Optimizing preparation design for metal-free composite resin crowns

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Restorative Dentistry

Background:

• Composite resin crowns are utilized for posterior restorations.
• Factors influencing fracture resistance of these crowns require further investigation.

Purpose of the Study:

• To evaluate the fracture resistance of posterior composite resin crowns.
• To test if minimal preparation designs yield acceptable fracture resistance.

Main Methods:

• Fabrication of 128 Artglass composite resin crowns on human molars.
• Varied preparation designs (shoulder/chamfer), occlusal reduction (0.5mm/1.3mm), convergence angles (4°/11°), and cements (glass ionomer/resin).
• Subjected crowns to thermal cycling and vertical load to determine fracture resistance.

Main Results:

• Occlusal thickness, cement type, preparation design, and convergence angle significantly impacted fracture resistance.
• Thicker crowns (1.3mm) and resin cement demonstrated superior fracture resistance.
• Chamfer finish lines and reduced convergence angles (4°) improved resistance.

Conclusions:

• Optimal fracture resistance for posterior composite resin crowns is achieved with increased occlusal thickness.
• Resin cement and reduced convergence angles are recommended for enhanced crown durability.
• Preparation design influences fracture resistance, with chamfer finish lines showing better outcomes.