Introduction to Teeth - Dental Biotribology - page 15

Fig. 1.9 Variations of wear rate versus load under different medium conditions [ 94 ]
As human tooth wear occurs so slowly, it needs months or years to be measur-
able. Teaford and Tylenda believed that microscopic changes in wear patterns on
human teeth could be detected in a matter of days and could be used as indicators of
rates of wear to the study of tooth wear [ 93 ]. Admittedly, the creation of wear fea-
tures on a surface may be a good indicator for only a certain type of wear.
Some factors such as load, pH, and the nature of the lubricant have been investi-
gated on the wear behavior of human enamel by Kaidonis et al. [ 94 ]. The results
indicated that under nonlubricated conditions, enamel wear remains low at a high
load due to the dry-lubricating capabilities of fine enamel powder; Under lubricated
conditions, low loads with an acidic lubricant lead to little enamel wear, whereas
very low pH resulted in a high wear rate under all loads. More results and trends in
wear rate were summarized in the graphical representation shown in Fig. 1.9 .
According to available databases and manual examinations on the three key-
words “tooth abrasion,” “toothpaste,” and “toothbrush,” Hunter et al. [ 95 ] obtained
the following conclusions: The toothbrush alone appeared to have no effect on
enamel and very little effect on dentin. Most toothpaste also had very little effect on
enamel and in normal use would not cause significant wear of dentin in a lifetime of
use. Wear of enamel and dentin could be dramatically increased if toothbrushing
followed an erosion challenge. However, these conclusions were at best drawn from
studies in vitro, from a few studies in situ, and at worst from case or anecdotal
reports. In fact, studies in vivo that investigated toothpaste abrasion alone would be
difficult and are perhaps impossible to design. In addition, Addy showed that avail-
able evidence supported a portable link between toothbrushing with or without