Evaluation of remineralization potential and mechanical properties of pit and fissure sealants fortified with nano-hydroxyapatite and nano-amorphous calcium phosphate fillers: An in vitro study.

Objectives: The aim of this study was: (i) to formulate pit and fissure sealants (PFS) containing nano-hydroxyapatite (nHAP) filler; nHAP filler and silica co-filler; nHAP and nano-Amorphous Calcium Phosphate (nACP) co-filler, (ii) to evaluate physical properties; degree of conversion (DOC), curing depth (CD) and mechanical properties; microshear bond strength (MBS) of fortified PFS, and (iii) to assess remineralization potential and release of Ca2= and PO4 ions from newly synthesized sealants.

Materials and Methods: Four PFS were prepared using monomers with mixture of 35.5 wt % BisGMA, 35.5 wt % triethylene glycol dimethacrylate and 28 wt % hydroxyethyl methacrylate. Bioactive nanofillers (nHAP and n-ACP) were added in various concentrations (0%-30%). Three commercial sealants were used as follows: unfilled (Clinpro; 3M ESPE), Fluoride releasing (Delton FS plus, Dentsply), ACP filled (Aegis, Bosworth). The samples ( n = 35.5/gp) were tested for MBS, DOC, and CD. Remineralization potential was assessed by scanning electron microscopy (SEM). The concentrations of Ca2= and PO4 released from the sealant specimens were analyzed with Ultraviolet-visible Spectrophotometer. Data obtained was statistically analyzed (one-way analysis of variance, Tukey's test, P < 0.05).

Results: 10% hydroxyapatite (HAP) =20% ACP sealant showed significantly higher DOC. A remineralized region on the surface between fissure sealant and tooth enamel was observed by SEM in all three HAP filled bioactive sealants. Decreasing the solution pH significantly increased ion release from sealant filled with 10% nHAP = 20% nACP ( P ≤ 0.001).

Conclusion: Results suggested that admixture of nHAP and nACP to PFS showed remineralizing capability, without declining their mechanical and physical properties.