[The changes of oral conditions caused by artificial crown contours in severely disabled patients].

The purpose of this study was to investigate the relation between the artificial crown contour and plaque accumulation in severely disabled patients who have muscle hypoactivity in the oral region. This relation was statistically analyzed by the change in CFU numbers of Mutans Streptococci, Lactobacillus, and total anaerobic bacteria. The results were as follows: 1. In the severely disabled group, there was no significant difference in the decrease of number of microorganisms between with and without tooth brushing. When the normal contour crown was exchanged for the under contour, however, the numbers of Mutans Streptococci and total anaerobic bacteria decreased significantly (p < 0.05). 2. In the normal control group, both the crown contour and tooth brushing were effective for decreasing the number of Mutans Streptococci and total anaerobic bacteria (p < 0.05). 3. In both groups, the number of Lactobacillus was decreased by changing the crown contours and by tooth brushing, with no statistical significance. 4. In view of the cariogenic potential of microorganisms, it is concluded that the under contour crown prevents plaque accumulation, and that this crown should be used on severely disabled patients, as it makes tooth brushing more effective.