Evaluation of rat periodontal ligament cell viability after hypothermic preservation under high hydrostatic pressure

Abstract

The purpose of this study was to find the ideal hypothermic condition for tooth storage by evaluating the rat periodontal ligament cell viability after two-day storage under different pressures and temperatures using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and caspase-3 fluorometric assay. The first and second maxillary molars of 4-week-old Sprague-Dawley female rats were extracted and stored under different hydrostatic pressure (no additional pressure, 2MPa, 5MPa, 20MPa, and 30MPa) and temperature (-2°C, -1°C, 0°C, and 4°C) for 2 days. Teeth immediately after extraction were used as control. After 2 days, MTT assay and caspase-3 fluorometric assay were performed to evaluate the periodontal ligament cell viability and apoptosis rate. For statistical analysis, one-way analysis of variance was used, and Tukey analysis was used for post-hoc comparison. According to MTT assay results, at all temperatures the 2MPa group had greater rat periodontal ligament cell viability than at other pressures, and at -2°C, -1°C, and 0°C, the cell viability was significantly higher at 2MPa than at no additional pressure or higher hydrostatic pressure (p<0.05). According to caspase-3 assay results, the rate of apoptosis was significantly higher in the 20MPa and 30MPa groups (p<0.05), but other groups were not significantly different from the immediate control group (p>0.05). Combining both assays, the 2MPa groups showed the highest cell viability and the lowest caspase-3 activity compared to no additional pressure or higher hydrostatic pressure groups. Within the 2MPa group, 0°C, -1°C and 4°C groups showed no statistical differences from the immediate control group.