The measurement of enamel wear of two toothpastes.
OBJECTIVE
The aim of this study was to compare the enamel abrasivity of a whitening toothpaste with a standard silica toothpaste.


METHODS
Polished human enamel blocks (4 x 4 mm) were indented with a Knoop diamond. The enamel blocks were attached to the posterior buccal surfaces of full dentures and worn by adult volunteers for 24 hours per day. The blocks were brushed ex vivo for 30 seconds, twice per day with the randomly assigned toothpaste (n = 10 per treatment). The products used were either a whitening toothpaste containing Perlite or a standard silica toothpaste. After four, eight and twelve weeks, one block per subject was removed and the geometry of each Knoop indent was re-measured. From the baseline and post-treatment values of indent length, the amount of enamel wear was calculated from the change in the indent depth.


RESULTS
The mean enamel wear (sd) for the whitening toothpaste and the standard silica toothpaste after four weeks was 0.20 (0.11) and 0.14 (0.10); after 8 weeks was 0.44 (0.33) and 0.18 (0.17), and after 12 weeks was 0.60 (0.72) and 0.67 (0.77) microns respectively. After four, eight and twelve weeks, the difference in enamel wear between the two toothpastes was not of statistical significance (p > 0.05, 2 sample t-test) at any time point.


CONCLUSIONS
The whitening toothpaste did not give a statistically significantly greater level of enamel wear as compared to a standard silica toothpaste over a 4-, 8- and 12-weeks period.
Joiner
Andrew
A
Unilever Oral Care, Port Sunlight Laboratory, Bebington, Wirral, UK. Andrew.Joiner@Unilever.com
Weader
Elizabeth
E
Cox
Trevor F
TF
D000328:Adult; D000537:Aluminum Oxide / Q000009:adverse effects*; D003743:Dental Enamel / Q000187:drug effects*; D006244:Hardness / Q000187:drug effects; D006801:Humans; D016014:Linear Models; D012822:Silicon Dioxide / Q000009:adverse effects*; D014072:Tooth Abrasion / Q000209:etiology*; D014099:Toothbrushing / Q000009:adverse effects; D014100:Toothpastes / Q000009:adverse effects*
D014100:Toothpastes; C003076:Perlite; D012822:Silicon Dioxide; D000537:Aluminum Oxide