title: Evaluation of cuspal deflection in premolar teeth restored with low shrinkable resin composite (in vitro study).
abstract: OBJECTIVE
  This study evaluated cuspal deflection in premolar teeth restored with low shrinkable resin composite.
  
  
  METHODS
  A total of 40 human premolars were used for cuspal deflection evaluation in this study. Each group was divided into four equal groups according to the type of resin composite and the adhesive used as follows: group A: Using low shrinkable resin composite (silorane) with its adhesive system; group B: Using low shrinkable composite (silorane) with G-bond; group C: Using Filtek Z350 composite with G-bond; and group D: Using Filtek Z350 composite with AdheSE. Cusp deflection was detected using Universal measuring microscope and laser horizontal metroscope.
  
  
  RESULTS
  This study was done to investigate the effect of polymerization shrinkage stresses of two resin composite materials (Filtek Z350 and Filtek P90) on cuspal deflection of mesio-occluso-distal restoration. For this study, the extracted non-carious maxillary second premolars were selected. Forty teeth that showed no more than 5% variation in their dimensions were used. A significant increase in cuspal deflection of cavities restored with the methacrylate-based (Filtek Z350) compared with the silorane (P90) resin-based composites was obtained.
  
  
  CONCLUSIONS
  The change in the organic matrix or materials formulation of the resin composite using silorane has a positive effect on controlling the cusp deflection.
authors.affiliation: Department of Restorative Dental Sciences, Alfarabi Colleges, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Labib Mohamed
authors.initials: LM
authors.lastname: Labib
authors.affiliation: Department of Operative Dentistry, Al-Azhar University, Cairo, Egypt.
authors.forename: Sameh Mahmoud
authors.initials: SM
authors.lastname: Nabih
authors.affiliation: Department of Preventive Dental Sciences, Alfarabi Colleges, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Kusai
authors.initials: K
authors.lastname: Baroudi
keywords: Cusp deflection; laser horizontal metroscope; resin composite; silorane