A 2-year retrospective study on CAD/CAM resin crowns on premolars

Purpose: Attributes of patients treated by CAD/CAM resin crowns on premolars (CAD/CAM crowns) and the prognoses of the CAD/CAM crowns were investigated. In addition, the effects of both the method of core buildup and the cement for luting, on the prognoses were analyzed.Methods: During the period from April 2014 to March 2016, the gender, age and teeth positions of patients treated by CAD/CAM crowns at Ohu University Dental Hospital were investigated. The results were compared with those of full metal crowns (FMC). Regarding the prognoses of the crowns, the cumulative survival curve of CAD/CAM crowns by the Kaplan-Meier method was drawn and compared with that of FMC by the log-rank test. In addition, the setting position, condition of abutment, and cement used for setting were set as explanatory variables and prognoses as the response variable. These data were analyzed by quantification theory type 2.Results: In patients treated with CAD/CAM crowns compared with FMC, the percentage of females was significantly higher, but average age was lower. In the 2-year prognosis, a significant number of CAD/CAM crowns detached and the relative risk was high. In analysis by quantification theory type 2, range and biased correlation coefficient showed high values for cements used, but discriminant predictive rate and correlation ratio were low.Conclusion: While CAD/CAM crowns were in demand among females in their late 50s, there were many detachments. Therefore, it is considered important to control the technique sensitivity factor by understanding the selection of abutment teeth, dental materials and adhesion system.