Comparative Analysis of Various Cavosurface Margins in Class II Restorations Using 3D Finite Element Method

Area of Science:

• Dental materials science
• Biomaterials engineering
• Restorative dentistry

Background:

• Restoring proximal surfaces of molars is crucial for dental function.
• Understanding the mechanical behavior of different preparation designs is essential for long-term restoration success.

Purpose of the Study:

• To compare the mechanical characteristics of four proximal lower first molar preparation designs.
• To evaluate stress distribution in slot and beveled preparations under various load scenarios using finite element analysis.

Main Methods:

• Finite element method (FEM) analysis was employed.
• Simulated occlusal loads were applied to four preparation designs: slot, slot with bevel, slot with bevel and rounded proximal box corners (RPBC), and slot with bevel, RPBC, and gingival bevel (GB).
• Tensile and shear stresses at restoration interfaces were analyzed.

Main Results:

• Slot preparations exhibited higher tensile stresses (up to 15 MPa) at the enamel interface compared to beveled preparations.
• Beveled restorations showed increased shear stresses in their thin beveled regions.
• Bevel incorporation significantly reduced normal stresses on restoration edges, shifting them to compressive stresses.

Conclusions:

• Slot preparations carry a risk of separation due to higher tensile stresses.
• Beveled restorations demonstrate reduced susceptibility to edge debonding under occlusal loads.
• Beveled restorations may still be vulnerable to shear debonding in thin marginal areas.