Occlusal geometrical considerations in all-ceramic pre-molar crown failure testing

Area of Science:

• Biomaterials science
• Dental materials
• Mechanical engineering

Background:

• All-ceramic dental restorations are widely used.
• Understanding factors affecting their mechanical integrity is essential for clinical success.
• Occlusal geometry, including cusp angle and notch radius, may influence the load-bearing capacity of ceramic crowns.

Purpose of the Study:

• To investigate the impact of occlusal geometry, specifically cusp angle and notch radius, on the failure load scatter of all-ceramic pre-molar crowns.
• To determine the relationship between occlusal geometry and load-bearing capacity under simulated functional conditions.

Main Methods:

• Forty-five all-ceramic pre-molar crowns with varying zirconia core thicknesses were tested.
• Crowns were subjected to load on implant abutments at different angulations (0°, 15°, 30°).
• Weibull analysis was used to evaluate failure load scatter, and cusp angle and notch radius were measured.

Main Results:

• No significant differences in fracture load were found between different abutment angulations or zirconia thicknesses.
• High scatter in failure loads was observed, except at 30° abutment angulation, indicated by low Weibull modulus.
• A direct relationship was identified between fracture load and the effective cusp angle.

Conclusions:

• Occlusal geometry plays a significant role in stress concentration within all-ceramic crowns.
• Both dental technicians and clinicians should consider occlusal geometry for optimal design and material selection of ceramic restorations.