A comparative evaluation of internal and marginal fits of custom post and core fabricated using conventional and two digital techniques: An in vitro study

Aim: The purpose of this in vitro study was to comparatively evaluate the marginal and internal fits of cobalt-chromium metal custom post and core fabricated using a conventional technique with two digital techniques. Settings and design: The study was designed in an in-vitro study setting. Materials and methods: Five sets of custom post and core restorations were fabricated using the conventional (Group 1) and two semi digital methods (digital scanning of the resin pattern and computer aided additive manufacturing, and digital scanning of the silicone impression and subsequent computer aided designing [CAD] computer aided manufacturing fabrication) (Group 2 and 3). Marginal and internal fits of the posts were evaluated using a micro computed tomography scan at various points. Statistical analysis used: A one way ANOVA test of the scores was made to evaluate the effect of different methods of custom post and core fabrication on marginal and internal fits. Bonferroni adjusted post hoc tests were conducted for intergroup comparison. Results: Least marginal gap was reported in Group 3 (82.5 +/- 14.36 mu m) followed by Group 1 (110 +/- 25.19 mu m) and Group 2 (112.5 +/- 26.75 mu m). Least internal gap at cervical, middle and apical as well as overall values were observed in Group 3 (78 +/- 9.25 mu m, 72 +/- 7.79 mu m, 160 +/- 15.81 mu m, 103.3 +/- 4.43 mu m) followed by Group 1 (113.5 +/- 25.35 mu m, 132.5 +/- 19.92 mu m, 502 +/- 74.63 mu m, 249.3 +/- 25.44 mu m) and Group 2 (114.5 +/- 21.68 mu m, 133.5 +/- 19.57 mu m, 598 +/- 87.86 mu m, 282 +/- 28.91 mu m) respectively. The results of one-way ANOVA and Bonferroni adjusted post hoc tests for marginal gap did not show any statistically significant difference between the three groups (P > 0.05) but revealed statistically significant difference (P = 0.02) in internal gap values at the cervical, middle, and apical regions as well as overall internal gap region between the three groups. Conclusions: Better marginal and internal fits were observed in custom post and core fabricated by digital scanning of the silicone impression and subsequent CAD as compared to those fabricated by the other two groups.