title: [Evaluation of the use of dental operating microscope in the management of blocked canals].
abstract: OBJECTIVE
  This study was performed to evaluate the value of dental operating microscope(DOM) in treating blocked canals.
  
  
  METHODS
  161 blocked canals in 113 teeth were treated with ultrasonic instruments under DOM. The etiology of canal blockage included calcification, resinifying therapy and broken instruments. All canals were grouped based on the cause of blockage, teeth site and blockage location in canals, and then the success rates of negotiating ,using SPSS10.0 software package, were analyzed with X(2) test.
  
  
  RESULTS
  The results showed that 131 canals were negotiated with a success rate of 81.37%.Blocked canals caused by calcification, resinifying therapy and broken instruments were managed with the success rate of 84.27%, 81.58% and 73.53%, respectively.There were no significant differences in the success rate(P>0.05). Blocked canals of anterior were managed successfully with a success rate of 93.48%,canals of premolar with a success rate of 84.61%,and canals of molar with a success rate of 72.37%. There were significant differences in the success rate between anterior and molar teeth(P<0.01).When the blockage was located in straight canals or above the root canal curvature,canals were negotiated with a success rate of 93.98>.However,the success rate decreased to 21.42> when the blockage located below the root canal curvature,and significant differences were found(P<0.01).
  
  
  CONCLUSIONS
  It is an effective way to use dental operating microscope to treat blocked canals, but the therapeutic effects might be affected by sites of the teeth and the blockage location in canals.
authors.affiliation: Department of Endodontics, Hefei Stomatological Hospital, Hefei 230001, Anhui Province, China.
authors.forename: Li-li
authors.initials: LL
authors.lastname: Yao
authors.forename: Yun-song
authors.initials: YS
authors.lastname: Gao
authors.forename: Fang
authors.initials: F
authors.lastname: Niu
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Fu-hua
authors.initials: FH
authors.lastname: Zhang
mesh_terms: D003762:Dental Instruments; D006801:Humans; D008853:Microscopy; D012390:Root Canal Therapy