Marginal Gap of Pre-Cemented Endocrowns: A Systematic Review of Measurement Methods and the Influence of Fabrication...

The aim of this systematic review was to analyze the existing literature on the methods used for in vitro marginal gap measurement of pre-cemented endocrowns and determine whether the fabrication method and material used influenced the marginal gap.

Systematic screening was conducted until January 2025 using EBSCO Host, Scopus, PubMed, and Web of Science databases. This systematic review followed PRISMA guidelines, including in vitro studies on marginal gaps in single-unit pre-cemented endodontic crowns while excluding in vivo and virtual assessments, and studies analyzing preformed and implant-supported crown assessments. The quality of the selected studies was evaluated using the Joanna Briggs Critical Appraisal Checklist. Welch's t-test and ANOVA were used to analyze differences in marginal gaps across the included variables.

Twenty-eight studies were included for analysis. The mean marginal gap for endocrowns across all included studies was 82.75 ± 33.10 µm. Endocrowns fabricated on maxillary teeth demonstrated a mean marginal gap of 77.01 ± 25.46 µm compared with 85.05 ± 36.04 µm for mandibular teeth (t = -0.66, p = 0.513). Endocrowns fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM) (86.65 ± 38.14 µm) had significantly smaller marginal gaps compared with those produced using conventional impressions (109.37 ± 30.05 µm) (t = 2.746, p = 0.038). Seven measurement methods were reported, with significant differences observed in marginal gap values across the different methods (F = 4.61, p = 0.013). Impression replica and stereomicroscopy were the most used marginal gap methods, used collectively in 19 (68%) of the included 28 studies. Impression replica (95.49 ± 31.57 µm) and stereomicroscopy (63.69 ± 26.81 µm) methods produced significantly different marginal gap measurements (p = 0.003). There were no significant differences in marginal gap between endocrown materials (p = 0.122), with marginal gaps ranging from 60.93 ± 26.66 µm in the less explored polymer-infiltrated ceramic to 95.21 ± 34.07 µm in the more frequently studied zirconia. Lithium disilicate remained the most heavily researched material with a pooled marginal gap of 84.04 ± 32.91 µm across all included studies.

The choice of measurement technique significantly influenced the reported marginal gap values, with impression replica, stereomicroscopy, and 3D superimposition being the most commonly used methods. While the fabrication method had a notable impact on marginal gaps in vitro, the choice of crown material did not.