title: Comparative evaluation of microleakage in class II cavities restored with Ceram X and Filtek P-90: An in vitro study.
abstract: BACKGROUND
  Polymerization shrinkage in composite resins is responsible for microleakage. Methacrylate-based composite resins have linear reactive groups resulting in high polymerization shrinkage. A recently introduced composite resin Filtek P90 is based on siloxanes and oxiranes which polymerize by cationic "ring opening" polymerization resulting in reduced polymerization shrinkage.
  
  
  OBJECTIVE
  Aim of this study was to compare microleakage in class II cavities restored with a nanoceramic restorative (Ceram X) and a silorane composite (Filtek P90).
  
  
  METHODS
  Standardized class II box type cavities were prepared on mesial (Groups Ia and IIa) and distal (Groups Ib and IIb) surfaces of twenty extracted permanent molar teeth with gingival floor ending 1 mm coronal and apical to the cementoenamel junction, respectively. The teeth in Group Ia and Ib were restored with Ceram X and Group IIa and IIb with Filtek P90. The specimens were thermocycled and microleakage evaluated.
  
  
  METHODS
  The data were statistically analyzed using Wilcoxon Signed-Rank test at the 0.05 level of significance.
  
  
  RESULTS
  Mean microleakage score of group la and lb was 1 ± 2.260 and 2.8 ± 1.229, respectively. And that of group Ila and llb was 0.2 ± .869 and 0.3 ± .588, respectively. When groups I and II were compared, results were statistically significant (P<0.05).
  
  
  CONCLUSIONS
  It was concluded that silorane-based composite may be a better substitute for methacrylate-based composites.
authors.affiliation: Department of Conservative Dentistry and Endodontics, J.N. Kapoor D.A.V. (C) Dental College, Yamunanagar, Haryana, India.
authors.forename: Poonam
authors.initials: P
authors.lastname: Bogra
authors.forename: Saurabh
authors.initials: S
authors.lastname: Gupta
authors.forename: Saru
authors.initials: S
authors.lastname: Kumar