Impact of peri-implant keratinized mucosa width on the long-term reconstructive outcomes of peri-implantitis: A retrospective analysis with a follow-up up to 10 years.

PURPOSE: To investigate the effect of mid-buccal peri-implant keratinized mucosa width (KMW) ≥2 mm or peri-implant KMW >0 mm and <2 mm on the long-term outcomes of peri-implantitis reconstructive treatment. MATERIALS AND METHODS: Twenty-nine patients (40 implants; mean follow-up: 9.2 ± 1.4 years) with at least one implant affected by peri-implantitis and surgically treated through a reconstructive procedure followed by a submerged healing were included. Patients were categorized according to their initial KMW: Group 1 (KMW ≥2 mm) and Group 2 (KMW >0 mm and <2 mm). Peri-implant clinical and radiographic parameters and a dedicated composite outcome were assessed at different follow-up visits during supportive peri-implant therapy for up to 10 years. Regression analyses were utilized to identify possible risk/predictive indicators for probing pocket depth (PPD) change and treatment success at the latest follow-up. RESULTS: The mean PPD did not exhibit any statistical difference from the baseline to the latest follow-up between the groups at both patient and implant levels. Long-term treatment success was 46.6% (Group 1) and 42.6% (Group 2) at patient level, it was 42.8% (Group 1) and 33.3% (Group 2), respectively, at implant level (p > 0.05). Group 1 demonstrated significantly higher vertical defect depth reduction than Group 2 (p = 0.018). Presence of buccal bony wall and mean PPD at the baseline were found to be associated with mean PPD change, while KMW at 6 months following surgery was identified as the only significant indicator for treatment success (p < 0.05). CONCLUSION: Implants with KMW ≥2 mm did not present significantly better long-term clinical outcomes following reconstructive therapy than those exhibiting KMW >0 mm and <2 mm. However, KMW values at the end of healing phase following a submerged approach had a significant impact on long-term treatment success.

Evaluation of salivary stress markers and inflammatory cytokine levels in peri-implantitis patients.

BACKGROUND AND OBJECTIVE: Psychological stress has been identified in some observational studies as a potential factor that may modify and affect periodontal diseases, but there are no similar data for peri-implantitis. The aim of this study was to determine the relationship between interleukin (IL)-1ß, IL-6, IL-10, interferon (IFN)α inflammatory cytokines and the psychological stress-related markers, glucocorticoid receptor-α (GRα), and salivary α-amylase (sAA) gene expression levels in saliva samples obtained from healthy implants and peri-implantitis patients. MATERIALS AND METHODS: The study included a total of 50 systemically healthy subjects. Peri-implant clinical parameters were recorded and psychological stress level was evaluated with the hospital anxiety and depression scale (HAD) and state-trait anxiety inventory (STAI) questionnaire forms. Following the evaluations, the patients were divided into 4 groups according their stress and clinical status (Ia, Ib, IIa, IIb). IL-1ß, IL-6, IL-10, IFNα, GRα, sAA gene expression levels in the saliva samples were quantified by quantitative polymerase chain reaction (qPCR). RESULTS: In the group of peri-implantitis who had a high score in stress level assessment scales, significantly higher IL-1ß, IL-6, sAA expression levels were observed (p < 0.001). The IL-10 gene expression levels were lower in the groups with a high score in the stress level assessment scales (p < 0.001). GRα gene was expressed at lower levels in the group of peri-implantitis who had a high score in stress level assessment scales but the difference was not statistically significant (p = 0.065). CONCLUSION: The study findings suggest that psychological stress may increase the inflammation associated with peri-implantitis by affecting cytokine expression levels. CLINICAL RELEVANCE: To prevent peri-implantitis or reduce its prevalence, it could be beneficial to evaluate stress levels and identify individuals experiencing stress.

Efficacy of concentrated growth factor versus collagen membrane in reconstructive surgical therapy of peri-implantitis: 3-year results of a randomized clinical trial.

