Dentin remineralization using a composite containing calcium orthophosphate particles associated to a mineral precursor in liquid phase (polymer-induced liquid-precursor, PILP): randomized clinical trial

Abstract

This aim of this project is to develop a resinous composite containing particles of DCPD (dihydrate dicalcium phosphate, CaHPO4.2H2O) for minimally invasive restorations and also to evaluate in vitro and in vivo effectiveness of functional human dentin remineralization (biomimetic) associated or not to the PILP process. DCPD particles will be synthesized by co-precipitation, characterized and used in the formulation of resinous composites associating DCPD and barium glass particles in different proportions. The degree of conversion, fracture toughness and ion release over 14 days of the composites will be evaluated. The material with the most favorable relationship between the KIc and the ion release will be adopted to remineralization studies. For the in vitro phase, dentin blocks (previously immersed in acetate buffer pH 5.0 for 66 hours) will be covered by a layer of the composite, associated or not to a pre-treatment of the surface on a solution containing mineral precursors in liquid phase (PILP solution). After 14 days of immersion in simulated body fluid, the dentin remineralization at the interface of the restorative material will be evaluated through mid-infrared spectroscopy by attenuated total reflectance (ATR-FTIR). The recovery of mechanical properties (elasticity and hardness modulus) along the thickness of the dentin layer will be evaluated by nanoindentation. Additionally, the cross-section of dentin subjected to different treatments will be observed in transmission electron microscopy. For the randomized clinical study, children in the mixed dentition phase with indication of restorative treatment in primary molars due to the presence of caries lesions on the occlusal surface will be selected (ICDAS 5 or 6). After the selective removal of the decayed tissue, the cavities will be restored according to one of the four treatments described in the in vitro phase and the exfoliation of the tooth will be awaited. The teeth will be analyzed according to the same methodologies described for the in vitro phase. The statistical treatment of the data will be defined based on preliminary analyzes of normality and homoscedasticity.