title: Influence of resin composite insertion technique in preparations with a high C-factor.
abstract: OBJECTIVE
  To evaluate the marginal microleakage in enamel and dentin/cementum walls in preparations with a high C-factor, using 3 resin composite insertion techniques. The null hypothesis was that there is no difference among the 3 resin composite insertion techniques.
  
  
  METHODS
  Standardized Class 5 cavities were prepared in the lingual and buccal aspects of 30 caries-free, extracted third molars. The prepared teeth were randomly assigned to 3 groups: (1) oblique incremental placement technique, (2) horizontal incremental placement technique, and (3) bulk insertion (single increment). The preparations were restored with a 1-bottle adhesive (Single Bond, 3M ESPE) and microhybrid resin composite (Z100, 3M ESPE). Specimens were isolated with nail varnish except for a 2-mm-wide rim around the restoration and thermocycled (1,000 thermal cycles, 5 degrees C/55 degrees C; 30-second dwell time). The specimens were immersed in an aqueous solution of 50 wt% silver nitrate for 24 hours, followed by 8 hours in a photo-developing solution and evaluated for microleakage using an ordinal scale of 0 to 4. The microleakage scores obtained from occlusal and gingival walls were analyzed with Wilcoxon and Kruskal-Wallis nonparametric tests.
  
  
  RESULTS
  The null hypothesis was accepted. The horizontal incremental placement technique, the oblique incremental technique, and bulk insertion resulted in statistically similar enamel and dentin microleakage scores.
  
  
  CONCLUSIONS
  Neither the incremental techniques nor the bulk placement technique were capable of eliminating the marginal microleakage in preparations with a high C-factor.
authors.affiliation: Department of Comprehensive Care, Case School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4905, USA. sillas.duarte@case.edu
authors.forename: Sillas
authors.initials: S
authors.lastname: Duarte
authors.forename: Welingtom
authors.initials: W
authors.lastname: Dinelli
authors.forename: Maria Helena Carmona
authors.initials: MH
authors.lastname: da Silva
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate; D002484:Cementation; D003188:Composite Resins; D003737:Dental Cavity Preparation / Q000145:classification*; D003763:Dental Leakage; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D006801:Humans; D008964:Molar, Third; D019279:Resin Cements; D012822:Silicon Dioxide; D018709:Statistics, Nonparametric; D015040:Zirconium
chemical_list: D003188:Composite Resins; D019279:Resin Cements; C083568:Z100 composite resin; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium