title: Effect of customization of master gutta-percha cone on apical control of root filling using different techniques: an ex vivo study.
abstract: OBJECTIVE
  (i) To compare the prevalence of extrusion of root filling material when placed using different root filling techniques, with or without customization of the master gutta-percha (GP) cone; and (ii) to investigate the effects of some factors influencing root filling extrusion and presence of voids.
  
  
  METHODS
  A total of 180 roots were selected, prepared and randomly allocated to three groups. Five general dental practitioners performed the root fillings; each filled one group of roots (n = 60) using each of three techniques; 'cold lateral compaction' (n = 20), 'warm vertical compaction' (n = 20) and 'continuous-wave' (n = 20) techniques. For each obturation technique, the master GP cone was customized using chloroform in 10 samples. Two groups of the roots were recycled to allow all five operators to fulfill their remit. Two observers, blind to operator and obturation technique, examined the radiographs (master apical file, post-obturation) to determine the presence of root filling extrusion and voids within the apical 5 mm, independently. Root filling extrusion was also confirmed by direct inspection of the root apex after obturation. The data were analysed using logistic regression models.
  
  
  RESULTS
  A total of 300 root fillings were performed; nine were excluded from the analysis. Most of the root fillings (80%, n = 233) were placed within 0.5 mm of the working length; only 20% (n = 58) were placed >0.5 mm beyond the working length. The odds of prevalence of extrusion (>0.5 mm) were significantly reduced by about 50% when cold lateral compaction or customization of GP were used. One operator produced 2.5 times more extruded root fillings than others. Curvature & length of root canal, apical size of prepared canal, as well as operator's preferred obturation technique had no significant influence on the prevalence of extrusion. Customization of GP was the sole factor to significantly reduce the prevalence of voids within the apical 5 mm of working length.
  
  
  CONCLUSIONS
  Root filling extrusion was significantly influenced by 'operator' and was reduced by cold lateral compaction and customization of the master cone. Customization of master cone was the only factor that reduced voids apically.
authors.affiliation: Unit of Endodontology, Eastman Dental Institute, University College London, London, UK.
authors.forename: S P
authors.initials: SP
authors.lastname: van Zyl
authors.forename: K
authors.initials: K
authors.lastname: Gulabivala
authors.forename: Y-L
authors.initials: YL
authors.lastname: Ng
mesh_terms: D002983:Clinical Competence; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000209:etiology*; D006171:Gutta-Percha / Q000009:adverse effects*; D006801:Humans; D016015:Logistic Models; D011897:Random Allocation; D012387:Root Canal Filling Materials / Q000009:adverse effects; D012389:Root Canal Obturation / Q000009:adverse effects / Q000379:methods*; D019227:Tooth Apex
chemical_list: D012387:Root Canal Filling Materials; D006171:Gutta-Percha