Fracture Resistance of Pulpotomized Primary Molar Restored with Extensive Class II Amalgam Restorations

Abstract

Objective: Loss of tooth structure due to dental caries and cavity preparation can reduce fracture resistance, especially in endodontically treated teeth. The aim of the present study was to evaluate fracture resistance of pulpotomized primary molar teeth restored with extensive multisurface amalgam restorations.

Materials and Methods: Eighty extracted carious human primary molar teeth were selected forpresent study. Teeth were divided in to eight groups of ten. Mesio- or disto-occlusal and Mesio-occluso-distal cavities with different cavity wall thickness (1.5 or 2.5 mm) were prepared in both first and second primary molar teeth. After restoring teeth with amalgam, all specimens were stored in distilled water at 37°C for 7 days. Then samples were thermocycled for 1000 cycles from 5°C to 55°C. The specimens then were subjected to a compressive load in a universal testing machine at a crosshead speed of 0.5 mm min-1. ANOVA and t-test were used for statistical analysis.

Results: Mean fracture resistance of first and second molar teeth were 975.5 N (SD=368.8) and 1049.2 N (SD=540.1) respectively. In the first molar group, fracture resistance of 2-surface cavities was significantly more than 3-surface cavities (P<0.001), however this difference was not statistically significant in the second molar group. In both first and second molar group, fracture resistance in cavities with 2.5 mm wall thickness, was significantly more than the group with 1.5 mm wall thickness.

Conclusion: The mean fracture resistance in pulpotomized primary molar restored with amalgam restorations was higher than reported maximum bite force in primary teeth even in extensive multi-surface restorations. Therefore, the teeth with large proximal carious lesions in schoolchildren could be restored with amalgam.