Determination of vertical dimension by hydraulic intraoral jack

This paper describes the application of a hydraulic intraoral jig to the establishment of the vertical dimension of occlusion for full denture construction. The device enables the patient to establish an occlusal height which is most comfortable without the intervention or guidance of the dentist. Six patients for whom new dentures were to be constructed in the University of Otago School of Dentistry were invited to participate in the study. A conventional technique of denture construction was employed, but an additional stage was introduced after the jaw records had been taken and the casts mounted. Each patient was instructed in the use of the hydraulic jig and was asked to find a comfortable bite height in his own time. The results were compared with occlusal heights determined by conventional subjective methods. The former results proved to be more repeatable than those utilizing rest position and an average free-way space. The results are discussed and the implications outlined. Suggestions for further research using the hydraulic jig are made and the authors conclude that the hydraulic jig may be used to determine vertical dimension for full denture construction.