Effects of root canal preparation on apical geometry assessed by micro-computed tomography.

INTRODUCTION Previous micro-computed tomography analyses of root canal preparation provided data that were usually averaged over canal length. The aim of this study was to compare preparation effects on apical root canal geometry. METHODS Sixty extracted maxillary molars (180 canals) used in prior studies were reevaluated for analyses of the apical 4 mm. Teeth were scanned by using micro-computed tomography before and after canal shaping with FlexMaster, GT-Rotary, Lightspeed, ProFile, ProTaper, instruments or nickel-titanium K-files for hand instrumentation. Apical preparation was to a size #40 in mesiobuccal and distobuccal and #45 in palatal canals except for GT (#20) and ProTaper (#25 in mesiobuccal and distobuccal and #30 in palatal canals, respectively). Data for canal volume changes, the structure model index (quantifying canal cross sections), and untreated surface area were contrasted by using analysis of variance and Scheffé tests. RESULTS Mean mesiobuccal, distobuccal, and palatal canal volumes increased after preparation (P < .05), but differences were noted for preparation techniques. GT rendered the smallest (0.20 +/- 0.14 mm(3)); K-files and ProFile showed the largest volume increases (0.51 +/- 0.20 mm(3) and 0.45 +/- 021 mm(3), P < .05). All canals were slightly rounder in the apical 4 mm after preparation indicated by nonsignificant increases in structure model index. Untreated areas ranged from 4%-100% and were larger in mesiobuccal and palatal canals than in distobuccal ones. Preparation with GT left significantly larger untreated areas in all canal types (P < .05); among root canal types, distobuccal canals had the least amounts of untreated surface areas. CONCLUSIONS Apical canal geometry was affected differently by 6 preparation techniques; preparations with GT instruments to an apical size #20 left more canal surface untouched, which might affect the ability to disinfect root canals in maxillary molars.

[1]  L Bergmans,et al.  Smooth flexible versus active tapered shaft design using NiTi rotary instruments. , 2002, International endodontic journal.

[2]  Ove A. Peters,et al.  Mechanical preparation of root canals: shaping goals, techniques and means , 2005 .

[3]  Ove A Peters,et al.  Current challenges and concepts in the preparation of root canal systems: a review. , 2004, Journal of endodontics.

[4]  J. Taylor.  An Introduction to Error Analysis , 1982 .

[5]  O. Peters,et al.  ProTaper rotary root canal preparation: effects of canal anatomy on final shape analysed by micro CT. , 2003, International endodontic journal.

[6]  A. Reader,et al.  The in vivo evaluation of hand/rotary/ultrasound instrumentation in necrotic, human mandibular molars. , 2007, Journal of endodontics.

[7]  Z. Ram.  Effectiveness of root canal irrigation. , 1977, Oral surgery, oral medicine, and oral pathology.

[8]  P J Liepins,et al.  Micro-computed tomography: a new tool for experimental endodontology. , 1999, International endodontic journal.

[9]  R E Walton,et al.  The influence of the method of canal preparation on the quality of apical and coronal obturation. , 1979, Journal of endodontics.

[10]  C M Bramante,et al.  A methodology for evaluation of root canal instrumentation. , 1987, Journal of endodontics.

[11]  E. Fu,et al.  Dynamic recording of irrigating fluid distribution in root canals using thermal image analysis. , 2007, International endodontic journal.

[12]  W. Saunders,et al.  Reduction in intracanal bacteria during root canal preparation with and without apical enlargement. , 2002, International endodontic journal.

[13]  H. Messer,et al.  The quality of apical canal preparation using hand and rotary instruments with specific criteria for enlargement based on initial apical file size. , 2002, Journal of endodontics.

[14]  T. Chow.  Mechanical effectiveness of root canal irrigation. , 1983, Journal of endodontics.

[15]  M Lucotte,et al.  [Endodontic therapy]. , 1985, Le Chirurgien-dentiste de France.

[16]  M. Iqbal,et al.  A comparison of LightSpeed LS1 and LightSpeed LSX NiTi rotary instruments in apical transportation and length control in simulated root canals. , 2007, Journal of endodontics.

[17]  S. K. Bentkover,et al.  Canal wall planning by engine-driven nickel-titanium instruments, compared with stainless-steel hand instrumentation. , 1997, Journal of endodontics.

[18]  P. Wesselink,et al.  The efficacy of ultrasonic irrigation to remove artificially placed dentine debris from human root canals prepared using instruments of varying taper. , 2005, International endodontic journal.

[19]  P. Nair.  On the causes of persistent apical periodontitis: a review. , 2006, International endodontic journal.

[20]  P. Rüegsegger,et al.  Three-dimensional Analysis of Root Canal Geometry by High-resolution Computed Tomography , 2000, Journal of dental research.

[21]  O A Peters,et al.  Root-canal preparation with FlexMaster: canal shapes analysed by micro-computed tomography. , 2003, International endodontic journal.

[22]  Asgeir Sigurdsson,et al.  The effectiveness of increased apical enlargement in reducing intracanal bacteria. , 2002, Journal of endodontics.

[23]  B. Pişkin,et al.  Observation of bacteria and fungi in infected root canals and dentinal tubules by SEM. , 1995, Endodontics & dental traumatology.

[24]  M. Haapasalo,et al.  Eradication of endodontic infection by instrumentation and irrigation solutions , 2005 .

[25]  O A Peters,et al.  Effects of four Ni-Ti preparation techniques on root canal geometry assessed by micro computed tomography. , 2001, International endodontic journal.

[26]  A. Sigurdsson,et al.  Reduction of intracanal bacteria using GT rotary instrumentation, 5.25% NaOCl, EDTA, and Ca(OH)2. , 2005, Journal of endodontics.

[27]  Dean Baugh,et al.  The role of apical instrumentation in root canal treatment: a review of the literature. , 2005, Journal of endodontics.

[28]  J. Marshall,et al.  Evaluation of apical debris removal using various sizes and tapers of ProFile GT files. , 2004, Journal of endodontics.

[29]  P. Wesselink,et al.  Does the first file to bind correspond to the diameter of the canal in the apical region? , 2002, International endodontic journal.

[30]  P R Wesselink,et al.  A primary observation on the preparation and obturation of oval canals. , 2001, International endodontic journal.