In vitro study on the retention and marginal adaptation of two different cad-cam ceramic endocrowns with different intra-coronal depths

Abstract

Marginal adaptation and retention of the endocrowns are crucial for the success and survival of endocrowns. This study investigated the effect of and intracoronal depth on the retention and marginal adaptation of selected CAD/CAM fabricated all-ceramic endocrowns. Thirty-six mandibular premolar teeth were prepared to receive CAM/CAM fabricated endocrowns. Samples were divided randomly into groups of lithium disilicate with 2 mm intracoronal depth (LD2), lithium disilicate with 4 mm intracoronal depth (LD4), polymer infiltrated ceramic network with 2 mm intracoronal depth (PICN2) and polymer infiltrated ceramic network with 4 mm intracoronal depth (PICN4). All endocrowns were cemented using ParaCore resin cement with 14N pressure and cured for 20 seconds. After cementation, fifty absolute marginal discrepancies (AMD) measurements were done using a stereomicroscope. All samples were subjected to thermocycling before the retention test using a universal testing machine with a 0.5 mm/min crosshead speed. The maximum force to detach the crown was recorded in Newton, and the failure mode was identified. Two-way ANOVA revealed that the AMD for PICN was statistically significantly better than LD (p=0.01). No statistically significant difference was detected in the AMD between the two intracoronal depths (p=0.72). PICN and endocrowns with 4 mm intracoronal depth had statistically significant better retention (p<0.05). 72.22 % of the sample suffered from cohesive failures and ten LD endocrowns suffered adhesive failures. Within the limitations of this study, PICN has superior marginal adaptation and retention compared to LD. Moreover, a deeper intracoronal depth improve retention of endocrown.