Abstract: Objective: Purpose of this study was to evaluate shrinkage range of cleared teeth caused by HNO3 with different temperature and concentration. Material and Methods:48 human teeth(24 human premolar teeth and 24 human axleteeth)were root canal-prepared and filled,then randomly distrialted On the basis of the temperature and density of HNO3 and whether or not the oscillate condition is added,we devided the teeth into 6 groups(each group 4 premolar teeth and 4 axleteeth).The condition of group A was 20°C,6% HNO3; Group B was 20°C,6% HNO3 with oscillation; Group C was 20°C,3% HNO3 ; Group D was 20°C,3% HNO3 with oscillation; Group E was 30°C,6% HNO3 with oscillation; Group F was 30°C,3% HNO3 with oscillation.After achieving the standard of the decalcification,allthe specimens were grandually dehydeated, and then cleared and conserved using methyl salicylate.Time-consumed and shrinkage range of all the specimens is recorded and analised, Results:The time of decalcification:group E was the fast term,then was group F, group B, group A, group D. Group Cwas the last one.The anastole of the specimens: group E >group B >group A, group F >group D >group C, group B >group D, group E >group F,there was singnificant difference.Group C was singnificant difference with other groups. Conclusions:Using shoker,higher temperature or density of HNO3 ,will make decalcification earlier and the anastole of specimens longer.In 20°C,3% HNO3 with oscillation to carry out the decalcification can use less time and make less anastole,the result of the tooth-clearing technique is the best. Key words: Clearing technique, decalcification, shrinkage range
Correspondence: WeiDong Niu Dalian Medical University(Tel:0411-84720029)