Rosuvastatin promotes benefits on induced periodontitis in hypertensive rats.

BACKGROUND AND OBJECTIVE: The potential benefits of statins in modulating periodontal disease is supported by in vitro and clinical studies showing statins can induce a lower expression of proinflammatory cytokines and matrix metalloproteinases. The aim of this study was to evaluate the effects of rosuvastatin (ST) on ligature-induced periodontitis in spontaneously hypertensive rats (SHR). MATERIAL AND METHODS: Fifty-four adult male rats were divided into three groups: SHR-C, SHR-L and SHR-L-ST (C, control; L, ligature groups). In the SHR-L-ST group, animals were treated with daily 2 mg/kg ST administration. In L groups, a ligature remained around mandibular first molars for 10 d. Each group was divided for killing at 10 or 21 d postoperatively. Microtomographic and histometric analyses were performed. Osteoclastogenesis was evaluated by tartrate-resistant acid phosphatase assay and gene expression of 84 proinflammatory mediators by polymerase chain reaction array. RESULTS: The SHR-L-ST group showed reduced bone loss and attachment loss in comparison with the SHR-L group at both 10 and 21 d postoperatively (p < 0.05). ST decreased the amount of tartrate-resistant acid phosphatase-positive cells compared with the SHR-L group at both 10 and 21 d (p < 0.05). The SHR-L-ST group presented 14 genes differentially expressed when compared with SHR-L group, featuring a downregulated gene profile at 10 d. CONCLUSION: Statin therapy may promote a protective effect against alveolar bone and connective tissue attachment losses attributable to periodontitis in hypertensive rats through inflammatory gene profile modulation.

Effects of Bifidobacterium animalis subsp. lactis HN019 on ligature-induced periodontitis in rats with experimental rheumatoid arthritis.

The purpose of this study was to evaluate the effects of systemic administration of the probiotic Bifidobacterium animalis subsp. lactis HN019 (HN019) on ligature-induced periodontitis in rats with experimental rheumatoid arthritis (RA). 28 rats were divided into four groups (n=7): RA (rheumatoid arthritis), RA/PROB (probiotic), RA/EP (experimental periodontitis) and RA/EP/PROB. From day zero, HN019 was added daily to the water of the PROB groups animals until the end of the experiment. From day seven, RA was induced. On day 28, in EP groups, ligatures were positioned around mandibular first molars and remained in position for 11 days, in order to induce periodontitis. The animals were euthanised on day 39. Microtomographic, histomorphometric, immunoenzymatic and microbiological analyses were performed. Data were statistically analysed (P<0.05). Group RA/EP/PROB presented reduced alveolar bone loss, tumour necrosis factor-α and interleukin (IL)-6 levels and increased IL-17 levels when compared with group RA/EP. There were no significant differences regarding connective tissue attachment level and IL-10 levels between groups RA/EP and RA/EP/PROB. Group RA/PROB showed decreased anti-citrullinated protein antibodies levels when compared with groups RA and RA/EP. Group RA/EP/PROB presented a higher rate of aerobic/anaerobic bacteria than group RA/EP. Systemic administration of HN019 promoted a protective effect against periodontal tissue destruction, decreasing both bone loss and inflammatory mediators and increasing the proportion of bacteria compatible with periodontal health, in rats with experimental RA and EP.

Osseointegration of oxidized and turned implants in circumferential bone defects with and without adjunctive therapies: an experimental study on BMP-2 and autogenous bone graft in the dog mandible.

The aim of the study was to compare the integration and implant stability of turned and oxidized titanium implants when placed in experimental bone defects with autogenous bone graft, BMP-2 or without adjunctive therapy. Four defects were prepared on each side of the mandible of 12 mongrel dogs five months after tooth extractions. Implants with turned and oxidized surfaces were placed in the defects. The circumferential gaps were filled with either autogenous bone grafts, a BMP-allogeneic dog mixture in a thermoplastic carrier, carrier alone or left without any treatment (control). There were no statistically significant differences between control and treated sites, neither for turned nor for oxidized implants with regard to histomorphometric measurements in ground sections and to implant stability as measured with resonance frequency analysis (RFA) after 4 and 12 weeks of healing. However, oxidized implants showed a significantly higher stability after 4 weeks and a tendency (p < 0.1) of that after 12 weeks. Histomorphometry showed more bone contacts for oxidized than for turned implants. It is concluded that oxidized implants gain stability more rapidly and integrate with more bone contacts than implants with a turned surface when placed in bone defects.

