title: Cone-beam Computed Tomography Volumetric Analysis and Comparison of Dentin Structure Loss after Retrieval of Separated Instrument by Using Ultrasonic EMS and ProUltra Tips.
abstract: BACKGROUND
  A separated instrument within the root canal may interfere in the successful outcome of endodontic treatment. The retrieval of fractured instruments might compromise the remaining tooth structure and subsequently resistance to tooth fracture. The aim of this study was to compare the change in volume of root canal and dentin thickness after retrieval of separated instrument by 2 different endodontic ultrasonic tips.
  
  
  METHODS
  Each of the instruments (EMS Endochuck and ProUltra #6, #7, and #8 tips) was used to remove 40 separated rotary ProTaper F2 instruments from the mesiobuccal roots of mandibular molar under ×15 magnification. Cone-beam computed tomography analysis of the samples was done to evaluate the change in volume, dentin thickness, weight, time taken, and success.
  
  
  RESULTS
  Paired sample t test showed statistically significant (P < .05) difference in volume before and after instrument retrieval in both the EMS group, where the increase was 112.52%, and in the ProUltra group, where the increase was by 55.35%. Intergroup comparison showed statistically significant (P < .05) decrease in dentin thickness; it was more for EMS as compared with ProUltra. Overall decrease in the mean weight of EMS group (18.42%) was more than that of ProUltra group (9.36%). The overall success rate for removal of fractured instrument in this study was 87.5%; however, the difference in success rate was not statistically significant. The mean time taken for retrieval by ProUltra system was 63.89 minutes, whereas it was significantly less (P < .05) for EMS system (50.22 minutes).
  
  
  CONCLUSIONS
  Removal of separated instrument with EMS resulted in more significant tooth structure loss as compared to ProUltra.
authors.affiliation: PDM Dental College and Research Institute, Bahadurgarh, Haryana, India.
authors.forename: Himani
authors.initials: H
authors.lastname: Garg
authors.affiliation: PDM Dental College and Research Institute, Bahadurgarh, Haryana, India. Electronic address: mandeepsgrewal@me.com.
authors.forename: Mandeep S
authors.initials: MS
authors.lastname: Grewal
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003722:Dental Alloys / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology; D003804:Dentin / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000473:pathology*; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D009532:Nickel / Q000737:chemistry; D011861:Radiography, Dental; D019252:Radiography, Dental, Digital / Q000379:methods; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation*; D014025:Titanium / Q000737:chemistry; D014082:Tooth Fractures / Q000628:therapy; D014092:Tooth Root / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Cone beam computed tomography (CBCT); EMS; ProTaper; ProUltra; dentin thickness; retrieval; volume