title: Evaluation of apical preparations performed with ultrasonic  diamond and stainless steel tips at different intensities using  a scanning electron microscope in endodontic surgery.
abstract: OBJECTIVE
  The objective of our study is to analyse (with the help of scanning electron microscopes) the quality of the dental root surface and the appearance of dental cracks after performing apical preparations using two different types of ultrasonic tips.
  
  
  METHODS
  We used 32 single-rooted teeth that underwent a root canal and apical resection. Afterwards, the teeth were divided into 4 groups of 8 teeth each, with preparations of the apical cavities in the following manner: Group 1: stainless steel ultrasonic tip at 33 KHz. Group 2: stainless steel ultrasonic tip at 30 KHz. Group 3: diamond ultrasonic tip at 30 KHz. Group 4: diamond ultrasonic tip at 33 KHz. The quality of the root surface and the presence of cracks were evaluated by one single observer using a scanning electron microscope.
  
  
  RESULTS
  All of the teeth in our study had cracks after the apical preparations. The mean number of cracks per tooth ranged between 6. ± 1.9 (group 1) and 3.5 ± 2.4 (group 4), with a significantly higher number found in the groups that used stainless steel tips (P=.03). The types of cracks produced involved: 8 complete cracks (4.5%), 167 incomplete cracks (94.4%), and 2 intradentinal cracks (1.1%), with no significant differences observed between the different frequencies used for each group.
  
  
  CONCLUSIONS
  Stainless steel ultrasonic tips provoked a larger number of cracks than diamond tips. The frequency of vibration used did not have any effect on the number of cracks found.
authors.affiliation: Faculty of dentistry, University of Seville, Sevilla, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Rodríguez-Martos
authors.forename: Daniel
authors.initials: D
authors.lastname: Torres-Lagares
authors.forename: Lizett
authors.initials: L
authors.lastname: Castellanos-Cosano
authors.forename: María-Angeles
authors.initials: MA
authors.lastname: Serrera-Figallo
authors.forename: Juan-José
authors.initials: JJ
authors.lastname: Segura-Egea
authors.forename: Jose-Luis
authors.initials: JL
authors.lastname: Gutierrez-Perez
mesh_terms: D001047:Apicoectomy / Q000295:instrumentation* / Q000379:methods*; D018130:Diamond; D006801:Humans; D008855:Microscopy, Electron, Scanning; D012390:Root Canal Therapy / Q000295:instrumentation* / Q000379:methods*; D013193:Stainless Steel; D014464:Ultrasonic Therapy / Q000295:instrumentation*
chemical_list: D013193:Stainless Steel; D018130:Diamond