Objectives: Resin adhesive could be used as a carrier of nano-hyrdoxy apatite particles added to treat early enamel caries. The aim of this study was to evaluate microtensile bond strength of a remineralizing enamel infiltrant to early carious enamel lesion.
Methods: An artificial caries model was used to induce early partially-cavitated enamel caries-like lesion in maxillay centrals. Nano hydroxyapatite particles (nHA) were applied in two forms to a low shrinkage low viscosity resin adhesive: particles were directly added to resin adhesive or silanated before addition. Unmodified ad-hesive was used as control. Micro-tensile bond strength (MTBS) was performed to evaluate bond strength to demineralized enamel after application of the remineralizing resin adhesive (n=20, α=0.05). Scanning electron microscopy (SEM) was performed to assess mode of failure and to study infiltrant-enamel interface.
Results: Direct addition of nano-particles resulted in significant reduction (F=32, P<0.001) in MTBS (19 MPa ± 3.8) compared to addition of silanated particles (24 MPa ± 3.2) which presented comparable values to the unmodified enamel infiltrant (26 MPa ± 4.1). SEM image analysis revealed adhesive failure observed for directly added particles while the other two groups demonstrated cohesive failure observed in the resin adhesive. On the other hand, direct addition of nHA resulted in partial remineralization of enamel (42% recovery in calcium content).
Conclusions: TTEMA/TEGDMA enamel infiltrant could be used as a carrier for nano hydroxyapatite particles without compromising bond strength to early carious enamel lesions.