Evaluation of the influence of smear layer removal on the sealing ability of two different filling techniques

Abstract

Objectives: This study investigates the effects of Nd:YAG laser irradiation and 17% EDTA irrigation on apical seals with clearing technique, when used prior to two root canal filling techniques. Methods: Sixty freshly extracted human maxillary and mandibular canines and mandibular premolars, each with one root canal, were instrumented with ProTaper rotary nickel-TITanium instruments and then randomly divided into six groups according to the final irrigation solutions and Nd:YAG laser irradiation for smear layer removal and filling techniques employed: Group I: 2.5% sodium hypochlorite (NaOCl) and cold lateral condensation technique (CLC), Group II: 17% EDTA and CLC, Group III: Nd:YAG laser and CLC, Group IV: 2.5% NaOCl and thermoplasticized injectable gutta-percha technique (TIT), Group V: 17% EDTA and TIT, Group VI: Nd:YAG laser and TIT. After filling, the root surfaces were coated with a double layer of nail varnish, with the exception of the apical 2 mm, and placed in indian ink for 7 days. All samples were rendered transparent to measure the maximum linear dye penetration. Results: Group 1 showed significantly greater dye leakage compared with groups 5 and 6 (P<0.05). However, no significant difference was found between other groups (P>0.05). Canals obturated with TIT showed less mean dye leakage than canals obturated with lateral condensation. Groups, finally irrigated with 17% EDTA and irradiated with Nd:YAG laser, were showed lower mean dye leakage than control groups for both filling techniques. Conclusions: Under in vitro conditions, we found that smear layer removal improved the ability of the filling materials to prevent the fluid movement. Also, TIT showed less apical leakage than cold lateral condensation technique in the presence or absence of the smear layer.

Objectives: This study investigates the effects of Nd:YAG laser irradiation and 17% EDTA irrigation on apical seals with clearing technique, when used prior to two root canal filling techniques. Methods: Sixty freshly extracted human maxillary and mandibular canines and mandibular premolars, each with one root canal, were instrumented with ProTaper rotary nickel-TITanium instruments and then randomly divided into six groups according to the final irrigation solutions and Nd:YAG laser irradiation for smear layer removal and filling techniques employed: Group I: 2.5% sodium hypochlorite (NaOCl) and cold lateral condensation technique (CLC), Group II: 17% EDTA and CLC, Group III: Nd:YAG laser and CLC, Group IV: 2.5% NaOCl and thermoplasticized injectable gutta-percha technique (TIT), Group V: 17% EDTA and TIT, Group VI: Nd:YAG laser and TIT. After filling, the root surfaces were coated with a double layer of nail varnish, with the exception of the apical 2 mm, and placed in indian ink for 7 days. All samples were rendered transparent to measure the maximum linear dye penetration. Results: Group 1 showed significantly greater dye leakage compared with groups 5 and 6 (P<0.05). However, no significant difference was found between other groups (P>0.05). Canals obturated with TIT showed less mean dye leakage than canals obturated with lateral condensation. Groups, finally irrigated with 17% EDTA and irradiated with Nd:YAG laser, were showed lower mean dye leakage than control groups for both filling techniques. Conclusions: Under in vitro conditions, we found that smear layer removal improved the ability of the filling materials to prevent the fluid movement. Also, TIT showed less apical leakage than cold lateral condensation technique in the presence or absence of the smear layer.