A randomised clinical trial to determine the abrasive effect of the tongue on human enamel loss with and without a prior erosive challenge
Abstract
Objectives
To
investigate the abrasive effect of the tongue on human enamel loss with
and without a prior dietary acid challenge in an in situ model.
Methods
A single center, single blind, randomly allocated, split mouth, four treatment regimen, in situ
study in healthy adult volunteers was undertaken. Twenty four subjects
wore two lower intra-oral appliances each fitted with 4 human enamel
samples 6 h/day for 15 days. The samples were treated with either 50 ml
orange juice or water for 5 min ex vivo 4 x/day; prior to being
licked or not licked with the subject’s tongue for 60 s. There were 2
samples per group per subject. Surface loss was measured by contact
profilometry.
Results
23
subjects completed the study with no adverse events. The mean loss of
enamel at 15 days was: 0.08 μm for water without licking, 0.10 μm with
water and licking; 1.55 μm with orange juice alone, 3.65 μm with orange
juice and licking. In the absence of erosive challenge, licking had no
detectable effect on enamel loss p = 0.28. Without licking, orange juice
had a highly significant effect on loss compared to water,
p < 0.001. Erosive challenge followed by licking more than doubled
the loss of enamel p < 0.001.
Conclusions
When
enamel was exposed to orange juice prior to licking, tissue loss as a
result of tongue abrasion of the eroded surface was increased, and
double that of the erosive challenge alone. Licking enamel with the
tongue had no perceptible effect on enamel loss in the absence of the
erosive challenge.
Clinical significance
Enamel
wear resulting from tongue abrasion on tooth surfaces softened by acid
challenge, can be an unavoidable consequence of oral function. This may
account for the pattern of erosive toothwear on palatal and occlusal
tooth surfaces, reinforcing the importance of restricting the frequency
of dietary acid challenge in susceptible individuals.
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