Abstract
Overdenture abutment teeth are susceptible to periodontal disease or dental caries because of poor oral hygiene. Very little is known about the effects of the shape of the abutment teeth on plaque control. To study this, we made a simulator whose basic structure was a cantilever made from a phosphor bronze square bar with strain gages. Device-1 could detect lateral and vertical forces applied to the bristles of a toothbrush. Device-2 could detect lateral and vertical forces exerted on an abutment tooth model. Device-2 could change the tooth model which was a column with a taper angle of 0°,10°,20°,30°, and 40° and a height of 0.5, 1.0, 1.5, and 2.0 mm, respectively. The measured error of both devices was less than 5%. Ten subjects, 22 to 45 years (average : 34 years) contributed to this experiment. Brushing forces were continuously monitored with a signal processor 7T-18A (Nippon-denki-sanei, Ltd.) and transferred to a Macintosh (Apple Computer, Inc.) during brushing of the model with the Bass' method by the subjects. The results of experiment showed that the forces exerted on the tooth model significantly increased, but not the forces exerted on the toothbrush, when the height of the tooth model increased or the taper angle decreased. Brushing force differed significantly among individuals. To detect the cervical area of tooth with a toothbrush for removal of dental plaque, the abutment tooth may have to be at least 1.5mm in height and should have a small or no taper angle.
