Influence of Ultrasonic Irrigation and Chloroform on Cleanliness of Dentinal Tubules During Endodontic Retreatment-An Invitro SEM Study

Background: Ultrasonic irrigation has been proved for its remarkable cleaning efficiency in the field of endodontics. But its role in endodontic re-treatment has been understated. There is not much data available to understand the effect of ultrasonic irrigation for the evaluation of cleanliness of dentinal tubules when it is used with or without chloroform, a gutta percha solvent during endodontic retreatment. Aim: To compare the influence of ultrasonic irrigation with syringe irrigation on cleanliness of dentinal tubules after gutta perch removal for endodontic retreatment with or without the use of chloroform a gutta percha solvent using scanning electron microscope (SEM). Materials and Methods: Freshly extracted 45 human mandibular premolar teeth for periodontal and orthodontic reasons were taken and were occlusally adjusted to a working length of 19 mm. The root canals of all teeth were prepared chemo mechanically to a master apical file size 40 and were divided in various groups. In Group 1 (n = 5; control group), the canals remained unfilled. In Groups 2 and 3 (n = 20 each), the canals were filled using lateral compaction with gutta-percha and AH plus sealer, removal of root fillings was undertaken after 2 weeks using Gates Glidden drills and H files without chloroform in Group 2 and with chloroform in group 3. The specimen of Group 2 and 3 were further divided into two subgroups I and II (n= 10). In subgroup I, irrigation was done using side vented needles and sodium hypochlorite. In subgroup II irrigation was done using passive ultrasonic irrigation with sodium hypochlorite. Thereafter, the roots were split and the sections were observed under SEM. The number of occluded dentinal tubules /total number of dentinal tubules were calculated for the coronal, middle and apical third of each root half. Statistical analysis was performed using one-way ANOVA followed by Tukey's test using standardized technique. Result: Results indicated that the cleanest dentinal tubules were found in the control group (Group 1 where the canals were unfilled) followed by the non chloroform group with ultrasonic irrigation (Group 3 subdivision II) followed by chloroform group with ultrasonic irrigation (Group 2 subdivision II), the non chloroform group with syringe irrigation (Group 3 subdivision I) and least cleanliness was found in the chloroform group with syringe irrigation (Group 2 subdivision I). Conclusion: Under the limitations of this study it could be concluded that both ultrasonic and syringe irrigation showed cleaner canals when chloroform was not used. Irrigation when done with ultrasonics leads to cleaner tubules than syringe irrigation. Hence, mechanical methods of retrieval in conjunction with use of passive ultrasonic irrigation should be a part of retreatment protocol.