Abstract This study was concerned with the position of the tooth and the associated forces developed during mastication. Strain gauges were incorporated in selected teeth in artificial dentures and, with an oscilloscope, were used to indicate the forces developed during chewing. The position of the mandible and the teeth were recorded by photographing through a fixed graticule a miniature electric globe attached to the centre of the chin. By a suitable arrangement of the subject and the oscilloscope a photograph of both indicator light and force trace were obtained on the same frame of film. The work involved the analysis of over 10,000 frames of film, for which an analyzing projector was used. The results showed that significant forces were not developed until the teeth were almost in contact and that after contact, the force increased without further movement being detected. No gross sliding of one occlusal surface over another was detected during normal mastication.