title: Volumetric dimensional change of six direct core materials.
abstract: OBJECTIVE
  This study evaluated the influence of water on the volumetric dimensional change of six direct placement core build-up materials by using Archimedes' principle.
  
  
  METHODS
  The effect on dimensional change due to the setting reaction was determined through the use of a silicone oil storage medium. The materials used were two dual-cured resin composites (CoreStore and Build-It FR), two chemically activated resin composites (CorePaste and Ti-Core), one metal-reinforced glass ionomer cement (Ketac-Silver), and one resin-modified glass ionomer (Fuji II LC Core). Using the manufacturers' instructions for each material, cylindrical specimens were prepared with dimensions of 7+/-0.1 mm in diameter and 2+/-0.1 mm in height. Each material had four groups (n = 5) based on storage conditions; silicone oil at 23 and 37 degrees C and distilled water at 23 and 37 degrees C. A 0.01 mg resolution balance was used to determine volumetric dimensional change using an Archimedean equation. Measurements were made 30 min after mixing, and at the time intervals of 1, 14, and 56 days.
  
  
  RESULTS
  All materials exhibited dimensional change. Ketac-Silver had the most shrinkage in silicone oil and Fuji II LC showed the highest expansion in distilled water. The glass ionomer materials showed more change than did any of the resin composite materials.
  
  
  CONCLUSIONS
  Current direct placement core materials show variation in the amount of volumetric dimensional change seen over a period of 56 days.
authors.affiliation: Department of Restorative Dentistry, Division of Dental Materials, Indiana University School of Dentistry, 1121 West Michigan Street, Indianapolis, IN 46202, USA.
authors.forename: Supattriya
authors.initials: S
authors.lastname: Chutinan
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Platt
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cochran
authors.forename: B Keith
authors.initials: BK
authors.lastname: Moore
mesh_terms: D000042:Absorption; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D003442:Crowns; D003890:Desiccation; D004129:Dimethylpolysiloxanes; D005899:Glass Ionomer Cements / Q000737:chemistry*; D012828:Silicones; D018709:Statistics, Nonparametric; D014867:Water
chemical_list: D003188:Composite Resins; D004129:Dimethylpolysiloxanes; D005899:Glass Ionomer Cements; D012828:Silicones; D014867:Water; C013830:baysilon