title: Influence of Taper of Root Canal Shape on the Intracanal Bacterial Reduction.
abstract: OBJECTIVE
  Taper is a factor that determines final root canal dimensions and consequently, the space available for the cleaning action of irrigants. Therefore, the aim of this study was to investigate the influence of taper on intracanal bacterial reduction.
  
  
  METHODS
  Sterilized root canals of 25 mandibular incisors were inoculated withE. faecalisand then divided into two experimental groups and one control group (A= saline, B= NaOCl + EDTA and C= control, not prepared). Groups A and B were prepared to an apical size of #30/0.04, a culture was obtained and then prepared to #30/0.08 and cultured again. Final irrigation sequence was 30 ml of saline for group A and 10 ml of 17% EDTA followed by 10 ml of 2.5% NaOCl and 10 ml of saline for group B. The CFU ml-1of the pre- and two post-operative samplings were recorded. Values were compared by performing ANOVA and FDR for multiple hypothesis testing.
  
  
  RESULTS
  No statistically significant difference between initial CFU ml-1readings was recorded, whereas significant differences between group A and B at both 4% and 8% tapers were noted. Furthermore, a linear-dependent reduction of CFU ml-1was recorded in each group from non-instrumented root canals to #30/0.04 and subsequently to #30/0.08. The positive control group shows the expected reduction of bacterial count.
  
  
  CONCLUSIONS
  Chemomechanical instrumentation was more efficient at reducingE. faecaliswhen the taper of root canals increased from 4% to 8% and NaOCl plus EDTA led to a greater intracanal bacterial reduction than saline, regardless of the taper achieved.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Mary Th
authors.initials: MT
authors.lastname: Paraskevopoulou
authors.affiliation: Department of Endodontics, Faculty of Dentistry, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Marouan G
authors.initials: MG
authors.lastname: Khabbaz
keywords: Disinfection; Intracanal bacterial reduction; Irrigation; Root canal preparation; Taper