title: Residual dentin thickness in mandibular premolars prepared with gates glidden and ParaPost drills.
abstract: BACKGROUND
  The main factor that determines the prognosis of restored pulpless teeth is preservation of sound dentin.
  
  
  OBJECTIVE
  This study evaluated the residual dentinal thickness (RDT) of mandibular premolars after preparation of post space with Gates Glidden and ParaPost drills.
  
  
  METHODS
  Twelve extracted single canal mandibular premolars were embedded in clear polyester resin to the cementoenamel junction (CEJ) in a muffle device. Three horizontal sections were made 1, 3, and 5 mm apical to the CEJ. Mesiodistal (MD) and faciolingual (FL) axes were carefully marked and the RDT was measured for each slice. Each tooth slice was reassembled in the muffle device with orientation pins, then secured with stabilizing pins. This procedure was repeated after enlarging the root canal to K-40 file and preparing the coronal root canal space with Gates Glidden drills and ParaPost drills Nos. 3, 4, and 5.
  
  
  RESULTS
  Residual dentinal thickness in a MD direction was 3.77 +/- 0.51 mm in the unprepared upper slice and 2.23 +/- 0.31 mm in the No. 5 ParaPost drill prepared lower slice, for a difference of 41%. The corresponding values for the FL direction were 4.35 +/- 0.51 mm and 4.08 +/- 0.46 mm, respectively (6%).
  
  
  CONCLUSIONS
  The average dentinal thickness 5 mm below the CEJ in the mesial and distal directions after post space preparation approached the accepted minimal 1 mm. A conservative approach to post space preparation was advocated.
authors.affiliation: The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. rafipilo@Post.Tau.Ac.il
authors.forename: R
authors.initials: R
authors.lastname: Pilo
authors.forename: A
authors.initials: A
authors.lastname: Tamse
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid / Q000033:anatomy & histology*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D003804:Dentin / Q000033:anatomy & histology*; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D008334:Mandible; D011176:Post and Core Technique / Q000295:instrumentation* / Q000706:statistics & numerical data; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D019237:Tooth Cervix / Q000033:anatomy & histology