Microhardness of sub-restoration dentine in primary molars after carious tissue removal to soft and firm dentine

Abstract

Objectives: To compare the microhardness of sub-restoration dentine after selective carious tissue removal and placing glass ionomer restorative cement. Methods: Forty-three primary molars with carious lesions extended to the inner third of dentine in subjects aged 8–12 years were included. The teeth were randomly assigned to the following carious tissue removal conditions: Group 1 - removal to the soft dentine, Group 2 - removal to the firm dentine, and Group 3 - removal to the hard dentine. Following restoration with glass ionomer restorative cement for three to six months, 30 tooth samples underwent microhardness testing performed on sub-restoration dentine and sound dentine. The Wilcoxon signed-rank test was used to compare the microhardness values of sound dentine and sub-restoration dentine within the group. The Kruskal–Wallis test was used to analyse the microhardness of the sub-restoration dentine across the three groups. Results: All 30 teeth available for analysis were asymptomatic, with no signs of pulpitis. The average microhardness values of sub-restoration dentine and sound dentine ranged from 16 to 23 KHN and 20 to 27 KHN, respectively. In each group, the microhardness value of the sub-restoration dentine was significantly lower than that of the sound dentine (p < 0.01). There were no significant differences in the microhardness values of sub-restoration dentine relative to that sound dentine among three groups (p = 0.86). Conclusion: The microhardness values of sub-restoration dentine with selective carious tissue removal were comparable to those with complete carious tissue removal after glass ionomer restorative cement placement.