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. Material and 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. Key words:Autoclave, CDC, extracted teeth, formalin, microhardness, sterilization.
Highlights
Human extracted teeth are commonly used in preclinical settings for education of dental students before they enter clinical environment
There was significant differences within Autoclave group for after intervention compared with before intervention (P
The results of the present study showed that 10% formalin has no significant effect on microhardness of enamel or dentin
Summary
Human extracted teeth are commonly used in preclinical settings for education of dental students before they enter clinical environment. A sterilization procedure for extracted teeth should ideally not affect the properties of dental substrates to the extent that the “feel” and cutting characteristics are noticeably different from the clinical situation, as this is one of the major advantages in using extracted teeth for educational purposes This is true when the teeth are used for research purposes; because, possible alteration of chemical and mechanical properties of teeth by these methods reduces the validity of the results, and these laboratory studies will not reflect real clinical situation [5]. 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. Two-week immersion in 10% formalin is recommended
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