OBJECTIVES: To compare the 3-year clinical and radiographic outcomes of two different reconstructive surgical management of peri-implantitis using a bone substitute in combination with either concentrated growth factor (CGF) or collagen membrane (CM). MATERIAL AND METHODS: Fifty-one patients who had at least one implant presenting peri-implantitis with an intrabony defect were filled with a xenogenic bone grafting material and covered either CGF or CM. Clinical and radiographic assessments were carried out at baseline and postoperative years 1 and 3. Three different composite outcomes were defined to evaluate treatment success at a 3-year follow-up. The effects of possible prognostic indicators on treatment success were identified by using multilevel regression analysis. RESULTS: The changes in probing depth (PD) and radiographic vertical defect depth (VDD) between baseline and year 1 and baseline and year 3 presented significantly greater decreases for the CM group in comparison with the CGF group (p < 0.05). No significant differences between the two treatment modalities were demonstrated regarding treatment success outcomes. History of periodontitis, VDD at baseline, and the number of intrabony defect walls revealed significant impacts on treatment success (p = 0.033; OR = 3.50, p = 0.039; OR = 0.975, and p = 0.024; OR = 7.0 and p = 0.019;OR = 6.0, respectively). CONCLUSIONS: CM in combination with a bone substitute seems to have slightly better outcomes compared to the CGF membranes in reconstructive surgical therapy of peri-implantitis. The history of periodontitis, baseline VDD, and peri-implant bone defect configuration could be possible predictors influencing treatment success. TRIAL REGISTRATION: ClinicalTrials.gov NCT04769609. CLINICAL RELEVANCE: For the reconstruction of peri-implant bone defects, using a bone substitute in combination with a collagen membrane may show more favorable outcomes.

The effects of decontamination methods of dental implant surface on cytokine expression analysis in the reconstructive surgical treatment of peri-implantitis.

The aim of this trial was to analyze the effect of implant surface decontamination procedures combined with reconstructive surgical treatment (RST) of peri-implantitis on gene expression levels of selected biomarkers in peri-implant crevicular fluid (PICF). Forty patients diagnosed with peri-implantitis were treated with RST + decontamination of the implant surface using sterile saline and ozone therapy (ozone group) or sterile saline alone (control group). The gene expression levels of interleukin (IL)-6, IL-8, IL-17, vascular endothelial growth factor (VEGF), sclerostin (SOST) and osteoprotegerin (OPG) were evaluated by qPCR analysis at baseline and 6-month follow-up. Changes in cytokine mRNA expression levels were analyzed and compared with clinical/radiographic parameters. Both decontamination methods lead to the downregulations of the selected gene expressions. Ozone group showed significantly higher clinical attachment level (CAL) and radiographic defect fill (DF) values at 6 months compared to the control group (p = 0.026 and p = 0.011). The downregulation of SOST levels was significantly associated with probing depth reduction and radiographic DF (p < 0.05). Implant surface decontamination procedures applied with the RST contribute to a notable reduction in immuno-inflammatory response. The additional use of ozone therapy could have favorable effects in anti-infective regimens of peri-implantitis therapy. SOST, which was found to have significant relationship with both clinical and radiographic outcomes, could be a valuable indicator for the progression of peri-implantitis and may aid the development of new therapeutic strategies for bone gain in the RST of peri-implantitis.

Gingival recession treatment with concentrated growth factor membrane: a comparative clinical trial.

