Damage to root dentin during retreatment procedures

Journal of Endodontics

Volume 37, Issue 1, January 2011, Pages 63-66

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Basic Research
Damage to Root DentinDuring Retreatment Procedures
Hagay Shemesh DMD, PhD, Alida C. Roeleveld DDS, Paul R. Wesselink DDS, PhD and Min-Kai Wu MD, MSD, PhD
Department of Endodontology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands

Available online 9 December 2010.

Abstract
Introduction
The aim of this study was to explore the influence of retreatment procedures on the appearance ofdefects on the root canal walls.
Methods
Two hundred mandibular premolars were divided into 4 groups. One group was left unprepared. The rest of the teeth were prepared with ProTaper files up to size F4 and filled with gutta-percha and AH26. One group was left filled and received no further treatments. The filling material was removed from the remaining teeth either with ProTaper retreatment filesor with Hedström files. Roots were then sectioned and inspected under a microscope. Data were analyzed with the nominal regression test (α = 0.05).
Results
No defects were observed in the unprepared group. Retreatment groups showed significantly more defects than the initial treatment group (P < .05).There was no difference between the appearance of defects after retreatment with Hedström filesand ProTaper retreatment files. The remaining dentin thickness and level of the root did not significantly influence the appearance of defects.
Conclusions
Retreatment procedures result in more defects than initial treatment. When assessing the outcomes of endodontic retreatment, the substantial damage to the root canal walls should be considered.
Key Words: Hedström file; nickel-titanium;retreatment; root dentin; rotary files
Article Outline
Materials and Methods
Canal Filling
Filling Removal
Evaluation
Examination of Roots
Statistical Analysis
Results
Discussion
Conclusions
Acknowledgements
References
Orthograde retreatment procedures are performed when initial root canal treatments fail. Although the outcome of these retreatments isfavorable (1), it was frequently associated with a lower healing rate than that of initial treatment. Procedural errors like perforations and inadequate root filling length were shown to be the most significant factors to influence the outcome (1) and (2) as well as presence of periapical lesion and good coronal restoration (3). When orthograde retreatment is indicated, efficient removal of the fillingmaterial from the root canal system is essential to ensure a favorable outcome (4) and (5). However, the complete removal of endodontic fillings is difficult or impossible (6). Several techniques can be used for this purpose, including stainless steel files, nickel-titanium (NiTi) rotary instruments, heat-bearing instruments, ultrasonics, and solvents. Novel techniques seek improved results throughNiTi rotary instruments and the operating microscope. One example of a dedicated rotary system for the removal of gutta-percha is the ProTaper Universal system for retreatment (Dentsply Maillefer, Ballaigues, Switzerland). It consists of 3 instruments: D1 with tip 30 and taper 0.09, D2 with tip 25 and taper 0.08, and D3 with tip 20 and taper 0.07.
Defects on the root canal wall were shown toappear after root canal preparation and filling (7) and (8). Nonetheless, the appearance of defects was only checked after initial endodontic treatment. Because retreatment requires more mechanical manipulations in the canal and further preparation of the root canal, it could be that more damage to the root canal wall is caused after these procedures.
The purpose of this experiment was to assess...