Survivability of Lithium Disilicate CAD/CAM Restorations Delivered by Predoctoral Students.

Objectives: With the increasing incorporation of digital workflows into the daily procedures of dental schools, it becomes essential to assess the competence of new generations of dentists to provide the best care when using these technologies. The aim of this retrospective study was to evaluate the survivability of monolithic lithium disilicate (LiDi) restorations prepared and delivered by predoctoral dental students. The primary variable investigated was the service time of the restorations, that is, the time the restorations were in clinical function, encompassing the time from the moment they were placed until failure and/or the last follow-up evaluation. Additionally, as secondary variables, the luting agent used, the cause of failure or replacement, as well as the determinants related to predoctoral student provider and patient were also evaluated.

Methods: After IRB protocol approval, a list of patients who received 4515 CAD/CAM restorations between January 2014 and September 2022 was mined from Axium. A total of 3700 cases were selected based on the criteria of inclusion, monolithic LiDi restorations designed and delivered by predoctoral junior and senior students. Survivability was calculated for included patient charts using Kaplan-Meier survival analysis. The effect of student-provider year, restoration type, tooth restored, cement used, and patient age, sex, and reported bruxism behavior was evaluated using Cox regression models.

Results: At 98 months, out of those 3700 restorations, 26 did not show any record as follow-up and, therefore, were excluded from analysis, and 288 failed (i.e., 7.8% of total included in the study). The survival rate was 92.2%, and the survival probability for LiDi CAD/CAM restorations was greater than 84%. Failure modes were as follows: 31.6% debonding, 20% LiDi fracture, 14.6% recurrent caries, 14% endodontic complication, 10.4% open margin, and 9.4% for other reasons.

Conclusions: Provider and patient-related factors affected survivability of LiDi CAD/CAM restorations. Survivability of LiDi CAD/CAM restorations designed and delivered by predoctoral students resulted in comparable survivability to that of practicing clinicians.