Abstract
The oblique, instead of horizontal, position of the handle, causes an uneven distribution of the pressure exerted on the bristles; those at the toe receive little or none, thus entailing inadequate or no cleansing of the teeth there, while those at the heel of the brush are subjected to unduly severe stress, causing them to break, or bend out of alignment, and so to become a liability in the brushing.
Black & white photograph
Files
| File name | Date Uploaded | Visibility | File size | ||
|---|---|---|---|---|---|
 |