Do composite resin restorations protect cracked teeth? An in-vitro study

Area of Science:

• Dental materials science
• Biomaterials engineering
• Restorative dentistry

Background:

• Cracked teeth pose a significant clinical challenge, potentially leading to tooth loss.
• Bonded restorations are used to stabilize tooth structure, but their efficacy in cracked teeth requires further investigation.
• Understanding the influence of restoration type and design on fatigue resistance is crucial for clinical success.

Purpose of the Study:

• To assess the effectiveness of bonded resin composite restorations in immobilizing cracked tooth segments under cyclic loading.
• To compare the fatigue resistance of direct versus indirect composite resin restorations.
• To evaluate the impact of inlay versus onlay restoration designs on the fatigue resistance of cracked teeth.

Main Methods:

• Sound human third molars were prepared with large mesio-occluso-distal cavities and a simulated crack.
• Teeth were randomly assigned to four groups: direct inlay, direct onlay, indirect inlay, and indirect onlay composite restorations.
• Specimens were subjected to cyclic loading up to 185,000 cycles or fracture, with failure modes recorded.

Main Results:

• Direct composite restorations demonstrated significantly higher survival rates compared to indirect restorations (p=0.001).
• No failures were observed in direct restoration groups up to 1000 N.
• No statistically significant difference in survival rates was found between inlay and onlay designs (p=0.901).

Conclusions:

• Direct composite resin restorations provide sufficient protection for cracked teeth, irrespective of cavity design.
• Current evidence does not support favoring either inlay or onlay designs over the other for cracked teeth based on fatigue resistance.
• Further in vitro and clinical studies are warranted to confirm these findings.