Strengthening of a model composite restoration using shape optimization: a numerical and experimental study.

Area of Science:

• Biomaterials science
• Dental materials
• Mechanical engineering

Background:

• Dental restorations are prone to debonding under occlusal loads.
• Optimizing cavity design is crucial for enhancing the longevity and performance of dental restorations.
• Current cavity designs may not optimally manage stress distribution at the tooth-restoration interface.

Purpose of the Study:

• To validate a novel cavity shape optimization approach for dental restorations.
• To improve the debonding resistance of restored teeth using a stress-induced material transformation (SMT) method.
• To compare the mechanical performance of optimized T-shape cavities with conventional designs.

Main Methods:

• Incorporation of the SMT optimization method into ABAQUS finite element analysis software via a UMAT subroutine.
• Optimization of MOD (M-O-D) restoration cavity shape in artificial premolars to minimize stress at the tooth-restoration interface under occlusal loads.
• Validation through finite element analysis and experimental fracture tests on restored model teeth.

Main Results:

• The SMT optimization identified a T-shape cavity as a superior design for MOD restorations.
• Numerical analysis showed up to a 69% reduction in interfacial stresses with the T-shape cavity compared to conventional designs.
• Experimental fracture tests demonstrated a 23% increase in mean debonding resistance (p<0.05) for teeth with T-shape cavities.

Conclusions:

• Cavity shape optimization is an effective strategy for enhancing the debonding resistance of dental restorations.
• The T-shape cavity design, derived from SMT, effectively reduces interfacial stresses under occlusal loading.
• This approach offers a promising method for improving the durability and clinical success of dental restorations.