Application of one-piece endodontic crowns fabricated with CAD-CAM system to molars

One-piece endodontic crowns in posterior teeth: An overview of systematic reviews

STATEMENT OF PROBLEM

The outcome of posterior nonvital teeth depends not only on endodontic factors but also on the effectiveness of the restoration. The growing trend in minimally invasive dentistry has led to increasing interest in 1-piece endodontic crowns as an alternative restoration. Nevertheless, their indications and longevity lack extensive exploration, thereby limiting their widespread acceptance in dental practice.

PURPOSE

The purpose of this overview was to synthesize the available evidence from systematic reviews (SRs) about 1-piece endodontic crowns and to identify clinical outcomes such as survival, success rates, and patient-reported outcome measures (PROMs).

MATERIAL AND METHODS

A systematic search was performed in the electronic databases MEDLINE/PubMed, Cochrane, Web of Science, and OpenGrey, as well as a manual search, up to June 2024, with no language or time restriction. SRs that addressed clinical studies related to 1-piece endodontic crowns or endocrowns were included. The risk of bias and methodological quality was measured using the ROBIS and AMSTAR-2 tools, respectively.

RESULTS

The search identified 468 articles, of which 9 SRs were included. The best evidence reported in the SRs was that survival or success rates for ceramic and indirect resin 1-piece endodontic crowns were high at 5 years, similar to those for conventional crowns. Loss of retention was the main cause of failure with similar failure rates for molars and premolars. Evidence for the use of zirconia and metal 1-piece endodontic crowns is limited, and no SR was found that addressed PROMs. Methodological quality was considered low or critically low in most SRs. However, the risk of bias was low for 2 of the 3 SRs that provided the best evidence in the meta-analysis for ceramic and indirect resin 1-piece endodontic crowns. Overlap in the included studies was very high.

CONCLUSIONS

Although the evidence generated by multiple RS only determined that ceramic and indirect resin 1-piece endodontic crowns can be a suitable and reliable option for restoring endodontically treated premolars and molars, with high success and survival rates comparable with those of complete crowns with posts, this overview concluded that it was not possible to provide firm conclusions regarding the outcomes of 1-piece endodontic crowns because of the lack of adequate high-quality primary studies with different materials, heterogenicity of the studies, variations in follow-up, preparation, and operative steps, and very high overlap of studies. Thus, additional well-designed clinical trials are necessary rather than SRs to strengthen the evidence in this area.

Impact of CAD/CAM Material Thickness and Translucency on the Polymerization of Dual-Cure Resin Cement in Endocrowns

The objective of this study is to evaluate the impact of the thickness and translucency of various computer-aided design/computer-aided manufacturing (CAD/CAM) materials on the polymerization of dual-cure resin cement in endocrown restorations. Three commercially available CAD/CAM materials-lithium disilicate glass (e.max CAD), resin composite (CERASMART), and a polymer-infiltrated ceramic network (ENAMIC)-were cut into plates with five different thicknesses (1.5, 3.5, 5.5, 7.5, and 9.5 mm) in both high-translucency (HT) and low-translucency (LT) grades. Panavia V5, a commercial dual-cure resin cement, was polymerized through each plate by light irradiation. Post-polymerization treatment was performed by aging at 37 °C for 24 h under light-shielding conditions. The degree of conversion and Vickers hardness measurements were used to characterize the polymerization of the cement. The findings revealed a significant decrease in both the degree of conversion and Vickers hardness with increasing thickness across all CAD/CAM materials. Notably, while the differences in the degree of conversion and Vickers hardness between the HT and LT grades of each material were significant immediately after photoirradiation, these differences became smaller after post-polymerization treatment. Significant differences were observed between samples with a 1.5 mm thickness (conventional crowns) and those with a 5.5 mm or greater thickness (endocrowns), even after post-polymerization treatment. These results suggest that dual-cure resin cement in endocrown restorations undergoes insufficient polymerization.