Compliance with supportive periodontal therapy. Part 1. Risk of non-compliance in the first 5-year period.

BACKGROUND: Supportive periodontal therapy (SPT) is needed for the success of periodontal therapy; however, patient compliance is poor. This study evaluates records from non-compliant patients in an attempt to identify a profile of patients with a higher risk of becoming non-compliant. METHODS: Data on 874 patients who had completed active periodontal treatment up to 5 years earlier and who had begun SPT were analyzed for risk of non-compliance. The factors evaluated were gender (326 males and 548 females); type of therapy (surgical or non-surgical) and age (< or =20; 21 to 30; 31 to 40; 41 to 50; and > or =51 years) and the relationships among them. RESULTS: The overall rate of non-compliance was 46.8%, and the relative risk for non-compliance was greater in the younger age groups (< or =40 years old) when compared to the older groups. Gender, age, and type of therapy as independent factors were not significant risk factors for non-compliance, but the association of the 3 factors produced interesting results. CONCLUSIONS: This study suggests that certain patient groups have a higher risk of non-compliance and that clinicians should intensify their efforts in motivating and instructing these patient groups in the importance of SPT.

Preprosthetic periodontal surgery in the interproximal area with modification of the COL area: anatomic and histologic study in dogs.

BACKGROUND: Due to its concave morphology, a COL creates difficulties for proper oral hygiene. When this characteristic is accentuated by tooth position or caries and when restorations are necessary, they should be corrected by preprosthetic surgery. However, there are no data proving the efficacy of the procedures. The purpose of this study was to evaluate tissue response to preprosthetic surgery to modify COL morphology. METHODS: Five mongrel dogs received apically positioned flaps, osteotomy/plasty, and RAI (restorative alveolar interface technique) on the maxillary right third bicuspid and first molar; on the same teeth on the left side, a large tissue excision similar to gingivectomy and RAI were performed. Histologic specimens stained with hematoxylin and eosin and Mallory were evaluated at hour 0 and 1, 2, 3, and 4 weeks under light microscopy. RESULTS: At hour 0, hemorrhage in the remaining interproximal tissue on the left side, and denuded bone modified by the osteotomy on the right side, were observed. At 1 week, both sides showed the presence of granulation tissue and the beginning of reepithelialization and fiber formation. At 2 weeks, the papillae were rebuilt and epithelialized, with fewer inflammatory cells and dilated blood vessels, with a convex morphology. At 3 weeks, the papillae were convex and saddle shaped, with thicker epithelium and denser connective tissue. The general aspect was similar to attached gingiva. However, on the right side, the total extension of the interproximal tissues was longer and had a less accentuated convex curvature. At 4 weeks, the tissues were more mature, but the morphologic and histological findings were similar to 3 weeks. CONCLUSION: Both techniques modified the COL morphology, suggesting that the RAI technique was effective; but the apically positioned flap with osteotomy and RAI created a more extensive convex surface and more interproximal space for the prosthesis. It is recommended that this technique be considered for use in humans.

Compliance with supportive periodontal therapy and its relation to the bleeding index.

This is a retrospective study of 418 patients who received active periodontal treatment between the years of 1984 and 1990. The patients were instructed to return for supportive periodontal treatment (SPT) at 3 to 6-month intervals. The objective of this study was to evaluate patient compliance with periodic recall visits, and to study the relationship of bleeding upon probing in those who returned regularly. The patients were divided into 3 groups: patients who returned periodically for supportive treatment, patients who interrupted the proposed maintenance treatment, and patients who never returned after active periodontal treatment. Analysis was made for each group to correlate the degree of compliance with gender, disease classification, and type of treatment received. To analyze bleeding upon probing, 2 groups of patients were selected: a test group with 39 patients who had attended at least 10 recall visits and participated in the study for more than 40 months, and a control group of 21 patients who interrupted the SPT for at least 12 months. The results showed that 26% of the treated patients returned for SPT and, of those, 40% returned irregularly. There was a statistical significant difference in compliance in relation to disease classification and the type of treatment received, but no correlation was found between compliance and gender. There was a statistically significant difference in compliance between the test group and the control group in relation to the variation of the bleeding index.

Slow release of tetracycline hydrochloride from a cellulose membrane used in guided tissue regeneration.

