Abstract
Purpose: In this retrospective study, the longevity of full and facing cast crowns placed by six general practitioners and influencing factors were investigated.
Methods: All participants (20 years or older) had first visited respective dental clinics more than 10 years ago and had a history of full and/or facing cast crowns placed by the six dentists. To reduce selection bias, information about only the first full and/or facing cast crowns placed was obtained from the medical charts and recorded in the case report form. Survival time was defined as the period of time until the crown was retreated. If the crown was still surviving at the last examination, the case was treated as a censored case. Survival analysis was performed using the Kaplan–Meier method and log-rank test, and the Cox proportional hazards model.
Results: Information about the survival time of 824 cast crowns, 542 full cast crowns and 282 facing cast crowns was obtained from 682 participants. Ten-year survival rates for full cast crowns and facing cast crowns were 74.2% and 75.3%, and their median survival times were 20.8 years and 19.7 years, respectively. Main reasons for retreatment of the crowns were crown dislodgement, periapical periodontitis, root fracture and prosthetic requests. It was revealed that treatment history (initially placed or replaced) had the greatest influence on the longevity of the cast crowns (hazard ratio: 3.4), followed by the operator, the number of remaining teeth at the time of placement, and the retreatment risk at the time of placement.
Conclusion: The median survival time for all cast crowns was estimated at 20.7 years, but was found to be significantly shorter for replaced crowns at 14.6 years.
