Influence of Taper of Root Canal Shape on the Intracanal Bacterial Reduction.

Mary Th Paraskevopoulou,Marouan G Khabbaz

doi:10.2174/1874210601610010568

Abstract

Objectives: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 with E. faecalis and 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-1 of 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-1 readings 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-1 was 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.Conclusion:Chemomechanical instrumentation was more efficient at reducing E. faecalis when 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.

Highlights

During and after its mechanical preparation, root canal (RC) should be cleaned with irrigation solutions
All instrumentation and irrigation sequences used in this study significantly reduced the number of bacterial cells in the root canals; total elimination of the bacteria was not achieved with any of the techniques
There was a statistically significant difference of CFU ml-1 between group A (Saline) and group B (NaOCl + EDTA), at 4% and 8% tapers (p

Summary

Introduction

During and after its mechanical preparation, root canal (RC) should be cleaned with irrigation solutions. Brunson et al [2] confirmed Wandelt’s statement, showing that an increase in root canal dimensions leads to an increase in the mean volume of irrigant used inside the canal. The clinician has the ability to alter root canal dimensions by changing the final apical preparation size and/or the taper. In the era where endodontic instruments were handly used, keeping the apical preparation as wide as possible was believed to be the only way for the irrigation fluids to reach and reduce the microbial population at the critical apical 3 mm of the root canal [3 - 7]. It is believed that if apical preparation could be kept as narrow as possible while increasing root canal taper by using nickel-titanium rotary systems, this would create a greater deposit for the irrigation fluids [8]. It would lead to the greater removal of dentin from the canal walls, producing a cleaner root canal [8]

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