The objective of this study was to evaluate if the biologic membrane utilized for GTR can be impregnated by tetracycline hydrochloride and if the chemotherapeutic agent, once impregnated, can be released in minimal inhibitory concentrations for a period compatible with clinical application. Initially, an in vitro study was done with cellulose membranes cut in pieces measuring 9 cm2. A volume of 100 microliters containing a 72,000 micrograms/ml solution of tetracycline was dispensed onto each fragment, and dried for 70 minutes at 37 degrees C. Four pieces measuring 0.5 cm2 were cut from different points of the 9 cm2 membrane (presumably, containing 400 micrograms of tetracycline), placed in test tubes containing 4 ml of sterile deionized water, and agitated for 2 minutes. A standard curve was made from known concentrations of tetracycline and compared to 10 microliters of the test solutions obtained by the elution of the 0.5 cm2 fragments. The concentrations were determined through the bioassay technique in 3 duplicate experiments. The samples recovered from the membrane fragments had a mean of 101 micrograms/ml of tetracycline liberated, demonstrating that the membrane was impregnated homogeneously by the chemotherapeutic agent. In a second phase, an in vivo study was carried out to determine the length of time the drug was liberated from the membranes and at which concentrations, in the presence of an inflammatory process. Fourteen 0.5 cm2 fragments containing 400 micrograms of tetracycline were placed in 14 polypropylene chambers containing 200 microliters of thioglycolate medium. The chambers were implanted in the peritoneal cavities of 14 mice, one chamber per animal, and left in from 1 to 14 days. They were then removed and the concentrations of tetracycline determined from 20 microliters samples using a bioassay. The results showed that the antibiotic was released slowly from the 1st through the 12th day in decreasing concentrations that varied from 218 to 20.8 micrograms/ml. The impregnated cellulose membrane can probably be used in GTR acting as a membrane and as a slow-release device, liberating the chemotherapeutic agent in concentrations high enough to eliminate periodontopathic microorganisms.

Rebuilding of microvascularization following surgical gingival elimination by split flap. Study by perfusion and diaphanization.

1. Intra-arterial vital perfusion was used in dogs to study the rebuilding of the large amount of gingiva and its vascularization, which were removed surgically by split flaps. 2. Visualization of the reconstruction of the microvascularization could be observed through thick (400 mu) sections cleared in methyl salicylate. 3. The periosteal vessels and the vascular plexi of the dentogingival junction were the only vessels remaining after the surgery, and served as progenitors for the rebuilding of the vascularization of the new soft tissue complex. 4. After 48 hours the cut vessels were closed and new capillaries were beginning to form. An intense superficial vascularization was connected by multiple vessels to the periosteal vasculature (4 days), showing the largest number of superficial blood vessels after 7 days, when the area was primarily re-epithelialized.

Manifestations of insulin-dependent diabetes mellitus in the periodontium of young Brazilian patients.

The periodontal condition of patients with insulin-dependent diabetes mellitus was evaluated in terms of plaque, gingival indices, pocket depth, and alveolar bone loss. Thirty male and female diabetic patients aged 5 to 18 years were compared with 30 non-diabetic subjects and correlated with sex and age. Statistical analyses of the data showed that the mean plaque index was significantly higher (P less than 0.01) among the diabetic patients (1.23) than among the control subjects (0.81). The plaque index was significantly higher (P less than 0.01) among diabetic females (1.34) than among diabetic males (1.10), whereas no sex differences were observed in the control group. The arithmetic means obtained for gingival index were statistically higher (P less than 0.01) for the diabetics (0.58) when compared with the controls (0.15), but no significant differences were obtained when the values were correlated with sex and age. Pocket depth did not differ statistically between groups. When pocket depth was correlated with sex, a statistically significant difference (P less than 0.05) was observed only for the palatal region, with a depth of 2.1 mm in female patients and 1.92 mm in male patients. When pocket depth was correlated with age, a positive correlation (P less than 0.01) was detected in the diabetic group for all regions investigated, whereas the correlation was not significant in the control group. Mean alveolar bone loss was higher in the anterior upper (1.94 mm) and anterior lower (1.87 mm) regions of the diabetic group when compared to the controls (1.52 and 1.37 mm respectively), the difference being significant at the 5% level of probability.(ABSTRACT TRUNCATED AT 250 WORDS)

Compliance with supportive periodontal therapy.

Analysis of 1,280 private patient records from a periodontal clinic showed poor compliance with supportive periodontal therapy (SPT). Data were analyzed according to sex, age, and type of treatment (with or without periodontal surgery). Analysis showed that 25.2% of the patients never returned and among those who report for SPT, only 40.1% did so regularly; the percent of surgical cases was greater (70.7%) and those patients had better compliance (77.6%); compliance of women was greater (76.5%); abandonment of supportive periodontal treatment was high (66.7%), and compliance increased with age. Several suggestions concerning clinical procedures are offered with the objective of motivating patients to give the necessary importance to supportive periodontal therapy.

