title: Micro-computed tomography analysis of post space preparation in root canals filled with carrier-based thermoplasticized gutta-percha.
abstract: OBJECTIVE
  To determine whether post space preparation deviated from the root canal preparation in canals filled with Thermafil, GuttaCore or warm vertically compacted gutta-percha.
  
  
  METHODS
  Forty-two extracted human permanent maxillary lateral incisors were decoronated, and their root canals instrumented using a standardized protocol. Samples were divided into three groups and filled with Thermafil (Dentsply Tulsa Dental Specialties, Johnson City, TN, USA), GuttaCore (Dentsply Tulsa Dental Specialties) or warm vertically compacted gutta-percha, before post space preparation was performed with a GT Post drill (Dentsply Tulsa Dental Specialties). Teeth were scanned using micro-computed tomography after root filling and again after post space preparation. Scans were examined for number of samples with post space deviation, linear deviation of post space preparation and minimum root thickness before and after post space preparation. Parametric data were analysed with one-way analysis of variance (anova) or one-tailed paired Student's t-tests, whilst nonparametric data were analysed with Fisher's exact test.
  
  
  RESULTS
  Deviation occurred in eight of forty-two teeth (19%), seven of fourteen from the Thermafil group (50%), one of fourteen from the GuttaCore group (7%), and none from the gutta-percha group. Deviation occurred significantly more often in the Thermafil group than in each of the other two groups (P < 0.05). Linear deviation of post space preparation was greater in the Thermafil group than in both of the other groups and was significantly greater than that of the gutta-percha group (P < 0.05). Minimum root thickness before post space preparation was significantly greater than it was after post space preparation for all groups (P < 0.01).
  
  
  CONCLUSIONS
  The differences between the Thermafil, GuttaCore and gutta-percha groups in the number of samples with post space deviation and in linear deviation of post space preparation were associated with the presence or absence of a carrier as well as the different carrier materials.
authors: Division of Endodontics, University of British Columbia, Vancouver, BC, Canada.
authors: A A
authors: AA
authors: Schroeder
authors: Centre for High-Throughput Phenogenomics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada.
authors: N L
authors: NL
authors: Ford
authors: Division of Endodontics, University of British Columbia, Vancouver, BC, Canada.
authors: J M
authors: JM
authors: Coil
mesh_terms: D000704:Analysis of Variance; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D006171:Gutta-Percha; D006801:Humans; D008422:Materials Testing; D012387:Root Canal Filling Materials; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000379:methods*; D055114:X-Ray Microtomography
chemical_list: D012387:Root Canal Filling Materials; D006171:Gutta-Percha
keywords: GuttaCore; Thermafil; carrier-based obturation; deviation; micro-computed tomography; post space preparation