Journal List > J Korean Acad Oral Health > v.38(1) > 1057595

Ku, Kim, Kang, Chung, Kwon, and Kim: Detection of early changes in caries lesion using QLF-D and OCT

Abstract

Objectives

We aimed to compare the differences in caries lesion changes when measured by QLF-D as fluorescence loss and by SS-OCT as lesion depth with respect to demineralized time, during formation of artificial early caries lesion. We also demonstrated that QLF-D and SS-OCT can be used effectively in monitoring the longitudinal progression of simulated caries lesions.

Methods

Ten bovine incisors were sectioned (5×4 mm) and embedded in epoxy resin. An acid-resistant nail varnish was applied to a part of the tooth surfaces to protect sound enamel (2×4 mm). To generate lesions, each specimen was immersed in 40 ml of a demineralizing gel for 20 days at 37°C. To measure mineral loss of the demineralized specimens, fluorescence loss (∆F, %) was measured by QLF-D and lesion depth (μm) was determined by SS-OCT from the captured cross-sectional image. All the specimens were analyzed daily by QLF-D image analysis software and SS-OCT image analysis program for 20 days. The repeated measures analysis of ∆F and lesion depth was used. The paired t-test was used to assess differences between each day. The correlation between ∆F and lesion depth was determined using the Pearson’s correlation coefficient.

Results

On the 5th, 10th, and 15th day, compared to baseline values, ∆F decreased in 12.7%, 25.0%, and 33.6% of the specimens, respectively, and the lesion depth increased in 9.9%, 16.0%, and 22.6% of the specimens, respectively. However, after 15 days, there was no change in the ∆F and lesion depth. High significant correlation was identified between the resultant values of ∆F obtained by QLF-D and those of lesion depth obtained by SS-OCT (r = ―0.811, P<0.0001).

Conclusions

The QLF-D and SS-OCT could detect subtle changes in mineral loss and lesion depth with respect to demineralized time. Furthermore, these devices were useful for monitoring changes in mineral amount and lesion depth.

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Fig. 1.
An image showing analysis of specimen and QLF-D device a (A).
jkaoh-38-10f1.tif
Fig. 2.
An image showing scanned specimen and SS-OCT device a (B).
jkaoh-38-10f2.tif
Fig. 3.
Images taken by blue light of QLF-D over demineralization time. (A) base line, (B) day 1, (C) day 5, (D) day 10, (E) day 15, and (F) day 20. In the image, a left arrow indicates the sound area and a right arrow shows the demineralized area of the photographed specimen.
jkaoh-38-10f3.tif
Fig. 4.
Images taken by SS-OCT over demineralization time. (A) base line, (B) day 1, (C) day 5, (D) day 10, (E) day 15, and (F) day 20. In the image, a left arrow indicates the sound area and a right arrow shows the demineralized area of the scanned specimen.
jkaoh-38-10f4.tif
Table 1.
Changes in fluorescence and lesion depth by demineralization time
Days 1st 2nd 3th 4th 5th 6th 7th 8th 9th 10th 11th 12th 13th 14th 15th 16th 17th 18th 19th 20th P-value*
LD 65.7 97.0 117.8 139.0 164.9 181.2 203.0 202.9 239.9 232.4 241.0 250.0 268.7 263.7 291.2 311.3 300.6 295.2 288.2 289.1 <0.0001
(17.2) (17.9) (21.0) (17.4) (25.3) (29.3) (27.4) (23.0) (15.5) (23.8) (15.4) (23.9) (11.1) (11.1) (22.4) (29.2) (23.8) (23.5) (22.4) (23.1)
P-value 0.001 0.006 0.002 <0.001 0.019 <0.001 0.992 0.003 0.501 0.200 0.201 0.040 0.685 0.001 0.036 0.268 0.493 0.288 0.923
∆F ―0.5 (1.6) ―5.2 (1.9) ―7.4 (1.4) ―10.1 (2.5) ―12.8 (2.3) ―16.7 (3.3) ―21.0 (4.4) ―22.6 (4.4) ―23.7 (4.6) ―25.1 (5.2) ―26.8 (4.0) ―28.3 (4.6) ―29.7 (5.0) ―30.7 (4.6) ―31.1 (4.5) ―29.9 (4.2) ―31.6 (4.4) ―31.6 (6.6) ―32.6 (4.6) ―33.6 (4.5) <0.0001
P-value <0.001 0.003 0.001 <0.001 <0.001 <0.001 0.001 <0.001 0.007 0.009 0.004 <0.001 0.025 0.198 0.009 0.001 0.983 0.277 0.008

All values are the mean (standard deviation). ∆F means the loss of fluorescence in demineralized enamel part compared to sound part (%). LD means the lesion depth measured in images taken by SS-OCT (mm). *P-values denote statistically significant differences within rows by repeated measures analysis. †P-values denote statistically significant differences by paired t-test.

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