A reproducible optical-microscopic framework for evaluating electronic apex locator performance in different...

This study presents a standardized experimental framework for assessing the different modes of locating the apical foramen in EAL-integrated endodontic motors using 3D-printed transparent resin teeth in two electrolyte solutions. Ten extracted human premolars were scanned using cone-beam computed tomography and replicated to produce 100 transparent resin tooth models. Root canal length determination was performed under static and dynamic conditions using two EAL-integrated endodontic motors in sodium chloride and chlorhexidine solutions. A dual optical microscope system enabled micron-level positional recording of the file tip relative to the apical terminus, independent of the electronic readout. Extracted human teeth served as reference specimens for validation. High agreement was observed among different operating modes of the endodontic motors, with no significant differences between irrigation solutions. Measurements demonstrated high repeatability and consistency across static and dynamic conditions. The proposed framework enables direct, objective, and reproducible evaluation of EAL performance by combining anatomical standardization with high-precision optical measurement. Transparent resin teeth allow continuous visualization of file behavior, facilitating assessment of dynamic motor functions that are difficult to quantify using conventional approaches. This framework provides a scalable platform for preclinical device evaluation, methodological validation, and simulation-based endodontic education.