OBJECTIVE: This clinical trial sought to evaluate the clinical effectiveness of concentrated growth factor (CGF) and compare it with connective tissue graft (CTG) with coronally advanced flap (CAF) in the treatment of Miller Class I gingival recessions (GR). METHODOLOGY: This split-mouth study included 74 Miller Class I isolated (24 teeth) or multiple (50 teeth) GRs in 23 jaws of 19 patients. GRs were randomly treated using CGF (test group: 37 teeth; 12 teeth in isolated GRs, 25 teeth in multiple GRs) or CTG with CAF (control group: 37 teeth;12 teeth isolated GRs, 25 teeth in multiple GRs). Clinical variables, plaque index (PI), gingival index (GI), probing depth (PD), recession depth (RD), recession width (RW), clinical attachment level (CAL), keratinized tissue thickness (KTT), keratinized tissue width (KTW), and root coverage (RC) were assessed at the baseline as well as at three and six months post-surgery. Healing index (HI) were obtained in the second and third weeks post-surgery. Postoperative pain was assessed for the first seven days using a horizontal visual analog scale (VAS). RESULTS: No significant change was observed in PI, GI, or PD values in either the intergroup or the intragroup comparisons. A statistically significant decrease was observed in CAL, RD, and RW, and KTT increased in all groups at three and six months compared with the baseline. The control group had greater increases in KTW, KTT, and RC at three and six months. No significant difference was found in CAL or RD at the third and sixth months between the two groups. Healing was found to be similar for both groups in the second and third weeks post-surgery. The VAS values in the control group were higher than in the test group, especially at the second, fourth, fifth, and seventh days postoperatively. CONCLUSIONS: CTG is superior to CGF with CAF for increasing KTT, KTW, and RC. CGF may be preferable due to decreased postoperative pain.

Efficiency of Concentrated Growth Factor in the Surgical Treatment of Multiple Adjacent Papillary Losses: A Randomized, Controlled, Examiner-Blinded Clinical Trial Using CAD/CAM.

This study aimed to create papilla with concentrated growth factor (CGF) in cases in which the interdental papilla was not able to fill the interproximal space (IPS) due to physiologic factors. A three-dimensional digital model of this space with the digital impression obtained from direct intraoral scanning of IPS was created. This study aimed to evaluate the efficacy of CGF in the regeneration of multiple adjacent papillary losses (MAPL), with the change in the IPS area calculated on intraorally scanned images obtained with digital impressions. This study included 160 teeth from 40 patients with 120 papillary losses. Patients were randomly allocated to the test group (TG) (n = 20), with 60 MAPL (three adjacent, lost interdental papillae per patient) receiving minimally invasive surgery with CGF, or the control group (CG) (n = 20), with 60 MAPL without surgery. A total of 480 images were uploaded to a software. The patients' age, gender, Plaque Index, bleeding on probing, and mean probing pocket depth values were evaluated. Papillary area (PA) were calculated between the two central, lateral-central, and lateral-canine teeth at baseline and posttreatment periods of 3, 6, and 12 months in both groups. Papillary filling percentage, keratinized-gingiva width, papillary thickness, thrombocyte, count and mean platelet volume were recorded in TG. Considering the variables in TG and CG, there was no difference in terms of age, gender, and periodontal parameters (P > .05). PA at 3, 6, and 12 months showed statistically significant differences from baseline values in TG (P < .001) but not in CG (P > .05). In TG, a moderate positive correlation was found between the midline papillary thickness and the 3-, 6-, and 12-month filling percentages (r: 0.506, P = .023; r: 0.509, P = .022; and r: 0.515, P = .02, respectively), and a high positive correlation was determined between thrombocyte count and the 6- and 12-month filling percentages (r: 0.733, P < .001; and r: 0.744, P < .001, respectively). CGF provided papillary regeneration in the treatment of MAPL and supported three-dimensional structure of the regenerated interdental papilla throughout 1 year.

Evaluation of the effect of the application of hyaluronic acid following laser-assisted frenectomy: an examiner-blind, randomized, controlled clinical study.

