Potential of an Er:YAG laser in the removal of calcium hydroxide from root canals

The purpose of this study was to assess the calcium hydroxide (CH) removal potential of an Er:YAG laser in combination with ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) irrigation.

Removal of the CH dressing prior to the root canal filling is mandatory, as its remnants may mechanically block the apical area of the root canal system and also have an effect on the texture, viscosity, working time, penetration, and adhesion of root canal sealers. However, the removal of CH from the canal space is challenging, because it should ideally be placed deep and densely, so that its biological effects can be exerted in close proximity to the appropriate tissues.

In this study, the mandibular premolar teeth were embedded in acrylic blocks and sectioned longitudinally through the canal, forming two halves following shaping of the root canals with ProTaper (Maillefer, Ballaigues, Switzerland) rotary instruments. The teeth were reassembled after standard grooves created onto canal walls were filled with CH. In group 1, conventional irrigation was performed with 10 mL of 17% EDTA and 10 mL of 5% NaOCl, and in goup 2, Er:YAG laser following conventional irrigation was performed. Images of the grooves taken before and after irrigation were scored and the Mann-Whitney U test was used to statistically evaluate the results.

The percentage of CH score reduction was 46.30% in group 1 and 60.58% in group 2. No significant difference was found between two groups (p>0.05).

The laser did not improve the removal of CH during conventional root canal irrigation performed with NaOCl and EDTA under the conditions of current study.