Comparison of the methods of disinfection/sterilization of extracted human roots for research purposes

Extracted human teeth are used to simulate dental procedures and are essential for practical education and research studies.

The aim of this study was to evaluate the efficacy of different sterilization methods for extracted human roots and to assess the effects of these methods on dentin microhardness.

The crowns of 40 mandibular incisors were removed. The roots were sectioned at 10 mm and divided into 4 groups (n = 10 per group): G1 - no sterilization (control); G2 - microwave radiation (650 W, 5 min); G3 - ethylene oxide (288°C, 3 h); and G4 - autoclave (121°C, 15 min). The roots were immersed in brain heart infusion (BHI) and incubated at 37°C in variable oxygen atmospheres. After 14 days, the samples were assessed for turbidity. Three slices were obtained from each root, and indentations were made at 30, 60 and 120 μm from the root canal lumen. The microbiological data was analyzed with the Kruskal-Wallis test and Dunn's post-hoc test. Microhardness was evaluated by means of the twoway analysis of variance (ANOVA) and Tukey's test (p < 0.05).

The roots submitted to autoclaving were 100% sterile, which differed from the other methods (p < 0.05); the control specimens had 0% sterility. For microhardness, significant differences were found between the methods, particularly for the apical third (68.06 ±12.50) (p < 0.05).

Although all the evaluated techniques reduced dentin microhardness, autoclaving should be used as the most reliable method of sterilization of extracted dental roots.