Expanded Polytetrafluoroethylene Barrier Research Articles

Avaliação histomorfométrica da combinação de rifamicina com hidroxiapatita sintética na reparação óssea em tíbia de coelhos: um estudo piloto

Objetivo: realizar avaliação histomorfométrica da associação do antibiótico rifamicina SV sódica à hidroxiapatita sintética na reparação óssea em tíbia de coelhos. Material e Métodos: doze coelhos brancos machos foram igualmente divididos em Grupo Teste e Controle. Lojas ósseas foram criadas nas tíbias dos animais e preenchidas com hidroxiapatita sintética e solução fisiológica (Grupo Controle) ou associação de hidroxiapatita sintética e rifamicina SV sal sódico (Grupo Teste). Além do mais, sobre todas as perfurações foram fixadas barreiras de politetrafluoretileno expandido. Os animais foram sacrificados após 7, 14 ou 21 dias da cirurgia, lâminas para análise em microscópio óptico foram preparadas (coloração H&E) e as análises realizadas. Resultados: a associação testada demonstrou superioridade no controle microbiológico local, na velocidade de formação e na quantidade final total de deposição de matriz óssea. Conclusão: a combinação de rifamicina com hidroxiapatita sintética parece apresentar vantagens nas condições testadas, incentivando a realização de novos estudos em modelo animal.

Guided Tissue Regeneration to Treat Mucogingival Defects Using a Collagen Sponge as a Space‐Filler Material for Cell Proliferation: Clinical Case Reports With Long‐Term Follow‐Up

Introduction: Guided tissue regeneration (GTR) protocols for root coverage have proposed space‐filler artifacts to create an area between the membrane and the root surface to provide adequate space for cell migration. Extensive instrumentation of the root to obtain a concave shape, suturing of the membrane to keep it convex, or the use of titanium‐reinforced membranes are some of the most common techniques for creating the space needed for regeneration. The primary objective of these case reports is to show the clinical application of collagen sponge as a space‐filler material in cases in which GTR procedures were used to treat marginal tissue recession.Case Presentation: These case reports describe the results obtained with root‐coverage procedures of a Miller Class I defect on the buccal surface of tooth #11 in two patients. Bioabsorbable polyglactin 910 and non‐absorbable expanded polytetrafluoroethylene barrier membranes were used along with a collagen sponge interposed on the root surface. It should be emphasized that the use of the collagen sponge was to create a biologic space and thereby induce cellular proliferation at the site of the recession. Three years after surgery, the treated areas showed complete root coverage with an increase of keratinized and attached gingiva with appropriate contour and thickness.Conclusion: These results demonstrate the possibility of using a collagen sponge as a space‐filler material in cases in which the principles of GTR are used in the successful treatment of root recession.

Bone level variation after vertical ridge augmentation: resorbable barriers versus titanium-reinforced barriers. A 6-year double-blind randomized clinical trial.

To compare the efficacy of two different techniques for vertical bone regeneration at implant placement with particulate autogenous bone at 6 years after loading by means of a double-blind, superiority, parallel-group randomized clinical trial. The study was conducted in a private center in Italy between April 2004 and December 2011. Patients in whom vertical bone augmentation was indicated in combination with the placement of single or multiple implants were eligible for inclusion in this trial. Patients were randomized to receive either resorbable collagen barriers supported by an osteosynthesis plate (test group) or nonresorbable titanium-reinforced expanded polytetrafluoroethylene barriers (control group). The outcome variables-radiographic bone variation at implant sites, implant failures, and complications- were evaluated 6 years after loading. Randomization was done by computer, with allocation concealed by opaque sequentially numbered sealed envelopes. The patients and the radiographic examiner were blinded to group assignment. Twenty-two patients were randomized: 11 to the resorbable barrier group and 11 to the nonresorbable (control) group. One control group patient dropped out. The mean bone level 6 years after surgery was 1.33 mm for the resorbable group and 1.00 mm for the nonresorbable group. The adjusted difference in bone changes between groups was 0.15 mm (95% confidence interval, -0.39 to 0.69, P = .5713). No implant failures or complications occurred after loading. No differences were observed in this comparison of resorbable and nonresorbable barriers with simultaneous implant placement for vertical ridge augmentation.

