Gold vs. CAD/CAM ceramic partial-crowns: 20-year randomized clinical study

Despite their widespread use, no systematic clinical long-term data are yet available comparing CAD/CAM partial ceramic crowns (PCCs) with cast gold partial crowns (CGPC). The null-hypothesis of this 20-year follow-up of a controlled prospective randomized split-mouth study was that CGPCs and PCCs reveal similar cumulative survival and clinical performance after 20 years of service.

In this clinical study, 29 patients initially received one CGPC (Degulor-C) and one PCC (Vita-Mark-II/Cerec3). The 20-year follow-up examination was performed by two independent investigators using both, modified USPHS and FDI criteria. Kaplan-Meier survival rates were calculated including failures from patient-files. Non-parametrical statistics (χ², log-rank(Mantel-Cox), α= 0.05) were applied.

Out of initially 29 patients, 19 patients and 36 restorations were considered for survival analysis revealing a cumulative survival of 69 % (CGPC) and 53 % (PCC), without statistically significant differences based on patient files. Regarding FDI and USPHS criteria, 11 patients (19 restorations) were available for clinical examination after a median (25-75 %) observation period of 238 (236-242) months (19.9 years). Within these 11 patients, 10 CGPC and 9 PCCs were still in service. All restorations showed ratings within the acceptable range exclusively (USPHS: Alpha for secondary caries, Alpha and Bravo for other criteria; FDI: scores 1-3). For USPHS criteria surface luster (p ≤ 0.002) and marginal discoloration (p ≤ 0.02), both CGPCs and PCCs, revealed significant deterioration over time. Additionally, marginal adaptation of PCCs deteriorated over time (p < 0.001) and was found significantly worse than that of CGPCs at 20-years (p = 0.003). In FDI criteria, CGPCs performed significantly better regarding surface staining (A2a; p = 0.047) and marginal adaptation (B6; p = 0.01) compared to PCCs.

All PCCs and CGPCs available for evaluation showed acceptable results after 20 years, with slight advantages for CGPCs in singular criteria. The present study is the first randomized controlled prospective study revealing that PCCs exhibit similar long-term cumulative survival as CGPCs with only slightly inferior performance and thus can be confidently recommended for long-term clinical application.