Introduction: To date, studies about the systemic effects of statins on bone tissue have led to different results. The aim of this study was to assess the osteoinductivity by statins when injected intramuscularly or subcutaneously in rats.Materials & Methods: In this experimental study, 68 injections of Simvastatin, Lovastatin, Atorvastatin in polyethyleneglycole with 1mg/ml and polyethyleneglycole 300 were injected either S.C in rat's backs or I.M into their hand and foot. After 6 weeks, the rats were killed and samples of the injection areas were provided and were studied under a microscope.Results: In two of the samples, few bony areas were seen which were a mixture of lamellar and woven bone. Around these areas' an osteoblastic rim was visible. In another sample, a chondral area with an active mesanchimal connective tissue which was in a differentiation state to become cartilage, was seen.Conclusion: Finding of this study and the gradual differentiation of muscular tissue to bony stem tissue in around samples, confirms the probable osteoinductivity effect of theses compound. To confirm further we propose that this effect should be investigated on stem cell cultures, in vitro.

Background: The fetal amniotic membrane is a biological graft with unique qualities which all lead to wound protection, reducing discomfort, and achieving adequate epithelialization. Materials and Methods: In this animal study, the second and third premolars of the mandible of 4 dogs were extracted. After 4 weeks, 20 mm of mandibular premolar site area were resected on both sides. The created defects on both sides were filled with xenograft. On one side, an amniotic membrane was placed over the graft particles and the reflected flap was sutured. The amount of bone formation in the defects was measured after 4 weeks for two of the dogs and after 8 weeks for the other two, using a caliper. Three histopathological samples from both sides were taken. The collected data were subjected to statistical analysis (Wilcoxon signed‑, rank and paired sample t‑, test) using SPSS software at a significant P = 0. 05. Results: In the test group, the quantity of bone was 56. 81, whereas in the control group bone quantity was 37. 38 with statistically significant differences (P = 0. 025). In the amniotic membrane group, the inflammation intensity after the graft procedure was moderate (50%) in comparison to the control group where the inflammation was severe (62. 5%) (P = 0. 041). Conclusion: The amniotic membrane can induce positive osteoinduction effects and be helpful in repairmen of bone defects such as the natural periosteum.

In recent years, application of Hydroxyapatite (HA) as the coating on metal substrates for biological stabilization of implants, stimulation of bone growth around the implant, and optimization of recovery time has attracted the attention of many researchers around the world. In this regard, the current study presented a review of HA and its composite coatings for tissue engineering applications. HA is one of the bioceramics that has been an interesting subject of research in recent years owing to its in-vitro bioactivity, osteoinduction, and osteoconduction properties. According to the previous reports, coated implants were performed successfully to achieve high corrosion resistance, bone growth and regeneration, and reduction of corrosion current density. The current research presented a review of the previous research works on the coating mechanism, physico-mechanical, in-vitro bioactivity, and biocompatibility properties of HA and its composite coatings on substrates. The obtained results revealed that HA and its composites had a synergistic effect on the metal substrates in terms of improving corrosion resistance, providing biocompatibility, direct bonding to tissue, accelerating treatment, and reducing costs imposed on the health care sector.

Objective(s): We investigated the role of various biomaterials on cell viability and in healing of an experimentally induced femoral bone hole model in rats. Materials and Methods: Cell viability and cytotoxicity of gelatin (Gel; 50 μ g/μ l), chitosan (Chi; 20 μ g/ μ l), hydroxyapatite (HA; 50 μ g/μ l), nanohydroxyapatite (nHA; 10 μ g/μ l), three-calcium phosphate (TCP; 50 μ g/μ l) and strontium carbonate (Sr; 10 μ g/μ l) were evaluated on hADSCs via MTT assay. In vivo femoral drill-bone hole model was produced in rats that were either left untreated or treated with autograft, Gel, Chi, HA, nHA, TCP and Sr, respectively. The animals were euthanized after 30 days. Their bone holes were evaluated by gross-pathology, histopathology, SEM and radiography. Also, their dry matter, bone ash and mineral density were measured. Results: Both the Gel and Chi showed cytotoxicity, while nHA had no role on cytotoxicity and cellviability. All the HA, TCP and Sr significantly improved cell viability when compared to controls (P<0. 05). Both the Gel and Chi had no role on osteoconduction and osteoinduction. Compared to HA, nHA showed superior role in increasing new bone formation, mineral density and ash (P<0. 05). In contrast to HA and nHA, both the TCP and Sr showed superior morphological, radiographical and biochemical properties on bone healing (P<0. 05). TCP and Sr showed the most effective osteoconduction and osteoinduction, respectively. In the Sr group, the most mature type of osteons formed. Conclusion: Various biomaterials have different in vivo efficacy during bone regeneration. TCP was found to be the best material for osteoconduction and Sr for osteoinduction.

Background: Ethylene oxide is widely used for secondary sterilization of bone allograft to reduce the risk of infection and associated complications. In this study the effects of ethylene oxide gas sterilization on the osteoinductivity of demineralized bone powder is investigated. Materials and Methods: Two separate implants consisting 30 mg aseptically prepared, and 30 mg ethylene oxide-sterilized demineralized bone powder was placed into two different muscle pouches created in the paravertebral muscles of eighteen rats. After 4 weeks, they were removed with 0.5 cm normal surrounding tissue. Histological examination was done to determine the presence or absence of osteoinduction.Results: All except one of eighteen aseptically prepared demineralized bone powder sites histologically contained new bone elements (94.4 %) and fourteen (77.7%) out of eighteen ethylene oxide sterilized demineralized bone powder sites showed evidence of new bone elements. There is no significant difference in osteoblast formation in the two groups (p>0.05).Conclusion: It is concluded that ethylene oxide sterilization in 42°C did not significantly reduce the osteoinductivity of demineralized bone powder. So, it can be considered as a suitable but not perfect method for secondary sterilization of demineralized bone powder.