Comparative study of biphasic calcium phosphates with different HA/TCP ratios in mandibular bone defects. A long‐term histomorphometric study in minipigs

Three biphasic calcium phosphate (BCP) bone substitute materials with hydroxyapatite (HA)/tricalcium phosphate (TCP) ratios of 20/80, 60/40, and 80/20 were compared to coagulum, particulated autogenous bone, and deproteinized bovine bone mineral (DBBM) in membrane-protected bone defects. The defects were prepared in the mandibles of 24 minipigs that were divided into four groups of six with healing times of 4, 13, 26, and 52 weeks, respectively. The histologic and histomorphometric evaluation focused on differences in amount and pattern of bone formation, filler degradation, and the interface between bone and filler. Collapse of the expanded polytetrafluoroethylene barrier membrane into the coagulum defects underlined the necessity of a filler material to maintain the augmented volume. Quantitatively, BCP 20/80 showed bone formation and degradation of the filler material similar to autografts, whereas BCP 60/40 and BCP 80/20 rather equaled DBBM. Among the three BCP's, the amount of bone formation and degradation of filler material seemed to be inversely proportional to the HA/TCP ratio. The fraction of filler surface covered with bone was highest for autografts at all time points and was higher for DBBM than BCP 80/20 and 60/40 at the early healing phase. TRAP-positive multinucleated cells were identified on BCP and DBBM surfaces without showing typical signs of resorption lacunae.

Long‐Term Results of Guided Tissue Regeneration Therapy With Non‐Resorbable and Bioabsorbable Barriers. III. Class II Furcations After 10 Years

The aim of this 10-year follow-up was to evaluate the long-term results after guided tissue regeneration (GTR) therapy of Class II furcation defects using non-resorbable and bioabsorbable barriers clinically. In nine patients with advanced periodontitis, nine pairs of contralateral Class II furcation defects were treated. Within each patient, one defect received a non-resorbable expanded polytetrafluoroethylene barrier (ePTFE; C) and the other a bioabsorbable (polyglactin 910; T) barrier by random assignment. At baseline and 12 and 120 +/- 6 months after surgery, clinical parameters were obtained. Twelve and 120 months after GTR therapy, statistically significant (P <0.05) horizontal clinical attachment level (CAL-H) gain was observed in both groups (C12: 1.9 +/- 0.5 mm; C120: 1.1 +/- 1.3 mm; T12: 1.9 +/- 0.8 mm; T120: 1.7 +/- 1.4 mm). However, one patient with furcations that had been assessed as Class I 12 months after GTR therapy had lost two teeth after 10 years, and another patient had lost more than 2 mm CAL-H at one furcation from 12 to 120 +/- 6 months post-surgery 10 years after implantation of an ePTFE barrier. Horizontal bone sounding revealed similar bone gain in both groups 120 +/- 6 months post-surgery (C120: 0.8 +/- 1.0 mm; T120: 1.1 +/- 1.1 mm). CAL-H gain achieved after GTR therapy in Class II furcations was stable after 10 years in 15 of 18 defects (83%). The study failed to show a statistically significant difference in stability of CAL-H gain between group C and T 10 years after GTR therapy.

The combined use of enamel matrix proteins and a tetracycline‐coated expanded polytetrafluoroethylene barrier membrane in the treatment of intra‐osseous defects

The purpose of this split-mouth study was to evaluate the clinical response of enamel matrix proteins (EMPs, Emdogain Gel in intra-osseous defects with or without a combined application of a tetracycline-coated expanded polytetrafluoroethylene barrier membrane (e-PTFE, Gore-Tex). Twelve pairs of intra-osseous periodontal defects in 11 patients received the application of EMPs on the exposed root surface (EMP). One of the two defects received randomly, as an adjunct to EMP treatment, a tetracycline-coated e-PTFE membrane (MEMP). At baseline, 6- and 12-month probing pocket depth (PPD), clinical attachment level (CAL) and probing bone level (PBL) were measured. After 12 months, the EMP defects showed a significant mean PPD reduction of 2.86+/-0.75 mm, a mean gain in CAL of 1.28+/-2.04 mm, a mean PBL gain of 1.63+/-1.21 mm and a mean increase of recession (REC) of 1.56+/-2.30 mm. The MEMP defects showed a significant mean PPD reduction of 3.02+/-1.55 mm, a mean gain in CAL of 1.65+/-1.29 mm, a mean PBL gain of 1.58+/-1.92 mm and a mean increase of REC of 1.38+/-1.63 mm. Except for significantly more post-operative discomfort at the MEMP sites, no significant differences were found between EMP and MEMP defects. Within the limits of this study, it is concluded that in the treatment of intra-osseous defects with EMP, the adjunctive use of a tetracycline-coated e-PTFE membrane failed to show more gain of CAL and PBL.

