Effectiveness of calcium hydroxide removal with irrigation techniques using ProTaper and ultrasonic activation: an in vitro study

Background: Residual calcium hydroxide might adversely affect the outcome of endodontic treatment results. Calcium hydroxide affect the adhesion of endodontic sealers to the canal walls and interfere with sealing ability of endodontic sealers. To remove this intracanal medicament, there are various irrigation techniques have developed. The aim of this study was to evaluate the effectiveness of different techniques in removing calcium hydroxide from the root canal. Materials and methods: Thirty extracted single-rooted mandibular premolar were instrumented and filled with calcium hydroxide and divided into three groups (n = 10/group). After 7 days, calcium hydroxide was removed. All root canals were received 2.5% NaOCl, followed by 17% EDTA and a final flush with 2.5% NaOCl. In group I, no additional agitation of the irrigant was performed. In group II, agitation was done for 20 s between irrigants with a size of F2 ProTaper rotary file. In group III, an ultrasonic activation was delivered for 20 s between irrigants. Finally, the roots were grooved longitudinally and split in two halves. Selected half of each tooth was observed under a stereomicroscope at 30x magnification. Results: In groups needle irrigation and ProTaper technique, score of residual calcium hydroxide in apical third is higher than cervical and middle thirds (p < 0.05). Needle groups demonstrated the significantly higher score of residual calcium hydroxide than ProTaper and ultrasonic groups (p < 0.05). Conclusion: None of irrigation techniques could remove all calcium hydroxide completely. Ultrasonic irrigation and ProTaper irrigation was more effective in removing calcium hydroxide than needle irrigation. Key words: calcium hydroxide, irrigation solution, ultrasonic irrigation.