Digital assessment of marginal accuracy in ceramic crowns fabricated with different marginal finish line configurations

Aim
To digitally evaluate the marginal adaptation of different types of all-ceramic crowns on two different marginal configurations such as Shoulder and Chamfer of the prepared teeth.
Methods
The marginal fit of the crown specimens on the model of the prepared teeth were assessed using the dual scan replica technique. Two plastic teeth were prepared; one having a Shoulder finishing line (A), while the other with a Chamfer finish line (B). Three types of different all-ceramic crowns, layered zirconia, monolithic zirconia, and pressed lithium disilicate, were fabricated for each prepared tooth (A) and (B). Measurements for assessing the marginal discrepancy were done on four designated points on the mesial, distal, buccal, and palatal surface of the superimposed image.
Results
The average marginal gap was the largest in the layered zirconia group, followed by monolithic zirconia, while pressed lithium disilicate crowns showed the least marginal gaps. Crowns with Chamfer finish lines were better fitting (less marginal gap) than the shoulder finish lines across all the groups.
Conclusions
Chamfer finish lines produced better fitting restorations, and heat-pressed lithium disilicate crowns showed better adaptation at the margins than both layered zirconia and monolithic zirconia.