Periodontal repair in dogs: guided tissue regeneration enhances bone formation in sites implanted with a coral‐derived calcium carbonate biomaterial

Previous studies suggest that a bioresorbable calcium carbonate coral implant (CI) supports space provision and bone formation for guided tissue regeneration (GTR). However, it could not be discerned whether observed effects were because of GTR or whether the CI possessed osteoconductive properties enhancing bone formation. The objective of this study was to evaluate bone formation associated with the CI biomaterial in the presence and absence of provisions for GTR. Routine, critical size, 6 mm, supra-alveolar periodontal defects were created in 12 young adult Beagle dogs. Five animals received the CI alone (Biocoral 1000). Seven animals received the CI/GTR combination using an expanded polytetrafluoroethylene barrier (GORE-TEX Regenerative Material). The animals were euthanized at 4 weeks postsurgery and tissue blocks of the experimental sites were collected and processed for histometric analysis. Clinical healing was uneventful. The histopathologic and histometric analysis revealed significantly increased bone formation (height and area) in sites receiving the CI/GTR combination compared with CI alone (2.3+/-0.6 versus 1.2+/-0.9 mm; and 3.1+/-0.8 versus 1.2+/-1.1 mm2; p<0.05). The CI biomaterial appeared to be mostly unassociated with new bone formation; the CI particles were observed sequestered in newly formed bone, fibrovascular marrow, and in the supra-alveolar connective tissue. Cementum formation was limited and observed in few sites for both treatment protocols. While GTR promoted new bone formation, the CI contributed limited, if any, osteoconductive effects.

Flow cytometry analysis of guided tissue regeneration-associated human periodontal cells.

Expanded polytetrafluoroethylene (ePTFE) barrier membranes have been widely used for guided tissue regeneration (GTR) of the human periodontal ligament (PL). However, the precise cellular and molecular events involved in the re-growth of the new tissue are still unclear. Retrieved membranes and the newly-regenerated soft tissue (RT) underlying the membranes were used to examine the cells associated with GTR compared with normal human PL and gingival cells. Flow cytometry (FCM) was used, for the first time, to analyze the spindle-shaped fibroblast-like cells which were adherent to these membranes and the cells which grew out of the RT. The results showed that the membrane-associated (M) cells had the lowest rate of proliferation and appeared to be larger and more granular than the other types of cell. Moreover, both the M- and RT-derived cells were found to express higher levels of the extracellular matrix (ECM) proteins collagen type 1, fibronectin, tenascin, and decorin. In addition, evidence based on FCM profiles identified distinct sub-populations of GTR cells in which fibronectin expression was markedly up-regulated compared with normal PL cells and which also differed in size and granularity. The results of this study show that cells associated with GTR barrier membranes and with the underlying tissue appear to have distinct phenotypic and functional activities consistent with the production of new periodontal connective tissue and periodontal regeneration.

Opposite Effects of Recombinant Human Transforming Growth Factor-β1 on Bone Regeneration In Vivo: Effects of Exclusion of Periosteal Cells by Microporous Membrane

The efficacy of local delivery of recombinant human transforming growth factor-β1 (rhTGF-β1) to promote bone regeneration, with or without cellular contribution from the periosteum, was evaluated in transosseous defects. Implantation of rhTGF-β1 into 5 mm in diameter “critical size defects” in the rat mandible resulted in a dose-dependent (0.1–20 μg/defect) bone bridging at both 12 and 24 days, independent of the type of delivery system [3% methyl cellulose gel, porous CaCO 3 particles, or poly(lactide- co-glycolide) beads]. The bridging, however, never exceeded 24% at 12 days or 34% after 24 days. In contrast, when access of cells from the periosteum to the defect was prevented by means of microporous expanded polytetrafluoroethylene barrier membranes (GORE-TEX® membrane), rhTGF-β1 caused a dose-dependent inhibition of bone regeneration. The bioactivity of the growth factor was confirmed by implantation of 5 or 10 μg rhTGF-β1 in 12 mm in diameter bicortical defects in rabbit calvaria, which resulted in complete bone healing within 28 days, whereas control defects displayed a bridging of 40%–50%. The findings support the concept, based on in vitro experiments by others, that TGF-β1 primarily has a proliferative effect on cells already committed to the osteoblastic lineage, but also imply that TGF-β1 may be inhibitory to induction of osteogenic cells in vivo.

