title: The effect of using an inverted master cone in a lateral compaction technique on the density of the gutta-percha fill.
abstract: OBJECTIVE
  We sought to measure and calculate the percentage of the gutta-percha-filled area in the apical root canal after the use of a standardized or inverted master cone in cold lateral compaction.Study design Two groups of extracted mandibular premolars with a single canal were instrumented with instruments of the same size; furthermore, they were obturated with laterally compacted gutta-percha cones with AH26 used as a sealer. In the first group, a standardized master cone was used with its narrow end in an apical position, whereas in the other group, an inverted master cone was used with its wide end in an apical position. The 2 master cones had the same apical diameter and fit in the apical canal. After lateral compaction, horizontal sections were cut at a level 3 and 5 mm from the apex of each filled tooth. Photographs of the sections were taken by using a microscope equipped with a digital camera; the photos were then scanned as tagged-image file format images. The cross-sectional area of the canal and the gutta-percha were measured by using an image-analysis program. The percentage of gutta-percha-filled area was calculated.
  
  
  RESULTS
  At both levels, the inverted master cone produced a significantly higher percentage, statistically, of gutta-percha-filled area than did the standardized master cone (P =.001 at 3 mm; P =.012 at 5 mm).
  
  
  CONCLUSIONS
  The use of an inverted master cone in cold lateral compaction may facilitate the apical placement of accessory cones, significantly increasing the volume of gutta-percha while reducing the volume of sealer in the apical root canal.
authors.affiliation: Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherland. n.wu@acta.nl
authors.forename: Min-Kai
authors.initials: MK
authors.lastname: Wu
authors.forename: Sjoerd D
authors.initials: SD
authors.lastname: de Groot
authors.forename: Luc W M
authors.initials: LW
authors.lastname: van der Sluis
authors.forename: Paul R
authors.initials: PR
authors.lastname: Wesselink
mesh_terms: D001729:Bismuth / Q000737:chemistry / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D004338:Drug Combinations; D004853:Epoxy Resins / Q000737:chemistry / Q000627:therapeutic use; D006171:Gutta-Percha / Q000737:chemistry / Q000627:therapeutic use*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D012387:Root Canal Filling Materials / Q000737:chemistry / Q000627:therapeutic use*; D012389:Root Canal Obturation / Q000379:methods*; D018915:Root Canal Preparation / Q000295:instrumentation; D012834:Silver / Q000737:chemistry / Q000627:therapeutic use; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry / Q000627:therapeutic use
chemical_list: D004338:Drug Combinations; D004853:Epoxy Resins; D012387:Root Canal Filling Materials; D012834:Silver; C028044:epoxy resin AH-26; D006171:Gutta-Percha; D014025:Titanium; D001729:Bismuth