Nanoleakage and internal adaptation of zirconia and lithium disilicate single crowns with knife edge preparation.

Aim The present in vitro study aimed at investigating the nanoleakage and internal adaptation of zirconia and lithium disilicate single crowns with feather edge preparation. Material and Methods Sound mandibular incisors were prepared and randomly divided first into 2 groups, accordingly to restorative materials, and then into 4 subgroups each, in relation to different luting agents. The samples were processed for nanoleakage and then observed for internal adaptation either with a stereomicroscope and a scanning electron microscope. Results The average internal adaptation values were 54.06 μm and 78.66 μm for zirconia and lithium disilicate crowns respectively. The lithium disilicate restorations showed marginal fractures in 39% of the specimens whilst no fractures were observed in the zirconia group. Conclusion Within the limitations of the present in vitro investigation, the feather edge preparation at the cervical margin can be recommended only when zirconia crowns are used.