title: In vitro evaluation of the effect of delaying toothbrushing with toothpaste on enamel microhardness subsequent to bleaching the teeth with 15% carbamide peroxide.
abstract: Changes in enamel surface microhardness as a result of bleaching with carbamide peroxide in various in vitro conditions have been reported. The present study evaluated the effect of oral hygiene procedures on enamel microhardness at three time intervals following bleaching with 15% carbamide peroxide. Although this was an in vitro study, the purpose was to address whether or not a patient's toothbrushing following at-home bleaching might affect surface changes in tooth enamel. Eighty enamel slabs were prepared from impacted human third molars that had been extracted surgically. Subsequent to placing the specimens in acrylic resin, their surfaces were smoothed, and they were randomly divided into four equal groups. The specimens were initially evaluated for microhardness by Vickers test. The bleaching procedure was carried out for 21 days for 6 hours daily. In each group, the surfaces of specimens were brushed with toothpaste immediately, 1 hour, and 2 hours after bleaching except for the control group. The specimens were stored in artificial saliva. Enamel microhardness was again measured at the end of the bleaching period. Then the differences in enamel microhardness between the two periods were calculated. Data were analyzed with a nonparametric Kruskal-Wallis test at a significance level of p<0.05. The differences in the microhardness values before and after intervention between the groups were not significant (p=0.59). Daily oral hygiene procedures either immediately or 1 or 2 hours after daily bleaching procedures and exposing the specimens to artificial saliva during the study period produced no significant differences in enamel microhardness values.
authors.affiliation: Department of Operative Dentistry, Tabriz University of Medical Sciences, Tabriz Dental School, Tabriz, Iran. elmiranavimi@yahoo.com
authors.forename: E J
authors.initials: EJ
authors.lastname: Navimipour
authors.forename: S
authors.initials: S
authors.lastname: Kimyai
authors.forename: S
authors.initials: S
authors.lastname: Nikazar
authors.forename: M
authors.initials: M
authors.lastname: Ghojazadeh
mesh_terms: D000077463:Carbamide Peroxide; D003743:Dental Enamel / Q000187:drug effects* / Q000473:pathology; D003799:Dental Stress Analysis / Q000295:instrumentation; D006244:Hardness; D006801:Humans; D010545:Peroxides / Q000627:therapeutic use*; D012464:Saliva, Artificial / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching / Q000295:instrumentation / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000627:therapeutic use*; D014099:Toothbrushing / Q000295:instrumentation / Q000379:methods*; D014100:Toothpastes / Q000627:therapeutic use*; D014508:Urea / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D010545:Peroxides; D012464:Saliva, Artificial; D058205:Tooth Bleaching Agents; D014100:Toothpastes; D000077463:Carbamide Peroxide; D014508:Urea