Comparison of Rotary Retreatment Instruments and H-files with/without Solvent Material

Objectives: The aim of this ex-vivo study was to evaluate the efficacy of Protaper retreatment files in comparison with hand files for removal of gutta-percha root fillings with and without solvent material.
Methods: Forty-eight extracted single-rooted human teeth with straight canals and mature apices were selected for this study. Root canals were shaped with ProTaper Universal instruments up to size F2. Root canals were obturated with laterally compacted gutta-percha and a zinc oxide eugenol sealer. The teeth were randomly divided into four retreatment groups (n=12): Group 1 Protaper Universal Retreatment; Group 2 Protaper Universal Retreatment with the solvent eucalyptol; Group 3 Hedstrom files; Group 4 Hedstrom files with the solvent eucalyptol. Time required to retreatment procedure were recorded for all the roots. Roots were divided into apical, middle and coronal parts and residual material within the root canal walls were scored on a scale of 1 (no debris) to 6 (> about 4 mm2), radiographically. Statistical analysis of working time was performed using One-way ANOVA (p<0,05). Root canal wall cleanliness were evaluated with the Kruskal-Wallis test and Mann Whitney-U test, statistically (p<0,05).
Results: Protaper Universal Retreatment instruments with eucalyptol (+Eu) reached the working lenght most rapidly, followed by Protaper Universal Retreatment instruments, Hedstrom files+Eu, Hedstrom files. Significant differences were found for retreatment time in all groups (p<0,001). With respect to root canal wall cleanliness, in general, coronal parts were found the best clean parts, followed by middle, and apical parts. However, there was no significant difference in coronal part and middle part in all groups (p=0,10; p=0,06). In apical part, only Group 2 showed significant efficiency for removal filling material than Group 3 (p=0,007).
Conclusions: Within the limits of this study, Protaper retreatment instruments were found faster in terms of root canal filling material removal. Additional use of a solvent decreased retreatment time for all instruments. Protaper retreatment instruments and Hedstrom files produced similarly clean canals except Group 2 as compared to Group 3 in apical part.