Partially saturated buffer systems with varying amount of fluoride have been used to create root surface lesions of various depths and mineral distribution. At ppm levels of fluoride at a pH of 5, the lesions are shallow and contain a mineralized surface. When little or no fluoride is present, a wide surface zone nearly devoid of mineral is formed and surface shrinkage occurs upon drying. The purpose of this study was to evaluate the remineralization of these two types of lesions which possess different mineral distributions.
The root surface lesions were created using a partially saturated lactic acid buffer at pH 5.0. Fluoride at concentrations of 0.02 – 2.0 ppm was added to the buffer system. 100 m thin sections were cut through the exposed lesion window and analyzed using polarized light microscopy (PLM) and microradiography (MRG). The sections were then coated with an acid resistant varnish except for the outer natural surface that had been exposed to the demineralizing solution. These sections were then exposed to a remineralizing solution containing (1.5 mM Ca. 0.9 mM P. .15 M Cl. 5 ppm F at pH 7.0). The sections were characterized by MRG at 0, 3, 7, 14, and 21 days.
The shallowest lesions were created in the presence of 2 ppm F and had a depth of about 80 (mu)m and a D Z of 980 Vol % m . The lesions showed changes in D Z of 3600 Vol % m . The changes in D Z were approximately 30%, 52%, 63%, and 70% after 3, 7, 14, and 21 days of remineralization. The in between fluoride group lesions showed similar amounts of remineralization. The site of remineralization was on the existing mineral with a build-up back to the surface. A limited amount of hypermineralization was noted at the longer exposure times as well as a radiolucent body even after 3 weeks of remineralization.
This work shows that the site of remineralization is initially on the remaining mineral and then back toward the surface.
Nicolas Rippel, ’99
Sponsor: Truman Jordan