connective tissue attachment(by new cementum with inserting collagen fibers) iscloser to the concept of regeneration than the con-nective tissue adaptation. When the values for newattachment and connective tissue adaptation areadded, the results still indicate a more favorable out-come for GTR (in spite of the fact that they did notreach statistical significance).

The observed osseous response was similar for the2 techniques. This result is in accordance with previ-ous studies using GTR8,27,29 and could be related to

the type of defect treated. When treating recessions,the 2 major concerns are providing enough space forregeneration between the membrane and the root sur-face and providing and maintaining an adequate bio-logical coverage of the membrane.22 The buccal alve-olar plate in this study was generally thin and the spacebeween the barrier and the root surface was providedonly by the short spacers on the inner surface of themembrane.

Pini Prato et al.30 reported a series of 9 patients withrecession treated by GTR with the same barrier usedin this study and followed for 6 months. Probing attach-ment gain was obtained but the mean root coverage(65%) did not seem to be as good as that obtainedwith non-resorbable membranes (73%) reported in aprevious clinical study.9 A possible explanation couldbe that the material is soft and does not maintainthe space effectively.22 Parma-Benfenati and Tinti31

reported a histologic evaluation in humans demon-strating that when an adequate space for regenera-

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Figure 16.Integration of the membrane with the surrounding tissues.Connective tissue penetrating through the perforations of theextenal layer of the membrane, spreading into the space betweenthe two layers is observed. Bone formation coronally to the apicalnotch area (bar = 0.2 mm; original magnification ×40; Masson’strichrome).

Table 1.

Mean, Standard Deviation, and RangeValues (mm) for Parameters EvaluatedAfter GTR and Coronally Positioned Flap(CPF)

Parameter GTR (n = 5) CPF (n = 5)(range) (range) P*

Total epithelium 1.96 ± 0.81 3.05 ± 0.97 0.16

(3.03/1.14) (4.26/1.95)

Epithelium on the root 1.76 ± 0.96 2.79 ± 0.73 0.17

(2.87/0.6) (3.54/1.95)

Connective tissue 0.11 ± 0.13 0.87 ± 0.54 0.051

(0.29/0.00) (1.66/0.30)

New cementum 3.87 ± 1.59 2.45 ± 0.35 0.16

(5.40/1.81) (3.02/2.08)

New bone 1.19 ± 0.53 1.41 ± 0.28 0.53

(1.82/0.51) (1.83/1.16)

Gingival position –0.40 ± 1.3 –0.29 ± 0.93 0.86

(0.82/–2.58) (1.18/–1.06)

Gingival recession –0.60 ± 1.12 –0.54 ± 0.50 0.89

(0.00/–2.58) (0.00/–1.06)

Defect extension 6.35 ± 1.50 6.64 ± 0.71 0.69

(8.16/4.80) (7.43/5.98)

*Paired t test.

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tioned flap. However, due to the small num-ber of teeth treated, these findings need tobe considered with caution and additionalhistological studies are necessary to eluci-date the nature of the attachment achievedwith different surgical approaches in thetreatment of localized gingival recessions.

ACKNOWLEDGMENTSSupported by Fundação de Amparo á Pesquisado Estado de São Paulo (FAPESP), São Paulo,Brazil (grants 97/04251-3 and 1998/3947-7).The authors thank Ana Claudia G.C. Mirandaand Dr. Adriana R.A.C. Marcantonio for thepreparation of the histological material.

REFERENCES1. Lindhe J. Textbook of Clinical Periodontology.

Copenhagen: Munksgaard; 1989:450-476.2. Allen EP. Use of mucogingival surgical pro-

cedures to enhance esthetics. Dent Clin N Am1988;32:307-330.

3. Grupe HE, Warren RF. Repair of gingival defects by asliding flap operation. J Periodontol 1956;27:92-95.

4. Harvey P. Management of advanced periodontics. PartI. Preliminary report of a method of surgical recon-struction. New Zealand Dent J 1965;61:180-184.

