Should adhesive debonding be simulated for intra-radicular post stress analyses?

Area of Science:

• Biomaterials Science
• Dental Materials
• Mechanical Engineering
• Finite Element Analysis

Background:

• Intra-radicular restorations are vital for restoring function in endodontically treated teeth.
• Understanding stress distribution and failure mechanisms is critical for long-term restoration success.
• The influence of interfacial debonding on the mechanical behavior of these restorations remains an area of investigation.

Purpose of the Study:

• To elucidate the influence of debonding on stress distribution and maximum stresses within intra-radicular restorations.
• To compare the mechanical performance of different intra-radicular post and core systems under simulated debonding conditions.
• To evaluate the impact of ferrule preparation on stress distribution and failure risk.

Main Methods:

• Finite element analysis (FEA) was employed to simulate five types of intra-radicular restorations: metallic cast post core (MP), glass fiber post core (GP), pre-fabricated metallic post core (PP), resin endocrowns (RE), and single-piece ceramic endocrowns (CE).
• Two cervical preparation designs were analyzed: no ferrule (f₀) and a 2mm ferrule (f₁).
• Simulations included three steps: intact bonds, bond failure between crown and tooth, and bond failure at tooth-post-crown interfaces, modeling contact friction and separation.

Main Results:

• Debonding at the tooth-post-crown interfaces (step 3) significantly increased stress ratios (σMC ratio) and reduced fatigue safety factors (SF) in no-ferrule (f₀) models.
• The post material critically influenced stress distribution and safety factors in f₀ models, with ceramic endocrowns (CE) and resin endocrowns (RE) exhibiting higher stress ratios and lower safety factors compared to metallic posts (MP).
• Models with a 2mm ferrule (f₁) showed minimal differences in stress distribution and safety factors across various post types after debonding.

Conclusions:

• Finite element analysis accurately predicts the failure performance of intra-radicular posts when frictional contact at interfaces is modeled.
• Assuming perfect bonding in FEA analyses of intra-radicular restorations may lead to misleading conclusions regarding their mechanical behavior and failure risk.
• The presence of a ferrule significantly mitigates the adverse effects of debonding on stress distribution and safety factors in intra-radicular restorations.