Enamel erosion depths measured on impressions by a white light interferometer.
OBJECTIVE
To investigate if measurements of the step heights on an impression of eroded enamel surfaces may give reliable values of the etching depths measured directly on the enamel.


METHODS
Twelve human enamel specimens, with one circular amalgam reference surface in each, were mounted on an epoxy block and ground flat. Baseline images were taken by a White Light Interferometer (WLI) followed by 12 min etch by 0.01 M HCl, pH 2.2. The mean etch depth on each specimen was calculated from three repeated measurements, both on the specimen surfaces and on the silicone polymer impressions of the surfaces. Paired samples t-test was used when comparing the precision of measurements on enamel vs on impression.


RESULTS
The mean lesion depths after 12 min etch measured on the 12 enamel surfaces and impressions were 9.9 µm and 10.6 µm, respectively. The direct and indirect measurements correlated well (r(2) = 0.95), with 7% higher mean etch depth measured on the impressions (p < 0.05). The reliability of three repeated measurements on enamel and impressions expressed by Intra Class Correlation (ICC) were 0.98 and 0.99, respectively. The average relative precisions of three repeated measurements on the 12 tooth and impression surfaces were (0.5 ± 0.1)% and (0.1 ± 0.02)%, respectively (p < 0.05). The accuracies were 0.4% and 7%, respectively.


CONCLUSIONS
WLI gave reliable but slightly higher etch depth measurements on impressions compared to enamel surfaces.
Faculty of Dentistry, University of Oslo, Norway. k.r.stenhagen@odont.uio.no
Kjersti Refsholt
KR
Stenhagen
Lene Hystad
LH
Hove
Børge
B
Holme
Anne Bjørg
AB
Tveit
D003743:Dental Enamel / Q000473:pathology*; D006801:Humans; D007368:Interferometry / Q000379:methods*; D015203:Reproducibility of Results; D014077:Tooth Erosion / Q000473:pathology*