title: Comparative evaluation of residual monomer content and polymerization shrinkage of a packable composite and an ormocer.
abstract: OBJECTIVE
  The aim of this study is to evaluate the residual monomer content and polymerization shrinkage of a packable composite (Surefil) and an ormocer (Admira).
  
  
  METHODS
  The study was conducted in two parts. In Part I, 10 samples of each material were prepared in a standardized split brass mould, using incremental curing technique. The residual monomer content was measured by observing change in weight before and after Soxhlet Extraction procedure. In part II, the volumetric polymerization shrinkage was calculated by measuring the difference in specific gravities of 10 uncured and 10 cured samples of each material using a modified version of ASTM D-792 method. The data obtained was put to statistical analysis using student's 't' test.
  
  
  RESULTS
  Part I - The percentage change in weight for Surefil was 0.525% while that for Admira was 0.374%, which was found to be statistically significant. Part II - The volumetric percentage shrinkage for Surefil ranged between 1.04-3.42% and that for Admira between 1.01-2.31%, which was not found to be significant statistically.
  
  
  CONCLUSIONS
  Admira may be considered more biocompatible than Surefil due to the lower residual monomer content in the former; however, both are comparable with regards to their polymerization shrinkage.
authors.affiliation: Department of Conservative Dentistry and Endodontics, D.J. College of Dental Sciences and Research, Niwari Road, Modinagar, Uttar Pradesh, India.
authors.forename: Shalini
authors.initials: S
authors.lastname: Sharma
authors.forename: Bhupinder Kaur
authors.initials: BK
authors.lastname: Padda
authors.forename: Veena
authors.initials: V
authors.lastname: Choudhary