title: [Effect of different decalcification condition on tooth-clearing technique].
abstract: OBJECTIVE
  To evaluate shrinkage range of cleared teeth caused by nitric acid with different temperature and concentration.
  
  
  METHODS
  48 human teeth were root canal-prepared and filled, then randomly and averagely divided into six groups on the basis of temperature and density of nitric acid and the condition of whether or not added the oscillate. Group A was 20 degrees C with 6% nitric acid, group B was 20 degrees C with 6% nitric acid and oscillate, group C was 20 degrees C with 3% nitric acid, group D was 20 degrees C with 3% nitric acid and oscillate, group E was 30 degrees C with 6% nitric acid and oscillate, group F was 30 degrees C with 3% nitric acid and oscillate. After achieving the standard of the decalcification, all the specimens were gradually dehydrated, and then cleared and conserved using methyl salicylate. Time-consumed and shrinkage range of all the specimens were recorded and analyzed.
  
  
  RESULTS
  The time of decalcification in group E was the fastest, then was group F, group B. Group C was the last one. The anastole of the specimens was group E > group B > group A, group F > group D > group C, group B > group D, group E > group D, there was significant difference (P < 0.05). Group C had significant difference with other groups (P < 0.05). The anastole rate of the specimens had no significant difference between group A and group B, group C and group D, group B and group F, group D and group F.
  
  
  CONCLUSIONS
  In 20 degrees C, 3% nitric acid with oscillate to carry out the decalcification can use less time and get less anastole. The result of the tooth-clearing technique is the best.
authors.affiliation: Dept. of Oral Medicine, School of Stomatology, Dalian Medical University, Dalian 116044, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Meng-Yu
authors.initials: MY
authors.lastname: Zhou
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Niu