Objectives <p>This study evaluated surgical temperature, accuracy, and efficiency in endodontic microsurgery (EMS) using the sleeveless guided system.</p> Materials and methods <p>Sleeveless and sleeve guided systems were fabricated. Thermocouples were used to measure temperature changes during guided preparation in models (<i>n</i> = 5) featuring bone blocks installed in anterior, premolar, and molar regions. 72 teeth in 6 EMS models used for simulating the clinical scenario of endodontic microsurgery were equally randomized into 6 groups by guide type (sleeveless/sleeve/freehand) and operator experience, with each group containing matched dentition (2 anterior/2 premolar/2 molar teeth per arch; <i>n</i> = 12). Preoperative and postoperative models were superimposed using 3-matic Medical evaluate preparation accuracy, with surgical duration compared for efficiency. Temperature data were analyzed via t-test; accuracy and efficiency were assessed using two-way ANOVA.</p> Results <p>The sleeveless guided system demonstrated significantly lower surgical area temperatures than the sleeve guided system (<i>P</i> &lt; 0.001). Compared to freehand, it reduced three-dimensional (3D) deviation by 1.14&#xa0;mm (52.8%), angular deviation by 4.06° (49.6%), and surgical time by 40.5&#xa0;s (<i>P</i> &lt; 0.05). When using sleeveless system, experienced operators exhibited reductions of 0.65&#xa0;mm in 3D deviation and 4.51° in angular deviation, whereas inexperienced operators demonstrated larger reductions of 1.96&#xa0;mm and 5.79° respectively. No significant differences were observed between guide systems in accuracy or efficiency (<i>P</i> &gt; 0.05).</p> Conclusion <p>The sleeveless guided system effectively reduces heat generation and enhances surgical accuracy and efficiency compared to freehand techniques significantly, with performance comparable to the sleeve guided system.</p> Clinical relevance <p>The sleeveless guided system demonstrates promising applications in EMS.</p>