title: Cuspal Deflection of Premolars Restored with Bulk-Fill Composite Resins.
abstract: OBJECTIVE
  This in vitro study compared cuspal deflection of premolars restored with three bulk-fill composite resins to that of incrementally-restored ones with a low-shrinkage silorane-based restorative material.
  
  
  METHODS
  Forty freshly-extracted intact human upper premolars were used. Reference points at buccal and palatal cusp tips were acid-etched and composite rods were horizontally bonded to them (TPH-Spectra-HV, Dentsply). Two acrylic resin guiding paths were made for each premolar to guide beaks of a digital micrometer used for cuspal deflection measurements. Standardized MOD cavities, 3 mm wide bucco-lingually and 3.5 mm deep, were prepared on each premolar. Prepared teeth were then equally divided into four groups (n = 10) and each group was assigned to one of four composite resin (QuiXX, Dentsply; X-tra fil, Voco; Tetric EvoCeram Bulk Fill, Ivoclar Vivadent; low-shrinkage Filtek LS, 3M/ESPE). Adper Single Bond-Plus, 3M/ESPE was used with all bulk-fill restoratives. LS-System Adhesive, 3M/ESPE was used with Filtek LS. For each prepared premolar, cuspal deflection was measured in microns as the difference between two readings between reference points before and after restoration completion. Means and SDs were calculated and data statistically-analyzed using One-way ANOVA and Tukey's test.
  
  
  RESULTS
  Filtek LS showed the lowest mean cuspal deflection value 6.4(0.84)μm followed by Tetric EvoCeram Bulk Fill 10.1(1.2) μm and X-tra fil 12.4(1.35)μm, while QuiXX showed the highest mean 13(1.05)μm. ANOVA indicated significant difference among mean values of groups (p < 0.001). Tukey's test indicated no significant difference in mean values between QuiXX and X-tra fil (p = 0.637).
  
  
  CONCLUSIONS
  Tetric EvoCeram Bulk Fill had significantly lower mean cuspal deflection compared with the two other bulk-fill composite resins tested. Filtek LS had the lowest significant mean cuspal deflection in comparison to all tested bulk-fill restoratives.
  
  
  CONCLUSIONS
  The use of Tetric EvoCeram Bulk fill composite resin restorative for class II MOD cavities resulted in reduced cuspal deflection in comparison to the two other bulk-fill composite resins tested. The silorane-based Filtek LS restorative resulted in the least cuspal deflection in comparison to all tested bulk-fill composite restoratives.
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Haytham
authors.initials: H
authors.lastname: Behery
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Omar
authors.initials: O
authors.lastname: El-Mowafy
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Wafa
authors.initials: W
authors.lastname: El-Badrawy
authors.affiliation: Department of Operative Dentistry, Faculty of Dental Medicine, Al-Azhar University, Cairo, Egypt.
authors.forename: Belal
authors.initials: B
authors.lastname: Saleh
authors.affiliation: Department of Operative Dentistry, Faculty of Dental Medicine, Al-Azhar University, Cairo, Egypt.
authors.forename: Sameh
authors.initials: S
authors.lastname: Nabih
mesh_terms: D001641:Bicuspid / Q000737:chemistry*; D003188:Composite Resins; D006801:Humans
chemical_list: D003188:Composite Resins