Dimensional changes of demineralized human dentine during preparation for scanning electron microscopy.
Dentine rods measuring approx. 0.7 x 0.7 x 5.0mm were prepared from the crowns of extracted human third molars. The specimens were demineralized in 0.5 M EDTA (pH 7.0) for 3 days and their volume measured with a digital micrometer under a dissecting microscope. The specimens were randomly assigned to experimental groups and were chemically dehydrated in acetone. Next they were dried using either hexamethyldisilazane, Peldri II, or critical-point drying techniques. The dimensions of the specimens were measured again after each step and the changes in volume were expressed as a percentage of the original demineralized volume. The effects of fixing the specimens in 10% buffered formalin before dehydration with acetone were also investigated for every drying procedure. Dehydration in acetone caused a small but significant reduction in the volume of demineralized formalin-fixed specimens but unfixed specimens did not change significantly. In general, all three drying procedures caused some shrinkage in demineralized dentine specimens. Unfixed specimens exhibited a volumetric shrinkage of approx. 15-20% after drying with any of the methods. Fixed specimens shrank more than unfixed specimens after drying (25-35%). Regardless of the drying technique, the specimens shrank a further 10-20% when measured in the vacuum chamber of the scanning electron microscope. Among the three drying techniques employed, hexamethyldisilazane seems to be a very useful alternative to critical-point drying for the preparation of dentine specimens for scanning electron microscopy.
Carvalho
R M
RM
Department of Operative Dentistry, Bauru School of Dentistry, University of São Paulo, Brazil.
Yoshiyama
M
M
Brewer
P D
PD
Pashley
D H
DH
D000134:Acid Etching, Dental; D016477:Artifacts; D003648:Decalcification Technique; D003804:Dentin / Q000737:chemistry / Q000187:drug effects; D003890:Desiccation / Q000379:methods; D004492:Edetic Acid / Q000494:pharmacology; D005466:Fluorocarbons; D016591:Histocytological Preparation Techniques; D006801:Humans; D008855:Microscopy, Electron, Scanning; D017646:Organosilicon Compounds; D016707:Tissue Fixation / Q000379:methods
D005466:Fluorocarbons; D017646:Organosilicon Compounds; C062793:Peldri II; D004492:Edetic Acid; C024548:hexamethylsilazane