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

Abstract

<p class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 200%; text-align: justify;"><span style="font-size: small;"><span style="font-family: Times New Roman;"><strong><span style="mso-bidi-font-style: italic;">Purpose:</span></strong> 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. </span></span></p><p class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 200%; text-align: justify; mso-layout-grid-align: none;"><span style="font-size: small;"><span style="font-family: Times New Roman;"><strong style="mso-bidi-font-weight: normal;">Material and Methods:</strong> Sixty freshly extracted human mandibular premolar and canine teeth, 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 obturation techniques employed: Group I: 2.5% sodium hypochlorite (NaOCl) and cold lateral condensation technique, Group II: 17% EDTA and cold lateral condensation technique, Group III: Nd:YAG laser and cold lateral condensation technique, Group IV: 2.5% NaOCl and thermoplasticised injectable gutta-percha technique (Dia-Gun system), Group V: 17% EDTA and Dia-Gun system, Group VI: Nd:YAG laser and Dia-Gun system. After obturation, 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 <span style="mso-bidi-font-weight: bold;">rendered transparent to measure the maximum linear dye penetration.</span></span></span></p><p class="MsoNormal" style="margin: 0cm 0cm 0pt; text-indent: 35.4pt; line-height: 200%; text-align: justify; mso-layout-grid-align: none;"><span style="font-size: small;"><span style="font-family: Times New Roman;"><strong>Results:</strong><span style="mso-bidi-font-weight: bold;"> </span>Group 1 showed significantly greater dye leakage compared with groups 5 and 6 (P<0.05).<span style="mso-bidi-font-weight: bold;"> However, no significant difference was found between other groups (P>0.05). Canals obturated with Dia-Gun system showed less mean dye leakage than canals obturated with lateral condensation. </span>Groups, finally irrigated with 17%EDTA and irradiated with Nd:YAG laser, were showed lower mean dye leakage than control groups for both obturation techniques.</span></span></p><p class="MsoNormal" style="margin: 0cm 0cm 0pt; text-indent: 35.4pt; line-height: 200%; text-align: justify; mso-layout-grid-align: none;"><span style="font-size: small;"><span style="font-family: Times New Roman;"><strong style="mso-bidi-font-weight: normal;"><span style="color: #231f20;">Conclusion:</span></strong><span style="color: #231f20;"> Under in vitro conditions, we found that smear layer removal improved the ability of the filling materials to prevent the fluid movement. Also, </span>Dia-Gun system<span style="color: #231f20;"> showed less apical leakage than cold lateral condensation technique in the presence or absence of the smear layer.</span></span></span></p><p class="MsoNormal" style="margin: 0cm 0cm 0pt; line-height: 200%; text-align: justify; mso-layout-grid-align: none;"><span style="font-size: small;"><span style="font-family: Times New Roman;"><strong style="mso-bidi-font-weight: normal;"><span style="color: #231f20;">Keywords:</span></strong><span style="color: #231f20;"> Apical leakage, Dia-Gun, EDTA, Nd:YAG laser, clearing technique</span></span></span></p>