Shamim Sultana, BDS,(a) Toru Nikaido, DDS, PhD,(a) Md Asafujjoha, BDS,(b) Junji Tagami, DDS, PhD,(a,c) and Khairul Matin, BDS, PhD(a,c)
(a)Cariology and Operative Dentistry, Department of Restorative Sciences, Tokyo Medical and Dental University, Tokyo, Japan, (b)Department of Conservative Dentistry, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh, and (c)Center of Excellence (COE) Program for Frontier Research on Molecular Destruction and Reconstruction of Tooth and Bone at Tokyo Medical and Dental University, Tokyo, Japan
Purpose: This study assessed the probable changes in surface properties of dentin preserved in four different storage media: 1) deionized water (Milli-Q), 2) sodium chloride buffered saline solution (NaCl), 3) Hank’s balanced salts solution (HBSS), and 4) phosphate buffered saline solution (PBS).
Materials and Methods: Equal sized dentin beams were prepared from bovine incisors and stored in the above mentioned storage media for different time periods (1, 7, and 30 days) which then subjected to nanoindentation measurements for hardness and elasticity. Surface roughness (Ra) of the samples was analyzed by a confocal laser microscope. Data were statistically analyzed by one-way ANOVA and Dunnet T3 tests.
Results: Nanoindentation showed that storing dentin in Milli-Q or NaCl media resulted in large decreases in hardness and elasticity, 14% and 18%, respectively by 1 day. After 7 days due to demineralization processes in Milli-Q and NaCl media, hardness and elasticity decreased about 27% and 31%, respectively relative to the starting values which were significantly lower than samples stored in the other two media. In HBSS and PBS, there were no significant alterations in mechanical properties during the 30-day long storage. Ra values of all stored samples were more or less the same as control samples except for samples stored in PBS for 30 days, in which the Ra was increased significantly.
Conclusion: PBS is preferred for short term preservation of dentin, as opposed to NaCl or Milli-Q, to avoid alterations in the mechanical properties of dentin surfaces. (Int Chin J Dent 2006; 6: 123-129.)
Key Words: dentin, hardness, modulus of elasticity, storage media, surface roughness.