title: Effect of storage solutions on microhardness of crown enamel and dentin.
abstract: OBJECTIVE
  The aim of this study was to determine alterations in microhardness of crown dentin and enamel, after 2 and 12-month storage in de-ionized water, 0.2% glutaraldehyde, Hanks' Balanced Salt Solution (HBSS), 0.1% sodium hypochlorite (NaOCl) or 0.1% thymol.
  
  
  METHODS
  Freshly extracted, nonsterile 60 intact human premolars were distributed to five groups. Six teeth from each group were evaluated after two, and other six teeth were evaluated after 12 months storage. After grinding and polishing of teeth, Vickers hardness was evaluated with making indentations on enamel and dentin, using a pyramid diamond indenter tip exerting 100 g load for 15 s.
  
  
  RESULTS
  After 2 months storage in solutions, range of the hardness values (HV) of enamel and dentin were in between 315-357 and 64-67, respectively. However, 12 months storage of the teeth resulted in a statistically significant decrease in microhardness when compared to microhardness of teeth stored for 2 months (P = 0.001). Although the differences were not significant regarding solutions, all solutions decreased the microhardness both in enamel and dentin (P > 0.05). However, decrease in microhardness was relatively less in de-ionized water and thymol solutions while glutaraldehyde decreased microhardness the most: 63% for enamel and 53% for dentin.
  
  
  CONCLUSIONS
  Microhardness of enamel and dentin was in an acceptable range when teeth were stored for 2 months in de-ionized water, glutaraldehyde, HBSS, NaOCl or in thymol; thus, teeth kept up to 2 months in these solutions can be used for mechanical in vitro tests. However, 12 months storage significantly decreased the microhardness of enamel and dentin.
authors.affiliation: Department of Restorative Dentistry, University of Illinois at Chicago College of Dentistry, USA.
authors.forename: Berdan
authors.initials: B
authors.lastname: Aydın
authors.affiliation: Department of Restorative Dentistry, Ege University, Turkiye.
authors.forename: Tijen
authors.initials: T
authors.lastname: Pamir
authors.affiliation: Department of Mechanical Engineering, Ege University, Turkiye.
authors.forename: Aysun
authors.initials: A
authors.lastname: Baltaci
authors.affiliation: Department of Biostatistics, Ege University, Turkiye.
authors.forename: Mehmet N
authors.initials: MN
authors.lastname: Orman
authors.affiliation: Department of Endodontics, Ege University, Turkiye.
authors.forename: Tugba
authors.initials: T
authors.lastname: Turk
keywords: Dentin; enamel; microhardness; storage of teeth; storage solutions