Bulent Ayas

Healing of periodontal defects treated with enamel matrix proteins and root surface conditioning: an experimental study in dogs

Application of enamel matrix proteins has been introduced as an alternative method for periodontal regenerative therapy. It is claimed that this approach provides periodontal regeneration by a biological approach, i.e. creating a matrix on the root surfaces that promotes cementum, periodontal ligament (PDL) and alveolar bone regeneration, thus mimicking the events occurring during tooth development. Although there have been numerous in vitro and in vivo studies demonstrating periodontal regeneration, acellular cementum formation and clinical outcomes via enamel matrix proteins usage, their effects on the healing pattern of soft and hard periodontal tissues are not well-established and compared with root conditioning alone. In the present study, the effects of Emdogain (Biora, Malmö, Sweden), an enamel matrix derivative mainly composed of enamel matrix proteins (test), on periodontal wound healing were evaluated and compared with root surface conditioning (performed with 36% orthophosphoric acid) alone (control) histopathologically and histomorphometrically by means of the soft and hard tissue profile of periodontium. An experimental periodontitis model performed at premolar teeth of four dogs were used in the study and the healing pattern of periodontal tissues was evaluated at days 7, 14, 21, 28 (one dog at each day), respectively. At day 7, soft tissue attachment evaluated by means of connective tissue and/or epithelial attachment to the root surfaces revealed higher connective tissue attachment rate in the test group and the amount of new connective tissue proliferation in the test group was significantly greater than the control group (p<0.01). New bone formation by osteoconduction initiated at day 14 in the test and control group. At day 21, the orientation of supra-alveolar and PDL fibers established, and new cementum formation observed in both groups. At day 28, although regenerated cementum was cellular in all of the roots in the control samples, an acellular type of cementum (1.32+/-0.83 mm in length and 3.16+/-0.23 microm in width) was also noted in six roots of test samples with an inconsistent distribution on the root surfaces. The amount of new cementum was significantly higher in the test group than the control group samples (p<0.01). The width of the cellular cementum in the control group was more than the cellular cementum in the test group, but the difference was not statistically significant (p>0.05). A firm attachment of acellular cementum to the root dentin with functional organization of its collagen fibers was noted, and, the accumulation and organization of cellular cementum in the control group was more irregular than the cellular cementum formed in the test group. The amount of new bone was 2.41+/-0.75 mm in the test and 1.09+/-0.46 mm in the control group at day 28. The rate of bone maturation (the number of osteons) was found higher in the test group (10.75+/-0.85) than the control group (5.50+/-0.86). Under the limitations of the study, our results reveal that when compared with root surface conditioning, enamel matrix proteins have more capacity for stimulating periodontal regeneration via their positive effects on root surfaces, i.e. inhibition of gingival epithelium down growth and stimulation of connective tissue proliferation and attachment to the root surfaces during wound healing. An acellular type of cementum regeneration and new alveolar bone formation by an accelerated osteoconductive mechanism are also achieved with application of enamel matrix proteins.

Gingival levels of monocyte chemoattractant protein-1 (MCP-1) in diabetes mellitus and periodontitis: an experimental study in rats

The objectives of this study were to investigate and compare the monocyte chemoattractant protein-1 (MCP-1) levels of gingival tissues in diabetes mellitus (DM) and periodontitis and to reveal the effects of MCP-1 on periodontal inflammation and destruction in these diseases. DM was created in 15 rats (group 1) by streptozotocin injection, and periodontitis was obtained by ligature induction in 15 rats (group 2). Fifteen systemically and periodontally healthy rats were used as control (group 3). Gingival MCP-1 levels were measured by enzyme-linked immunosorbent assay (ELISA). Periodontal inflammation was quantified by the inflammatory cell infiltration in the gingival samples, whereas periodontal destruction was assessed by the alveolar bone loss in the experimental regions. MCP-1 concentrations were higher in groups 1 and 2 than in group 3 (p < 0.001). Increased gingival inflammatory cell infiltration and alveolar bone loss were observed in groups 1 and 2 compared to group 3 (p < 0.001). There were positive correlations among the MCP-1 level, gingival inflammatory cell infiltration, and alveolar bone loss in groups 1 and 2 (p < 0.001). Our results suggest that (1) DM may lead to enhanced MCP-1 production in periodontal tissues likewise for periodontitis and (2) there may be a positive correlation between the MCP-1 concentration and diseased nature of periodontium in both diseases.

Effects of Simvastatin on Mandibular Distraction Osteogenesis

PURPOSE The aim of this study was to evaluate the effects of local and systemic simvastatin application on distraction osteogenesis. MATERIALS AND METHODS Eighteen New Zealand white rabbits underwent unilateral mandibular distraction osteogenesis. After 7 days of neutral fixation, 0.4 mm twice per day, distraction was performed for 10 days. Simvastatin was applied locally during the osteotomy phase with a gelatin sponge carrier and systemically during the distraction osteogenesis period by oral gavage. All animals were killed at the end of the consolidation period of 14 days. The distracted mandibles were harvested and evaluated by plain radiography, by peripheral quantitative computed tomography, and with histomorphometry. RESULTS Radiographic evaluation with peripheral quantitative computed tomography showed that the area of the regenerate increased by 9.6% in the local simvastatin group and by 19.3% in the systemic simvastatin group as compared with the control group. In both experimental groups the density of the regenerate increased by 6.7% as compared with the control group. Statistical evaluation of radiographic data showed that all of these changes were not significant. Histomorphometric evaluation determined that there was no statistical difference among groups with regard to the ratios of bone tissue volume to fibrous tissue volume and bone tissue volume to marrow tissue volume. CONCLUSIONS The results of this study suggest that simvastatins effect on enhancing distraction regenerate is limited with the applied doses and methods.

Assessment of Vascular Endothelial Growth Factor and Matrix Metalloproteinase-9 in the Periodontium of Rats Treated With Atorvastatin

BACKGROUND The aim of this study is to examine, for the first time, the role of systemic and local atorvastatin application on periodontium using histomorphometric and immunohistochemical analysis during and after experimental periodontitis induction with or without the presence of microbial dental biofilm. METHODS One hundred ten male Wistar rats were used. Silk ligatures were placed around the cervical area of the mandibular first molars; rats in the healthy control group received no ligatures (n = 10). In experimental periodontitis groups (n = 90), systemic and local atorvastatin and saline were administered in three different periods; the control periodontitis group (n = 10) received no treatment. Histomorphometric analysis, which included alveolar bone area, alveolar bone level, and attachment loss, and immunohistochemical analysis, which included immunoreactivity of vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9, were performed after the rats were sacrificed at the end of the experimental procedure. RESULTS There was a greater increase in alveolar bone area and VEGF immunoreactivity, as well as a greater decrease in alveolar bone and attachment loss and MMP-9 immunoreactivity, with systemic and local atorvastatin application during and after induction of experimental periodontitis. Local atorvastatin application showed better results on periodontium with regard to alveolar bone findings. CONCLUSIONS Systemic and local atorvastatin application showed beneficial effects on periodontium during and after induction of experimental periodontitis. Within the limits of this study, it can be concluded that atorvastatin, which is used for hypercholesterolemia treatment, can also be used as a protective and therapeutic agent for periodontal disease.

The Effect of Cyclosporin A on Alveolar Bone in Rats Subjected to Experimental Periodontal Disease

Cyclosporine A (CsA), broadly used in organ transplantation, may contribute to pathogenesis of osteoporosis. The aim of this study was to investigate the effects of CsA on alveolar bone in rats subjected or not to experimental periodontal disease using biochemical, radiographic, and histometric analysis. Forty Wistar rats were divided into 4 equal groups: Group I (Control), Group II (CsA was injected subcutaneously in a daily dose of 10 mg/kg), Group III (Ligature was placed around the mandibular molars), Group IV (Ligature+CsA). After 60 days, rats were decapitated, serum alkaline phosphatase and calcium levels were measured. Radiographic-alveolar bone loss (ABL), histometric-ABL, and percentage of new alveolar bone formation (NABF%) were determined on mandibular molars. Significant increase in serum alkaline phosphatase levels (p < 0.001), no significant difference in calcium levels were observed (p > 0.05) in Group IV compared to Group III. Radiographic and histometric-ABL were significantly less (p < 0.001), NABF% was significantly greater (p < 0.05) in Group IV than in Group III. No significant difference in any of the parameters between Group II and Group I was found. It can be concluded that in the presence of periodontal disease, CsA treatment may bring out an imbalance in the alveolar bone homeostasis by decreasing resorption and stimulating formation of alveolar bone in rats.

Biochemical Analysis of Pentraxin 3 and Fibrinogen Levels in Experimental Periodontitis Model

Objective. Pentraxin 3 (PTX3), newly discovered inflammation marker, is a member of acute-phase proteins. The hypothesis, synthesis of gingival tissue and serum PTX-3 increases in the experimental periodontitis model (with 10-day and 40-day periods), was tested by detecting gingival tissue and serum PTX-3 levels in rats with experimental periodontitis. Methods. Thirty rats were randomly divided into three groups of ten animals each: ligature-induced experimental periodontitis groups (with 10-day (Group1) and 40-day periods (Group2)) and healthy group (Group3). At the end of experimental period, rats were sacrificed, and radiological and histomorphometric analyses were performed on the mandibles. PTX3 levels were measured in gingival tissue and serum samples using ELISA. Plasma fibrinogen levels were measured according to the nephelometric method. Results. Significant alveolar bone resorption and periodontal inflammation were evident in periodontitis groups. Levels of PTX3 in gingival tissue were statistically higher in Group 1 than those in groups 2 and 3 (P < 0.01). No significant difference was found in serum PTX3 levels between experimental periodontitis and control groups (P > 0.05). Plasma fibrinogen levels were significantly increased in the experimental periodontitis groups (P < 0.001). Conclusion. PTX3 seems to be associated with tissue destruction in earlier periods of inflammatory periodontal disease, contrary to the fibrinogen findings.

