Physical properties of root cementum: part 2. Effect of different storage methods.

This study examined the effect of 5 disinfection and storage protocols over different time periods on the hardness and elastic modulus of human premolar cementum. The sample consisted of 20 first premolars, which were divided into 5 groups of 4 teeth and stored in 1 of the following ways: (1) Miltons solution (1% sodium hypochlorite) for 10 minutes, (2) Miltons solution for 24 hours, (3) 70% alcohol, (4) desiccation, or (5) Milli Q (deionized water, Millipore, Bedford, Mass). Teeth in groups 1 and 2 were initially stored in Milli Q, tested within 6 hours, placed in their respective media, and retested. Groups 3, 4, and 5 were tested within 6 hours, then at 1 month, 2 months, and 3 months after extraction. Group 5 was further studied at 9 months, and 2 teeth in Group 4 were tested at 4 months. The hardness and elastic modulus of cementum was tested with the Ultra-Micro Indentation System (UMIS-2000, Commonwealth Scientific Industrial Research Organization, Australia) on unprepared specimens mounted on a 3-dimensional jig assembly. The results showed that storage in Miltons solution for 10 minutes had no significant effect on the hardness or elastic modulus, whereas storage for 24 hours caused a significant decrease in the hardness of cementum (P =.03). Storage in 70% alcohol for up to 4 months and in Milli Q for up to 9 months had no significant effects. Desiccation caused a significant increase in both the hardness and the elastic modulus from baseline to 3 months (P =.02 and P =.04, respectively), with most changes occurring within the first month. It was concluded that Miltons solution for 10 minutes could be considered an appropriate method for disinfection and removal of periodontal ligament fragments; however, its use for 24 hours should be avoided. Seventy percent alcohol and Milli Q are better storage methods, and desiccation should be avoided.