title: [The effect of different gutta-percha master cones on first penetration depth of spreader and apical microleakage].
abstract: OBJECTIVE
  This study was to evaluate the effect of different master cones on apical microleakage through comparing first penetration depth of spreader and the leakage concentration of glucose in the curved root canal of the extracted posterior teeth filled with different gutta-percha master cones.
  
  
  METHODS
  Sixty-six extracted roots of human posterior teeth with a single, curved canal were collected and divided into five experimental groups of 11 roots in each group (Group A:master cone 0.06 tapered, 25#; Group B: 0.06 tapered, 20#; Group C: 0.04 tapered, 30#; Group D: 0.04 tapered, 25#; Group E: 0.02 tapered, 25#) using cold lateral condensation as positive control group(group F, AH-PLUS sealer) of 5 roots and negative control (group G, integrated teeth) of 6 roots. The first penetration depth of spreader and the concentration of glucose in apical reservoir at 1, 2, 4, 7, 10, 15, 20 and 30 days were measured, respectively. The data was analysed with ANOVA and LSD test using SPSS 16.0 software package.
  
  
  RESULTS
  The value of working length minus the first penetration depth of spreader in group D was significantly smaller than that in group A and group C(P<0.05),and that in group E was significantly smaller than that in group A ,B,C(P<0.05), but no significant difference(P>0.05) in other groups. The concentration of leakage glucose in group F was significantly higher than that in the other six groups(P<0.05),and there were no significant difference in the five experimental groups (P>0.05),which had no significant difference from the negative control group G(P>0.05).
  
  
  CONCLUSIONS
  Choosing smaller tapered master cone could get better apical filling in curved canals, but it has no superiority in apical sealing in short time.
authors.affiliation: Department of Stomatology, Jinshan Hospital, Fudan University, Shanghai 200540, China. liuliuhui463@sohu.com
authors.forename: Liu-hui
authors.initials: LH
authors.lastname: Liu
authors.forename: Xiao-li
authors.initials: XL
authors.lastname: Xie
authors.forename: Min-min
authors.initials: MM
authors.lastname: Chen
authors.forename: Ling-yun
authors.initials: LY
authors.lastname: Yin
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D006171:Gutta-Percha; D006801:Humans; D012387:Root Canal Filling Materials; D012389:Root Canal Obturation; D018915:Root Canal Preparation; D012390:Root Canal Therapy
chemical_list: D012387:Root Canal Filling Materials; D006171:Gutta-Percha