title: Comparison of the remaining dentin thickness in the root after hand and four rotary instrumentation techniques: an in vitro study.
abstract: OBJECTIVE
  The aim of the present study was to compare the remaining dental thickness (RDT) in the mesiobuccal root of mandibular first molars at 3 and 7 mm from the anatomic apex after instrumentation with ProTaper, light speed LSX, K3 and M2 and to compare with that of K-files.
  
  
  METHODS
  In this study, 60 extracted, untreated human mandibular first molars with fully formed apices, with curvature less than 35° and no root resorption were used. Prepared specimens were cut horizontally at 3 and 7 mm short of anatomic apex. The least dentin thickness from canal to external root surface was observed under 3× magnification and recorded using Clemax measuring tool and the sections were reassembled. Group I-instrumentation with ProTaper, group II-instrumentation with K3, group III-instrumentation with Light Speed LSX, group IV-instrumentation with M2 and group V- instrumentation with K-files and RDT was measured.
  
  
  RESULTS
  Results showed that group V removed lesser amount of dentin compared to all other groups while all the three instrumentation techniques removed almost equal amount of dentin apically.
  
  
  CONCLUSIONS
  Cleaning and shaping of the root canal space involves the elimination of pathogenic contents as well as attaining a uniform specific shape. However, the RDT following the use of various intraradicular procedures is an important factor to be considered as an iatrogenic cause that may result in root fracture. To avoid this, newer rotary instruments are being introduced.
authors.affiliation: Professor and Head, Department of Conservative Dentistry and Endodontics, Sree Sai Dental College and Research Institute Srikakulam, Andhra Pradesh, India.
authors.forename: M S Rama
authors.initials: MS
authors.lastname: Rao
authors.forename: Abdul
authors.initials: A
authors.lastname: Shameem
authors.forename: Rashmi
authors.initials: R
authors.lastname: Nair
authors.forename: Sureshbabu
authors.initials: S
authors.lastname: Ghanta
authors.forename: Rekha P
authors.initials: RP
authors.lastname: Thankachan
authors.forename: Johnson K
authors.initials: JK
authors.lastname: Issac
mesh_terms: D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D004867:Equipment Design; D006801:Humans; D008963:Molar / Q000648:ultrastructure; D009811:Odontometry / Q000295:instrumentation / Q000379:methods; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D019227:Tooth Apex / Q000648:ultrastructure