title: Light curable dental composites designed with colloidal crystal reinforcement.
abstract: OBJECTIVE
  Methods to prepare dental composites with a periodic filler arrangement were developed following a strategy of colloidal crystallization. The aims of this study were to determine the influence of suspension medium, silane treatment and amine additive on colloidal particle redispersion and subsequent ordering, and to evaluate the effect of filler ordering on mechanical properties of composites.
  
  
  METHODS
  Dry monodisperse silica particles (spherical, approximately 500-nm diameter) were redispersed in selected solvents and monomers (e.g. triethyleneglycol dimethacrylate, TEGDMA) to form sediments or dispersions with ordered particle arrangements. Ordering was evaluated by microscopy and mechanical properties of the composites were measured using compression tests (n=6).
  
  
  RESULTS
  A face-centered cubic packed structure could form in both the sediment from silica dispersions in polar solvents and stable dispersions in TEGDMA. Dimethylaminoethyl methacrylate (DMAEMA) was found to disrupt an ordered structure when non-silanized silica particles were used. Silanization with 3-methacryloxypropyl trimethoxysilane (MPS) promoted filler ordering. Standard compression tests on composites containing 60wt% silica in TEGDMA with or without DMAEMA indicated that DMAEMA had a clearly significant effect (p<0.05) on failure strain, compressive strength, and toughness, and a marginally significant effect on modulus (p=0.12).
  
  
  CONCLUSIONS
  Significant increases in compressive strength (16%), failure strain (71%), and toughness (135%) were observed for composites with ordered filler compared to non-ordered composites.
authors.affiliation: Center for Bioengineering and Biomaterials, College of Engineering, Temple University, 1947 North 12th Street, Philadelphia, PA 19122, United States.
authors.forename: Quan
authors.initials: Q
authors.lastname: Wan
authors.forename: Joel
authors.initials: J
authors.lastname: Sheffield
authors.forename: John
authors.initials: J
authors.lastname: McCool
authors.forename: George
authors.initials: G
authors.lastname: Baran
mesh_terms: D003102:Colloids; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D003460:Crystallization; D003799:Dental Stress Analysis; D004548:Elasticity; D006244:Hardness; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008689:Methacrylates; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D012821:Silanes; D012822:Silicon Dioxide; D013329:Structure-Activity Relationship
chemical_list: D003102:Colloids; D003188:Composite Resins; D008689:Methacrylates; D011109:Polymethacrylic Acids; D012821:Silanes; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D012822:Silicon Dioxide; C049840:2-(dimethylamino)ethyl methacrylate