Endodoncia

Effectiveness of different techniques for removing gutta-percha during retreatment

A. V. Masiero1 & F. B. Barletta2
Department of Dentistry and Endodontics, School of Dentistry,Universidade Federal de Pelotas, Pelotas, Brazil; and Department of Endodontics, School of Dentistry, Universidade do Planalto Catarinense, Lages, Brazil; 2Department of Dentistry and Endodontics, School of Dentistry,Universidade Luterana do Brazil, Canoas, Brazil
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Abstract
Masiero AV, Barletta FB. Effectiveness of different techniques for removing gutta-percha during retreatment. International Endodontic Journal, 38, 2–7, 2005.

Aim To evaluate the effectiveness of various techniques for removing filling material from root canals in vitro. Methodology Eighty extracted mandibular premolar teeth wereselected for the study. The teeth were root filled using thermomechanical compaction of gutta-percha. After 8 months, the filling material was removed and canals were reinstrumented using the following techniques: group I – hand instrumentation with K-type files (SybronEndo, Orange, CA, USA); group II – K3 Endo System (SybronEndo); group III – M4 system (SybronEndo) with K-type files (SybronEndo); andgroup IV – Endo-gripper system (Moyco Union Broach, York, PA, USA) with K-type files (SybronEndo). The amount of filling debris remaining on root canal walls was assessed radiographically; the images were digitized and analysed using AutoCAD 2000 software. Total canal area, area of the cervical, middle and apical thirds, and area of remaining filling material were outlined by one operator. The ratiosbetween these

areas were calculated as percentages of remaining debris. Thereafter, data were analysed by means of oneway anova and the post-hoc Duncan test to identify differences between the four techniques. Results Multiple comparisons of the percentages of remaining filling material in the entire canal did not reveal any significant differences between the methods of removal. However, wheneach third was analysed separately, significant differences for remaining debris were present between groups. The apical third had the most remaining material, whilst the cervical and middle thirds were significantly cleaner (P ¼ 0.002). Comparison of the techniques revealed that teeth instrumented with K3 rotary instruments had a lower ratio of remaining filling material in the apical third (P ¼0.012). Conclusion In the apical third, K3 rotary instruments were more efficient in removing gutta-percha filling material than the other techniques, which were equally effective for the other thirds. Keywords: gutta-percha, nickel-titanium, root canal retreatment, rotary instrumentation.
Received 5 February 2003; accepted 28 July 2004

Introduction
Conventional endodontic retreatment has largelyreplaced endodontic surgery for the management of failed root canal treatment. This has been informed by better understanding of the factors involved in post-

Correspondence: Fernando Barletta, Praca Dom Feliciano, ¸ 126/111. Porto Alegre, RS 90020-160, Brazil (Tel.: +55 51 99555255; fax: +55 51 33353364; e-mail: fbarletta@ terra.com.br).

treatment disease and the development of new instrumentsand techniques. However, the removal of gutta-percha filling material, particularly from apparently well-condensed root canals (Ladley et al. 1991), may be time-consuming. Unfortunately, this is essential for the success of retreatment (Friedman et al. 1990). Mechanical systems have been proposed as an alternative to hand instrumentation for removing guttapercha. However, few studies (Hulsmann &Stotz 1997, ¨ Bramante & Betti 2000, Barletta & Lagranha 2002) have

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International Endodontic Journal, 38, 2–7, 2005

ª 2005 International Endodontic Journal

Masiero & Barletta Removal of filling material

investigated and compared the effectiveness of these instruments in the removal of filling material. Therefore, the objective of the present in vitro study was to evaluate the...