Efficiency of rotary nickel-titanium FlexMaster instruments compared with stainless steel hand K-Flexofile--Part 2. Cleaning effectiveness and instrumentation results in severely curved root canals of extracted teeth.

AIM To determine the cleaning effectiveness and the shaping ability of FlexMaster nickel-titanium rotary instruments and stainless steel hand K-Flexofiles during the preparation of curved root canals in extracted human teeth. METHODOLOGY A total of 48 root canals with curvatures ranging between 25 degrees and 35 degrees were divided into two groups of 24 canals. Based on radiographs taken prior to the instrumentation with the initial instrument inserted into the canal, the groups were balanced with respect to the angle and the radius of canal curvature. Canals were prepared by FlexMaster instruments using a crown-down preparation technique or by K-Flexofiles using a reaming working motion up to size 35. After each instrument, the root canals were flushed with 5 mL of a 2.5% NaOCl solution and at the end of instrumentation with 5 mL of NaCl. Using the pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. After splitting the roots longitudinally, the amount of debris and smear layer were quantified on the basis of a numerical evaluation scale, using a scanning electron microscope. RESULTS Completely cleaned root canals were not found with any of the two instruments. In general, K-Flexofiles resulted in significantly less debris(P < 0.001) and less smear layer (P < 0.05) than Flex-Master instruments, but these differences were not significant in the apical third of the canals (P > 0.05). FlexMaster instruments maintained the original canal curvature significantly better (P < 0.0001) than K-Flexofiles. No significant differences were detected between the instruments (P > 0.05) for the time taken to prepare the canals. CONCLUSIONS Under the conditions of this study, K-Flexofiles allowed significantly better canal cleaning than FlexMaster instruments. FlexMaster instruments maintained the original curvature significantly better.

[1]  E. Schäfer,et al.  Efficiency of rotary nickel-titanium FlexMaster instruments compared with stainless steel hand K-Flexofile--Part 1. Shaping ability in simulated curved canals. , 2002, International endodontic journal.

[2]  T. Cengiz,et al.  The effects of sodium hypochlorite and calcium hydroxide on tissue dissolution and root canal cleanliness. , 1997, International endodontic journal.

[3]  E. Schäfer,et al.  A comparative scanning electron microscopic investigation of the efficacy of manual and automated instrumentation of root canals. , 2000, Journal of endodontics.

[4]  L. Spångberg,et al.  Biologic effects of dental materials. 3. Toxicity and antimicrobial effect of endodontic antiseptics in vitro. , 1973, Oral surgery, oral medicine, and oral pathology.

[5]  Buchanan Ls,et al.  Cleaning and shaping the root canal system: negotiating canals to the termini. , 1994 .

[6]  P R Wesselink,et al.  Efficacy of three techniques in cleaning the apical portion of curved root canals. , 1995, Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics.

[7]  Wolfgang Hoppe,et al.  Roentgenographic investigation of frequency and degree of canal curvatures in human permanent teeth. , 2002, Journal of endodontics.

[8]  Consensus report of the European Society of Endodontology on quality guidelines for endodontic treatment. , 1994, International endodontic journal.

[9]  B. Y. Cha,et al.  Shaping ability of three ProFile rotary instrumentation techniques in simulated resin root canals. , 2000, Journal of endodontics.

[10]  O. Bolanos,et al.  Scanning electron microscope comparisons of the efficacy of various methods of root canal preparation. , 1980, Journal of endodontics.

[11]  S. Zecchi Orlandini,et al.  Scanning electron microscope study on the efficacy of root canal wall debridement of hand versus Lightspeed instrumentation. , 1999, International endodontic journal.

[12]  M. Goldman,et al.  A scanning electron microscopic comparison of a high volume final flush with several irrigating solutions: Part 3. , 1983, Journal of endodontics.

[13]  K. Kahnberg,et al.  Intraradicular bacteria and fungi in root-filled, asymptomatic human teeth with therapy-resistant periapical lesions: a long-term light and electron microscopic follow-up study. , 1990, Journal of endodontics.

[14]  M. Hülsmann,et al.  Complications during root canal irrigation--literature review and case reports. , 2000, International endodontic journal.

[15]  M Hülsmann,et al.  Root canal cleanliness after preparation with different endodontic handpieces and hand instruments: a comparative SEM investigation. , 1997, Journal of endodontics.

[16]  Y. Haikel,et al.  Effectiveness of four methods for preparing root canals: a scanning electron microscopic evaluation. , 1988, Journal of endodontics.

[17]  S A Thompson,et al.  Shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated root canals. Part 1. , 1997, International endodontic journal.

[18]  S. Mizrahi,et al.  A scanning electron microscopic study of the efficacy of various endodontic instruments. , 1975, Journal of endodontics.

[19]  G. Gambarini.  Shaping and cleaning the root canal system: a scanning electron microscopic evaluation of a new instrumentation and irrigation technique. , 1999, Journal of endodontics.