title: Frequency of overinstrumentation with an acceptable radiographic working length.
abstract: The aim of this in vitro study was to determine how frequent a seemingly accurate working length ending radiographically 0 to 2 mm short of the radiographic apex resulted in an instrumentation beyond the apical foramen. Under simulated clinical conditions working lengths of 169 root canals were radiographically determined in 91 extracted teeth. In all cases the measuring files adjusted to the final working length (Iwork) were located 0 to 2 mm short of the radiographic apex. Iwork was subsequently compared with the actual reference length (Iref) representing the distance between the apical foramen and the coronal reference. Instrumentation beyond the apical foramen (Iwork > ref) occurred in premolars in 51% (95% confidence interval: 36%; 66%) of the cases, in molars in 22% (95% confidence interval: 14%; 30%), and in anterior teeth in no case. These results suggest that in premolars and molars a radiographically working length ending 0 to 2 mm short of the radiographic apex provides, more often than expected, a basis for unintentional overinstrumentation.
authors.affiliation: Department of Conservative Dentistry, School of Dental Medicine, University of Tübingen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: ElAyouti
authors.forename: R
authors.initials: R
authors.lastname: Weiger
authors.forename: C
authors.initials: C
authors.lastname: Löst
mesh_terms: D001641:Bicuspid / Q000000981:diagnostic imaging; D016001:Confidence Intervals; D003481:Cuspid / Q000000981:diagnostic imaging; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D006801:Humans; D007180:Incisor / Q000000981:diagnostic imaging; D008963:Molar / Q000000981:diagnostic imaging; D011670:Pulpectomy / Q000295:instrumentation / Q000379:methods; D011859:Radiography; D015203:Reproducibility of Results; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D019227:Tooth Apex / Q000000981:diagnostic imaging*; D014092:Tooth Root / Q000000981:diagnostic imaging