Evaluation of filling material remnants after basic preparation, apical enlargement and final irrigation in retreatment of severely curved root canals in extracted teeth

Abstract

Aim To compare the retreatment ability of several rotary and reciprocating file systems in curved root canals of extracted teeth and to evaluate the influence of additional apical enlargement performed after a basic retreatment on the amount of remaining filling material. Methodology A total of 65 round curved root canals were used. The root canals were prepared with the ProTaper Next rotary system to size 25, .06 taper and filled with an epoxy resin‐based sealer and gutta‐percha using continuous wave vertical compaction and warm injection back‐filling. The canals were randomly divided into four groups according to the retreatment system used: Group I. ProTaper Universal Retreatment system + ProTaper Gold (PTG) instrumentation system up to PTG F2; Group II. Reciproc Blue system up to the instrument RB25; Group III. Reciproc system up to the instrument R25; Group IV. Wave One Gold (WOG) system up to the instrument WOG25. After the basic retreatment, additional apical enlargement was performed in each group with an instrument that was one size larger: in Group I, II and III up to apical size 40, and in Group IV up to 35. The final irrigation protocol included the following: 15% ethylenediaminotetraacetic acid followed by NaOCl irrigation. The volume of filling material was measured using an industrial micro‐CT four times: after root canal filling (Volume I), after basic retreatment with size 25 files (Volume II), after additional root canal enlargement with larger instruments (Volume III), and after the final irrigation protocol (Volume IV). The decrease in the amount of filling material after each retreatment protocol was analysed using a Kruskal–Wallis test. Intergroup analyses were performed with a Kruskal–Wallis test and between‐group differences were further analysed with Mann–Whitney U test. Results There were no significant differences amongst the systems tested in the amount of remaining filling material, or the reduction rates after each phase of the retreatment procedures (P > 0.05). Intragroup analysis indicated that the use of a larger final instrument removed significantly more filling material in all groups (P < 0.001). Conclusion The four tested instrumentation systems were equally effective in removing filling materials from curved root canals in extracted teeth. Additional apical enlargement with larger files improved the removal of filling remnants after basic retreatment.

Effect of Sonic Agitation of a Binary Mixture of Solvents on Filling Remnants Removal as an Alternative to Apical Enlargement—A Micro-CT Study

“…The present investigation aimed to study the effectiveness of the sonic agitation of a mixture of solvents on the volume of filling material remnants in mandibular incisors, and to assess if it would compare to progressive apical enlargement. Similar to other investigations, the sample was standardized, based on an initial radiographic evaluation and apical gauging, to avoid relevant bias regarding canal anatomy and filling material volume [ 11 , 12 ]. Statistical analysis revealed a similar volume of filling materials before retreatment and between groups and sections ( Table 1 ).…”

“…Even though the referenced study evaluated the remaining pulp tissue and debris instead of residual filling materials, the results demonstrate the influence of the irrigation strategy overcoming the insufficiencies of the instrumentation approach, irrespective of the canal configuration (round vs. oval). Further research should focus particularly on the effect of different apical preparation sizes in conjunction with activated irrigation and whether it would result in similar filling removal [ 12 , 28 ].…”

“…An increased enlargement of apical re-preparation has been associated with a lower volume of residual filling materials [ 7 , 10 , 12 ]. This difference has been reported between additional instrumentation with larger tip sizes (size 35–40) compared to size 25.…”

“…Adjunctive procedures show controversial outcomes and still do not enable the thorough cleaning of root canals [ 5 , 6 , 7 , 8 , 9 , 10 ]. Using a larger preparation size would be expected to result in fewer unprepared areas and, consequently, a higher volume of old filling material removal, optimizing disinfection [ 7 , 10 , 11 , 12 , 13 ]. Nevertheless, a correlation between disinfection and optimal canal size was failed to be proved [ 14 , 15 ].…”

Evaluation of Three Ni-Ti Systems in Retreatment of Curved Root Canals Obturated by Gutta-Percha With iRoot SP

“…Numerous studies presented that some mechanical nickel-titanium (Ni-Ti) instruments, in particular rotary and reciprocating systems, exhibited e ciency in root canal retreatment [11,12,13,14,15,16,17]. In these studies, Protaper Universal Retreatment (PTR) system, Waveone Gold (WOG) system, and Reciproc Blue (RB) system are regularly applied to curved root canal retreatment.…”