Survival of Mouse Tooth Germs After Freezing in Liquid Nitrogen as Demonstrated by Differentiation of Isologous Transplants

Cryopreservation of mature teeth before replantation in monkeys (I). Effect of different cryoprotective agents and freezing devices

Cryopreservation is clinically relevant in storage of teeth for transplantation or replantation. The effect of cryopreservation was studied by histometric analysis of 60 teeth replanted in 10 green Vervet monkeys. The following cryopreserving agents were examined: 5% and 10% dimethylsulfoxide (DMSO) and 10% glycerol. Furthermore, 2 types of freezing method were compared: automatic biological freezing (Cryoson) and a simplified freezing device of Sperling. Cryopreserved teeth were stored for 1 week at - 196 degrees before replantation. The histometric analysis carried out 8 weeks after replantation showed that 5% DMSO had the best effects in protecting the periodontal ligament (PDL) during cryopreservation. This medium induced no replacement resorption and secured a considerable extent of normal periodontal ligament compared to the control teeth replanted immediately without cryopreservation. 10% DMSO and 10% glycerol also preserved the PDL but with a lower degree of survival and a higher degree of ankylosis. 10% DMSO exposed at 0 degree C followed by immediate replantation did not induce any pathological effect on the PDL. All cryopreserved teeth showed some degree of inflammatory resorption. However, this could be due to the expected necrosis of the pulp tissues of the frozen teeth because of the lack of diffusion of cryoprotectant agent into the pulp of mature teeth.

The prevention of contamination of teeth stored for transplantation

Tissue culture media and their application to the storage of teeth are described. The problems of contamination in culture and a method of achieving a sterility level of 73 percent are discussed. Contamination was reduced at each stage, using unerupted teeth, chlorhexidine disinfection, saline irrigation, ultrasonics, a laminar-flow cabinet, and four antibiotics in culture. A method of microbiologic screening is outlined.