Biomimetic remineralization via sodium trimetaphosphate and polyacrylic acid: effect on the structural and mechanical stability of the resin-caries affected dentin bonds produced by an in vitro dentin caries induction protocol

• Grant number: 24/15119-8
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2025
• End date: February 29, 2028
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Josimeri Hebling Costa
• Grantee: Maria Luiza Barucci Araujo Pires
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Adhesive interfaces are frequently produced on modified dentin substrates, like caries-affected dentin (CAD). This substrate is less mineralized, more porous, contains more exposed collagen, has greater water content, and has increased proteolytic activity compared to sound dentin. Thus, producing a strong and stable adhesion between resin materials and this substrate is challenging. To simulate the CAD and conduct more realistic studies, it is important to use laboratory models to induce dentin caries capable of mimicking the abovementioned characteristics. This substrate would enable, for example, to investigate the biomimetic remineralization, a strategy that uses analogs of non-collagenous proteins to stabilize calcium phosphate particles in nanometric dimension. The nanoparticles would then be able to occupy the intrafibrillar spaces and promote the functional remineralization of the CAD and the stability of the hybrid layer. Therefore, the overall aim of the present project is to define an in vitro dentin caries induction protocol compatible with the formation of a CAD and to use this substrate to investigate the effect of the biomimetic remineralization mediated by sodium trimetaphosphate (STMP) and polyacrylic acid (PAA) on the structural and mechanical stability of resin-CAD bonds. The project is divided into four phases. In the first phase, different in vitro protocols to induce dentin caries will be compared by physical, chemical, and mechanical characterization of the substrates produced before and after the selective removal of carious tissue. In the second phase, marketed adhesive systems will be modified by incorporating STMP and PAA in the primers and sources of calcium and phosphate ions in the Bonds. The experimental materials will be evaluated for their physical-chemical properties. The third phase will evaluate different clinically feasible methods of using STMP and PAA in the adhesive protocol to CAD, and, finally, the fourth phase will investigate mechanical properties, and the stability of the bonds produced by the best method defined in the previous phase. The following analyses will be performed to answer the project's objectives: ATR-FTIR; nanohardness and elastic modules; MEV; Raman spectroscopy; bond strength (24 h and 18 mo); nanoleakage and in situ zymography. To evaluate the effect of modifications on the characteristics of the adhesive systems, it will be performed ATR-FTIR, water sorption and solubility, contact angle, ultimate tensile strength, and ion release. Data will be submitted to appropriate statistical tests after verifying the type of distribution and homoscedasticity/sphericity. Statistical inferences will be made at the 5% level of significance. (AU)