Inhibition of enamel mineral loss by fissure sealant: An in situ study

Abstract

ObjectivesThis study evaluated the effect of fluoride and non-fluoride sealants on hardness decrease (HD) and marginal adaptation (MA) on enamel substrates after cariogenic challenge. MethodsOcclusal enamel blocks, from human third molars, were randomly divided into six groups (n=12), according to occlusal fissures condition (S – sound; C – caries-like lesion; CF – caries-like lesion+topical fluoride) and sealants (F – FluroShield; H – Helioseal Clear Chroma). Lesion depths were 79.3±33.9 and 61.3±23.9 for C and CF groups, respectively. Sealants were placed on occlusal surface and stored at 100% humidity (37°C; 24h/d). HD was measured by cross-sectional microhardness analysis at the sealant margin distances: −1 (under sealant), 0 (sealant margin), 1, 2 (outer sealant). Sealant MA was observed by polarized light microscopy and scored according to: 0 – failure (no sealant MA or total sealant loss); 1 – success (sealant MA present). MA and HD were analysed by ANOVA-R and mixed model analysis, respectively. ResultsFor HD (ΔS), F values (6900.5±3686.6) were significantly lower than H values (8534.6±5375.3) regardless of enamel substrates and sealant margin distances. Significant differences were observed among sealant margin distances: −1 (5934.0±3282.6)<0 (8701.5±6175.7)=1 (8473.2±4299.4)=2 (7761.5±4035.1), regardless of sealant and substrate. MA was similar for all groups (p≥0.05). ConclusionMA was not affected by sealant type or substrate condition, whereas enamel HD was favourably impacted by fluoride in the sealant. In addition, sealants were more effective as a physical barrier than as its chemical potency in reducing enamel HD. Clinical significanceSealing with a fluoride material is a recommended procedure to prevent caries of occlusal permanent molars in high-caries-risk patients, even though those exhibiting white spot lesions, since the enamel hardness decrease when fluoride sealant was used in vitro.