Objectives <p>This study investigated how different access cavity designs and irrigation solutions influence the removal of calcium hydroxide from root canals.</p> Materials and methods <p>Eighty-four mandibular molars were divided into three groups according to their access cavities (traditional access cavity, ultra-conservative access cavity, and support access cavity) and treated with calcium hydroxide mixed with rhodamine B. Each group was further divided into four subgroups based on the irrigation solutions used: 6&#xa0;ml salin, 6&#xa0;ml 17% EDTA, 6&#xa0;ml 70% ethanol, and 6&#xa0;ml 0.2% chitosan. All irrigation solutions were applied for 3&#xa0;min. After irrigation, apical sections were examined with CLSM and analyzed using ImageJ. Statistical analysis was performed using two-way ANOVA followed by Tukey post hoc tests with 95% confidence intervals. (<i>p</i> &lt; 0.05).</p> Results <p>The Truss access cavity design resulted in cleaner canals than the ultra-conservative access cavity (<i>p</i> &lt; 0.05) but There was no significant difference between the truss access cavity and the conventional access cavity (<i>p</i> &gt; 0,05). While 70% ethanol and 0.2% chitosan showed similar effectiveness (<i>p</i> &gt; 0,05), 70% ethanol was significantly more effective than 17% EDTA and saline (<i>p</i> &lt; 0.05).</p> Conclusions <p>Access cavity design may influence the effectiveness of calcium hydroxide removal during endodontic treatment. Truss access cavities provided cleaning performance comparable to traditional access cavities while preserving tooth structure. Additionally, 70% ethanol and 0.2% chitosan may be considered potential alternatives to 17% EDTA for calcium hydroxide removal.</p>