Abstract: Objective： To evaluate the two-year outcomes of primary molars pulpotomy using mineral trioxided aggregate (MTA) and to find out the potential influence factor, with the help of electronic medical record database. Methods: Children who received primary molars pulpotomy in the Department of Pediatric Dentistry in Peking University School and Hospital of Stomatology from May, 2014 to November, 2015 were searched in the Electronic Medical Record Database of Peking University School and Hospital of Stomatology, via the database for scientific research provided by the corporation of Kaientai. The children who were healthy, no more than 8 years old and followed up over 1.5 years were selected as the subjects of this study. At the same time, those children who didn’t have complete medical records and X-rays before and after treatment were removed. Basic information, the relevant medical records and radiographic records of those children were collected. All molars were examined clinically and radiographically, and classified into 1 of 5 outcomes: N, H, P0, PX, PY. Molars classified into P0, PX and PY were regarded as failed. Survival analysis was applied. The survival rate and survival time of the deciduous teeth were calculated．Multivariate analysis was performed by using Cox proportional hazard model. Results: One hundred and fifteen children were finally included，aged from 2.6 to 8.2 years, with the mean age of (4.5±1.1) years. 211 primary molars were included, and the average follow up time was (880±154)  days. A good level of agreement between the raters was found for molars with five outcomes(κ=0.913). Intrarater reliability was good for molars with five outcomes (κ=0.916). Forty-nine molars failed by September, 2017. Fortythree molars had abnormal radiographic manifestation. Six molars suffered premature loss. Only fourteen molars had an associated gingival swelling or parulis, or pa-thologic mobility upon clinical examination. The cumulative survival probability of half a year, one year, one year and a half, two years, two year and a half for the pulpotomy was 100%, 98.5%, 92.9%, 90.5%,73.8% through the Kaplan-Meier method, respectively. Through the analysis of Cox proportional hazard model, the survival probability was significantly higher when the age was younger. When sodium hypochlorite and the saline were used as the irrigation at the same time, the survival probability was not improved for those teeth with more bleeding in the operation compared with that used saline only. The teeth with preformed metal crown (PMC) gained longer median survival time than those restored with resin composite and others, but the difference was not significant, either. What’s more, gender, the restoration time of PMC, the restoration of the opposite teeth were not found to be associated with the success of the treatment. Conclusion: The cumulative survival probability of two years after the primary pulpotomy was 90.5%, complying the current instructions in our department. The survival probability of the molars after the treatment was significantly affected by the age.

Key words: Primary molars, Pulpotomy, Survival analysis