title: A specialized motion capture system for real-time analysis of mandibular movements using infrared cameras.
abstract: BACKGROUND
  In the last years, several methods and devices have been proposed to record the human mandibular movements, since they provide quantitative parameters that support the diagnosis and treatment of temporomandibular disorders. The techniques currently employed suffer from a number of drawbacks including high price, unnatural to use, lack of support for real-time analysis and mandibular movements recording as a pure rotation. In this paper, we propose a specialized optical motion capture system, which causes a minimum obstruction and can support 3D mandibular movement analysis in real-time.
  
  
  METHODS
  We used three infrared cameras together with nine reflective markers that were placed at key points of the face. Some classical techniques are suggested to conduct the camera calibration and three-dimensional reconstruction and we propose some specialized algorithms to automatically recognize our set of markers and track them along a motion capture session.
  
  
  RESULTS
  To test the system, we developed a prototype software and performed a clinical experiment in a group of 22 subjects. They were instructed to execute several movements for the functional evaluation of the mandible while the system was employed to record them. The acquired parameters and the reconstructed trajectories were used to confirm the typical function of temporomandibular joint in some subjects and to highlight its abnormal behavior in others.
  
  
  CONCLUSIONS
  The proposed system is an alternative to the existing optical, mechanical, electromagnetic and ultrasonic-based methods, and intends to address some drawbacks of currently available solutions. Its main goal is to assist specialists in diagnostic and treatment of temporomandibular disorders, since simple visual inspection may not be sufficient for a precise assessment of temporomandibular joint and associated muscles.
authors: Laboratory of Biomedical Engineering, Faculty of Electrical Engineering, Federal University of Uberlandia, Av. Joao Naves de Avila, 2121, Uberlandia, MG CEP 38408-100, Brazil. danielfurtados@yahoo.com.br
authors: Daniel Antônio
authors: DA
authors: Furtado
authors: Adriano Alves
authors: AA
authors: Pereira
authors: Adriano de Oliveira
authors: Ade O
authors: Andrade
authors: Douglas Peres
authors: DP
authors: Bellomo
authors: Marlete Ribeiro
authors: MR
authors: da Silva
mesh_terms: D000465:Algorithms; D002138:Calibration; D004867:Equipment Design / Q000295:instrumentation / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007259:Infrared Rays; D007568:Jaw / Q000502:physiology; D007574:Jaw Relation Record / Q000295:instrumentation / Q000379:methods; D008297:Male; D008334:Mandible / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D015203:Reproducibility of Results; D012984:Software; D011795:Surveys and Questionnaires; D013704:Temporomandibular Joint / Q000502:physiology; D013705:Temporomandibular Joint Disorders / Q000175:diagnosis / Q000503:physiopathology