Effectiveness of Brush-Finisher in calcium hydroxide removal from root canal system

Introduction
It is very important to remove all intra-canal dressing placed between endodontic visits. The most common canal dressing is calcium hydroxide. Apart from its well-known benefits, calcium hydro­xide is considered difficult to be completely removed from root canal system. In the literature, in an assessment of the effect of material removal from root canals, superiority of some instruments over the other are reported. Objectives: The aim of the study was to analyze the impact of Brush-Finisher on removing an intra-canal dressing in different root canal widths.

Material and methods
The study was performed using extracted single-rooted teeth, which were prepared to standardize all samples and divided into 2 groups, including large canals (LC, n = 8) and narrow canals (NC, n = 8) groups. As a control group of narrow and wide canals, a syringe with an endodontic needle was used (LC, n = 8 and NC, n = 8). Calcium hydroxide paste was placed into the canals. After 2 weeks, cleaning procedure was performed using 2% NaOCl and a Brush-Finisher. After agitation of the rinsing solution, radiographs were taken in bucco-lingual and mesio-distal projections. Then, all radiographs were uploaded to graphic software, and the roots were divided into 3 parts: apical, middle, and coronal, and a crisscross pattern was carried out. Every square field located along the course of canal was calculated and evaluated in terms of the absence or presence of canal dressing. P-value of < 0.05 was assumed statistically significant. For comparison of individual proportions, N-1 c2 test was used, while Marascuilo procedure was applied to evaluate significance between particular comparison of pairs.

Results
Significant difference between efficacy of Ca(OH)2 removal was observed comparing middle and coro­nal level in LC group (0.077) as well as between apical and middle level (0.106) and coronal and middle level (0.082) in NC group.

Conclusions
Activation of irrigation with the Brush-Finisher was more beneficial in removing Ca(OH)2 in narrow rather than large canals. Cleaning was less efficient in middle levels of both groups.