SURVIVAL OF CAST GOLD AND CERAMIC ONLAYS PLACED IN A SCHOOL OF DENTISTRY

ABSTRACT Bassam Taha Al-Rawi: Survival of Cast Gold and Ceramic Onlays Placed in a School of Dentistry (Under the Direction of Terry Donovan) Introduction: Indirect partial veneer restorations such as onlays have been used for many years to restore extensively damaged teeth as a conservative option to complete veneer crowns. Originally onlay restorations were fabricated with cast gold, but in recent years onlays have also been fabricated with different types of contemporary ceramic materials. Little is known of the comparative survival rates of cast gold onlays versus the survival rates of ceramic onlays. This study was done to compare the survival rates of cast gold and ceramic onlays placed in a dental school setting. Material and Methods: An electronic search was conducted in the Electronic Patient Records (EPR) at Adams School of Dentistry – University of North Carolina at Chapel Hill. American Dental Association (ADA). Onlay codes were searched in the EPR database (From 1998 till 2019). Progress notes and radiographs were scrutinized to establish the survival time of the restoration. Any complications that occurred during the life time of the restorations such as fracture, debonding, need for endodontic treatment, replacement or extraction were noted. The survival was summarized by categorization based on ranges of survival time in years; GROUP 1: 1 to 5 years, GROUP 2: 6 to 22 years. The mean survival time and Standard deviation were calculated. One-way ANOVA was used to determine whether there was a statistically significant difference in the survival times between gold and ceramic onlays. Results: 205 (20.7%) out of the 987 onlays lacked follow up documentation and were therefore excluded from the study. Of the 782 onlays included in this study, 565 were made of cast gold and 217 of ceramic. The mean survival rate of cast gold onlays was 86.6% and that of ceramic onlays was 81.1%. For the restorations in Group 1 (1 to 5 years), the gold onlays outperformed the ceramic onlays with a mean survival time of 2.43 and 2.03 years respectively. Ceramic onlays had a mean survival time of 19.75 years while gold had a mean survival of 17.63 years for the restorations in Group 2 (16 to 22 years). These results were statistically significant. Debonding was the most common mode of failure for the gold onlays while fracture of the onlay was the most common failure mode of ceramics. Conclusion: It was concluded that while the survival rate of ceramic onlays (81.1%) was inferior to that of cast gold onlays (86.6%), it was relatively acceptable, especially considering most of the restorations reviewed used materials that are significantly inferior to monolithic lithium disilicate (MLD), which is used almost exclusively today.