Treatment of interproximal angular defects by guided tissue regeneration: 1 year follow‐up

SUMMARY The periodontal regeneration of interproximal bone defects of the posterior teeth produced by guided tissue regeneration (GTR), with expanded Polytetrafluoroethylene barrier membranes and conventional therapy, was clinically evaluated in 20 intrabony periodontal defects in 10 patients. The material included the presence of at least two proximal angular lesions for the same patient, probing pocket depth ≥ 6 mm, bone defect depth ≥ 3 mm, and 2‐wall defects with crestal involvement relative to the tooth circumference ranging from 90 to 270°. Healing was clinically evaluated by surgical re‐entry of GTR‐treated sites (10 sites) and debridement only sites (10 sites) 1 year after initial surgery following a strict plaque control regimen. A significant correlation was observed between probing depth reduction, attachment gain and defect depth (test sites); there was increased bone fill in GTR‐treated lesions of 2.95 ± 1.3 mm corresponding to a 69.4% improvement compared to control sites, and 1–3 ± 1.0 mm corresponding to a 32% improvement (P &lt; 0.0039). The results demonstrated that bone regeneration is highly reliable, as compared to conventional therapy, in cases of severe periodontal bone loss from posterior teeth provided that the principles of GTR are applied.

Treatment of exposed implant threads using a synthetic bone graft

The aim of this study was to evaluate clinically and histologically the use of a synthetic bone graft (Ionogran) alone and in combination with guided bone regeneration (GBR) to facilitate bone regeneration and augmentation around exposed implant threads. Five male Beagle dogs were used in this investigation. Prior to the study all 3rd and 4th premolars were extracted. After 3 months, a flap was elevated and two Brånemark implants were inserted in each quadrant in such a way that two-three threads remained exposed over the alveolar bone. On the control sites the synthetic bone graft was then placed around the exposed threads and the flaps were repositioned and sutured. On the test sites, the same procedure was performed, but an expanded polytetrafluoroethylene barrier was placed to cover the bone graft and implants. Three months after implant placement, the barriers on the test sites were removed, healing abutments were inserted on all implants, and a thrice weekly plaque control regime was initiated. The following clinical parameters were measured at 1, 2, and 3 months: Plaque Index, Gingival Index, Probing Depth and Clinical Attachment Level. Three months after abutment connection the animals were killed and specimens were obtained for histological evaluation. Clinical parameters revealed a significant improvement on the experimental sites compared to control sites during the 3 month loading phase. Histological analyses, however, could not determine a difference in the nature of the implant/tissue interphase between experimental and control sites.

Platelet-derived growth factor-modulated guided tissue regenerative therapy.

The goal of this study was to develop an effective regenerative therapy capable of achieving periodontal regeneration of Class III furcation defects. We attempted to achieve this goal by combining three therapeutic approaches. First, the lesion was protected by an expanded polytetrafluoroethylene barrier membrane that prevents migration of gingival fibroblasts as well as osteogenic cells from the mucoperiosteal flaps. Second, platelet-derived growth factor-BB (PDGF-BB), which has potent chemotactic and mitogenic effects on periodontal ligament fibroblasts (PDL), was used to promote migration of fibroblasts and their proliferation on the root surface. Third, the root surface, demineralized by citric acid conditioning, was chosen as the primary site for PDGF-BB application. The demineralized root surface appeared to have the capability of providing a sustained release of the applied growth factor. This seemed to facilitate rapid repopulation of PDL fibroblasts on the root surface and new PDL formation in the early stages of repair, which contributed to complete periodontal regeneration without root resorption and ankylosis in later stages. Combining these approaches, we developed a therapy referred to as "PDGF-modulated guided tissue regenerative therapy." Unlike guided tissue regenerative therapy alone (without PDGF-BB), this therapy effectively promoted periodontal regeneration of Class III furcation defects in the beagle dog without significant ankylosis or root resorption.

An expanded polytetrafluoroethylene barrier (Gore-Tex Surgical Membrane) reduces post-myomectomy adhesion formation

To evaluate the effects of the expanded polytetrafluoroethylene barrier (PTFE), Gore-Tex Surgical Membrane, in reducing postmyomectomy adhesion formation. Multicenter randomized clinical trial. Twenty-seven women having myomectomy with at least two incisions on the uterine fundus and posterior uterine wall of similar length were enrolled in the study. At laparotomy, the two incision sites were randomly assigned to be covered with PTFE or were left uncovered. A second-look laparoscopy to evaluate adhesion formation and to lyse adhesions was done from 2 to 6 weeks after the myomectomy. Adhesions were scored using a 0- to 11-point scoring system. At laparoscopy, 15 of 27 incisions covered with PTFE (55.6%) and only 2 of 27 uncovered sites (7.4%) were completely free of adhesions. The mean adhesion score at the PTFE sites was significantly lower (1.88 ± 0.46; SEM) than at the control sites (7.55 ± 0.57). The PTFE barrier is effective in reducing postmyomectomy adhesion formation.

