Histologic Evaluation of the Effect of Mecsina Hemostopper on Bone Regeneration for Critical-Size Defects.

PURPOSE: Acceleration of the bone healing period and/or increasing the quality of newly formed bone still have great importance in the field of oral and maxillofacial surgery. The aim of this study was to evaluate the effect of isolated liquid Mecsina (herbal extract) and its combination with xenogeneic graft material (bovine bone graft) on bone regeneration. MATERIALS AND METHODS: Full-thickness critical-size defects with 10-mm diameter and 2-mm depth were created on the calvarial bone region in 28 Sprague Dawley male rats. Four groups were generated: Mecsina Hemostopper, Mecsina Hemostopper + graft group, only graft group, and empty control group. On the 28th day following surgery, all animals were sacrificed. The calvarial samples were evaluated both histopathologically and histomorphometrically. RESULTS: According to the histopathologic evaluation result, vascular proliferation was significantly higher in the groups in which Mecsina Hemostopper was used as a single material or in combination with graft material (P < .05). Histomorphometric evaluation showed that trabecular and osteoid thickness were significantly higher in all Mecsina application groups (P < .05). CONCLUSION: Mecsina Hemostopper was found to be an effective agent in increasing cell proliferation and providing more qualified bone formation. The combination of Mecsina and xenogeneic bone graft was found to be one of the most effective augmentation options for critical-size defects in rats. Mecsina Hemostopper could be used to get more qualified bone formation clinically, but more clinical research is needed in the future.

Evaluation of Stress Distribution of Four Different Fixation Systems at High- and Low-Level Subcondylar Fractures on a Nonhomogenous Finite Element Model.

PURPOSE: The aim of the present study was to provide insight into a suitable fixation system for subcondylar fractures located at different levels. MATERIALS AND METHODS: High and low subcondylar fractures were simulated on a nonhomogenous mandibular model, and rhombic, trapezoid, and lambda plates and 2 miniplates were used for fixation. The stress in the bone and displacement of the fracture site were measured using finite element analysis. RESULTS: For both high and low subcondylar fractures, the lowest von Mises stress was measured in the rhombic plate system. For high subcondylar fractures, the highest tension in the cortical bone was measured in the trapezoid plate system, and the highest compression was measured in the rhombic plate system. For low subcondylar fractures, the highest tension in the bone was measured in the rhombic system and the highest compression was measured in the trapezoid system. In both high and low subcondylar fracture models, the least displacement amount was measured in the 2-plate system. CONCLUSIONS: The results of the present study have shown that the rhombic plate system might be the proper choice for high subcondylar fractures and the 2-plate system might provide better results for low subcondylar fractures.

Comparison of Success Rate of Dental Implants Placed in Autogenous Bone Graft Regenerated Areas and Pristine Bone.

Autogenous bone grafting still has been considered as the "gold standard" and wildly used in the case of alveolar bone reconstruction. The aim of the present study is to evaluate the success rate of implants placed in autogenous block augmented ridges and implants placed in pristine bone (PB). This study included 113 patients. Fifty-three patients were treated with autogenous block grafts and particulate bone, after 6 months of healing implant placements were performed in autogenous bone augmented (ABA) areas. In 60 patients implant placement was performed, with no need for grafting and implants were placed into the PB. Follow-up data (pain, mobility, exudation from peri-implant space, success rate, marginal bone resorption) were collected after 5 years of prosthetic loading. The cumulative implant success rate at the 5-year examination was 92.45% for the ABA group and 85% for PB group. There were 3 failed implants in the ABA group and 3 in PB group. Average marginal bone loss was 1.47 mm on ABA group and 1.58 mm on PB group. No statistically significant differences for pain, exudation from peri-implant space, implant mobility, implant success, peri-implant bone loss parameters, and patient satisfaction level were found between groups. The obtained data demonstrated that the success rate of implants placed in regenerated areas are very similar to the success rate of implants those placed in PB.

Effect of Induced Membrane on Guided Bone Regeneration in an Experimental Calvarial Model.

