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Marginal ridge strength in Class II tunnel restorations
D J Fasbinder1, R D Davis, J O Burgess
1Department of Restorative Dentistry, University of Texas Health Science Center at San Antonio.
American Journal of Dentistry
|April 1, 1991
Summary
Small tunnel preparations in teeth are safe, maintaining marginal ridge strength. Restoring with glass ionomer cermet also preserves tooth strength, crucial for dental restorations.
Area of Science:
- Dentistry
- Biomaterials
- Dental Mechanics
Background:
- Class II cavities often require extensive tooth preparation.
- Tunnel preparations offer a more conservative approach to Class II cavities.
- Understanding the biomechanical integrity of tunnel preparations is essential.
Purpose of the Study:
- To evaluate the compressive fracture resistance of marginal ridges after Class II tunnel preparations.
- To assess the effect of glass ionomer cermet restoration on marginal ridge strength.
Main Methods:
- Extracted human bicuspid and molar teeth underwent tunnel preparations with varying bur sizes.
- Control groups remained unprepared; experimental groups were restored with glass ionomer cermet.
- Teeth were thermocycled, and marginal ridges were tested for compressive fracture resistance using an Instron Universal testing machine.
Main Results:
- Tunnel preparations up to a certain size did not significantly reduce marginal ridge strength.
- Glass ionomer cermet restorations restored the strength of most tunnel preparations.
- The largest bicuspid tunnel preparation (#6 bur) showed a statistically significant reduction in strength compared to controls.
Conclusions:
- Conservative tunnel preparations can be biomechanically sound for Class II cavities.
- Glass ionomer cermet effectively restores the fracture resistance of undermined marginal ridges.
- Careful consideration of preparation size is necessary to maintain structural integrity.