title: Changes in color and staining of dental composite resins after wear simulation.
abstract: OBJECTIVE
  The objectives were to measure the discoloration as well as the change in staining of composite resins after wear simulation.
  
  
  METHODS
  Generalized wear simulation was performed with a three-body wear testing device for 400,000 cycles for six composite resins. A flat-planed stylus made with polyacetal resin was loaded perpendicularly under a load of 76-80 N. Color of nonworn and worn areas was measured with a spectrophotometer before and after staining with 0.5% methylene blue solution. Nonworn surface served as a control. Differences in color between nonworn and worn surfaces were calculated to indicate the change in color due to wear. Color change after staining with 0.5% methylene blue solution for nonworn and worn surfaces was calculated to observe the changes in staining.
  
  
  RESULTS
  Color difference (DeltaE(*) (ab)) between nonworn and worn surfaces was in the range of 0.8-1.4 before staining, which increased to 1.1-3.9 after staining. Color change by staining with methylene blue in nonworn surface was 6.8-20.6, and that in worn surface was 5.2-17.8. Therefore, staining in nonworn surface was higher than that in worn surface (p < 0.05). Generalized wear simulation for approximately 3 years of clinical service resulted in acceptable color change before staining (DeltaE(*) (ab) < 3.3). After staining, color difference between nonworn and worn surface increased to not-acceptable value in one composite resin investigated.
authors.affiliation: Department of Dental Biomaterials Science, Dental Research Institute, College of Dentistry, Seoul National University, Seoul, Korea. ykleedm@snu.ac.kr
authors.forename: Yong-Keun
authors.initials: YK
authors.lastname: Lee
authors.forename: Huan
authors.initials: H
authors.lastname: Lu
authors.forename: Makoto
authors.initials: M
authors.lastname: Oguri
authors.forename: John M
authors.initials: JM
authors.lastname: Powers
mesh_terms: D000080:Acetals / Q000737:chemistry; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D008422:Materials Testing; D008751:Methylene Blue / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013053:Spectrophotometry; D013194:Staining and Labeling; D013499:Surface Properties
chemical_list: D000080:Acetals; D003188:Composite Resins; D003764:Dental Materials; D011108:Polymers; D012996:Solutions; C016067:polyacetal; D008751:Methylene Blue