Assessment of Prosthetic Rehabilitation of Partially Edentulous Patients with Collapsed Vertical Overlap using Electromyography, Cephalometric, and Clinical Examination Sana’a Yemen 2004-2008

Statement of the problems: There have been no previous studies on the effect of increasing vertical dimension of occlusion ( VDO ) on masticatory muscles, TMJs, and occlusal plane orientation in partially edentulous patients with collapsed face height. Objectives: This study was carried out to evaluate the effect of increasing VDO and prosthetic rehabilitation on two group of 20 partially edentulous subjects with severe occlusal wear on masticatory muscles and TMJs, and on horizontal and vertical maxillomandibular relationships. Materials and methods: 20 subjects were selected for this study with a mean age of 61 years old ranging between 47-75. All selected patients were partially edentulous with good general health, free of myofacial pain dysfunction syndrome and they were class 1 maxillomandibular relationships. Selected patients were divided into two groups: 1. Group 1 were subjected to sudden increase in their VDO to clinical rest position using transitional partial dentures. 2. Group 2 were subjected to incremental increase in their VDO using transitional partial denture. For both groups, the final prosthesis were constructed and inserted 12 weeks after using transitional prosthesis. VI Methods of evaluation: 1. EMG evaluation of masticatory muscles a. Before increasing VDO in postural position and maximal clenching b. After increasing VDO in postural position and maximal clenching 2. Radiographic evaluation of horizontal and vertical dimensions of the maxillomandibular relationships. 3. Clinical and subjective assessment after prosthetic rehabilitation. Results: Increasing VDO and prosthetic rehabilitation of subjects of both groups displayed the following results: 2. EMG muscles activity a. The FMG voltages in postural position before and after increasing VDO and prosthetic rehabilitation revealed high range of variations among subjects of both groups and among subjects of each group. EMG voltages for right and left temporalis and masseter muscles in all subjects of both groups displayed significant reduction, b. In maximal clenching the variations were also seen, and mean values of the muscle activity showed slight increase ( 5-8%) after increasing VDO and prosthetic rehabilitation . 1. Radiographic evaluation of the maxillomandibular relationships through cephalometric analysis of the radiographs before and after increasing VDO a. In horizontal dimension, no marked changes in the values of the angles related to horizontal dimension. b. In vertical direction, there was statistical significant increase in the values of the angles and lines related to vertical dimension . Clinical and subjective evaluation of the subjects revealed no distinct symptoms or discomfort and subjects chewing ability and appearance were rated as goo