OBJECTIVE: The effect of the hyaluronic acid (HA) on laser-assisted frenectomy wound healing has not been tested. This controlled, randomized, examiner-blinded clinical study aimed to compare the outcomes of laser-assisted frenectomy with and without an HA-containing gel application. METHOD AND MATERIALS: The study included 40 patients aged 18 to 40 years, with high labial frenulum attachment requiring frenectomy. Following laser-assisted frenectomy, HA-gel was applied topically to the wound surface at the day of frenectomy and on days 3, 7, and 14 postoperatively in the test group, and no application was made to the control group. The photographs were taken at the day of frenectomy and on days 3, 7, and 14 postoperatively. A total of 160 images were uploaded to the software. The changes in the area measurements from baseline values were calculated. A visual analog scale (VAS) was used to evaluate patients' satisfaction. RESULTS: The primary outcome variable was the change in the wound area from baseline to postoperative 3, 7 and 14 days. The area measurements and VAS scores were significantly lower in the test group than in the control group at all postoperative assessment time points (P < .001). According to the percentage changes calculated at postoperative assessment points, the highest percentage was found on day 14 in the test group, and the lowest value was identified on day 3 in the control group. CONCLUSION: HA was observed to be a viable option for decreasing the surface area of the wound and to act as a wound dressing following frenectomy. HA application also increased patient satisfaction postoperatively.

Gingival recession treatment with concentrated growth factor membrane: a comparative clinical trial

Abstract Objective This clinical trial sought to evaluate the clinical effectiveness of concentrated growth factor (CGF) and compare it with connective tissue graft (CTG) with coronally advanced flap (CAF) in the treatment of Miller Class I gingival recessions (GR). Methodology This split-mouth study included 74 Miller Class I isolated (24 teeth) or multiple (50 teeth) GRs in 23 jaws of 19 patients. GRs were randomly treated using CGF (test group: 37 teeth; 12 teeth in isolated GRs, 25 teeth in multiple GRs) or CTG with CAF (control group: 37 teeth;12 teeth isolated GRs, 25 teeth in multiple GRs). Clinical variables, plaque index (PI), gingival index (GI), probing depth (PD), recession depth (RD), recession width (RW), clinical attachment level (CAL), keratinized tissue thickness (KTT), keratinized tissue width (KTW), and root coverage (RC) were assessed at the baseline as well as at three and six months post-surgery. Healing index (HI) were obtained in the second and third weeks post-surgery. Postoperative pain was assessed for the first seven days using a horizontal visual analog scale (VAS). Results No significant change was observed in PI, GI, or PD values in either the intergroup or the intragroup comparisons. A statistically significant decrease was observed in CAL, RD, and RW, and KTT increased in all groups at three and six months compared with the baseline. The control group had greater increases in KTW, KTT, and RC at three and six months. No significant difference was found in CAL or RD at the third and sixth months between the two groups. Healing was found to be similar for both groups in the second and third weeks post-surgery. The VAS values in the control group were higher than in the test group, especially at the second, fourth, fifth, and seventh days postoperatively. Conclusions CTG is superior to CGF with CAF for increasing KTT, KTW, and RC. CGF may be preferable due to decreased postoperative pain.

Could drug burden be associated with severe periodontitis in patients receiving haemodialysis?

BACKGROUND: Periodontitis increases the risk of cardiovascular disease in the general population by triggering systemic inflammation. AIM: To investigate the relationship between systemic inflammation and periodontitis, and clarify any association between severe periodontitis and the medications used by patients receiving haemodialysis. DESIGN: A cross-sectional study. PARTICIPANTS: The study was undertaken with 56 patients receiving haemodialysis. MEASUREMENTS: Demographic and laboratory data and prescribed drugs regularly used by patients were recorded from hospital records. During the dialysis session, a validated Xerostomia Inventory score was completed. A complete dental/periodontal examination was also undertaken on all patients by the same periodontist. RESULTS: In the study population, stage I periodontitis was determined in 41%, stage II periodontitis in 17%, stage III periodontitis in 21%, and stage IV periodontitis in 21%. Male gender, hypertension, coronary artery disease, ß antagonists, calcium channel blockers, sodium polystyrene sulphonate, teeth brushing less than twice a day and high sensitive C-reactive protein > 8 mg/l were significantly associated with severe periodontitis. CONCLUSION: Drugs, including ß antagonists, calcium channel blockers, polystyrene sulphonate, co-morbid conditions and poor or insufficient oral care could facilitate an increase in the severity of periodontitis in patients receiving haemodialysis. Severe periodontitis also seems to be associated with cardiovascular disease and inflammation in patients with chronic renal disease.

