Effect of storage media on subsequent water loss and regain by human and bovine dentine and on mechanical properties of human dentine in vitro.

This study was designed to determine whether storage media and time affect any changes in water loss with dehydration of dentine. The effect of storage of prepared bars was also compared with storage of whole teeth. Prepared bovine dentine bars were stored for 3 days or 12 weeks in deionized water, phosphate-buffered saline or neutral-buffered formalin and whole teeth were stored in neutral-buffered formalin for 12 weeks before the preparation of dentine bars. Specimens were removed from storage and weight loss with dehydration, determined gravimetrically, was equated directly to water loss. Tensile and three-point bend tests were made on human dentine bars that had been stored in deionized water or neutral-buffered formalin for 3 days. Results were subjected to analysis of variance and Duncan's new multiple-range test. Weight loss by evaporation from dentine at 22.3 degrees C and 53.2% relative humidity was rapid and non-linear, reaching 5.05 +/- 0.55% for bovine dentine compared with 3.33 +/- 0.63% for human dentine after 7 days. Water loss with dehydration was not affected by 3-day storage of specimens in different media or by 12-week storage of whole teeth, but was affected when prepared specimens were stored for 12 weeks. Different storage media had no significant effect (p > 0.05) on the strength or toughness of human dentine. Water loss in human dentine was associated with shrinkage of specimens, but these dimensional changes were fully recovered with rehydration. Storage of teeth in neutral-buffered formalin followed by minimal storage time for prepared specimens is recommended to minimize changes in dentine after extraction.