title: Nanohybrid vs. fine hybrid composite in Class II cavities: clinical results and margin analysis after four years.
abstract: OBJECTIVE
  This controlled prospective split-mouth study evaluated the clinical behavior of two different resin composites in extended Class II cavities over a period of four years.
  
  
  METHODS
  Thirty patients received 68 direct resin composite restorations (Grandio bonded with Solobond M: n=36, Tetric Ceram bonded with Syntac: n=32) by one dentist in a private practice. All restorations were replacement fillings, 24 cavities (35%) revealed no enamel at the bottom of the proximal box, in 33 cavities (48%) the proximal enamel width was less than 0.5mm. The restorations were examined according to modified USPHS criteria at baseline, and after six months, one, two, and four years. At each recall, impressions were taken for replica preparation. Replicas of 44 select subjects were assessed for marginal quality under a stereo light microscope (SLM) at 130x and 22 replicas were assessed under a scanning electron microscope (SEM) at 200x.
  
  
  RESULTS
  Both recall rate and survival rate were 100% after four years of clinical service. No significant difference was found between the restorative materials (p>0.05; Mann-Whitney U-test). Hypersensitivities were significantly reduced over time (p<0.05; Friedman test). A significant deterioration over time was found for the criteria marginal integrity (66% bravo after four years), tooth integrity (15% bravo), filling integrity (73% bravo) and proximal contact (p<0.05; Friedman test). SLM and SEM analysis of restoration margins revealed differences in the amount of perfect margins, in favor of Tetric Ceram (p<0.05).
  
  
  CONCLUSIONS
  Both materials performed satisfactorily over the four-year observation period. Due to the extension of the restorations, wear was clearly visible after four years of clinical service with 50% bravo ratings.
authors.affiliation: Department of Pediatric Dentistry, University Medical Center Carl Gustav Carus, Technical University Dresden, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Krämer
authors.forename: Christian
authors.initials: C
authors.lastname: Reinelt
authors.forename: Gert
authors.initials: G
authors.lastname: Richter
authors.forename: Anselm
authors.initials: A
authors.lastname: Petschelt
authors.forename: Roland
authors.initials: R
authors.lastname: Frankenberger
mesh_terms: D000328:Adult; D003188:Composite Resins; D003737:Dental Cavity Preparation / Q000145:classification; D045662:Dental Etching / Q000379:methods; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D017220:Dentin-Bonding Agents; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053761:Nanocomposites; D010316:Particle Size; D011446:Prospective Studies; D016628:Replica Techniques; D019279:Resin Cements; D019233:Retreatment; D055815:Young Adult
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C509998:Grandio; D019279:Resin Cements; C425825:Solobond M; C078484:Syntac dentine adhesive; C121818:Tetric ceram