[A clinical and physiological evaluation of masticatory center in unilateral shortened arch and RPD treatment].

The purpose of this study was to elucidate the relation between distribution of occlusal contacts in unilateral shortened arch and prosthodontic treatment, those occlusal loads, coordinates of the points and amounts, in relation to masticatory musculature activities by EMG and Prescale. Occlusal contacts and loads were measured by extra-thin-layer of pressure indicator (Prescale Fuji Film Co.), with an exclusive analyzing computer system. Masticatory muscular EMG and occlusal contacts were recorded with Prescale at i.p. clenching. Ten bilateral shortened arch-cases were used as control and fifteen unilateral shortened dental arches were studied in periodically at pre- and post-RPD treatments. These data were analyzed and evaluated in those of the control group. These results were as follows: 1) The location of the occlusal load center in dentate mouth was about median line of the maxillar first molar region, but in unilateral shortened arch the load center was biased about one premolar breadth anteriorly and inclined toward remaining dentate side. 2) The center of supporting area of unilateral shortened arch edentation was biased toward the remaining side and slightly to incisal arch. 3) After wearing eligible designed RPD for over one year, in the unilateral edentate arch, the location of the load center was improved at the dentate arch, presuming physiological and functional recovery, and also activated masticatory musculatures. 4) The prosthodontic restoration for unilateral edentate cases (unilateral shortened arch) was quite effective in clinical and physiological stand points.