5. Sullivan HC, Atkins JH. Free autogenous gingival grafts.III. Utilization of grafts in the treatment of gingival reces-sion. Periodontics 1968;6:152-160.

6. Miller PD. Root coverage using a free soft tissue auto-graft following citric acid application. Part I. Technique.Int J Periodontics Restorative Dent 1982;2(1):65-70.

7. Langer L, Langer B. Subepithelial connective tissue grafttechnique for root coverage. J Periodontol 1985;56:715-720.

8. Gottlow J, Karring T, Nyman S. Guided tissue regener-ation following treatment of recession-type defects inthe monkey. J Periodontol 1990;61:680-685.

9. Pini Prato GP, Tinti C, Vincenzi G, Magnani C, CortelliniP, Clauser C. Guided tissue regeneration versus mucogin-gival surgery in the treatment of human buccal gingivalrecession. J Periodontol 1992;63:919-928.

10. Tinti C, Vincenzi G, Cortellini P, Pini Prato G, Clauser C.Guided tissue regeneration in the treatment of humanfacial recession. A 12-case report. J Periodontol1992;63:554-560.

11. Trombelli L, Schincaglia GP, Checchi L, Calura G. Com-bined guided tissue regeneration, root conditioning andfibrin-fibronectin system application in the treatment ofgingival recession. A 15-case report. J Periodontol1994;65:796-803.

12. Wilderman MM, Wentz FM. Repair of a dentogingivaldefect with a pedicle flap. J Periodontol 1965;36:218-231.

13. Caffesse RG, Kon S, Castelli WA, Nasjleti C. Revascu-larization following the lateral sliding flap procedure. JPeriodontol 1984;55:352-358.

14. Sugarman EF. A clinical and histological study of theattachment of grafted tissue to bone and teeth. J Peri-odontol 1969;40:381-387.

15. Pfeiffer JS, Heller R. Histologic evaluation of full andpartial-thickness lateral repositioned flaps: a pilot study.J Periodontol 1971;42:331-333.

Figure 17.Histometric parameters expressed as a percentage of the defect.

tion was provided and maintained using a titanium-reinforced ePTFE membrane, an excellent result interms of regeneration could be accomplished in thetreatment of a buccal recession. The authors reported,after 9 months of healing, a new connective attachmentof 5.6 mm and regeneration of bone of 6.7 mm.

The space-making ability of the polylactic acidmembrane could have been improved with a newdesign including longer resorbable spacemakers onthe inner surface of the membrane.30

Considering the treatment of gingival recessions,the first requirement for a surgical technique seems tobe its predictability for root coverage. This will pro-vide better esthetics and/or less hypersensitivity forthe patient. In the present study, both proceduresresulted in an acceptable defect coverage (90.5% and91.9% for the GTR group and the CPF group, respec-tively). When clinically evaluated, the use of non-resorbable membranes in gingival recessions resultedin a similar reduction in the recession with a greaterreduction in the probing depth and more attachmentgain than the 2-step mucogingival procedure (coronallypositioned free gingival graft) after a 4-year follow-up.32 However, Trombelli et al.33 comparing the use ofa polyglycolide/lactide bioabsorbable membrane withthe subpedicle connective tissue graft in the treatmentof gingival recessions reported a root coverage of 48%for GTR and 81% for the graft after 6 months. Thetreatment outcome was significantly better followingthe graft in terms of recession depth reduction, rootcoverage and keratinized tissue increase.

The present histological study was not able to detectstatistical differences in the regenerative parametersbetween the treatment of gingival recessions with apolylactic acid membrane or with a coronally posi-

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

30. Pini Prato GP, Clauser C, Cortellini P. Resorbable mem-branes in the treatment of human buccal recession. A9 case report. Int J Periodontics Restorative Dent 1995;15:259-268.

