THE INFLUENCE OF AIR-DRYING ON HYPER-REMINERALIZATION OF DEMINERALIZED DENTIN - A STUDY ON BULK AS WELL AS ON THIN WET SECTION OF BOVINE DENTIN

The influence of air-drying on the remineralization of demineralized bovine dentine was examined in wet bulk samples, in dried bulk samples as well as in wet thin sections. Bulk samples of bovine dentine were first demineralized in an acidic gel (pH = 5) at 37 degrees C for 3 weeks. After 24-hour pre-treatment of either air-drying or immersion in water, the bulk samples were remineralized in a solution containing 1.5 mM Ca, 0.9 mM phosphate and 10 ppm F- (pH = 7) at 37 degrees C for 2, 4 or 8 days. Separately thin sections prepared from demineralized bulk dentine were immersed in water for 24 h and were also exposed to the remineralization solution for 2, 4 or 8 days. The results show that air-drying of the bulk samples increased remineralization of dentine considerably; the microradiographic parameters (1(d), Delta Z and 1(a)) show that the degree of remineralization ranks: thin wet sections > bulk dried > bulk wet. Especially, the remineralization inside lesions was greatly enhanced in thin sections and dried samples. It is presumed that the increased remineralization in dried samples is caused by a 'sponge effect', in which the remineralization fluid is sucked up in a dried shrunken lesion, resulting in fast and deep penetration of remineralization solution and/or presumably increased nucleation.