title: Effect of polyvinyl siloxane impression material on the polymerization of composite resin.
abstract: BACKGROUND
  Polyvinyl siloxane impression material has been widely used as a lingual matrix for rebuilding missing tooth structure with composite resin. The composite resin is light polymerized in contact with the polyvinyl siloxane impression material. However, polyvinyl siloxane impression material has been shown to interact with other dental materials.
  
  
  OBJECTIVE
  The purpose of this study was to assess the effect of polyvinyl siloxane impression materials on the polymerization of composite resins by assessing the Vickers microhardness and degree of conversion of polyvinyl siloxane.
  
  
  METHODS
  The composite resins were light polymerized in contact with 3 polyvinyl siloxane impression materials (Flexitime Easy Putty; President Light Body; Xantopren L Blue) (n=8) and in contact with a matrix strip as the control group (n=8). Vickers microhardness and degree of conversion on contact surfaces were measured to evaluate the polymerization of composite resins. The depth of the effect was assessed by Vickers microhardness on section surfaces and observed with scanning electron microscopy. The results were analyzed by 1-way analysis of variance and the post hoc Tukey honest significant differences test (α=.05).
  
  
  RESULTS
  The Vickers microhardness and degree of conversion values on the contact surfaces of the experiment groups were significantly lower than those of the control group (P<.05); the Vickers microhardness values on the section surfaces indicated that there was no significant difference at the same depth of different groups (P>.05). The scanning electron microscope observation showed that an approximately 10-μm deep unpolymerized layer was found in the experimental group.
  
  
  CONCLUSIONS
  Polyvinyl siloxane impression materials have an inhibitory effect on the polymerization of the composite resins, but just limited to within approximately 10 μm from the surface in contact with the impression material.
authors.affiliation: Attending Doctor, College of Stomatology, Chongqing Medical University, Chongqing, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.affiliation: Associate Professor, Department of Dental Materials Sciences, Academic Centre for Dentistry Amsterdam, University of Amsterdam and Free University, Amsterdam, The Netherlands.
authors.forename: Cornelis Johannes
authors.initials: CJ
authors.lastname: Kleverlaan
authors.affiliation: Doctoral student, Department of Endodontics and Operative Dentistry, West China School of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Kunneng
authors.initials: K
authors.lastname: Liang
authors.affiliation: Professor, Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences and Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China. Electronic address: deqinyang@outlook.com.
authors.forename: Deqin
authors.initials: D
authors.lastname: Yang
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003760:Dental Impression Materials / Q000737:chemistry*; D006244:Hardness; D008855:Microscopy, Electron, Scanning; D058105:Polymerization / Q000187:drug effects*; D011145:Polyvinyls / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane