Predictions of cement microfracture under crowns using 3D-FEA.

Area of Science:

• Biomaterials Science
• Dental Materials Science
• Mechanical Engineering

Background:

• Dental restorations require durable luting cements to ensure longevity.
• Understanding stress distribution in luting cement is crucial for preventing restoration failure.

Purpose of the Study:

• To investigate the influence of crown margin type, cement type, cement thickness, loading direction, and magnitude on stress within luting cement.
• To identify factors contributing to cement microfracture in dental restorations.

Main Methods:

• Utilized three-dimensional Finite Element Analysis (FEA) on 32 computer models of a mandibular first premolar.
• Simulated shoulder and chamfer margin preparations with four cement types at two thicknesses.
• Applied axial and oblique loading at 10 and 100 MPa to determine stress concentrations.

Main Results:

• Elevated stresses occurred under 100 MPa oblique loading, particularly with chamfer margins.
• Oblique loading generated 10 to 150 times higher stresses than axial loading.
• Higher Young's modulus in cements correlated with greater stress; cement thickness had minimal effect except for zinc phosphate.

Conclusions:

• Chamfer margin designs increase stress near margins, risking cement microfracture and crown failure.
• Glass-ionomer and composite resin cements exhibit superior mechanical properties for resisting microfracture.
• Material selection and margin design are critical for enhancing the durability of dental cement.