Regenerative surgical treatment of peri-implantitis using either a collagen membrane or concentrated growth factor: A 12-month randomized clinical trial.

BACKGROUND: Platelet concentration based membranes, as well as collagen membranes in combination with bone substitutes, have demonstrated successful outcomes in regeneration of peri-implant bone defects (PBD). PURPOSE: The aim of this study was to evaluate the clinical and radiographic outcomes of regenerative surgical treatment (RST) of peri-implantitis using a bone substitute combined with two different bioresorbable barrier membranes, either collagen membrane (CM) or concentrated growth factor (CGF), during 12-month follow-up. MATERIALS AND METHODS: Fifty two patients, who had at least one peri-implantitis lesion was treated by using a bone substitute in combination with CGF or CM. After surgical procedures, implants were allowed for submerged healing. Clinical assessments were conducted at baseline, 6 and 12 months postoperatively, while radiographic evaluation was performed at baseline and 12 months. RESULTS: Significant reductions were obtained in the mean gingival index (GI), bleeding on probing (BOP), probing depth (PD), clinical attachment level (CAL) and mucosal recession (MR) values at both 6 and 12 months postoperatively compared to baseline for both treatment procedures (P < 0.05). At 6 months, no statistically significant difference was observed for all clinical parameters between the groups, whereas the mean PD, CAL and vertical defect depth (VDD) values were statistically significant in favor of the CM group at 12 months (P < 0.05). The mean defect fill (DF) in the CM group (1.99 ±0.76) was not statistically significantly different from that observed in the CCF group (1.63 ±1.00) (P = 0.154). CONCLUSIONS: The outcomes of the present study suggest that both regenerative approaches yielded significant improvements in both clinical and radiographic assessments. The procedure using a collagen membrane in combination with a bone substitute showed better results at 12 months in RST of peri-implantitis.

The effects of ozone therapy as an adjunct to the surgical treatment of peri-implantitis.

PURPOSE: The decontamination procedure is a challenging aspect of surgical regenerative therapy (SRT) of peri-implantitis that affects its success. The purpose of the present study was to determine the impact of additional topical gaseous ozone therapy on the decontamination of implant surfaces in SRT of peri-implantitis. METHODS: A total of 41 patients (22 males, 19 females; mean age, 53.55±8.98 years) with moderate or advanced peri-implantitis were randomly allocated to the test group (ozone group) with the use of sterile saline with additional ozone therapy or the control group with sterile saline alone for decontamination of the implant surfaces in SRT of peri-implantitis. Clinical and radiographic outcomes were evaluated over a period of 12 months. RESULTS: At the 12-month follow-up, the plaque and gingival index values were significantly better in the ozone group (P<0.05). Probing depth decreased from 6.27±1.42 mm and 5.73±1.11 mm at baseline to 2.75±0.7 mm and 3.34±0.85 mm at the end of the 12-month observation period in the ozone and control groups, respectively. Similarly, the clinical attachment level values changed from 6.39±1.23 mm and 5.89±1.23 mm at baseline to 3.23±1.24 mm and 3.91±1.36 mm at the 12-month follow-up in the ozone and control groups, respectively. According to the radiographic evidence, the defect fill between baseline and 12 months postoperatively was 2.32±1.28 mm in the ozone group and 1.17±0.77 mm in the control group, which was a statistically significant between-group difference (P<0.05). CONCLUSIONS: Implant surface decontamination with the additional use of ozone therapy in SRT of peri-implantitis showed clinically and radiographically significant. Trial registry at ClinicalTrials.gov, NCT03018795.

