title: In vitro microleakage of packable composites in Class II restorations.
abstract: OBJECTIVE
  To evaluate the microleakage in Class II resin restorations at different margins and the polymerization shrinkage of the composites used.
  
  
  METHODS
  Four standardized Class II (3 x 5 x 2 mm) cavities were prepared in 32 teeth. The sample had the gingival margin either 1 mm below or above the cementoenamel junction. Teeth were divided and restored according to the following protocols: (1) Single Bond + P60; (2) Prime & Bond NT + Surefil; (3) Bond-1 + Alert; and (4) Prime & Bond 2.1 + TPH. After 7 days, the specimens were thermocycled (500 cycles between 5 to 55 degrees C with a 15-second dwell time), immersed in 0.5% methylene blue for 24 hours, sectioned, and evaluated (both surfaces) at the gingival margin by two examiners, using a 0 to 3 marginal infiltration score system. The polymerization shrinkage of the composites (n = 6) was evaluated by the disk deflective method. Microleakage data was evaluated by nonparametric repeated measures ANOVA. The percentage of polymerization shrinkage was evaluated by ANOVA and Tukey's test.
  
  
  RESULTS
  Only protocol 3 showed a significant difference between enamel and cementum margin. No difference was detected among the protocols in the enamel margin. Only protocol 1 provided a good seal in the cementum margin. All packable composites showed lower polymerization shrinkage than the hybrid tested.
  
  
  CONCLUSIONS
  All protocols are able to prevent dye penetration in enamel margins; however, protocol 1 is preferable to reduce the microleakage in the cementum margin. The packable composites showed lower polymerization shrinkage compared to the hybrid resin.
authors.affiliation: Department of Dental Materials, Dental School, University do Oeste de Santa Catarina, Joaçaba-SC, Brazil. aloguercio@hotmail.com
authors.forename: Alessandro Dourado
authors.initials: AD
authors.lastname: Loguercio
authors.forename: José Roberto
authors.initials: JR
authors.lastname: de Oliveira Bauer
authors.forename: Alessandra
authors.initials: A
authors.lastname: Reis
authors.forename: Rosa Helena Miranda
authors.initials: RH
authors.lastname: Grande
mesh_terms: D000096:Acetone; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D003763:Dental Leakage / Q000209:etiology*; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000009:adverse effects / Q000379:methods*; D017220:Dentin-Bonding Agents; D006801:Humans; D008689:Methacrylates; D008963:Molar; D011108:Polymers / Q000737:chemistry; D011109:Polymethacrylic Acids; D019279:Resin Cements
chemical_list: C406265:Alert composite resin; C115611:BOND-1 adhesive; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C443708:P60 Condensible Resin Composite; D011108:Polymers; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; C403464:SureFil packable composite; C467914:TPH spectrum; C444444:prime and bond 2.1; C115612:single bond; D000096:Acetone; D017438:Bisphenol A-Glycidyl Methacrylate