OBJECTIVE: The aim of this study was to evaluate the effect of induced membrane on guided bone regeneration and to compare its effect with poly-tetra-flourur-ethylene (PTFE) membrane and collagen membrane. METHODS: Sixteen white Vienna rabbits were used for experiments. Initially 1 defect was created on the parietal bone of all animals and cement was placed inside the defects. After 8 weeks, the bone cements were removed, without damaging the induced membrane formed in the defect cavity. And then 2 more defects were created. All defects were filled with xsenogenic graft materials and were covered with newly formed induced membrane, d-PTFE membrane and collagen membrane. Eight animals were sacrificed at 4th week and other 8 animals were sacrificed at 8th week and all bone specimens were histologically evaluated. RESULTS: New bone formation and bone marrow ratios were significantly higher in induced membrane and d-PTFE membrane group compared to collagen membrane group (P < 0.05) at 4th week. Mature bone ratios were significantly higher in induced membrane and d-PTFE membrane group compared to collagen membrane group (P < 0.05) at 8th week. The best CD31 value was detected with d-PTFE membrane group at 4th week and with induced membrane at 8th week. CONCLUSION: Induced membrane can act as a strong barrier membrane and stimulate bone regeneration. Induced membrane technique can be accepted as a good alternative for the reconstruction of critical size defects in maxillofacial region.

Effects of Platelet-Rich Fibrin Membrane on Sciatic Nerve Regeneration.

Alternative treatment approaches to improve the regeneration capacity of damaged peripheral nerves are currently under investigation. The objective of the present study was to evaluate the effects of platelet-rich fibrin (PRF) membrane after sciatic nerve crush injury in rabbits by histomorphometric and electromyographic analysis. The left sciatic nerves of 20 male Vienna rabbits were clamped for 30 seconds to induce crush injuries. Animals were randomly divided into 2 groups: PRF and control. For each animal in the PRF group, a PRF membrane was wrapped around the injured part of the sciatic nerve to form a tube. No additional treatment was performed in the control group. After a 12-week healing period, tissue samples from the injured nerve region were harvested and the g-ratio of axons, axon density, and impulse transmission changes were evaluated. Analysis revealed that axon density differences were not statistically significant between groups (P = 0.139). The rate of nerve fibers with optimum g-ratio was significantly lower in the PRF group than in the control group (P = 0.02). Conduction velocity differences between groups were not statistically significant. Although PRF application has previously shown positive regeneration effects on maxillofacial tissues, local PRF membrane application in tube form did not show any histomorphometric or functional improvement in peripheral nerve crush injury recovery.

The effects of ozone application on genotoxic damage and wound healing in bisphosphonate-applied human gingival fibroblast cells.

OBJECTIVES: Medication-related osteonecrosis of the jaws (MRONJ) is an extremely therapy-resistant disease involving the jaws especially following bisphosphonate treatment. Bisphosphonates accumulate in bone in concentrations sufficient to be directly toxic to the oral epithelium. Current therapeutic options are inadequate for the prevention and treatment of MRONJ. The aim of this study was to investigate effects of ozone gas plasma therapy on wound healing in bisphosphonate-applied human fibroblasts. MATERIAL AND METHODS: Human primary gingival fibroblasts were cultured. Cytotoxic concentrations (IC50) of bisphosphonates (pamidronate (PAM), alendronate (ALN), and zoledronate (ZOL)) were determined by MTT test. A 60 µg/µl for 30 s of ozone gas plasma application was performed to all experimental culture flasks after drug treatment at 24-h intervals as 3 s/cm2. Genotoxic damages were evaluated by comet assay and wound healing was determined by in vitro scratch assay. RESULTS: PAM, ALN, and ZOL applications caused genotoxic damage on primary human gingival fibroblast DNA. Ozone gas plasma therapy significantly decreased the genotoxic damage (p < 0.05), and this application provided 25, 29, and 27% less genotoxic damage in order of ALN, PAM, and ZOL groups. Ozone gas plasma therapy significantly increased wound healing rates both in postsurgical 24th and 48th hours for all doses of experimental drug groups (p < 0.05). CONCLUSION: The ozone gas plasma application decreased genotoxic damage effect of bisphosphonate usage while improved the wound closure rate on human gingival fibroblasts. CLINICAL RELEVANCE: Ozone gas plasma therapy may be helpful in prevention of gingival healing delay in MRONJ pathogenesis especially when applied simultaneously with surgical intervention.