Abstract
The purpose of this study was to quantitatively clarify the stress distribution on oral tissue when toothbrushing force is transmitted through the bristles of a toothbrush.
We analysed dynamically two cases of toothbrush movement by the non-linear finite element method and the following results were obtained;
1. Toothbrushing movement in a gingiva model.
Two kinds of toothbrush, round end bristles and extremely tapered end bristles were each pressed 1 mm toward the periodontal tissue and set in motion horizontally with 6 mm reciprocation.
The result of analysis showed that the toothbrush with round end bristles generated a stress of 300-600g/cm2 on the gingiva. On the other hand, the 130-200g/cm2 from the toothbrush with extremely tapered end bristeles, was considerably lower than that of the former.
2. Entry of the bristle end into the periodontal pocket model.
We compared ease of entry into the periodontal pocket of two kinds of bristles, extremely tapered end bristles and lightly tapered end bristles.
Two bristles were tried for entrance into the periodontal pocket.
The result of analysis was that extremely tapered end bristles were easy to insert smoothly into the periodontal pocket, but lightly tapered end bristles were not.
The stress of lightly tapered end bristles on periodontal tissue was 6-7 times higher than that of extremely tapered end bristles.
In the case of the entry angle being changed, ease of entry was nearly equal to that of extremely tapered end bristles.
