Method: Practices were randomized to perform direct pulp caps with either MTA or CaOH. Subjects ≥7yo, with a pulp exposure on a permanent tooth that did not demonstrate radicular radiolucency, spontaneous and/or lingering pain to temperature or biting, were eligible. Practices were trained/calibrated based on assigned pulp cap material. Subjects were contacted by phone at 30 days, then recalled semi-annually for up to two years. The primary outcome was pulp cap survival, and secondarily evaluated for positive response to vitality testing with no radiologic signs of pathology (reported 2012 IADR). Additionally, exposure type, rubber dam in place at times of exposure and pulp capping, exposure size, bleeding amount, time to control bleeding, time from exposure to pulp capping, and restoration type were analyzed for effect on pulp cap failure by Cox proportional hazard regression with robust standard errors that account for intra-practice correlation (p≤0.05).
Result: 35 practices in Northwest PRECEDENT performed direct pulp caps on 376 subjects; 358 with follow up data. The failure rate at 24 months for CaOH=39%; MTA=21% (p=0.055). Hazard ratio (95% CI) for CaOH vs MTA was 1.72 (0.98-3.02). Hazard ratios (95% CI) for potential pulp cap failure co-factors: Exposure type (carious vs. mechanical/traumatic): 2.2 (0.6-7.5); Rubber dam in place at time of exposure (yes/no: 0.91 (0.5-1.8); Rubber dam in place at time of pulp cap (yes/no): 0.95 (0.5-1.9); Exposure size (0.5mm increments): 1.09 (0.9-1.4); Bleeding amount ( Light vs. moderate/heavy): 1.2 (0.6-2.1); Time to control bleeding (minutes): 1.03 (0.9-1.1); Time to place pulp cap (minutes): 1.02 (0.9-1.1).
Conclusion: No observed pulp capping co-factors significantly affected pulp cap outcomes. Supported by NIDCR grants DE016750 and DE016752.