title: Benefits and limitations of adding hyperbranched polymers to dental resins.
abstract: Volumetric shrinkage reduction is a constant challenge in the improvement of dental resins. The inclusion of hyperbranched polymers (HBPs) with modified functionalities (hydroxyl, propionate, and methacrylate) instead of conventional dimethacrylate monomers has the potential to reduce shrinkage, but can also affect other properties. The null hypothesis was that the addition of HBPs (from 5 to 40 mass%) to a 50/50 mass% Bis-GMA/TEGDMA mixture reduces shrinkage without affecting degree of conversion, elastic modulus, glass transition temperature, Wallace hardness (before/after ethanol storage), and viscosity. This hypothesis was rejected, since HBP incorporation significantly affected most properties either negatively or positively. When HBP amounts in the resin were increased, the following general trends were observed: Volumetric shrinkage decreased significantly (p < 0.0001), down to about one-third of the control value at 40% HBP; Wallace hardness (both before and after ethanol) and viscosity increased progressively, while elastic modulus showed a parabolic profile, with a maximum at 10% HBP; and finally, degree of conversion and glass transition temperature were relatively stable, regardless of the HBP content. These results indicate that HBPs with modified end groups might be interesting substitutes for Bis-GMA/TEGDMA.
authors.affiliation: Institute of Condensed Matter and Nanosciences - Bio- and Soft-Matter, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Dewaele
authors.forename: J G
authors.initials: JG
authors.lastname: Leprince
authors.forename: I
authors.initials: I
authors.lastname: Fallais
authors.forename: J
authors.initials: J
authors.lastname: Devaux
authors.forename: G
authors.initials: G
authors.lastname: Leloup
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry; D006244:Hardness; D008689:Methacrylates / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry; D014783:Viscosity
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D011108:Polymers; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate