title: Evaluation of root-end cavity preparation using ultrasonic retrotips.
abstract: OBJECTIVE
  To evaluate and compare the efficiency of root-end preparations using ultrasonic retrotips coated with diamond and zirconium nitride.
  
  
  METHODS
  Eighty-five extracted single-rooted teeth were root filled, and then resected 3 mm from their apices. Root-end cavities were prepared with KiS (zirconium nitride-coated retrotip), CT-5 (stainless steel tip) or diamond-coated (DC) ultrasonic retrotips, and 10 teeth served as controls. Thirty teeth were used for evaluation of the time required to prepare the root-end cavity, the number of microcracks produced on the resected surface and the number of dentinal tubule openings on the root-canal wall using scanning electron microscope (SEM) images. A further 55 teeth were used for evaluation of dye penetration following filling of the root-end cavities with Super EBA. The degree of dye penetration in millimetres was measured under the microscope after 7 days of immersion in India ink. Statistical analyses were performed using the one-way ANOVA and Scheffe's F-test as the post hoc test.
  
  
  RESULTS
  There was no significant difference in the number of microcracks and dentinal tubule openings present in the root apices prepared by the three retrotips. The time required for root-end cavity preparation using the DC retrotip was significantly less than that using the other groups (P<0.01). Positive controls showed dye penetration throughout the length of the root-end cavity, and negative controls showed no dye penetration. There was no significant difference between the three experimental groups in dye penetration.
  
  
  CONCLUSIONS
  In this laboratory study, the time required to prepare root-end cavities using KiS retrotips was the same as that using CT-5 retrotips, and longer than that using DC retrotips. There was no significant difference in the number of microcracks or dye penetration between the three kinds of retrotips.
authors.affiliation: Pulp Biology and Endodontics, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. h-ishikawa.endo@tmd.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Ishikawa
authors.forename: N
authors.initials: N
authors.lastname: Sawada
authors.forename: C
authors.initials: C
authors.lastname: Kobayashi
authors.forename: H
authors.initials: H
authors.lastname: Suda
mesh_terms: D000704:Analysis of Variance; D001047:Apicoectomy; D002244:Carbon; D004396:Coloring Agents; D001840:Dental Bonding; D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D018130:Diamond; D004867:Equipment Design; D006801:Humans; D008855:Microscopy, Electron, Scanning; D012387:Root Canal Filling Materials / Q000737:chemistry; D018915:Root Canal Preparation / Q000295:instrumentation*; D013499:Surface Properties; D013997:Time Factors; D019227:Tooth Apex / Q000648:ultrastructure*; D014465:Ultrasonics; D015040:Zirconium
chemical_list: D004396:Coloring Agents; D017220:Dentin-Bonding Agents; D012387:Root Canal Filling Materials; C028433:chinese ink; D002244:Carbon; D018130:Diamond; C084074:Super EBA; D015040:Zirconium