The fracture resistance of restored mandibular molars using different cavity designs: An in vitro comparative evaluation.

BACKGROUND

The stress distribution of a restored tooth is different from that of an intact sound tooth. The fracture resistance of a restored tooth depends on cavity design, remaining tooth structure, and material used.

AIM: This in vitro study evaluated and compared the fracture resistance of mandibular molars restored using composite resin.

MATERIALS AND

METHODS

Forty freshly extracted, intact mandibular molars were used, with their roots embedded in acrylic resin for stability. Cavities were prepared using a No. 2 round bur and straight fissure diamond, then divided into four groups with specific variations in cavity dimensions. Samples were tested using a universal testing machine, applying vertical load along the long axis at the central fossa to record fracture load.

STATISTICAL ANALYSIS: One-way analysis of variance and Tukey's post hoc analysis were used for statistical analysis.

RESULTS

Fracture resistance of the groups, listed in descending order, was: Lingual wall 1.5 mm (2417 ± 160 N) > Buccal wall 1.5 mm (2122 ± 75.9 N) > Lingual wall 1 mm (1966 ± 75.7 N) > Buccal wall 1 mm (1335 ± 216 N).

CONCLUSION

The lingual wall 1.5 mm exhibited the highest fracture resistance, while the buccal wall with 1 mm thickness showed the least resistance.