Influence of Marginal Preparation Design on Microleakage and Marginal Gap of Endocrown Cemented with Adhesive Resin Cement

Purpose: The aim of this in vitro study was to evaluate the microleakage and vertical marginal gap of lithium disilicate ceramic endocrown with either butt margin or shoulder finish line. Materials and methods: Fifteen endodontically treated mandibular premolars were grouped into 3 groups (n=5) according to type of restoration. Group 1: A glass fiber post and resin core and all-ceramic crown with shoulder finish line as control group. Group2: Endocrown with butt margin. Group3: Endocrown with shoulder finish line (1mm wide shoulders and 2 mm axial wall heights). E-max all-ceramic restorations (IPS E-max press Ivoclar-Vivadent) were made and adhesively cemented with resin cement. A digital-microscope (Scope Capture Digital Microscope, Guangdong, China), magnification X50 was used to determine the marginal gap in (μm). Samples were sectioned and the dye penetration along the margin was assessed with the microscope at 25× magnification. The total dye penetration depth along the restoration-tooth interface was measured in (μm). Data were analyzed using one way analysis of variance (ANOVA) and post hoc significance difference tests. Difference was significant at P<0.05. Results: Gr 1 (Fiber post and conventional crown) recorded statistically significant (p <0.05) highest vertical marginal gap mean value (73.02 ± 24.94μm), followed by Gr3 (endocrown with shoulder F.L) (46.72±13.1 μm), then, Gr 2 (endocrown with butt margin) (44.66±10.71μm) as indicated by one way ANOVA test. Pair-wise Tukey’s post-hoc test showed non-significant difference in the vertical marginal gap mean value (P>0.05) between endocrown groups; (2) and (3). For microleakage, Gr 3 (endocrown with shoulder F.L) recorded statistically significant (p <0.05) highest marginal leakage mean value (109.76±4.4μm), followed by Gr 1 (Fiber post and conventional crown) (84.17±1.9 μm). While Gr 2 (endocrown with butt margin) recorded the lowest statistically significant (p <0.05) mean value (55.46±4.1 μm) as indicated by one way ANOVA test. Pair-wise Tukey’s post-hoc test showed significant difference (p <0.05) between all groups. Conclusion: Within the limitations of this study, (1) Endocrown was superior to conventional crown regarding vertical marginal gap. (2) Endocrown margin design had no significant effect on vertical marginal gap. (3) Endocrown with butt joint margin resulted in less marginal leakage than that with shoulder finish line. (5482) Amal Abdallah A. Abo-Elmagd and Mohamed Abdel-Aziz E.D.J. Vol. 61, No. 4