Abstract: Abstract: Objective The aim of this study was to investigate the influence of crown to implant ratio on marginal bone loss of maxillary bone and clinical effects around short dental implants. Methods 17 implants of 12 patients were included for investigation. All implants were from the same type and had an intraosseous length of 6 mm and a diameter of 5 or 4.5 mm with 4-5 mm of the residual bone height in maxillary posterior region from January 2015 to June of 2017. Measurements of marginal bone loss were performed at a mean of 18 months after prosthetic loading and the mean follow-up for clinical evaluation was 18 months. Statistical analysis was performed using GraphPad Prism 7.0 software package. Results Overall a survival rate of 100%. Marginal bone loss around 17 short implants measured 0.45mm (SD: 0.07mm) and was found to have no significant correlation with calculated Crown-to-Implant ratio (r=0.19; P=0.47). Conclusions It is suggested that high crown-to-Implant ratios have no significant influence on early marginal bone loss.But high C/IR may increase the risk of inflammation of soft tissue.

Key words: crown-to-implant ratio, short dental implants, maxillary posterior region