El-Sheikh, Ali Mohamed; (2001) Some mechanical and physiological aspects of passive tactile sensibility associated with dental implants. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The purpose of this study was to investigate the hypothesis that passive tactile sensibility associated with dental implants is related to a number of mechanical and physiological variables, and that the phenomenon changes in nature with maturation of osseointegration. The investigation was carried out in-vivo using patients who had been treated with dental implants. These were subjected to a range of loading conditions using two modalities, external (i.e. externally applied loading) and internal (i.e. non-masticatory functionally generated loading). External loading was produced with a precision custom-made loading device, operated by a computer-controlled stepper motor. This was developed as part of the study and enabled a wide range of loading profiles. Passive tactile sensibility was investigated in a group of twenty edentulous subjects. Eight loading profiles were used to apply pushing forces directly between the abutments until the subjects felt the first sensation of pressure. The forces were measured with a strain gauge transducer mounted on the device. To validate the loading system, passive tactile sensibility from natural teeth was measured in a group of eight partially dentate subjects with missing teeth in the anterior region of the mandible, using only two loading profiles. Changes which might occur in passive tactile sensibility during the three-month healing phase following implant placement were also investigated in another group of five edentulous subjects. Internal loading was produced via functional mandibular deformation. A range of individual displacement transducers was developed to measure three types of functional mid-line mandibular deformation in a pilot study involving a group of five edentulous subjects who had been treated with dental implants. These measured medial convergence, corporal rotation and antero-posterior shear, via a multi-channel data logging system. These displacements were then restricted with individual superstructures, although ultimately this group was reduced to three subjects. Passive tactile sensibility during functional mandibular movements was then measured in relation to force transmission through the superstructure with surface- mounted strain gauges. This study showed that some mechanical and physiological variables affect passive tactile sensibility associated with dental implants. It also showed a significant increase in passive tactile sensibility during the healing phase following implant placement in the immediate loading situation. Additionally, it demonstrated the value of mid-line mandibular deformation and its occurrence simultaneously in three planes during functional movements. The implant sensory function could be explained by activation of the receptors in the peri-implant area through bone deformation when triggering of more remote receptors was avoided.

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