title: Modulated photoactivation methods--effect on marginal and internal gap formation of restorations using different restorative composites.
abstract: This study evaluated the effect of modulated photoactivation methods on gap formation of restorations using different composites.
  
  
  METHODS
  Sixty human third molars were selected, sectioned (two fragments), and ground to expose a flat enamel area. A cavity (5 mm long x 2 mm wide x 2 mm deep--outer margins in enamel and inner margins in dentin) was prepared on the central area of flattened surface. Single bond adhesive system was applied according to manufacturer's instructions. The specimens were assigned into 12 groups (n = 10), according to the restorative composite (Filtek Z250, Herculite XRV, and Heliomolar) and the photoactivation method [continuous light (CL); soft-start (SS); pulse delay (PD); and intermittent light (IL)]. Outer margins were stained using Caries Detector, observed under stereomicroscope, and images were transferred to a computer measurement program. Then, the specimens were sectioned in slices and the internal gaps were assigned using the same method. The length of gaps was expressed as a percentage of total length of the margins. Data (internal adaptation) were submitted to ANOVA and Tukey's test.
  
  
  RESULTS
  All restorations showed perfect seal of the enamel outer margins. Modulated photoactivation methods (SS, PD, and IL) showed a significant reduction on internal gap formation when compared with CL, regardless of the composite. Filtek Z250 showed the best internal adaptation, regardless of the photoactivation method.
  
  
  CONCLUSIONS
  Modulated photoactivation methods decrease the internal gap formation of composite restorations, and should be encouraged on clinical practice.
authors.affiliation: Dental Materials Area, Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, Sao Paulo, Brazil. robalonso@fop.unicamp.br
authors.forename: Roberta C B
authors.initials: RC
authors.lastname: Alonso
authors.forename: Gisele M
authors.initials: GM
authors.lastname: Correr
authors.forename: Leonardo G
authors.initials: LG
authors.lastname: Cunha
authors.forename: Carlos A
authors.initials: CA
authors.lastname: De Moraes Souto Pantoja
authors.forename: Regina M
authors.initials: RM
authors.lastname: Puppin-Rontani
authors.forename: Mário A C
authors.initials: MA
authors.lastname: Sinhoreti
mesh_terms: D000180:Acrylic Resins / Q000528:radiation effects*; D000293:Adolescent; D000328:Adult; D003188:Composite Resins / Q000528:radiation effects*; D003743:Dental Enamel / Q000601:surgery*; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D006801:Humans; D008027:Light; D010777:Photochemistry; D011140:Polyurethanes / Q000528:radiation effects*; D019279:Resin Cements / Q000528:radiation effects
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; C444701:Filtek Z250; C513708:Heliomolar; D011140:Polyurethanes; D019279:Resin Cements; C065770:Herculite XR