31. Parma-Benfenati S; Tinti C. Histologic evaluation of newattachment utilizing a titanium-reinforced barrier mem-brane in a mucogingival recession defect. A case report.J Periodontol 1998;69:834-839.

32. Pini Prato G, Clauser C, Cortellini P, Tinti C, Vincenzi G,Pagliaro U. Guided tissue regeneration versus mucogin-gival surgery in the treatment of human buccal reces-sions. A 4-year follow-up study. J Periodontol 1996;67:1216-1223.

33. Trombelli L, Scabbia A, Tatakis DN, Calura G. Sub-pedicle connective tissue graft versus guided tissueregeneration with bioabsorbable membrane in the treat-ment of human gingival recession defects. J Periodon-tol 1998;69:1271-1277.

Send reprint requests to: Dr. Enilson A. Sallum, Division ofPeriodontics, School of Dentistry at Piracicaba, Av. Limeira901 - Caixa Postal 52, 13414-018 - Piracicaba - SP - Brazil.Fax: 55-19-430-5218; e-mail: easallum@fop.unicamp.br

Accepted for publication June 22, 1999.

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16. Cortellini P, De Sanctis M, Pini Prato G, Baldi C, ClauserC. Guided tissue regeneration procedure using a fibrin-fibronectin system in surgically induced recessions indogs. Int J Periodontics Restorative Dent 1991;11:151-163.

17. Gottlow J, Nyman S, Karring T, Lindhe J. Treatment oflocalized gingival recessions with coronally displacedflaps and citric acid. An experimental study in the dog.J Clin Periodontol 1986;13:57-63.

18. Lundgren D, Laurell L, Gottlow J, et al. The influence ofthe design of two different bioresorbable barriers on theresults of guided tissue regeneration therapy. An intra-individual comparative study in the monkey. J Peri-odontol 1995;66:605-612.

19. Cortellini P, Clauser C, Pini Prato G. Histologic assesmentof new attachment following the treatment of a humanbuccal recession by means of guided tissue regenera-tion procedure. J Periodontol 1993;64:387-391.

20. Weng D, Hurzeler MB, Quinones CR, Pechstadt B, MotaL, Caffesse RG. Healing patterns in recession defectstreated with ePTFE membranes and with free connec-tive tissue grafts. A histologic and histometric study inthe beagle dog. J Clin Periodontol 1998;25:238-245.

21. Vincenzi G, Chiesa A, Trisi P. Guided tissue regenerationusing a resorbable membrane in gingival recession-typedefects: a histologic case report in humans. Int J Peri-odontics Restorative Dent 1998;18:25-33.

22. Pini Prato GP, Clauser C, Tonetti MS, Cortellini P. Guidedtissue regeneration in gingival recessions. Periodontol2000 1996;11:49-57.

23. Minabe M. Critical review of the biological rationale forguided tissue regeneration. J Periodontol 1991;62:171-179.

24. Greenstein G, Caton J. Biodegradable barriers andguided tissue regeneration. Periodontol 2000 1993;1:36-45.

25. Gottlow J. Guided tissue regeneration using biore-sorbable and non-resorbable devices: initial healing andlong-term results. J Periodontol 1993;64:1157-1165.

26. Laurell L, Falk H, Fornell J, Johard G, Gottlow J. Clin-ical use of a bioresorbable matrix barrier in guided tis-sue regeneration therapy. Case series. J Periodontol 1994;65:967-975.

27. Sallum EA, Sallum AW, Nociti FH Jr, Marcantonio RAC,Toledo S. New attachment achieved by guided tissueregeneration using a bioresorbable polylactic acid mem-brane in dogs. Int J Periodontics Restorative Dent 1998;18:503-510.

28. Pasquinelli KL. The histology of new attachment utiliz-ing a thick autogenous soft tissue graft in na area ofdeep recession: A case report. Int J Periodontics Restora-tive Dent 1995;15:248-257.

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