Biomedical Engineering Reference
In-Depth Information
Fig. 1.8
Labial view of
mandibular anterior teeth in a
40-year-old male bruxist [
10
]
substance intervening. Erosion is a chemical process of the removal of hard tissue;
many drinks, such as lemons, citrus fruits, cola, vinegar, and fruit juices have a pH
of 3 or less, and frequent consumption of these leads to excessive tooth destruction
[
87
,
88
]. In addition, early diagnosis on the mode of lesion is important in order to
prevent further tooth loss.
1.5.4
Wear Rate
The rate of wear is very important in dental medicine, but it is very difficult to mea-
sure in vivo, and most reports on tooth wear are descriptive. In 1980, Roulet et al.
[
88
] measured a wear rate of 33 μm a year of the functional cusps in mandibular
molars. In 1983, Molnar et al. [
89
] examined the cusp heights of dental casts taken
from individuals during a growth study of Aboriginal children from ages 6-18.
They found that an average of 0.5 mm of cusp height was lost by 18 years of age, a
wear rate of 41 μm per year, and that this value was greater than those of Europeans
due to the differences in diet. Further investigations on wear rate were performed by
Lambrechts et al. [
90
]. The mean age of the subjects at the first examination was 20
years old (range: 18-23 years). The results showed that the average steady wear rate
on occlusal contact areas was about 29 μm per year for molars and about 15 μm per
year for premolars with a computerized three-dimensional measuring technique
over a period of 4 years. The influence of age from 5 to 18 years old on the behavior
of horizontal tooth wear was investigated by Nystrom et al. [
91
], and the size of
wear facets on all anterior teeth increased with age. In 1997, the enamel wear rate
of 18 young adults over two consecutive years was measured independently by
volume loss and mean depth loss by Pintado et al. [
92
]. A steady wear rate of
0.04 mm
3
per year by volume and 10 μm per year by depth, averaged over all teeth,
was experienced. The greater wear was observed for the canines and for the bruxers,
while no significant difference in tooth wear on the basis of gender was found.
