Early detection of enamel demineralization by optical coherence tomography

Abstract

Enamel is the outermost layer of the tooth that protects it from invasion. In general, an acidic environment accelerates tooth demineralization, leading to the formation of cavities. Scanning electron microscopy (SEM) is conventionally used as an in vitro tool for the observation of tooth morphology changes with acid attacks. Yet, SEM has intrinsic limitations for the potential application of in vivo detection in the early demineralization process. In this study, a high-resolution optical coherence tomography (OCT) system with the axial and transverse resolutions of 2.0 and 2.7 μm in teeth has been utilized for characterizing the effect of the acidic environment (simulated by phosphoric acid) on the enamel topology. The scattering coefficient and the surface roughness of enamel can be directly derived from the OCT results, enabling a quantitative evaluation of the topology changes with demineralization. The dynamic process induced by the acid application is also recorded and analyzed with OCT, depicting the evolution of the demineralization process on enamel. Notably, the estimated enamel scattering coefficient and surface roughness significantly increase with the application time of acid and the results illustrate that the values of both parameters after demineralization are significantly larger than those obtained before the demineralization, illustrating both parameters could be effective to differentiate the healthy and demineralized teeth and determine the severity. The obtained results unambiguously illustrate that demineralization of the tooth surface can be successfully detected by OCT and further used as an indicator of early-stage cavity formation.

Handheld optical coherence tomography for clinical assessment of dental plaque and gingiva

“…Dental OCT has shown promising results with improved spatial resolutions over standard imaging modalities, and several review articles are also available. [11][12][13][14] Both hard tissues and soft tissues have been investigated to study tooth decay, 15,16 enamel cracks, 17 restoration evaluation, 18 calculus, 19 pulp chamber, 20 oral cancers, 21,22 and periodontal diseases. 23,24 Although OCT can assess various features in the oral cavity, challenges exist for the further clinical translation of OCT technologies.…”

“…25,26 Several research groups have developed customized systems for dental imaging, ranging from handheld probes [27][28][29] to endoscope-based designs. 30 However, many studies are yet limited to ex vivo tissues and in vitro samples, 16,31 or in vivo imaging from volunteers in laboratory settings. 28,30 In addition, the capability of OCT as a longitudinal tracking tool has not been investigated for assessing dental plaque and gingivitis, and only a few studies have examined the capability in tooth composites.…”

An Intraoral OCT Probe to Enhanced Detection of Approximal Carious Lesions and Assessment of Restorations

“…In the past, numerous studies have shown the potential of the image-based, non-invasive optical coherence tomography (OCT) in dental applications, including caries diagnosis and the evaluation of tooth-colored restorations [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Introduced in 1991 in medicine [ 28 ], it is routinely used in ophthalmology for early detection of pathological changes at the retina and optic nerve [ 29 ].…”

Early stage dental caries detection using near infrared spatial frequency domain imaging

“…Whilst some of these methods are quantitative, they are typically highly sensitive to surface effects such as stains and brown spots 15 , and as a result, none of these methods have become widespread in clinical practice, as demonstrated by the low rate of detection of early-stage dental caries. In the recent past the main optical method being explored for use in the detection of dental caries is polarization enhanced Optical Coherence Tomography 16 which more recently has been focused on the detection of early white spot caries 17 where some quantification has taken place. However, these methods are typically slow, as OCT provides point-based detection, and OCT has not reached the level of traction in dental practice that it has in other fields, in particular ophthalmology.…”