The goal of using virtual and augmented reality technologies in therapeutic interventions simulation, in the fixed prosthodontics (VirDenT) project, is to increase the quality of the educational process in dental faculties, by assisting students in learning how to prepare teeth for all-ceramic restorations. Its main component is an e-learning virtual reality-based software system that will be used for the developing skills in grinding teeth, needed in all-ceramic restorations. This paper presents a domain ontology that formally describes the knowledge of the domain problem that the VirDenT e-learning system dealt with. The ontology was developed based on the UML models of the VirDenT information system, making sure in this way the ontology captures knowledge identified and described in the analysis of the information system. At first, we constructed the taxonomy of these concepts, using the DOLCE ontology and its modules. Then, we defined the conceptual relations between the concepts. We also added SWRL rules that formally describe the business rules and knowledge previously identified. Finally, with the assistance of the Pellet reasoner system, we checked the ontology consistency.