[Objective evaluation of the mandibular position by the change in the function of the middle ear. 1. Centric relation and lateral eccentric position].

Tympanometric measurement has been made on centric relation and working side and non-working side in 19 healthy subjects (12 males and 7 females aged 23-27) and the following conclusions have been obtained: 1. The Tympanogram in the healthy subjects showed a symmetrical pattern, being of type A bilaterally, in all the cases, and no lateral or sexual difference was seen any item of measurement. 2. S. C. value increased in order of centric relation, working side and non-working side, but decreased in IMP., PRS. and EAC.. 3. Significant differences were observed in the items of measurement regarding S. C. and IMP. all between centic relation and working side, centric relation and non-working side, working side and non-working side. These findings show a correlation between the function of middle ear and the horizontal mandibular position. Therefore these findings suggest the possibility of tympanometric measurement becoming one of the parameters as the method for objective evaluation of the mandibular position as the change in the function of the middle ear.