Internal fit of lithium disilicate and resin nano-ceramic endocrowns with different preparation designs

Purpose Investigation of different central cavity designs on internal fit of endocrowns fabricated from two materials. Materials and methods Forty maxillary premolars were endodontically treated and divided into 8 groups [n = 5]: LS10, LS6, LD10, LD6, ES10, ES6, ED10 and ED6 (“L” restored with Lava™ Ultimate [resin nano ceramic], “E” restored with IPS e.max ® CAD [lithium disilicate], “S” shallow depth [3 mm], “D” extended depth [5 mm], “6”-degree and “10”-degree axial wall divergence). All restorations were fabricated using CEREC CAD/CAM system. Samples were tested for internal fit using CBCT imaging (Next Generation i-CAT scanner) before and after adaptation. Data was tabulated and statistically analyzed. Results Lava™ Ultimate showed significant better internal fit compared to IPS e.max ® CAD endocrowns both before and after adaptation [ p = 0.007 and 0.003, respectively]. Samples with 6-degree axial wall divergence showed significant better internal fit compared to those with 10-degree axial wall divergence before adaptation [ p = 0.041]. Before adaptation, group LS6 showed the best internal fit [403.00 ± 115.30 μm] followed by LD6, LD10, ES6, ES10, ED10, LS10 and ED6. After adaptation, group LS10 showed the best internal fit [394.80 ± 21.17 μm], followed by LS6, LD10, ED6, LD6, ES6, ED10, and ES10. Conclusion Resin nano-ceramic endocrowns presented better internal adaptation compared to lithium disilicate endocrowns, regardless of the preparation design.