Removal of resin-based root canal filling materials with K3 rotary instruments: relative efficacy for different combinations of filling materials.

Division of Cariology, Operative Dentistry and Endodontics, Department of Oral Health Sciences, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakko-cho-dori, Chuo-ku, Niigata 951-8514, Japan.
Dental Materials Journal (Impact Factor: 0.94). 02/2008; 27(1):75-80. DOI: 10.4012/dmj.27.75
Source: PubMed

ABSTRACT Removal of resin-based root canal filling materials may cause serious problems during root canal retreatment. This study compared the working time and amount of canal enlargement when different resin-based root canal filling materials were removed with K3 rotary instruments with or without heat-softening using System B. Root canal sealer/filling point combinations tested were Epiphany/Resilon, SuperBond/Resilon, SuperBond/gutta-percha, and Canals N/gutta-percha. The materials were filled into simulated curved resin canals and removed with K3 instruments in a standardized crown-down procedure. In terms of working time, Epiphany/Resilon required a significantly longer working time than the others. However, heat application with System B significantly reduced the working time for the removal of Epiphany/Resilon. In terms of canal enlargement, there were no significant differences among the tested groups as determined with digital morphometry. It was thus concluded that Epiphany removal with K3 rotary instruments might result in extended working time, but which could be reduced with heat-softening using System B.

Download full-text


Available from: Takashi Okiji, Jun 29, 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Roggendorf MJ, Legner M, Ebert J, Fillery E, Frankenberger R, Friedman S. Micro-CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments. International Endodontic Journal, 43, 200–209, 2010.AbstractAim  To assess the efficacy of removing Activ GP or GuttaFlow from canals using NiTi instruments.Methodology  Root canals in 55 extracted pre-molars were prepared to apical size 40, 0.04 taper. The teeth were imaged with micro-CT, and 30 teeth selected that had consistent apical size and taper of the shaped canals. They were randomly assigned to root filling with either the glass-ionomer-based ActivGP system (n = 15) or the polyvinylsiloxane-based GuttaFlow system (n = 15). After 2 weeks, canals were retreated stepwise with size 40–50 EndoSequence 0.04 taper instruments. Micro-CT scans (8 μm) were taken after use of each instrument to detect root filling residue in the coronal, middle and apical segment, and the retreatment time recorded. Residue, expressed as percentage of canal surface area, was compared between groups with t-tests, and within groups with repeated measures anova and Bonferroni-adjusted pairwise comparisons. Retreatment time was analysed with one-way anova.Results  The percentage of sealer residue-coated canal surface was consistently highest (P < 0.001) in the apical third of canals, and it did not differ significantly between the two root filling groups. Stepwise enlargement from size 40 to 50 significantly decreased the amount of sealer residue in both groups (P < 0.001). Retreatment time did not differ significantly between groups.Conclusions  Both root fillings with ActivGP and GuttaFlow were removed with nickel-titanium rotary instruments. Enlargement of canals up to two sizes beyond the pre-retreatment size was necessary to minimize the amount of sealer remaining.
    International Endodontic Journal 02/2010; 43(3):200 - 209. DOI:10.1111/j.1365-2591.2009.01659.x · 2.27 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Despite improvements and advances in materials and methods, root canal treatment is not always suc-cessful. As a result, practitioners are faced with the challenges of managing endodontic failure in every-day clinical practice. Non-surgical retreatment is a widely practised option and offers another chance of salvaging a failing, previously root-treated tooth. Understanding the causes of failure is critical to correcting the inadequacies related to a previously root canal-treated tooth. Persistent intraradicular in-fection is the commonest cause of failure 1,2 . During initial root canal treatment, the detectable presence of residual intraradicular bacteria has a significant effect on outcome 3 ; it was reported that after five years the success rate dropped from 94% to 68% 4 . Other causes of failure include extraradicular infec-tion, cystic lesions, extruded root canal filling or other exogenous materials causing a foreign body reaction, cholesterol crystals and scar tissue formation 5,6 . From a microbiological perspective, a distinc-tion has to be made between teeth that are tech-nically well root canal-treated and those that are not, as this will have a bearing on the retreatment approach. Teeth with inadequately instrumented and poorly obturated root canals may be associated with larger periapical radiolucencies. Those that have not been properly chemomechanically debrided tend to have a similar microbiota to untreated root ca-nals 3,7 . On the other hand, well-treated cases as-sociated with continuing periapical pathosis have a different microbiological balance, both qualitatively and quantitatively. In these cases, there are fewer microbial species and the microbiota is dominated by facultative rather than strict anaerobes 3,7,8 . A fundamental step in non-surgical retreatment is the removal of the existing root filling material to permit radicular access. Different root filling materials require different techniques of removal. The endodontic literature is littered with studies exploring the relative merits of one technique of removal over another. In this review, the focus is on the experimental models and techniques employed to investigate the removal of root filling materials during non-surgical retreatment. The correlation and clinical relevance to everyday endodontic practice is also discussed.
  • Source