Effects of decontamination and implant surface characteristics on re-osseointegration following treatment of peri-implantitis.

BACKGROUND: Although considerable bone fill may occur following treatment of peri-implantitis, re-osseointegration appears to be limited and unpredictable. OBJECTIVES: To evaluate the effects of various decontamination techniques and implant surface configurations on re-osseointegration of contaminated dental implants. MATERIAL AND METHODS: Three months after tooth extraction, implants consisting of a basal part and an exchangeable intraosseous implant cylinder (EIIC) were placed in the mandibles of dogs. The EIIC was machined (M), sandblasted and acid-etched (SLA), or titanium plasma sprayed (TPS). Ligature-induced peri-implantitis was initiated 8 weeks post-implantation and lasted until bone loss reached the junction of the two implant parts. Three treatment modalities were applied: (T1) the EIIC was exchanged for a pristine EIIC; (T2) the EIIC was sprayed in situ with saline; and (T3) the EIIC was removed, cleansed outside the mouth by spraying with saline, steam-sterilized, and remounted. A collagen barrier was placed over each fixture, and 3 months later, samples were processed for histology and histomorphometry. RESULTS: T2 revealed the highest bone-to-implant contact (BIC) level (significantly better than T1 and T3). T2 also yielded the highest bone crest level (significantly better than T1), followed by T3 (significantly better than T1). SLA showed the highest BIC level (significantly better than M), followed by TPS. There were no statistically significant differences in bone crest height between implant types. CONCLUSIONS: Both SLA implants and in situ cleansing resulted in the best re-osseointegration and bone fill of previously contaminated implants.

The relationship between periodontal status and alkaline phosphatase levels in gingival crevicular fluid in men with hypergonadotropic hypogonadism.

PURPOSE: The aim of this preliminary study was to determine the possible relationship between alkaline phosphatase (ALP) levels in the gingival crevicular fluid (GCF) and periodontal disease in men with hypergonadotropic hypogonadism (HH). MATERIALS AND METHODS: A total of 41 patients were divided into four groups. 9 with HH and periodontitis (P/HH), 11 with HH and gingivitis (G/HH), 12 with systemically healthy and periodontally healthy (H/C) and 9 with systemically healthy and periodontitis (P/C). The clinical evaluation of patients was based on the following parameters; the plaque index (PI), gingival index (GI), probing depths (PD) and attachment level (AL). The levels of ALP in the GCF were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: No significant difference could be detected in the mean clinical parameter data between the P/HH and P/C groups (p > 0.05). The periodontitis patients in both groups (P/C and P/HH) had higher mean probing depths than the H/C and G/HH patients (p < 0.001). The concentrations and total amounts of ALP in the GCF were significantly higher in both periodontitis groups compared to healthy and gingivitis groups (p < 0.01). The serum ALP levels were significantly higher in the P/HH group when compared to the other groups (p < 0.001). CONCLUSION: The findings of this study suggested that HH could be implicated as a contributing factor to the progress of periodontal disease.

New formation of periodontal tissues around titanium implants in a novel dentin chamber model.

Direct bone-to-implant contact, defined as "osseointegration", is considered most optimal for long-term stability and survival of dental implants. However, the possibility of the formation of a tooth-like attachment apparatus around implants has also been demonstrated. The purpose of this study was to explore the formation of periodontal tissues around titanium implants using a novel and unique experimental model. After resection of the crowns of the maxillary canine teeth in nine mongrel dogs, the roots were hollowed to a depth of 5 mm leaving a thin dentinal wall. Slits were prepared in the cavity wall to create passages from the chamber to the periodontal ligament area. A custom-made, titanium implant was placed into the center of each chamber. Machined, titanium plasma sprayed (TPS) and sand blasted with large grit and acid attacked (SLA) surfaces were used. A collagen barrier was placed over the submerged chamber. Following 4 months of healing, jaw sections were processed for histology. Newly formed periodontal ligament, alveolar bone, and root cementum filled the space between the implant and the wall of the chamber. Ingrown bone was neither in contact with dentin nor with the implant. Thus, an interposed soft connective tissue layer was present. Healing by fibrous encapsulation was observed around most implants. However, cellular cementum was deposited on one TPS and one SLA implant and on the dentinal walls of the chamber. This study shows a remarkable capacity for new periodontal tissue formation at a site where no such tissues ever existed. Maintenance of original periodontal tissue domains most likely prevented osseointegration of the implants. The cementum layer deposited on two implants was likely formed through cementoconductivity rather than by differentiation of periodontal ligament cells upon contact with the implant surface.

