Histologic effects of demineralized bone matrix on regeneration of alveolar socket in diabetic rats

INTRODUCTION: The aim of this in vivo study was to determine the effect of demineralized bone matrix (DBM) on alveolar bone repair in type I diabetic rats. MATERIALS AND METHODS: This study was carried out on 40 adult (8 weeks-old) albino rats with an average weight of 200-250 grams. The animals were divided into four groups (n=10) as follows: group 1 nondiabetic rats, group 2, 3 and 4 were diabetic rats; group 4 rats took one unit of insulin daily.  Diabetes was induced by Alloxan Monohydrate through the tail veins of the rats in groups 2-4. Only group 4 received insulin NPH 1 unit daily. After 10 days, the upper right incisors of all samples were extracted and the socket was filled with DBM in groups 3 and 4. The animals were sacrificed at the end of week 1 and 2. The specimens were prepared and stained with H&E. RESULTS: Histological results of group 4 displayed osteoblastic activity and bone formation with collagen fibers at the end of the first week and thick bone trabeculae formation in vicinity of DBM at the end of second week. In group 3, DBM showed some osteoinductivity at the end of the first week, but in some regions DBM particles were degraded by osteoclastic activity. Bone trabeculae formed with a dispersed and separate pattern at the end of second week. In group 2 hematoma and inflammation were dominant histological features at the end of first and second weeks; poor bone formation was detected in these two groups (2 and 3). In group 1, the results were as expected. CONCLUSION: It seems demineralized bone matrix simulate osteoblastic activity

Comparison of the Effects of Microfilled and Hybrid Composite Resin Restorations on the Fracture Resistance of Extensively Weakened Teeth

Background and Aim : Composite resins can play an important role in dentin support and enamel strength via bonding to tooth structure. The purpose of this study was to compare the effects of hybrid and microfilled composite restorations on the fracture resistance of extensively weakened teeth .   Materials and Methods : In this case control study 40 intact maxillary premolars were mounted in transparent acrylic resin blocks. The samples were divided into 4 groups (n=10 each). Group PC comprised of intact teeth, without preparation and restoration. In other three groups MOD preparations with constant depths and converged walls toward occlusal surfaces were prepared. Group NC composed of teeth with preparations but without any restoration. Group HR included prepared and restored teeth using a hybrid composite and Group MR contained prepared and restored samples with a microfilled composite. Samples were thermocycled (500 cycles in 5-55° C), then were placed under compressive loads in a universal testing machine, and the curves were drawn with a software called Test Xpert .   Results : Mean fracture resistance in HR, MR, PC, and NC groups were 48.1010, 59.1773, 83.1420, and 21.9220, respectively. There was a statistically significant difference among the groups(P<0.05).   Conclusion : The increasing effect of microfilled group on the fracture resistance of restored teeth is significantly more than that of hybrid group

Natural Resistance Associated Macrophage Protein 1 Gene Polymorphism is Associated with Chronic Periodontitis Not Peri-Implantitis in an Iranian Population: A Cross Sectional Study

In inflammatory diseases such as peri-implantitis (PI) and chronic periodontitis (CP) both adaptive and innate immunity play a part. Natural resistance associated macrophage protein 1 (NRAMP1) has considerable effects on macrophage function (phagocytosis) and host innate immune response against infections. The present study was to investigate the relationship of NRAMP1 gene polymorphisms with PI and CP in an Iranian population. In this cross sectional study 79 patients with CP, 38 patients with PI and 84 healthy controls presenting to the Periodontology Department of Shahid Beheshti University of Medical Sciences were enrolled. DNA was extracted from fresh blood samples of arm vein of participants and transferred to KBiosience institute (United Kingdom) for genotyping. X2 and Fisher’s exact tests were used by SPSS software v.19 for statistical analyzes. Significant differences were detected in the distribution of genotypes between control and CP groups both for rs17235409 and rs2276631 polymorphisms (P:0.044 and P:0.028 respectively). Distribution of genotypes differed insignificantly in comparison of PI and control groups for rs2276631 (P:0.623) and either rs17235409 (P:1) polymorphisms. Based on our results, we conclude that presence of G allele in both rs2276631 and rs17235409 location may be a protective factor against CP. More studies with a larger sample size in different populations are required for confirming NRAMP1 as a genetic determinant in periodontal disorders