title: Reduced polymerization stress through non-bonded nanofiller particles.
abstract: The stress that results from the placement of dental composite in a confined setting compromises the integrity of the marginal seal. Dental composites which include nanofiller particles that are not treated with a functional agent to couple them to the resin matrix can result in lower stress levels. Three types of nanofillers were evaluated having either a functional silane coating, a non-functional silane coating. or no coating. These were added at five different vol% levels to a photo-sensitized mixture of three dimethacrylate monomers alone or at three different vol% levels to the same resin filled with mini-filler particles to a clinically realistic level. The stress generated by these materials when cured in a confined setting was measured in a mechanical testing machine. The effect of monomer molecular weight on the stress levels was evaluated by preparing three resin formulations with varied co-monomer levels and filling them with bonded or non-bonded nanofillers. Reductions in polymerization stress of up to 31% were achieved among both the nanofilled resins and the mini-filled composite. The materials which contained a heightened level of diluent monomer produced significantly higher stress levels (ANOVA/Tukey's test, p < 0.05). Significant reductions in polymerization stress can be achieved through minor alterations in composite chemistry.
authors.affiliation: Department of Biomaterials and Biomechanics, School of Dentistry, Oregon Health and Science University, Portland, USA. condonj@ohsu.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Condon
authors.forename: Jack L
authors.initials: JL
authors.lastname: Ferracane
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D003738:Dental Cements / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000379:methods*; D008027:Light; D008422:Materials Testing / Q000379:methods*; D012821:Silanes / Q000737:chemistry*; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D012821:Silanes