Effects of Desensitizer Containing Copolymer and Fluoride on Dentin Demineralization

Objectives: To evaluate the effects of dentin desensitizer containing sodium fluoride and methacrylate-co-p-styrene sulfonic acid (MS polymer) on root dentin demineralization using transverse microradiography (TMR).
Methods: Specimens (n=24) from bovine root dentin were equally divided into four groups; MS Coat One (MSO: MS polymer without fluoride), MS Coat F (MSF: MS polymer with 3000ppm F) (Sun Medical, Japan), Fluor Jelly (FJL: 9000ppm F paste) (Bee-Brand Medico Dental, Japan) and Control (n=6). For the MSO and MSF groups, each desensitizer was rubbed into the dentin surfaces (10s) and left in place (20s). For the FJL group, the paste was applied onto the dentin surface (30s). After each treatment, all specimens were rinsed with deionized water and exposed to acidic solution (1.5mM CaCl2, 0.9mM KH2PO4, 50mM acetic acid, 0.2ppm F, pH5.0), refreshed every 24 hours (37°C, 4d). Then 300 µm-thick sections were cut perpendicularly to the experimental surface from each specimen, and mineral profile and integrated mineral loss (IML) were determined from radiographic images obtained by TMR.
Results: TMR images revealed MSF and FJL groups had narrower demineralization zones than did MSO and Control groups. Also, MSF and FJL groups showed distinct radio-opaque surface layers. In mean mineral profiles, MSF and FJL groups showed high mineral volume % at the surface and lesion bodies compared to MSO and Control groups. The IML (vol%×µm) was 5698±585 for Control, 5457±681 for MSO, 2854±326 for MSF, and 3326±461 for FJL, with values for MSF and FJL significantly lower than those of the other two groups (ANOVA, Tukey’s, p<0.05).
Conclusions: Dentin desensitizer containing 3000ppm F and MS polymer has the same anti-demineralization effect as 9000ppm F paste because calcium fluoride and the MS polymer complex act as not only a mechanical protective film but a fluoride ion releasing reservoir.