RESUMO
Innovative dental restorative materials should be highly bioactive to induce therapeutic effects at the bonding interface during intimate contact with biological fluids. This study aimed at evaluating the remineralisation properties of innovative light-curable resin-based dental materials containing bioactive calcium-phosphosilicates micro-fillers. The apatite formation ability was assessed by ATR-FTIR, XRD, calcium-chelation dye-assisted confocal microscopy (CLSM) and SEM analysis after soaking in SBF. Changes in transition glass temperature (Tg), water sorption/solubility, alkalinising activity (pH) Knoop micro-hardness (KHN), were also evaluated. Four experimental resin-based materials containing various silicate-base micro-fillers and a control filler-free resin blend were formulated. Disc-shaped specimens were polymerised and submitted to pH/alkalinising activity and water sorption/solubility analyses. The bioactivity and the apatite precipitation induced by the tested materials were evaluated through ATR/FTIR vibrational analysis, SEM and XRD analyses subsequent to SBF storage. Knoop micro-hardness (KHN) and differential scanning calorimetry (DSC) were also performed. The experimental resins containing the bioactive micro-fillers were able to induce apatite precipitation subsequent to prolonged SBF storage (30-90 days). However, the resins containing the bioactive ZnO/polycarboxylated micro-fillers (BAG-Zn; ßTCS-Zn) showed the lowest water sorption and solubility mass changes (P < 0.05). A significant increase of the KHN and Tg subsequent prolonged SBF storage was also observed. The use of such light-curable bioactive materials in restorative dentistry might represent a potentially therapeutic approach to increase the longevity of the restorations via apatite deposition the mineral-depleted tissues at the bonding.
RESUMO
OBJECTIVES: The purpose of this study was to evaluate how curing protocol affects the extent of polymerization of dual-cured resin cements. METHODS: Four commercial resin cements were used (DuoLink, Panavia F 2.0, Variolink II and Enforce). The extent of polymerization of the resin cements cured under different conditions was measured using a (1)H Stray-Field MRI method, which also enabled to probe molecular mobility in the kHz frequency range. RESULTS: Resin cements show well distinct behaviours concerning chemical cure. Immediate photo-activation appears to be the best choice for higher filler loaded resin cements (Panavia F 2.0 and Variolink). A photo-activation delay (5 min) did not induce any significant difference in the extent of polymerization of all cements. SIGNIFICANCE: The extent of polymerization of dual-cured resin cements considerably changed among products under various curing protocols. Clinicians should optimize the materials choice taking into account the curing characteristics of the cements.
