Effect of disinfection and storage media on surface microhardnessof human enamel blocks

Protocolized disinfection and storage are critical to ensuring the quality of dental specimens used in in vitro studies. However, few evaluations have addressed the effect of different combinations of disinfection and storage media on the surface microhardness of human enamel blocks.

To evaluate the effect of different disinfection and storage media on the microhardness of human enamel blocks over four time periods.

The study received ethical approval. The surface microhardness of human enamel blocks was measured at baseline (T0). Subsequently, three blocks were assigned to each of six different disinfection-storage media combinations: acetic acid (5%) - chloramine (1%) [AA-CT], hypochlorite (5.25%) - chloramine (1%) [NaOCl-CT], chloramine (0.5%) - chloramine (1%) [CT-CT], acetic acid (5%) - thymol (0.02%) [AA-TH], hypochlorite (5.25%) - thymol (0.02%) [NaOCl-TH], and chloramine (0.5%) - thymol (0.02%) [CT-TH]. After two weeks (T1), one month (T2), three months (T3) or six months (T4) of storage at 4°C, microhardness was reassessed. Percentages of microhardness variation (mineral gain/loss) from baseline were calculated for each time. Data were analyzed using one-way ANOVA and two-way ANOVA to identify differences among disinfection-storage medium combinations and storage times, respectively.

A total 72 enamel blocks were analyzed. The microhardness variation percentages showed that the CT-TH combination (T1: 0.00%; T2: 4.05%; T3: 2.78%; T4: -4.74%; p>0.005) had the least variation, and that the microhardness values in the six groups at T3 were the most stable and did not differ significantly (p= 0.630).

Combinations of chloramine-thymol and chloramine-chloramine generated the fewest changes in microhardness in enamel blocks, and are suitable for preserving extracted teeth.