Bioactive Glass-containing Pit and Fissure Sealant: Prevention of White-spot Lesions

Objectives: Dental sealants are an effective prophylactic treatment against pit and fissure caries in children. Microhardness serves as a measure of enamel softening during caries development. This study compared the microhardness of teeth adjacent to bioactive glass-containing sealants compared to traditional sealant materials.
Methods: Bioactive glass (BAG) was prepared in our labs with two compositions: 65mol% silica and 85 mol% silica. Each had 4mol% phosphate and the balance was calcia. Ultradent Corporation provided unfilled monomer resin which was mixed with BAG at 25% filler load. Ultraseal® XT Hydro served as a control. Eighteen unerupted, human third-molars were sterilized and prepared following a standard class I preparation guideline. Teeth were randomly assigned to one of three treatments: sealed with BAG65 sealant; sealed with BAG85 sealant; sealed with Ultraseal® XT Hydro.

Each tooth was placed in individual test tubes with 3% sucrose enriched BHI media containing 120µL of Streptococcus mutans (ATCC 25175) solution. Tubes were incubated (37°C, 5% CO²). Media was changed every other day. After 10 days, the teeth were embedded in epoxy, sectioned and polished through P4000 grit. Knoop micro-hardness testing was performed using a Wilson VH1202 (Buehler, Lake Bluff, IL). Indentations were created both beneath the sealant and directly adjacent to it. Mean adjusted hardness values were compared using ANOVA with post-hoc Tukey to look for significant differences (α=0.05)
Results: Adjacent to the sealant, and up to 300μm deep (into the enamel surface) the BAG sealants were significantly harder than the control sealant.
Conclusions: The bioactive glass-containing sealants allowed less softening of the enamel, both at the surface as well as up to 300μm deep. This effect could be due to the antimicrobial effect of bioactive glass, or the calcium ion release by the glass. Either way, this should make it a superior agent against the development of caries.