title: Post-gel polymerization contraction of "low shrinkage" composite restoratives.
abstract: This study compared the post-gel contraction of two "low-shrinkage" composites (InTen-S [IS], Ivoclar-Vivadent; Aelite LS [AL], BISCO Inc) and an ormocer (Admira [AM], Voco) to two conventional mini-filled composites (Renew [RN], BISCO; Z100 [ZO], 3M ESPE). A strain-monitoring device and test configuration were used to measure the linear polymerization shrinkage associated with the various composites (A2 shade) during and up to 60 minutes post light polymerization. Each specimen was irradiated for 40 seconds using a halogen curing light (Max, Dentsply-Caulk) with an intensity of 401 mW/cm2. Five specimens were made for each composite. Data was analyzed using one-way ANOVA/Scheffe's post-hoc test at significance level 0.05. The linear percentage shrinkage immediately after light polymerization and at 60 minutes post light polymerization ranged from 0.10 +/- 0.02 to 0.40 +/- 0.02% and 0.22 +/- 0.02 to 0.60 +/- 0.05%, respectively. Post-gel shrinkage ranking of the materials was as follows: immediately after light polymerization - IS < AL < AM < ZO < RN and at 60 minutes post light polymerization - IS < AL = AM < ZO < RN. The shrinkage associated with IS, AL and AM was significantly lower than for ZO and RN immediately after light polymerization and at 1, 10, 30 and 60 minutes post light polymerization. The post-gel polymerization shrinkage of IS, AL and AM was significantly lower than conventional mini-filled composites.
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore. rsdyapuj@nus.edu.sg
authors.forename: A U J
authors.initials: AU
authors.lastname: Yap
authors.forename: M S
authors.initials: MS
authors.lastname: Soh
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D018772:Dental Marginal Adaptation; D003799:Dental Stress Analysis; D005782:Gels; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry / Q000528:radiation effects; D015394:Molecular Structure; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry / Q000528:radiation effects; D012833:Siloxanes / Q000737:chemistry / Q000528:radiation effects; D013997:Time Factors; D015040:Zirconium / Q000737:chemistry / Q000528:radiation effects
chemical_list: C485363:Aelite LS; D003188:Composite Resins; D005782:Gels; C485362:InTen-S composite; D008689:Methacrylates; D011108:Polymers; C485364:Renew composite; D012833:Siloxanes; C083568:Z100 composite resin; C479084:admira; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium