A COMPREHENSIVE REVIEW OF VARIOUS LASER-BASED SYSTEMS USED IN EARLY
DETECTION OF DENTAL CARIES
Figure 4. Multispectral near-infrared
reflectance imaging:
(a) clinical presentation of caries on
the tooth;
(b) cross-section of tooth with caries;
(c) Multispectral near-infrared
reflectance imaging
(Source of image: Zakian C et al. Nearinfrared hyperspectral imaging of teeth
for dental caries detection. J Biomed Opt.
2009;14(6):064047)
and compared that range of contrast with visible
reflectance and LF. Forty-four human molars were
painted with an acid-resistant varnish leaving a
window (4 mm×4 mm) on the occlusal surface of
each tooth exposed for demineralization.
In the unprotected windows, artificial lesions were
induced using a demineralizing solution at pH 4.5.
Near-IR reflectance images were obtained over
several near-IR spectral distributions, visible light
reflectance and LF with 405 nm excitation and
detection at wavelengths greater than 500 nm. In
each sample, the severity of the demineralization
window was non-invasively assessed using cross
polarization optical coherence tomography (CPOCT).
The CP-OCT results showed that the severity of
the carious lesions varied significantly across the
sample windows and that visible light does not
precisely reflect the large variation in the lesion
severity as compared to near-IR reflectance.
Reflectance measurements at certain nearIR wavelengths have been reported to more
accurately reflect variation in the depth and
severity of the lesions. 27 Chung et al. 27 reported
that near-IR measurements at higher wavelengths
(1,200nm to 1,600nm) reflect the variation in the
depth and severity of the lesions more accurately
as compared to shorter wavelengths.
In another study, Wu and Fried28 compared
the image contrast of artificial carious lesions
produced on the buccal and occlusal surfaces of
teeth using fluorescence, visible reflectance and
near-IR reflectance.
The results demonstrated that near-IR reflectance
at wavelength 1,310-nm yielded the greatest
contrast than visible reflectance though it remained
statistically
comparable
with
fluorescence
imaging.28
In a recent study Söchtig et al.29 suggested that NIR
transillumination is a method that may help avoid
bitewing radiographs for diagnosis of caries in
routine dental practice.
However, further studies over a greater range
of lesion severity are needed to determine the
optimum performance ranges for this imaging
technique.
Conclusion
Lasers-based caries systems are useful tools in
the early detection of caries as compared to
traditional visual and radiographic examination
techniques; however, further studies are needed
to assess the caries diagnostic efficacy of the
various commercially available laser-based caries
diagnostic systems.
Conflict of interest and financial disclosure
The authors declare that they have no conflict
of interest and there was no external source of
funding for the present study.
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