title: The risk of furcal perforation in mandibular molars using Gates-Glidden drills with anticurvature pressure.
abstract: OBJECTIVE
  The aim of this study was to determine whether using Gates-Glidden (GG) drills and anticurvature pressure in curved mesial root canals of mandibular molars could remove more dentin from the mesial canal wall and remove less dentin from the distal canal wall at a level 2 mm below the furcation.
  
  
  METHODS
  In 5 groups of mesial roots with an average curvature of 32-34 degrees, 103 canals were prepared using a size #2 or #3 GG drill in the coronal third (straight portion of the canal only) or coronal half (straight portion and part of the curved portion), with or without applying anticurvature pressure. Using a modification of the Bramante muffle mold the cross-section of the mesial root at 2 mm below bifurcation was photographed twice, before and after the use of GG; the photos were then scanned as tagged image files. The thickness of the mesial and distal canal walls wer measured using an image analysis program. The reduction of the wall thickness after the use of GG was calculated.
  
  
  RESULTS
  Before enlargement, the average and minimal thickness of the distal wall was 0.92 and 0.43 mm respectively, thinner than that of the mesial wall (1.50 and 0.87 mm, correspondingly). After the use of GG, the reduction of the mesial wall was similar to the reduction of the distal wall (P > .05 for all groups). In 4 groups the maximal reduction of the distal wall was > or =0.72 mm.
  
  
  CONCLUSIONS
  After using GG drills and anticurvature pressure, dentin was uniformly removed regardless of the size of the GG and the depth of placement of GG. Flaring with GG drills in mandibular molars may result in perforations; application of anticurvature pressure did not reduce the risk.
authors.affiliation: Department of Cariology, Endodontology, and Pedodontology, Academic Centre For Dentistry Amsterdam, Amsterdam, the Netherlands. m.wu@acta.nl
authors.forename: Min-Kai
authors.initials: MK
authors.lastname: Wu
authors.forename: Luc W M
authors.initials: LW
authors.lastname: van der Sluis
authors.forename: Paul R
authors.initials: PR
authors.lastname: Wesselink
mesh_terms: D003762:Dental Instruments / Q000009:adverse effects*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008334:Mandible; D008963:Molar; D009811:Odontometry; D023861:Photography, Dental; D011312:Pressure; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation*; D018677:Tooth Injuries / Q000209:etiology / Q000517:prevention & control; D014092:Tooth Root / Q000033:anatomy & histology* / Q000293:injuries