Removal efficacy of various calcium hydroxide/chlorhexidine medicaments from the root canal

To compare the efficiency of removing calcium hydroxide [Ca(OH)(2)]/chlorhexidine (CHX) (gel), Ca(OH)(2)/CHX (solution) and Ca(OH)(2)/saline pastes with the use of instrumentation and irrigation with sodium hypochlorite and ethylene diamine tetraacetic acid (EDTA) solutions. Moreover the role of the patency file in the cleanliness of the apical third of the root canal was evaluated.

Sixty-four human single-rooted teeth with straight canals were used. Root canal preparation was performed with a stepback technique using Hedström (H) files. Teeth were randomly assigned to three groups and subsequently filled with one of the pastes: Ca(OH)(2)/CHX (gel), Ca(OH)(2)/CHX (solution) and Ca(OH)(2)/saline paste. The medicaments were removed 10 days later using instrumentation and irrigation with 1% sodium hypochlorite and 17% EDTA, with or without obtaining patency of the apical foramen with a size 10 H-file. The crowns were removed at the cemento-enamel junction and the roots were grooved longitudinally and split into halves. Images of all halves were acquired with the use of a flatbed scanner. A scoring system of 1 to 4 was used to assess the amount of residue on the cervical, middle and apical third of the canal. Data were subjected to statistical analysis using Kruskal-Wallis and Mann-Whitney tests, with Bonferroni correction, at 95% confidence level (P < 0.05).

Remnants of medicament were found in all experimental teeth regardless of the experimental material used and the use of the patency file. When examining the root canal as a whole, Ca(OH)(2)/CHX (gel) paste was associated with significantly larger amount of residue, whereas the Ca(OH)(2)/CHX (solution) paste was associated with less amount (P < 0.05) than the other two medicaments with or without the use of a patency file.

None of the techniques used in this study removed the inter-appointment root canal medicaments effectively; the use of the patency file facilitated removal of more of the medicament in the apical third of those straight canals.