40-Years Outcome of Old-School Indirect Pulp Capping: Practice-Based Retrospective Evaluation

(1) Background: The aim of this in vitro study was to evaluate the success of indirect pulp capping (IPC) procedures over a period of 40 years. (2) Methods: The investigation of 1412 dental records included 159 patients with 366 IPC teeth having been treated 1969-1980. Teeth revealed caries within the inner third of dentin, were symptom-free, and showed no pulp exposure. Caries was excavated thoroughly, teeth with accidentally exposed pulp were excluded. Zinc-oxide-eugenol was used for IPC. Posterior teeth were restored with amalgam fillings, anterior teeth received direct resin composite fillings. Gathered parameters with possible influences on survival rates were age, gender, tooth location/position, date of vital therapy, numbers of filled surfaces, type of primary restoration material, successional treatments on each tooth and the last date of surveillance. Data collection and statistical analysis was performed by using Excel sheets and DataTab. Significant differences among groups were computed by cox regression analysis and significance level was set at p=0.05. Kaplan Meier curves were utilized to illustrate survival rates. (3) Results: Treatment success was given by keeping vitality beyond 365 days. Loss of vitality within 365 days was determined as treatment failure. Treatment outcome was assessed after different time periods (1 and 6 months; 1, 2, 5, 10, 20 and 40 years) Pulp vitality dropped from 95% after 3 months to 32% after 40 years. Cavity size had a significant influence on pulp survival, tooth position did not, however, third molars at least initially showed a better outcome. Beyond the 1-year recall, no differences for the evaluated parameters were present. (4) Conclusions: IPC showed an excellent long-term success revealing a 1.7% annual failure rate after 40 years of clinical service. Larger defects suffer more pulp damage over the long run.