Hippocampal cell loss after an anterior and posterior anastomotic vein occlusion model in rats

Estimation of the cell number after cortical venous ischemia/infarction induced by anterior and posterior anastomotic veins occlusion in a rat model is very important. Twenty male Sprague‐Dawley rats were used in this experiment. Small burr‐holes were made over the anterior (the crossing point of the line drawn from the posterior border of the orbital rim and the line drawn along the para‐midline to the superior sagittal suture) and posterior (just inferior point of the posterior ending of the zygomatic arch) anastomotic veins. Bipolar coagulation technique and micro‐scissor were used to sacrifice the venous vessels after final inspection and description. Specimens were evaluated by histopathological and unbiased stereological methods for microscopic evaluation and volumetric analysis, respectively. Significant cell loss was seen in the pyramidal and granule cells of the cornu ammonis and dentate gyrus of the hippocampus after venous ischemia. Cell loss was also pronounced when seen in the histological examination. The present results suggest that the sacrifice of anterior and posterior anastomotic veins can be used as an experimental rat model in the evaluation of pyramidal and granule cell loss in the hippocampus that often assesses the neural damage inflicted by this intervention.

Effects of grape seed extract on periodontal disease: an experimental study in rats

Abstract Natural compounds capable of modulating the host response have received considerable attention, and herbal products are suggested as adjunctive agents in periodontal disease treatment. Objective This study aimed to demonstrate the effect of grape seed extract (GSE) on periodontitis. Material and Methods Ligature induced periodontitis was created in 40 rats and they were assigned to four equal groups. One group was fed laboratory diet (group A) while three groups received GSE additionally. Silk ligatures were placed around the cervical area of the mandibular first molars for four weeks to induce periodontitis. The GSE groups were reallocated regarding GSE consumption as: for two weeks before ligation (group B; totally eight weeks), from ligation to two weeks after removal of the ligature (group C; totally six weeks), and for two weeks from ligature removal (group D; totally two weeks). Sections were assessed histologically and immunohistochemically. Inflammatory cell number (ICN), connective tissue attachment level (CAL), osteoclast density (OD), IL-10 and TGF-β stainings in gingival epithelium (GE), connective tissue (GC), and periodontal ligament (PL) were used as the study parameters. Results Lower ICN, higher CAL, and lower OD were observed in the GSE groups (p<0.05). IL-10 was more intensive in the GSE groups and in the GEs (p<0.05). Group B showed the highest IL-10 for PL (p<0.05). TGF-ß was higher in the GEs of all groups (p<0.017). Conclusions The results suggest anti-inflammatory activities of GSE, but further investigations are needed for clarification of these activities.

Histological evaluation of Ankaferd blood stopper, ferric sulfate and formocresol as pulpotomy agents in rat molars

The aim of this study is to evaluate the use of Ankaferd blood stopper (ABS) as a pulpotomy agent in rat molars and to compare it to ferric sulfate (FS) and formocresol (FC). Pulpotomies of 72 rat molar teeth were performed with ABS, FS and FC. Access cavities were sealed with Intermediate Restorative Material. Histological evaluations were conducted at 7, 15 and 30 days post-operatively. Statistical analysis was performed using the Kruskal-Wallis and Dunn′s multiple comparison tests. There was no significant difference in inflammatory cell response between groups at 7 and 15 days (P > 0.05). However, at 30 days, a higher density of inflammatory cells was observed in the FC group when compared with the other groups (P < 0.05). No significant differences in hard-tissue formation were observed between groups at any time tested. Based on the histological findings of this study, ABS may be considered an acceptable alternative to FC and FS for primary teeth pulpotomies. Further, clinical research is needed to confirm this finding.

Evaluation of apoptotic cell death on liver and kidney tissues following administration of levetiracetam during prenatal period.

Abstract Objective: Levetiracetam is a new generation antiepileptic drug used in treatment of patients with epilepsy and has adverse effects on different tissues. We aimed to evaluate the apoptotic effects of levetiracetam exposure during pregnancy on liver and kidney tissues of rat pups. Methods: We analyzed the newborn rat pups exposed to levetiracetam during prenatal period. Fifteen pregnant female rats were divided into three groups. The group 1 and 2 rats were treated with different doses of levetiracetam (25 mg/kg/d and 50 mg/kg/d, respectively) from gestational days 1–22 during pregnancy. Group 3 (control group) was treated with the same volume of saline. Apoptosis was evaluated by the terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) method. Liver and kidney tissues from rat pups were used for investigation. Results: The percent of TUNEL positive apoptotic cells in group 1 were 22 and 17.5 for kidney and liver, respectively. The percent of TUNEL positive apoptotic cells in group 2 were 20.9 and 20.9 for kidney and liver, respectively. The percent of TUNEL positive apoptotic cells in group 3 were 18.4 and 17.1, respectively, for kidney and liver. The apoptotic index was the same in kidney and liver tissues of all groups. Conclusion: Our results demonstrate that the prenatal exposure of levetiracetam has no apoptotic effects on liver and kidney of rat pups and, it has biosafety in pregnancy in terms of apoptosis. The first study evaluating the apoptotic effects on liver and kidney tissues following administration of levetiracetam during prenatal period.