Ceramic partial coverage restorations (PCRs) are minimally invasive treatment options for complex tooth damage. This study aimed to review the fracture resistance and fracture patterns of non-endodontically treated posterior teeth restored with PCRs using various restoration types (overlay, onlay, etc.), preparation designs, and two ceramic groups (lithium silicate-based and hybrid ceramic materials). Three databases (PubMed, Web of Science, and ScienceDirect) were used to search for specific key terms according to the PRISMA diagram. Finally, 34 articles were included for analysis. The fracture resistance and fracture patterns were summarized, and RoBDEMAT was used to assess the risk of bias. With ≥ 1 mm restorative occlusal thickness irrespective of materials, premolars restored with PCRs exhibited vertical fracture loads ranging from 682 to 1,954 N, which were lower than those of molars with a similar condition (1,024 to 4,995 N). Molars restored with 1–2 mm-thick lithium-silicate-based overlays and MOD preparation tended to have lower ranges of vertical-load fracture resistance lithium disilicate (LDS): 1,295-1,326 N; zirconia-reinforced lithium silicate (ZLS): 2,066 − 2,189 N compared to overlays without MOD retention LDS: 1,406-4,995 N; ZLS: 2,177-2,738 N. However, the effect of the MOD box was less significant in premolars. Increasing occlusal thickness tended to enhance fracture resistance, but interactions with other factors (e.g., preparation design, ceramic type, and bonded dental substrate) altered the results. Adding proximal boxes or MOD preparation increased the risk of severe fractures. Hybrid ceramics for PCRs showed promising tooth fracture loads under certain conditions, but their fracture resistance compared to LDS remained controversial. Although MOD overlays may decrease the load-bearing capacities of tooth-restoration assemblies compared to anatomic overlays in some conditions, the overall fracture loads for both restoration types always exceeded maximum bite forces. Considering other relevant factors will help clinicians design the appropriate restoration type for each clinical situation.
Sirikatitham et al. (Tue,) studied this question.