The efficacy of programmed cryo-preservation under pressure in rat periodontal ligament cells

Abstract

The purpose of this study was to evaluate the viability of peri odontal ligament cells in rat teeth usingslow cryo-preservation method under pressure by means of MTT assay and WST-1 assay. Eighteen teeth ofSprague-Dawley white female rats of 4 week-old were used for each group. Both sides of the first and second maxillary molars were extracted as atraumatically as possible underTiletamine anesthesia. The experimental groups were group 1 (Immediate control), group 2 (Cold preserva-tion at 4℃for 1 week), group 3 (Slow freezing), group 4 (Slow f reezing under pressure of 3 MPa). F-medi-um and 10% DMSO were used as preservation medium and cryo-protectant. For cryo-preservation groups,thawing was performed in 37℃water bath, then MTT assay and WST- 1 assay were processed. One wayANOVA and Tukey method were performed at the 95% level of confi dence. The values of optical densityobtained by MTT assay and WST-1 were divided by the values of e osin staining for tissue volume stan-dardization. In both MTT and WST-1 assay, group 4 showed significantly higher viability of periodontal ligament cellsthan group 2 and 3 (p < 0.05), but showed lower viability than immediate control group. By the results of this study, slow cryo-preservation method under pressure suggests the possibility forlong term cryo-preservation of the teeth.