Bone augmentation using a synthetic bone graft in dogs

The aim of this investigation was to evaluate clinically and histologically the use of a synthetic bone graft (Ionogran) alone and in combination with guided bone regeneration (GBR) for alveolar ridge augmentation. Five beagle dogs were used in this study. Prior to the augmentation procedure the maxillary and mandibular second, third and fourth premolars were extracted. Three months after the extractions, impressions from the area of the ridges were taken. Particles of Ionogran were then placed under mucoperiosteal flaps in each quadrant. On the experimental sites, an expanded polytetrafluoroethylene barrier was placed between the flap and the particles. Impressions were retaken at 1 and 3 months after surgery. Three months after surgery, the animals were sacrificed and specimens were prepared for histological evaluation. Computer-assisted volumetric analyses from the casts revealed an increase in ridge volume from baseline in both groups at 1 and 3 months. There was no difference in the height of the augmentation between the test and control sites. The histological results of this study indicate that this new synthetic bone graft appears to be a safe biocompatible grafting material. There were no apparent histological differences between the graft alone and graft/GBR sites. In both groups, however, graft particles were surrounded by dense fibrous connective tissue and bone formation was limited to the graft bone interface.

Treatment of Mandibular 3-Wall Intrabony Defects by Flap Debridement and Expanded Polytetrafluoroethylene Barrier Membranes. Long-Term Evaluation of 32 Treated Patients.

The purpose of this study was to evaluate the healing potential of deep, primarily 3wall intrabony defects which were treated by flap debridement and expanded polytetrafluoroethylene (ePTFE) membranes and followed for extended time periods. All of the treated defects were in the mandibular arch. Thirty-two patients were treated and reexamined at an average of 3 years 5 months. Twenty-four of these patients had re-entry procedures at the second examination. Sixteen of these patients were examined a third time at an average of 4 years 3 months. The patients were evaluated for changes in probing depth (PD), clinical attachment level (CAL), recession, changes in crestal resorption, and defect bone fill. The paired t-test for related samples was used to test for differences between examinations. Between Exams 1 and 2 there was a statistically significant reduction of pocket depth (3.8 mm), gain in clinical attachment level (4.2 mm), and an increase in recession (-1.2 mm). For the 24 patients who had re-entry procedures there was an average defect fill of 4.3 mm (P < 0.0001) and 0.33 mm of crestal resorption (P < 0.0001). The 16 patients who were examined 3 times sustained decreases in PD, gains in CAL, and recession recorded at the second examination. These changes were statistically significant at Exam 3. The results of this study demonstrate that deep, 3-wall intrabony defects treated by debridement and ePTFE barrier membranes will have significant decreases in PD, gains in CAL, recession, decreases in crestal resorption, and gains in bone fill. These gains can be maintained over extended time intervals and are considered to be predictable. J Periodontol 1993; 64:1138-1144.

Surgical treatment of intrabony periodontal defects using expanded polytetrafluoroethylene barrier membranes: influence of defect configuration on healing response.

Twenty-six proximal, intrabony periodontal defects with probing depths equal to or exceeding 6 mm in 23 patients were treated with gingival flap surgery supported by an expanded polytetrafluoroethylene barrier membrane. The material included 1, 2, and 3-wall defects with crestal involvement relative to the root circumference ranging between 90 degrees and 270 degrees. Healing was evaluated clinically 12 months after surgery. Deep defects exhibited greater probing depth reduction and attachment gain than shallower defects. Probing depth reduction, attachment gain, and bone fill were positively correlated to the depth of the 3-wall intrabony component of the defect. The extent of crestal involvement, and wall form in the fundus of the defect did not appear to influence the healing response. The treatment also affected the proximal surface of the defect-adjacent tooth, which showed some reduction in bone level as well as gingival recession. Thus, the overall healing pattern following barrier membrane-supported flap surgery appears similar to that generally observed for conventional reconstructive flap surgery in intrabony periodontal defects.