In vitro demineralization inhibition of enamel caries utilizing an unfilled resin

Smooth surface caries remain a concern in children, particularly those that are diagnosed with "baby bottle caries." The purpose of this study was to evaluate the caries inhibition of an unfilled resin placed on smooth enamel surfaces. Incisors were obtained and painted with an acid-protective varnish, excluding 2 mm x 6 mm windows on the labial surface. Each tooth had an unfilled resin placed over half the area of the window; the remaining area was not treated. One hundred microns longitudinal sections were obtained from the treated and non-treated sites. Polarized photomicrographs were taken of each section, in imbibition media of air, water and Thoulet's (R.I.: 1.41, 1.47), representing a minimum of 1%, 5%, 10%, and 25% pore volume respectively. The sections were then painted with an acid-protective varnish so that only the external surface was exposed and placed in separate closed environments of a non-fluoridated artificial saliva. One section from each tooth had unfilled resin on the external surface, one section had only natural enamel exposed, and a third section had the external surface varnished to act as a control. The teeth were thermocycled at 10 degrees C and 50 degrees C, 20 cycles per day for three months; they were also cycled through artificial caries challenge (pH 4.4) for 35 minutes, three times per day. Sections were then photographed under polarized light, as before, and areas of lesions were digitized. Results demonstrated caries to be present on all non-treated enamel surfaces exposed to the artificial caries challenge. Significantly less enamel demineralization occurred when an unfilled resin was placed on it (p < 0.001).