[Method of functional impression in prosthetic treatment with distal extension with dental-mucosal support]

Having examined the biomechanical problems regarding free-end tooth-tissue borne dentures caused by the different resilience of denture support structures and changes in the resilience of fibre-mucosa, and having reviewed the impression methods now in use, the authors describe a functional impression method used to obtain a clinical and instrumental record of the individual conditioning of fibre-mucosa support by functional occlusal stress. The aim was to reduce the resilience of fibre-mucosa to levels comparable to periodontal and articular levels. The purpose was to achieve an optimal functional morphology of the prosthetic occlusal surface in order to guarantee the static and dynamic equilibrium of the denture. The authors describe a protocol based on weekly relining sessions and clinical and instrumental controls performed at every other session until optimal results have been obtained. Instrumental tests were carried out using the computerised occlusal analyser: T-SCAN version II. The authors used this device to measure the redistribution of occlusal forces acting on the occlusal surface in an antero-posterior and latero-lateral direction in subsequent sessions and the corresponding position of the centre of forces in the central area. In line with the results of earlier studies carried out by other researchers, the authors confirm that when maximum conditioning of the fibre-mucosa support is achieved, it only retains a slight residual elasticity.