title: In vivo evaluation of the surface of posterior resin composite restorations: a pilot study.
abstract: BACKGROUND
  Several methods have been used to determine the surface characteristics of resin composites in vivo and compare composite wear rates with enamel wear rates.
  
  
  OBJECTIVE
  This pilot study describes the surface characteristics of resin composites and the wear of resin composites and enamel during 1 year of in vivo service.
  
  
  METHODS
  A single Class II posterior resin composite restoration (Z100) was placed in 10 patients. Restored teeth and unrestored adjacent control teeth were measured for wear 4 times within the first year. A null point contact stylus profiler and fitting software were used to measure epoxy casts. Maximum depth of wear, average depth of wear, and characteristics of the restoration margin were determined. Paired t tests were used to compare the control and restored teeth, and ANOVA was used to assess the progression of wear over time (P<.05).
  
  
  RESULTS
  After 1 year, maximum depth of wear over the entire preparation region was on average 204.8 microm (+/- 129.8), significantly greater than the 36. 8 microm (+/- 10.1) average maximum depth of wear of enamel at occlusal contact areas on control teeth (P=.009). Maximum depth of wear progressed over time (P=.009). Fracture of excess composite, commonly called flash fracture, occurred in 50% of the restored teeth extending over the preparation margin.
  
  
  CONCLUSIONS
  Composite restorations wore significantly faster than enamel contact areas on control teeth. Also of concern were the marginal flash fractures that could facilitate secondary caries.
authors.affiliation: School of Dentistry, University of Minnesota, Minneapolis, USA. pesun001@tc.umn.edu
authors.forename: I J
authors.initials: IJ
authors.lastname: Pesun
authors.forename: A K
authors.initials: AK
authors.lastname: Olson
authors.forename: J S
authors.initials: JS
authors.lastname: Hodges
authors.forename: G C
authors.initials: GC
authors.lastname: Anderson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001641:Bicuspid; D003188:Composite Resins; D003743:Dental Enamel / Q000502:physiology; D019232:Dental Restoration Failure; D019554:Dental Restoration Wear; D003793:Dental Restoration, Permanent / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008963:Molar; D010865:Pilot Projects; D012822:Silicon Dioxide; D013499:Surface Properties; D015040:Zirconium
chemical_list: D003188:Composite Resins; C083568:Z100 composite resin; D012822:Silicon Dioxide; D015040:Zirconium