title: The effect of protocol for disinfection of extracted teeth recommended by center for disease control (CDC) on microhardness of enamel and dentin.
abstract: BACKGROUND
  According to the guideline of the United States center for disease control (CDC), the extracted teeth should be sterilized by autoclaving or storage in 10% formalin before using for educational or research purposes. The objective of this study was to evaluate the effect of this protocol on microhardness of dentin and enamel.
  
  
  METHODS
  Thirty extracted single-root teeth were used in this study. The crowns were resected, and the roots were longitudinally sectioned into two halves. The Vickers microhardness (VHN) of specimens was measured on polished canal dentin and buccal enamel surfaces. The crowns were randomly divided into three groups (n=10). Group 1 and 2 were sterilized using autoclave and formalin, respectively while group 3 (control) was stored in synthetic tissue fluid. The root halves were also randomly divided into 3 groups (n=20) which were treated as mentioned above for crown samples. Following sterilization, VHN of samples was measured again. ANOVA and paired samples t-tests were used to analyze the data.
  
  
  RESULTS
  Autoclaving caused a significant reduction in microhardness of dentin (P <0.001, 12.04% decreases in VHN). However, there were no significant differences for before and after sterilization within other groups.
  
  
  CONCLUSIONS
  Based on the results of this study, the CDC protocol is recommended in studies related to enamel microhardness. However, Autoclaving is not an appropriate sterilization method in studies related to dentin microhardness. In these studies, two-week immersion in 10% formalin is recommended.
  
  
  BACKGROUND
  Autoclave, CDC, extracted teeth, formalin, microhardness, sterilization.
authors.affiliation: DDS, MSc, Assistant Professor of Endodontics, Dental and periodontal research center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Amin
authors.initials: A
authors.lastname: Salem-Milani
authors.affiliation: DDS, MSc, Associate Professor, Department of Endodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Zand
authors.affiliation: PhD, Assistant Professor of Biostatistics, Department of Statistics and Epidemiology, Faculty of Health and Nutrition, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Asghari-Jafarabadi
authors.affiliation: PhD, Associate Professor of Pharmaceutics, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Parvin
authors.initials: P
authors.lastname: Zakeri-Milani
authors.affiliation: DDS, Dentist, private practice.
authors.forename: Alireza
authors.initials: A
authors.lastname: Banifatemeh