Review of the human masticatory system and masticatory robotics

A masticatory robot refers to a robot that can perform at least some defined human masticatory functions. This paper briefly reviews the masticatory system, masticatory measurements and computational models of mastication that are relevant to masticatory robotics. Also critically reviewed is the state of the art of the robotics research in engineering of the jaw system. The masticatory system has two rigid components: a fixed maxillary (upper) jaw and a mobile mandibular (lower) jaw, which are joined by two temporomandibular joints (TMJ). Unique features of the TMJ are described. The role of muscles of mastication is explained with regard to their role in rhythmic opening and closing of the mandible in three-dimensional space. Because the breakdown of food is performed directly by the teeth; the functionalities of the incisor, pre-molar and rear molar are presented. Two computational models of the masticatory system are presented in which Hill-type muscle models are used. We also describe masticatory robots developed for dental training, jaw simulation, food texture and breakdown analysis, and speech therapy with regard to muscle modelling, TMJ models, masticatory biomechanics and controls of actuation. Finally, we discuss the major accomplishments and challenges in masticatory modelling and robotics; and we compare a number of such robots in the light of relevant biomechanical aspects of the mastication system.