Objective:The purpose of this study was to evaluate the effect of different concentrations of platelet-rich plasma (PRP) on the proliferation of undifferentiated periodontal ligament (PDL) fibroblasts.Materials and Methods:The undifferentiated PDL fibroblasts were obtained from two healthy human premolar teeth and cultured in Dulbecco's modified Eagle's medium. Cell wells were divided into five groups. Experimental groups received 0.1%, 5%, or 50% PRP; the positive and negative control groups were cultured in fetal bovine serum (FBS) 12% and in a medium without FBS 12%, respectively. The plates were incubated at 37°C for 1, 2, 3, 4, and 7 days. PDL cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide proliferation assay. Statistical analysis of the data was accomplished using repeated measure ANOVA and Tukey's test. P < 0.05 was considered statistically significant.Results:The 5% PRP had the greatest effect on undifferentiated fibroblast proliferation, which was significant on the 3rd day. There was no significant difference between 0.1% PRP and positive control during the first 3 days. The group with 50% PRP presented significantly lower proliferation, compared to other experimental and control groups.Conclusions:It may be concluded that the growth-stimulating effect of PRP is dose dependent with the best results in low concentrations.

Background. Dental implants are one of the most successful treatments for restoring tooth function and beauty. Identifying the causes of dental implant failure is useful and vital. This review was aimed at studying the possible role of vitamin D in early implant failure. Method and Material. This review was designed based on the PRISMA guideline. Data was collected using keywords including implant, vitamin D, deficiency, failure, dental, OR tooth in international databases including PubMed, Scopus, Web of Science, Cochrane, and Embase, until 2020. Based on the inclusion and exclusion criteria, data were extracted and gathered in a checklist. Results. Finally, twelve studies were selected from five different countries. In 6 studies (2 animal studies and four human studies), there was no significant relationship between vitamin D deficiency and dental implant failure. In the other six studies (1 animal study and five human studies), there was a significant relationship in this regard. Conclusion. It is difficult to conclude the association between vitamin D and implant failure based on the literature’s researches. However, vitamin D appears to play an essential role in implant success through its effects on immune system modulation.