Bacterial colonization of the external and internal sulci and of cellulose membranes at time of retrieval.

Membrane exposure with bacterial contamination is often considered one of the main reasons for the lack of predictability in achieving complete regeneration of periodontal defects. Ten cellulose membranes, retrieved from 7 patients treated for Class II furcation lesions in lower molars with at least 4 mm of exposure at time of retrieval were studied. Contamination of exposed membranes was studied using SEM analysis of four surfaces of the membrane, upper external, lower external, upper internal, and lower internal surfaces. DNA probe analysis of three periodontopathic bacteria, Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinmycetemcomitans, was carried out for specimens collected from the external and internal sulci. The results suggest that bacterial contamination of the membranes could be controlled if proper pre- and postoperative care is followed, since significant amounts of any of the three periodontopathogenic bacteria studied were not found. The SEM analysis corroborated the DNA probe analysis since the predominant morphotypes detected were not suggestive of periodontopathogenic bacteria. The importance of membrane contamination and of root concavities in the lack of predictability of the GTR procedure is discussed.

Supportive periodontal therapy in South America. A retrospective multi-practice study on compliance.

BACKGROUND: Supportive periodontal therapy is needed for the success of periodontal therapy but there is little information about the extent of patient cooperation. It is known, however, that cooperation is poor and a matter of concern. METHODS: The present study is part of a more extensive study including information from 5,041 patient records from private periodontal practices in Brazil, Venezuela, Chile, and Argentina. Patient cooperation was measured according to gender, age, type of therapy (surgical or non-surgical), maintenance period (first year, 5 years, 10 years, 15 years, and 20 years), and level of cooperation (non-compliant, regular or irregular) for each of the 4 practices. RESULTS: We observed a great variation in the behavior of the patients from different practices, suggesting that studies on compliance cannot be generalized because differences in culture, economic conditions, knowledge of oral hygiene, and even the philosophy of treatment should be considered. The most significant data were sometimes similar for 2 or 3 of the countries but never for all 4 practices. CONCLUSIONS: Compliance is a very complex matter and findings from individual studies cannot be generalized.

Gingival fluid fucose to protein ratios as indicators of the severity of periodontal disease.

Total fucose and protein was measured in gingival fluid samples collected from 16 human subjects. A significantly higher total protein concentration was found for the control (clinically normal) group when compared to the experimental (severe clinical inflammation) group. This is probably due to the higher gingival flow rate found in the experimental group. The total fucose analyses showed no statistical difference between both groups, but when fucose to protein ratios were studied, a significantly higher ratio was found for the experimental group when compared to the controls. This probably represents the breakdown of plasma and tissue glycoproteins which may occur as a result of inflammation.

Management of soft tissue ridge deformities with acellular dermal matrix. Clinical approach and outcome after 6 months of treatment.

BACKGROUND: Soft tissue ridge defects often hamper ideally shaped artificial crowns and are basically treated using autogenous soft tissue grafts or alloplastic materials. These approaches present disadvantages such as the necessity of creating additional surgical fields to harvest the graft and the requirement of primary closure, which may reduce ridge height. This investigation evaluated the use of acellular dermal matrix (ADM) in the treatment of soft tissue ridge defects. METHODS: Eight patients, non-smokers with non-contributory medical history, provided 18 sites corresponding to missing teeth in the anterior maxillary arch. The ideal horizontal gain (desired gain) was waxed up in study casts, which served as templates for construction of modified acrylic stents with orthodontic wires. These stents served as references for ideal horizontal gain and also as fixed reference points for further evaluation. The distance from the orthodontic wire to the buccal plate of the defect also represented its baseline horizontal component. Vertical variations were evaluated with another stent and, in this case, no desired gain was considered. After raising partial-thickness flaps, the ADM material was rehydrated and folded to fill the defect and reproduce the desired gain. Flaps were sutured with no tension, and part of the material was intentionally left exposed to avoid pressure on the incision line and prevent height loss. Patients used local and systemic antimicrobials, and the sutures were removed at 7 days. RESULTS: Evaluations were carried out at 30 days, and 3 and 6 months, and all sites healed uneventfully. Neither infection nor significant pain was reported by the patients, and the material was covered by tissue at about 21 days. Mean horizontal gain of 1.72 +/- 0.59 mm (58.5%) at 6 months and mean shrinkage of 1.22 +/- 0.46 mm (41.4%) were observed. There was a mean improvement in vertical gain of only 0.61 +/- 0. 77 mm, although 66. 7% of the treated sites showed a 1 to 2 mm gain. Clinically, the total gain in the subjects was very effective and matched the receptor tissues nicely. CONCLUSIONS: ADM may be a suitable material for the treatment of soft tissue ridge deformities due to its biocompatibility, color matching, and horizontal gain. Additional controlled, comparative trials are necessary to establish its advantages and potential compared to autogenous soft tissue techniques.

