title: Influence of cavity preparation and curing method on the marginal seal of resin composite restorations: an in vitro evaluation.
abstract: OBJECTIVE
  To evaluate the influence of cavity design and photocuring method on the marginal seal of resin composite restorations.
  
  
  METHODS
  Seventy-two bovine teeth were divided into 2 groups: group 1 received box-type cavity preparations, and group 2 received plate-type preparations. Each group was divided into 3 subgroups. After etching and bonding, Z250 resin composite (3M Espe) was applied in 2 equal increments and cured with 1 of 3 techniques: (1) conventional curing for 30 seconds at 650 mW/cm2; (2) 2-step photocuring, in which the first step was performed 14 mm from the restoration for 10 seconds at 180 mW/cm2 and the second step was performed in direct contact for 20 seconds at 650 mW/cm2; or (3) progressive curing using Jetlite 4000 (J. Morita) for 8 seconds at 125 mW/cm2 and then 22 seconds at 125 mW/cm2 up to 500 mW/cm2. The specimens were thermocycled for 500 cycles and then submitted to dye penetration with a 50% silver nitrate solution. Microleakage was assessed using a stereomicroscope. Data were analyzed using analysis of variance and Tukey test (5% level of significance).
  
  
  RESULTS
  A statistically significant difference was found between groups when a double interaction between photocuring and cavity preparation was considered (P = .029).
  
  
  CONCLUSIONS
  No one type of cavity preparation or photocuring method prevented micro-leakage. The plate-type preparation showed the worst dye penetration when conventional and progressive photocuring methods were used. The best results were found using the 2-step photocuring with the plate-type preparation.
authors.affiliation: Department of Restorative Dentistry, São José dos Campos School of Dentistry, State University of São Paulo (UNESP), São Paulo, Brazil. andrecervantesbrsp@yahoo.com.br <andrecervantesbrsp@yahoo.com.br>
authors.forename: André Luiz Cervantes
authors.initials: AL
authors.lastname: Jorge
authors.forename: Maria Amélia Máximo
authors.initials: MA
authors.lastname: de Araújo
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry* / Q000528:radiation effects; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003737:Dental Cavity Preparation / Q000379:methods*; D003763:Dental Leakage / Q000175:diagnosis; D018772:Dental Marginal Adaptation; D011140:Polyurethanes / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes