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 adhesive to early carious enamel lesion
Methods: an artificial caries model was used to induce early non cavitated enamel caries-like lesion in maxillay centrals. Nano hydroxyapatite particles (nHA) were applied in two forms to a self-etch resin adhesive: particles were directly added to resin adhesive or silanated before addition. Unmodified adhesive was used as control. Micro-tensile bond strength (MTBS) was performed to evaluate bond strength to demineralized enamel after application remineralizing resin adhesive (n=20, α=0.05). Scanning electron microscopy (SEM) was performed to assess mode of failure and to study adhesive enamel interface.
Results: Direct addition of nano-particles resulted in significant reduction (F=32, P<0.001) in MTBS (12 MPa±3.8) compared to addition of silanated particles (24 MPa ± 3.2) which presented comparable values to the control group (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. Direct addition of nHA resulted in partial remineralization of enamel (42% recovery in calcium content.
Conclusions: Self-etch resin adhesive could be used as a carrier for nano hydroxyapatite particles without compromising bond strength to early caries-like enamel lesions.