Dentin Remineralization under Biofilm via Calcium Phosphate Adhesive

Objectives: Bonded interface, as the weak link in dental restoration, limits the longevity of composite. The remineralization of dentin at bonded interface would help to strengthen the bonded interface and inhibit secondary caries, thus, would prolong the longevity of restoration. The aim of this study was to investigate the remineralization of demineralized human dentin in a dental biofilm environment via an adhesive containing nanoparticles of amorphous calcium phosphate (NACP).
Methods: Dentin demineralization was promoted by subjecting samples to a Streptococcus mutans acidic biofilm for 24 hours (h). Samples were then divided into control group, commercial fluoride-releasing adhesive group, and NACP adhesive group. All samples were next subjected to a remineralization protocol consisting of 4-h exposure per 24-h period in brain heart infusion broth plus 1% sucrose (BHIS) followed by immersion in artificial saliva for the remaining period. The 4-h duration in BHIS displayed a degree of correlation with oral conditions in respect to the accumulated food cycling in a 24-h period orally. The pH of BHIS after 4-h immersion was measured every other day. After 10 days, the biofilms were determined of colony-forming unit (CFU) count, lactic acid production, and Ca, P content. The mineral changes in the demineralized dentin samples were analyzed by transverse microradiography.
Results: The NACP adhesive achieved acid neutralization, decreased biofilm CFU count, decreased biofilm lactic acid production and increased biofilm Ca, P content. The NACP adhesive group had higher remineralization value than the commercial fluoride-releasing adhesive group.
Conclusions: The NACP adhesive was effective in remineralizing dentin lesion in a biofilm model. It is promising to protect bond interface, inhibit secondary caries, and prolong the longevity of restoration.