Split thickness flap, apically replaced, with protected linear periosteal fenestration.

The split thickness flap, apically replaced, with internal linear periosteal fenestration, is a combination of two known techniques. This procedure is another choice to solve mucogingival problems. The advantages in addition to securing a firmer bond of periosteum to bone and mucosa to periosteum at the selected position are: there is no bone exposed, healing is apparently faster and postoperative pain is minimal. An experimental work, carried out on dogs to study the histological reactions after this procedure, is in progress. The results of these observations will be reported in a future publication.

Clinical comparison of cellulose and expanded polytetrafluoroethylene membranes in the treatment of class II furcations in mandibular molars with 6-month re-entry.

The present study compared two barrier membranes, ePTFE and cellulose, used to treat Class II furcations in mandibular molars. Fifteen patients with no history of systemic diseases and presenting matched pair defects were selected. The following soft tissue measurements were taken at baseline (after the hygienic phase), and 6 months after surgery: gingival recession, probing depth, clinical attachment level, and width of keratinized tissue. At the time of membrane placement, and 6 months later (re-entry), the following hard tissue parameters were recorded: cemento-enamel junction (CEJ) to alveolar crest, CEJ to base of osseous defect, alveolar crest to base of osseous defect, and horizontal defect depth. According to the surgical protocol, the ePTFE membranes were completely covered by the flaps (subgingival placement), whereas the cellulose membranes extended 1 mm coronal to the gingival margin (supragingival placement). Healing was uneventful in all cases and membranes remained in place for 4 weeks. Data were analyzed using the Wilcoxon signed-rank test at the 5% level of significance. No statistically significant differences were found between the ePTFE and cellulose membranes, respectively (in mm): probing depth reduction (2.87+/-1.0 versus 3.27+/-1.1), gain in attachment level (2.53+/-1.2 versus 2.8+/-1.3), defect fill (3.0+/-1.4 versus 4.0+/-2.3), horizontal furcation fill (2.87+/-1.1 versus 2.93+/-1.0), alveolar crest resorption (2.4+/-10 versus 2.73+/-1.2), and intrabony defect fill (0.6+/-1.2 versus 1.27+/-1.7). We conclude that both ePTFE and cellulose membranes are effective, not showing statistical differences in efficacy. A larger study may be necessary to show differences in efficacy and adverse effects.

Manifestations of insulin-dependent diabetes mellitus in the periodontium of young Brazilian patients. A 10-year follow-up study.

Eight female and 3 male patients from a group of 30 patients studied 10 years earlier and who had received no periodontal treatment during this period, in order to evaluate the progression of untreated periodontal disease in patients with insulin-dependent diabetes mellitus, were evaluated in terms of plaque accumulation, gingival inflammation, probing depth, and alveolar bone loss. The total number of dental surfaces that presented clinically detectable plaque deposits increased significantly (29% to 43%; P < 0.01; chi 2 = 46.36). Site-specific comparisons for plaque index between studies showed a significant variation (P < 0.01) in the upper arch only for palatal surfaces and in the lower arch for the buccal and lingual surfaces. The total dental surfaces with inflamed surrounding gingiva increased from 11% to 33% in this study (P < 0.01; chi 2 = 175.78). Site-specific comparison for gingival index showed a significant variation for all upper surfaces, while such difference for the lower arch was significant only for the buccal and lingual surfaces. The arithmetic means for the probing depth for the upper buccal, upper palatal, lower buccal, and lower lingual surfaces increased significantly (P < 0.01). The arithmetic means of alveolar bone loss also increased significantly for the upper posterior and lower regions (P < 0.01) and for the upper anterior and lower anterior regions (P < 0.05). The correlation between age and probing depth was significant only for the upper palatal region (P < 0.01). The correlation between age and bone loss was significant only for the upper posterior region (P < 0.05). The results of this follow-up study suggest that despite little variation in plaque accumulation, gingival inflammation, probing depth, and bone loss increased after a 10-year interval in patients who had received no periodontal treatment during this period.

