Hydroxyapatite Dental Inserts for Tooth Restoration: Stress and Displacement Analysis.

Area of Science:

• Biomaterials Science
• Dental Materials
• Mechanical Engineering

Background:

• Composite restorations cause volumetric contraction during polymerization, leading to stress and displacement in tooth tissues.
• Hydroxyapatite (HAP) inserts are used to minimize restoration contraction but their impact on tooth tissue stress has not been fully evaluated.

Purpose of the Study:

• To investigate the effects of HAP inserts on stress and displacement in tooth tissues during composite polymerization and subsequent occlusal loading.
• To evaluate the potential of HAP inserts in preserving prepared teeth, particularly endodontically treated ones.

Main Methods:

• Finite element analysis (FEA) was used to simulate polymerization shrinkage (3.7% contraction rate) and occlusal loading.
• HAP inserts of 1.7 mm and 4.7 mm thickness were modeled as dentin substitutes.
• Stress and displacement in dentin, enamel, and restoration were analyzed.

Main Results:

• HAP inserts reduced contraction-induced displacement by 44.4%–66.7% and maximal stress by 8.1%–52%.
• Occlusal loading showed reduced displacement (12.1%–33.3%) and enamel stress (32.8%–40.6%) with HAP inserts.
• While dentin stress reduction was minimal (3%–8.8%), stress at the cavity base, especially in deep cavities, was notably decreased.

Conclusions:

• HAP inserts effectively reduce stress and displacement in dental restorations, contributing to tooth preservation.
• The use of HAP inserts is beneficial in restorative dentistry, particularly for preventing vertical root fractures in endodontically treated teeth.