## 1 Introduction  
Periapical surgery aims at treating persistent endodontic pathosis remaining after conventional root canal therapy [1; 2; 3]. The past 30 years have seen immense development in this field. Nowadays, periapical surgery is mostly performed as endodontic microspurgery, and it should be so, given the advantages of this approach over the conventional method [4; 5]. Endodontic microsurgery amalgamates the benefits of magnification and illumination offered by the microscope, integrates modern microinstruments alongside microsurgical techniques, and employs biomaterials [4; 6; 7; 8]. With these improvements, the success rate has increased from 44.2-53.5% (conventional periapical surgery) to 90.5-91.1% (endodontic microsurgery) [9; 10]. Despite these technological improvements, the success of surgical treatments is highly influenced by the operator factor as well. The experience of the dentist or the surgeon is a key factor during any intervention. Several studies suggested that guided surgeries may be of superior precision compared with freehand manipulation. [PERSON] and colleagues indicated that surgical guidance can offer enhanced precision and consistency in endodontic surgery, with added benefits of three-dimensional presurgical visualization [11]. [PERSON] and colleagues highlighted the effectiveness of trephine burs when guided by 3D surgical guides, demonstrating their ability to achieve precise osteotomies, with predictable positioning, angulation, and depth of preparation [12]. The findings of [PERSON] et al., drawn from simulated surgery on 3D-printed teeth, support the notion that guided endodontic microsurgery yields improved osteotomy and resection outcomes, along with optimal root-end resection volume and level angle [13]. Additionally, [PERSON] et al., through a retrospective analysis of 24 cases, concluded that guided trephine bur root-end resection yields comparable success rates to the established outcomes of freehand bur resection [14]. Irrespective of performing traditional periapical surgery or modern endodontic microsurgery, it is essential to surgically remove the apical 3 mm of the root along with the persistent periapical lesion [5; 15]. This requires a skilled operator, visualization, and accuracy. Digitalization, in the form of routinely using CBCT in endodontic microsurgery cases, facilitates accurate diagnosis and meticulous case evaluation. It enables precise localization of the root apex and the adjacent periapical lesion, while also safeguarding delicate neighboring tissues [16; 17]. A CBCT image with appropriate resolution can also help us decide in which cases a periapical surgical procedure can be safely performed and in which cases it should be avoided owing to the close proximity of vital anatomical structures [18]. Still, adequate root resection without unnecessary tissue removal remains a challenge [19]. Endodontic microsurgery can be further simplified by using digitally planned, 3D-printed, polymer-based templates and guides for certain steps during the procedure [20]. Digital guides have been used for endodontic microsurgery since 2007 [21]. [PERSON] and colleagues virtually planned osteotomies with the help of an implant planning software (CADImplant Inc., Burlington, MA, USA), and five examiners performed freehand and guided apicectomy via the CAD/CAM templates according to the 3D plan [11]. However, the method was inchoate: it laid the foundation for guided endodontic surgical interventions, demonstrating its higher accuracy. Since then, polymer-based templates and guides have been used for multiple purposes, gradually improving and adding more features to achieve the required accuracy and to aid root-end resection at any given point of the oral cavity [12; 22; 23]. The first step was to accurately define the osteotomy window [24], and even to retract soft tissues during endodontic surgery [25]. These actions were only intended to make the surgical intervention manageable and easier, without any guidance at the apicoectomy itself.