Abstract
Introduction: New regulations in Europe require polymeric micronsized fillers to be biodegradable. The purpose of this research was to explore fabricated polymeric ion releasing fillers (PIRFs) that were made from alginate polymers and examined the effect of incorporating 3 different concentrations of (PIRFs) (2.5 w/w% , 5w/w% , and 10 w/w%) and compared how the inclusion of these 4 different PIRF loadings effected the depth of cure, flexural strength, and viscosity of a sealant. Methods: For all formulations the continuous phase was 65w/w% bisGMA and 35w/w% TEGMA. Camphorquinone and ethyl dimethylaminobenzoate were used as a photoinitiator at 1w/w% of the formulation. OX50 was used as the fumed silica at 3w/w% of the formulations. Schott Ultrafine 1.5w/w% glass was used as the glass filler. The size of the PIRFs was determined from the SEM image. The cross section of the composite containing the PIRFs was imaged after it was sputter coated with gold. The viscosity of each mixture was measured for 90 seconds using a rheometer at 1, 10, and 25 RPM. The depth of cure and flexural strength were measured following the procedures outlined in ISO4049 for dental materials. Results: At a shear rate of 1 rpm, the colloids containing PIRFs shear thickened as a function of time, exhibiting rheopectic behavior. At the shear rates of 10 or 25rpm, the colloids shear thinned as a function of time, exhibiting thixotropic behavior. Since the viscosity reduced as the shear rate increased, all of the materials were pseudoplastic. The 2.5 w/w% had the highest depth of cure measurement amongst the PIRFs filled colloids at all intervals of cure time for 5, 10, and 20 seconds. However, we observed a lower depth of cure as the PIRFs concentration increased. Nevertheless, even at the highest PIRFs concentration studied at 10% and lowest cure time at 5 seconds the depth of cure was still above 2 mm which is acceptable for a dental sealant. When PIRFs are added to composites without glass to reinforce the material, the flexural strength of the material is considerably reduced. However, the addition of PIRFs produced a composite with adequate flexural strength up to 10 w/w% with 20 w/w% glass and up to 5 w/w% with 50 w/w% glass in the presence of glass loading 20–50%, which replicates sealants and fillings. Conclusion: PIRFs have the potential to be added as a biodegradable filler for an effective sealant.