The effect of tooth preparation design on the breaking strength of Dicor crowns: 3.

The dimensions of 120 maxillary first premolar all-ceramic tooth preparation designs were measured and analyzed to determine relationships between design features and recorded differences in the strengths of restorations fabricated for each preparation design. To assess clinical feasibility, the remaining dentin thickness of each preparation design was measured. A total occlusal convergence angle of 10 degrees provided the best combination of restoration strength and remaining dentin thickness. Five degrees produced the weakest restorations, and 15 degrees and 20 degrees required greater tooth reduction and pulp proximity. Stronger restorations were noted when the shoulder finish line had a sharp axiogingival line angle, possessed minimal cervical inclination, and was located as close as possible to the same occlusocervical level on all four axial surfaces.