title: Volumetric contraction and methacrylate conversion in photo-polymerized amorphous calcium phosphate/methacrylate composites.
abstract: Because of its relatively high solubility in aqueous media and its rapid transformation to hydroxyapatite, amorphous calcium phosphate (ACP) has been utilized as the filler phase of resin-based bioactive composites that have remineralization potential. The objectives of this study were to determine how various methacrylate resins and various types of ACP fillers affect acrylic vinyl conversion and polymerization shrinkage (PS). Several types of photo-crosslinkable resin systems were prepared and admixed with a mass fraction of 40% of either unhybridized, silica- or zirconia-hybridized ACP. After visible light-activated photo-polymerization ACP composites were assessed by near infrared spectroscopy for degree of vinyl conversion and by mercury dilatometry for PS. It was found for these composites that vinyl conversion was independent of filler type but strongly dependent on the type and composition of the resin phase. PS, on the other hand, showed more complex dependence both on the resin type and composition and, in some cases, on the type of ACP. In order to obtain ACP/methacrylate-based composites with maximal vinyl conversion, resin type and composition are of primary importance. However, in order to minimize volume contraction on polymerization it appears necessary to consider both the resin and filler type of these bioactive composites.
authors.affiliation: American Dental Association Health Foundation-Paffenbarger Research Center, National Institute of Standards and Technology, 100 Bureau Drive Stop 8546, Gaithersburg, MD 20899-8546, USA. drago.skrtic@nist.gov
authors.forename: D
authors.initials: D
authors.lastname: Skrtic
authors.forename: J W
authors.initials: JW
authors.lastname: Stansbury
authors.forename: J M
authors.initials: JM
authors.lastname: Antonucci
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry* / Q000528:radiation effects*; D002130:Calcium Phosphates / Q000737:chemistry* / Q000528:radiation effects; D003188:Composite Resins / Q000138:chemical synthesis / Q000737:chemistry / Q000528:radiation effects; D003720:Densitometry; D004355:Drug Stability; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry* / Q000528:radiation effects; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry* / Q000528:radiation effects*; D012821:Silanes / Q000138:chemical synthesis / Q000737:chemistry / Q000528:radiation effects; D014753:Vinyl Compounds / Q000138:chemical synthesis / Q000737:chemistry / Q000528:radiation effects
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D003188:Composite Resins; D008689:Methacrylates; D011108:Polymers; D012821:Silanes; D014753:Vinyl Compounds; C485828:alpha-tricalcium phosphate; C519480:amorphous calcium phosphate; C485830:tetracalcium phosphate; C476909:vinylsilane; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous