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.