Evaluation of periodontal healing in class II furcation defects following guided tissue regeneration with two different types of polylactic acid membranes.

BACKGROUND: Guided tissue regeneration procedures provide predictable reconstruction of periodontal tissues in the treatment of furcation involvements in animals and humans. This study was to compare long-term effectiveness of two different types of polylactic acid (PLA) membranes on periodontal regeneration in surgically created class II furcation defects in dogs. METHODS: Full thickness mucoperiosteal flap was raised on the buccal aspects of the experimental teeth and class II furcation defects having 5 mm vertical dimensions were created on mandibular premolar III and IV on each quadrant. The exposed root surfaces were thoroughly planed and PLA membranes were placed over the experimental defects on both sites. One site received liquid polymer membrane (LPM), and resorbable periodontal mesh (RPM) membranes were applied to the other site. The animals were sacrificed at 7 months after surgery and the specimens were processed for histological evaluation. RESULTS: The average length of new attachment formed on the treated roots in both groups ranged from 3.02 mm to 4.5 mm. Complete bone filling was observed at the furcation sites. No statistically significant differences were found between two membranes in any of the parameters (P > 0.05). CONCLUSION: This study demonstrates favorable regenerative outcomes by the use of two different types of PLA membranes that could be used as alternatives for guided tissue regeneration (GTR).

Effect of polylactide/glycolide (PLGA) membranes loaded with metronidazole on periodontal regeneration following guided tissue regeneration in dogs.

BACKGROUND: Bioabsorbable membranes have been successfully used for guided tissue regeneration (GTR) and local delivery systems because they are biocompatible and do not require second surgery for removal. Several studies have demonstrated that metronidazole, when applied topically, produced immediate effects on microbiological and clinical parameters, most notably a reduction in probing depth and loss of attachment. The purpose of this study was to evaluate the regenerative potential of a metronidazole-loaded biodegradable (polylactide/glycolide) (PLGA) GTR membrane in dogs. METHODS: Six male adult dogs with 36 created osseous defects were enrolled. Bilateral dehiscence type defects in 5 mm diameter were created at buccal aspect of the alveolar bone in maxillary premolar teeth. After full thickness flap elevation, exposed root surfaces were thoroughly planed. In the experimental sites, PLGA membranes with or without metronidazole were fitted and placed over the defects. On the control defects only root planing was performed. Gingival flaps were replaced slightly coronal to the cemento-enamel junction. Animals were sacrificed at 60 days. The histometric analysis was evaluated with the following parameters: defect height (DH), apical extension of junctional epithelium (AEJE), new cementum height (NCH), new bone height (NBH), and new gingival connective tissue height (NCTH). RESULTS: Postoperative clinical healing was similar in the 3 groups. There were no statistically significant differences between the 2 experimental groups in any parameters. Statistically significant differences were observed for AEJE, NCH, NBH, and NCTH in experimental groups when compared with the controls. Statistically significantly greater NCH, NBH, and NCTH were seen in the experimental groups than the controls and control defects showed longer AEJE than the experimental defects. CONCLUSIONS: These results suggest that PLGA membranes with and without metronidazole may have a beneficial effect on periodontal regeneration.