Endodontic access cavity preparation represents a critical stage of root canal treatment because it establishes the pathway for identification, negotiation, cleaning, shaping, disinfection, and obturation of the root canal system. Traditionally, access cavity preparation has emphasized complete removal of the pulp chamber roof and establishment of straight-line access to facilitate instrumentation. However, increasing recognition of the biomechanical importance of remaining tooth structure has led to the development of minimally invasive and conservative access cavity concepts. Preservation of pericervical dentin and other strategically important structures has become a central objective of contemporary endodontic treatment. At the same time, advances in cone-beam computed tomography, optical magnification, dental operating microscopes, ultrasonic instruments, flexible nickel-titanium systems, laser technology, and enhanced irrigation have expanded the possibilities for conservative access preparation. More recently, static-guided and dynamic-guided endodontics have enabled digitally planned access to anatomically complex and calcified root canal systems, while artificial intelligence has shown potential for automated recognition and characterization of root canal anatomy. Nevertheless, the available evidence does not establish a universally superior access cavity design. Excessively conservative preparations may compromise canal detection, instrumentation, irrigation, and disinfection, whereas unnecessarily extensive preparations may weaken the remaining tooth structure. Therefore, contemporary access cavity preparation should be individualized according to tooth morphology, canal anatomy, restorative status, calcification, remaining tooth structure, and available technology. This narrative review discusses the evolution of access cavity preparation, current concepts, technological advancements, clinical outcomes, complications, and future directions, with emphasis on achieving an appropriate balance between adequate endodontic access and preservation of structurally important dental tissues.