title: The Effect of the Dental Operating Microscope on the Outcome of Nonsurgical Root Canal Treatment: A Retrospective Case-control Study.
abstract: BACKGROUND
  The aim of the current investigation was to assess the effect of the use of a dental operating microscope on the outcome of nonsurgical root canal treatment (NS RCT) while treating the mesiobuccal (MB) root of the maxillary first molar.
  
  
  METHODS
  This retrospective investigation included endodontically treated maxillary first molars (ETMs) with apparent adequate previous NS RCT and restorations referred for endodontic retreatment at the endodontic graduate clinic. Inclusion criteria were ETMs that were diagnosed with irreversible pulpitis and normal periapical tissues before the initial NS RCT and ETMs that presented with a minimum of 1 identifiable periapical lesion (PAR) at 1 of the roots at the time of retreatment. One hundred ninety-five ETMs were included and divided into 2 groups: (1) the initial NS RCT had been performed using a microscope (n = 83) and (2) NS RCT had been performed without the use of a microscope (n = 112). Data extracted were whether the second MB (MB2) canal was located initially and the presence of an MB PAR at the time of retreatment. Data were statistically analyzed using binary logistic regression (α = 0.05).
  
  
  RESULTS
  The MB root was 3 times more likely to present with a PAR at the time of retreatment if the initial NS RCT was performed without the use of a microscope (P < .05, odds ratio = 3.1). There was a significant association between a missed MB2 canal and an MB PAR in the group in which the initial NS RCT was performed without the use of a microscope (P < .05, odds ratio = 5.1). However, in cases in which the initial NS RCT was performed using a microscope, a missed MB2 canal was not associated with the presence of an MB PAR.
  
  
  CONCLUSIONS
  With proper education, dentists can gain further insight into recognizing limitations in treating cases that require advanced training and advanced optics such as a microscope. Based on this strategy, it would appear that the outcome of NS RCT can be improved.
authors.affiliation: Department of Endodontics, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Navid
authors.initials: N
authors.lastname: Khalighinejad
authors.affiliation: Department of Endodontics, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio. Electronic address: Axa53@case.edu.
authors.forename: Anita
authors.initials: A
authors.lastname: Aminoshariae
authors.affiliation: Department of Endodontics, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: James C
authors.initials: JC
authors.lastname: Kulild
authors.affiliation: Department of Public Health, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Kristin A
authors.initials: KA
authors.lastname: Williams
authors.affiliation: Department of Endodontics, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Jeannie
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Endodontics, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Andre
authors.initials: A
authors.lastname: Mickel
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008853:Microscopy / Q000379:methods; D008875:Middle Aged; D012189:Retrospective Studies; D012390:Root Canal Therapy / Q000295:instrumentation* / Q000379:methods; D016896:Treatment Outcome