title: Incremental filling technique and composite material--part I: cuspal deformation, bond strength, and physical properties.
abstract: OBJECTIVE
  To evaluate the effect of composite resins (one conventional and two low-shrink composites) and filling techniques on cuspal strains (CS), microtensile bond strength (μTBS), composite ultimate tensile strength (UTS), and mechanical properties of the composites at various depths in molars with large Class II restorations.
  
  
  METHODS
  One hundred seventeen human molars received standardized Class II mesio-oclusal-distal cavity preparations and restorations with three composites (Filtek LS [3M-ESPE]; Aelite LS [BISCO]; and Filtek Supreme [3M-ESPE]) using three filling techniques (bulk, eight increments, and 16 increments). CS was measured using strain gauges, after which the same restored teeth were used to assess μTBS and UTS. The elastic modulus (E) and Vickers hardness (VH) at different depths were determined from microhardness indentations. The CS, μTBS, UTS, E, and VH data were statistically analyzed using split-plot analysis of variance and Tukey test (p=0.05).
  
  
  RESULTS
  The CS was higher when using 16 increments. The 'low-shrink' composites caused lower CS. The μTBS and UTS were similar for eight- and 16-increment techniques and higher when compared to the bulk filling in all composites. E and VH were constant through the depth when applied in eight or 16 increments.
  
  
  CONCLUSIONS
  Type of composite and filling technique affected the CS, μTBS, UTS, and mechanical properties of large Class II restorations. The eight-increments filling technique resulted in generally less CS with the same μTBS and UTS than was obtained with 16 increments, without affecting E and VH through the depth of the composites.
authors.forename: A A
authors.initials: AA
authors.lastname: Bicalho
authors.forename: R D
authors.initials: RD
authors.lastname: Pereira
authors.forename: R F
authors.initials: RF
authors.lastname: Zanatta
authors.forename: S D
authors.initials: SD
authors.lastname: Franco
authors.forename: D
authors.initials: D
authors.lastname: Tantbirojn
authors.forename: A
authors.initials: A
authors.lastname: Versluis
authors.forename: C J
authors.initials: CJ
authors.lastname: Soares
mesh_terms: D003188:Composite Resins / Q000008:administration & dosage / Q000627:therapeutic use*; D001840:Dental Bonding / Q000379:methods*; D003737:Dental Cavity Preparation / Q000379:methods*; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D008963:Molar / Q000601:surgery; D008964:Molar, Third / Q000601:surgery; D013718:Tensile Strength
chemical_list: D003188:Composite Resins