Influence of substrate design for in vitro mechanical testing.

Area of Science:

• Biomaterials science
• Dental materials
• Mechanical engineering

Background:

• Assessing stress distribution in adhesively-cemented monolithic crowns is crucial for clinical longevity.
• The influence of substrate material and anatomical features like roots and periodontal ligaments on stress distribution requires further investigation.

Purpose of the Study:

• To evaluate how dental substrate simulator material and the presence of root and periodontal ligament affect stress distribution in adhesively-cemented monolithic crowns.
• To determine the validity of simplified substrate models for finite element analysis (FEA) of crown behavior.

Main Methods:

• Non-linear finite element analysis (FEA) was performed on five 3D models with varying substrate materials and anatomical representations (with/without periodontal ligament and pulp chamber).
• Monolithic crowns made of zirconia-reinforced lithium silicate were modeled over each substrate.
• An axial load of 600 N was applied to the occlusal surface to analyze maximum principal stress (MPa) on the restoration.

Main Results:

• The crown intaglio surface was consistently the most stressed region across all evaluated substrates.
• Stress levels (average and peak) were comparable between substrates representing a whole tooth (with/without periodontal ligament) and a tooth with a pulp chamber.
• Simplified epoxy-resin substrates (with/without pulp chamber and roots) exhibited 13% lower stress peaks compared to more complex models.

Conclusions:

• Simplified dental substrates can be utilized for evaluating the mechanical behavior of posterior full crowns under axial loading.
• The rigidity of the substrate specimen is a critical factor to consider when using simplified models.
• FEA results suggest that simplified models offer a reliable and potentially more efficient method for analyzing crown behavior, provided rigidity is accounted for.