title: Effect of nano-carbonate apatite to prevent re-stain after dental bleaching in vitro.
abstract: OBJECTIVE
  This study examined the effect of nano-carbonate apatite (n-CAP) to prevent re-staining and the change of enamel surface after dental bleaching in vitro.
  
  
  METHODS
  Twenty-four bovine specimens were bleached for 2 weeks with 10% carbamide peroxide (CP). After bleaching, the specimens were divided into the following four groups: distilled and deionized water (DDW, negative control), 10% n-CAP, NaF (positive control) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP, positive control). Each group was subjected to pH cycling for 7 days. The specimens were treated for 4 min 3 times per day and re-staining was induced naturally by artificial saliva in the remineralization process. After pH cycling, the changes in colour were evaluated with spectrophotometry and scanning electron microscopy (SEM). The difference in colour between before and after pH cycling was evaluated using an ANOVA and Tukey test.
  
  
  RESULTS
  After pH cycling, the colour difference of n-CAP group was significantly lower than that of the DDW and CPP-ACP groups (p<0.05). SEM showed that n-CAP particles were deposited regularly on the damaged surface compared to the other groups.
  
  
  CONCLUSIONS
  10% n-CAP could significantly maintain the initial colour and protect the damaged enamel structure after bleaching.
authors.affiliation: Department of Preventive Dentistry and Public Oral Health, Research Center for Orofacial Hard Tissue Regeneration Brain Korea 21 project, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Y S
authors.initials: YS
authors.lastname: Kim
authors.forename: H K
authors.initials: HK
authors.lastname: Kwon
authors.forename: B I
authors.initials: BI
authors.lastname: Kim
mesh_terms: D000818:Animals; D001031:Apatites / Q000627:therapeutic use*; D000077463:Carbamide Peroxide; D002327:Cariostatic Agents / Q000627:therapeutic use; D002364:Caseins / Q000627:therapeutic use; D002417:Cattle; D003116:Color; D003461:Crystallography; D003743:Dental Enamel / Q000187:drug effects / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000627:therapeutic use*; D010545:Peroxides / Q000627:therapeutic use; D011897:Random Allocation; D012008:Recurrence; D012464:Saliva, Artificial / Q000737:chemistry; D012969:Sodium Fluoride / Q000627:therapeutic use; D013053:Spectrophotometry; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000627:therapeutic use; D014075:Tooth Discoloration / Q000517:prevention & control*; D014089:Tooth Remineralization; D014508:Urea / Q000031:analogs & derivatives / Q000627:therapeutic use; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; D002327:Cariostatic Agents; D002364:Caseins; D010545:Peroxides; D012464:Saliva, Artificial; D058205:Tooth Bleaching Agents; C447032:casein phosphopeptide-amorphous calcium phosphate nanocomplex; D014867:Water; D000077463:Carbamide Peroxide; C030782:carboapatite; D014508:Urea; D012969:Sodium Fluoride