title: An ex vivo comparison of three different gutta-percha cones when compacted at different temperatures: rheological considerations in relation to the filling of lateral canals.
abstract: OBJECTIVE
  To compare ex vivo the penetration of three brands of gutta-percha cones, compacted under a constant force and heated to different temperatures, into artificial lateral canals.
  
  
  METHODS
  Resin blocks with simulated main canals, each having two lateral canals (C at 6.5 and A at 13 mm from the surface of the resin block), were selected. A gutta-percha cone, either Mynol MF, Hygenic MF or GT Tulsa 0.04 was compacted into each main canal for 5 s using a wire rod with a diameter of 0.7 mm soldered to the bottom of a metal cylinder, with a force of 2.7 kg at controlled temperatures of 37, 42, 47, 52, 60 degrees C. The penetration of each brand of gutta-percha into 60 lateral canals (10 at each temperature) was measured using a stereomicroscope. Statistical analysis was performed using the ANOVA, the Scheffè test and the t-test.
  
  
  RESULTS
  None of the three brands of cones entered up to 0.1 mm within either lateral canal until a temperature of 47 degrees C was reached; at that temperature only Mynol cones (P < or = 0.05) penetrated in four of 10 A-level canals (mean 0.13 +/- 0.19 mm) and in all 10 C-level canals (mean 0.43 +/- 0.12 mm). The A-level lateral canals were penetrated at 52 degrees C by Mynol cones (mean 0.76 +/- 0.34 mm) to a significantly greater distance (P < or = 0.05) than Tulsa cones (mean 0.31 +/- 0.12 mm) and Hygenic cones (mean 0.11 +/- 0.08 mm). At 60 degrees C the Mynol cones (mean 1.93 +/- 0.34 mm) penetrated significantly more (P < or = 0.05) than the Tulsa cones (mean 0.86 +/- 0.22 mm) and Hygenic cones (mean 0.67 +/- 0.19 mm). The C-level lateral canals were penetrated at 52 degrees C by Mynol cones (mean 0.91 +/- 0.29 mm) to a significantly greater distance (P < or = 0.05) than Tulsa cones (mean 0.47 +/- 0.16 mm) and Hygenic cones (mean 0.46 +/- 0.15 mm), whilst no significant difference was found at 60 degrees C.
  
  
  CONCLUSIONS
  When heated and compacted, the three gutta-percha cones penetrated the lateral canals to different degrees. They penetrated more than 0.43 mm into the lateral canals only at temperatures higher than 47 degrees C.
authors.affiliation: Department of Dental Sciences, Alma Mater Studiorum, University of Bologna, Bologna, Italy. info@endodonziamauroventuri.it
authors.forename: M
authors.initials: M
authors.lastname: Venturi
authors.forename: R
authors.initials: R
authors.lastname: Di Lenarda
authors.forename: L
authors.initials: L
authors.lastname: Breschi
mesh_terms: D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D006171:Gutta-Percha / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D011312:Pressure; D012212:Rheology; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012389:Root Canal Obturation / Q000379:methods; D013499:Surface Properties; D013696:Temperature; D014783:Viscosity
chemical_list: D012387:Root Canal Filling Materials; D006171:Gutta-Percha