Sulcular exudate protein levels as an indicator of the clinical inflammatory response.

Protein concentrations in gingival fluid exudate were obtained in both the clinically minimal and severe inflammatory states. A comparison of the results indicated no significant differences in the two groups studied. Since total protein concentrations do not appear to reflect accurately the clinical inflammatory status of the gingival tissues, specific components of the protein molecule should be studied.

Guided tissue regeneration associated with bovine-derived anorganic bone in mandibular class II furcation defects. 6-month results at re-entry.

BACKGROUND: The use of graft materials with guided tissue regeneration (GTR) in Class II furcation defects is aimed at improving the outcome of the regenerative technique. In this regard, however, there are a limited number of studies discussing the results obtained when GTR and graft materials are used in the treatment of Class II furcation defects. Furthermore, most studies employ either allogeneic or autogenous materials. The present trial sought to determine whether the use of a bovine-derived anorganic bone (ABB) in conjunction with GTR influenced the outcome of mandibular Class II furcation treatment. METHODS: This study included 14 patients who provided 15 pairs of similar periodontal defects. Each defect was randomly assigned to treatment with either a cellulose membrane in combination with bovine-derived anorganic bone (GTR+ABB) or membrane alone (GTR). Following basic therapy, baseline measurements were recorded including probing depth (PD), clinical attachment level (CAL), and gingival margin position (GMP). Hard tissue measurements were performed during surgery to determine alveolar crestal height (CEJ-AC), and vertical (VDD) and horizontal defect depth (HDD). Membranes remained in position for at least 4 weeks. After 6 months, all sites were re-entered and soft and hard tissue measurements were recorded. RESULTS: Both surgical procedures resulted in statistically significant probing depth reduction and gain in clinical attachment levels, with no significant difference between groups. Gingival recession was more pronounced in the GTR+ABB group (0.87 +/- 0.83 mm), but not statistically different from the GTR group (0.46 +/- 1.19 mm). Vertical defect resolution was significant in both groups (GTR: 1.60 +/- 1.50 mm; GTR+ABB: 1.80 +/- 2.11 mm), without differences between groups. Only horizontal furcation resolution (GTR: 2.47 +/- 0.99 mm; GTR+ABB: 3.27 +/- 1.39 mm) was significantly different between groups (P <0.05). CONCLUSIONS: The use of ABB with GTR techniques improved horizontal defect resolution in mandibular Class II furcation defects, but did not yield superior results regarding soft tissue changes when compared to sites treated with GTR alone. Evaluation of a larger sample could indicate differences and advantages between the evaluated approaches and confirm the real necessity of associating filling materials with GTR.

Root trunk concavities as a risk factor for regenerative procedures of class II furcation lesions in dogs.

BACKGROUND: The purpose of this study was to evaluate the influence of root trunk concavities on guided tissue regeneration. METHODS: The second, third, and fourth mandibular bicuspids of 4 healthy mongrel dogs were used. Full flaps were elevated and furcation lesions (5 mm in height and 2 mm in depth) were surgically created. One mm deep concavities were prepared on the root trunks and part of the crown of all teeth. The second bicuspids remained as controls (C); the left third and fourth bicuspids received normal expanded polytetrafluoroethylene (ePTFE) membranes (NM) and the right bicuspids received modified ePTFE membranes (MM). The MM were made by removing the collar from an NM, cutting it into 2 mm segments, and suturing each of the segments to the collar of each MM. Normal and modified membranes were sutured to their corresponding teeth and the flaps sutured. After the healing period, the mandibles were removed and the teeth processed for histomorphometry. RESULTS: The results showed that the junctional epithelium measured a mean of 0.71 mm for C, 0.64 mm for NM, and 0.14 mm for MM. The differences between C and MM and between NM and MM were both statistically significant at the 5% level (Kruskal-Wallis test). Mean bone height measurements for the buccal surfaces from the furcation roofs were 2.79 mm for C, 2.60 mm for NM, and 1.06 mm for MM and for the mid-portion 1.10 mm for C, 1.23 mm for NM, and 0.30 mm for MM. Differences were statistically significant at the 1% level between C and MM and between NM and MM for the buccal measurements, and at the 5% level between NM and MM for the mid-portion measurements. CONCLUSIONS: Root trunk concavities are important risk factors for regenerative procedures. The collars of the membranes should be modified to improve results when concavities are present.