Dieser Fallbericht schildert die Diagnostik und Behandlung eines Unterkiefereckzahnes mit ungewöhnlicher Anatomie. Mithilfe der DVT und des Dentalmikroskops wurden zwei Wurzeln mit drei Wurzelkanälen aufgefunden und behandelt. Keywords: Unterkiefereckzahn, Anatomie, DVT, Dentalmikroskop, drei Wurzelkanäle

Aim: This study aimed to investigate whether a conservative endodontic access cavity design results in an identical assessment of the number and shape of root canals compared to a traditional endodontic access cavity design. Materials and methods: A total of 84 extracted human molars were examined by 28 students studying for a master’s degree in endodontics, with each student examining three molars. The students were divided into pairs. A conservative endodontic access cavity was prepared in each molar, and the teeth were evaluated independently by both students in the pair to determine the number and shape of the canal orifices. The access cavity was then extended to a traditional endodontic access cavity and independently evaluated again by the same persons. The data were then statistically evaluated using a Wilcoxon signed rank test, chi-square test and McNemar test with the level of significance set at P < 0.05. Results: For 30 teeth (35.7% total; 37.9% maxillary, 30.8% mandibular), the number of canals detected varied between conservative and traditional endodontic access cavities (P < 0.001). For 152 canals (28.5% total; 26.6% maxillary, 33.6% mandibular), the evaluation of the canal geometry changed (P < 0.001). There were no significant differences in absolute value between the two types of access in terms of the number of canals and the round geometry of the canal orifices, although more oval canals were detected with traditional endodontic access cavities. No absolute difference was found in detected second mesiobuccal root canals in maxillary molars or in the middle mesial canal in mandibular molars. Conclusion: The conservative endodontic access cavity approach is more susceptible to misinterpretation of the number and shape of canal orifices than the traditional approach. Keywords: minimally invasive, orifice assessment, reliability, root canal detection, traditional access