Authors: Bergenholtz G, Lekholm U, Milthon R, Engstrom B.
Title: Influence of apical overinstrumentation and overfilling on re-treated root canals.
Journal: J Endod
Date: Oct 1979
Citation: 5(10):310-4
Category: Endodontic Retreatment
Evidence-based Ranking: 2
Purpose/ Objectives: To study the effects of over-instrumentation and overfilling on the results of the re-treatments performed in the previous study.

Material and Methods: 660 previously filled roots were retreated. Indications for re-treatment were either technically incomplete root fillings without observable periapical bone lesions (technical group) or periapical bone lesions distinctly observable on radiographs (osteitis group). The new root filling was obturated with gutta-percha and resin in chloroform as an adhesive in the canal. 344 patients (556 root canals) returned for reexamination after two years.

Results: Overfills were found in 195 (35%) of the 556 re-treated root fillings; 72 (22%) within the technical group, and 123 (52%) within the osteitis group. The total number of periapical lesions on roots having overfills was 92 (47%), whereas 49 (14%) of periapical lesions were recorded on roots not overfilled. There was a significant higher incidence of periapical lesions on overfilled roots than on roots without excess filling.

AuthorÂ’s Conclusion: Results suggest that the root filling material was not the immediate cause of the unsuccessful cases, but that unsuccessful cases were caused either by a persistent root canal infection or by a reinfection in the apical areas favored by the over instrumentation.

ReviewerÂ’s Comments: In this study, sealer was not used during the obturation. Root filling was made by using gutta-percha dip in chloroform as an adhesive in the canal. I think the shrinkage of G.P. from chloroform-dip and the irritation from the chloroform itself could also attribute to failure.