The aim of this study was to determine the diagnostic accuracy of swept-source optical coherent tomography (SS-OCT) in detecting and estimating the depth of proximal caries in posterior teeth in vivo. SS-OCT images and bitewing radiographs were obtained from 86 proximal surfaces of 53 patients. Six examiners scored the locations according to a caries lesion depth scale (0-4) using SS-OCT and the radiographs. The results were compared with clinical observations obtained after the treatment. SS-OCT could detect the presence of proximal caries in tomograms that were synthesized based on the backscatter signal obtained from the proximal carious lesion through occlusal enamel. SS-OCT showed significantly higher sensitivity and larger area under the receiver operating characteristic curve than radiographs for the detection of cavitated enamel lesions and dentin caries (Student's t -test, p < 0.05). SS-OCT appears to be a more reliable and accurate method than bitewing radiographs for the detection and estimation of the depth of proximal lesions in the clinical environment.

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(1) Background: Dental caries, if diagnosed at the initial stage, can be arrested and remineralized by a non-operative therapeutic approach preserving tooth structure. Accurate and reproducible diagnostic procedure is required for the successful management of incipient caries. The aim of this study was to evaluate the diagnostic accuracy of 3D swept-source optical coherence tomography (3D SS-OCT) for enamel caries at smooth tooth surface if the lesion was with remineralization. (2) Methods: Forty-seven tooth surfaces of 24 extracted human teeth visibly with/without enamel caries (ICDAS code 0–3) were selected and used in this study. The tooth surfaces of investigation site were cleaned and visually examined by four dentists. After the visual inspection, SS-OCT scanning was performed onto the enamel surfaces to construct a 3D image. The 2D tomographic images of the investigation site were chosen from the 3D dataset and dynamically displayed in video and evaluated by the examiners. A five-rank scale was used to score the level of enamel caries according to the following; 1: Intact enamel. 2: Noncavitated lesion with remineralization. 3: Superficial noncavitated lesion without remineralization. 4: Deep nonvacitated lesion without remineralization. 5: Enamel lesion with cavitation. Sensitivity and specificity for 3D OCT image and visual inspection were calculated. Diagnostic accuracy of each diagnostic method was calculated using weighted kappa. Statistical significance was defined at p = 0.05. (3) Results: 3D SS-OCT could clearly depict enamel caries at smooth tooth surface as a bright zone, based on the increased backscattering signal. It was noted that 3D SS-OCT showed higher sensitivity for the diagnosis of remineralized lesions and deep enamel lesions without cavitation, as well as cavitated enamel lesions (p < 0.05). No significant difference of specificity was observed between the two diagnostic methods (p > 0.05). Furthermore, 3D SS-OCT showed higher diagnostic accuracy than visual inspection (p < 0.05). (4) Conclusions: Within the limitations of this in vitro study, 3D SS-OCT showed higher diagnostic capacity for smooth surface enamel caries than visual inspection and could also discriminate lesion remineralization of enamel caries.

要 旨 歯科医療現場における齲蝕の診断は困難を伴い，病変の深さや拡がりを正確に行う非侵襲的な画像表示方法の開発 が望まれている．歯科用 X 線写真の初期齲蝕に対する感度は低く，透過像として検出できるのは象牙質内部まで深く 進行している病変であることが多い．本研究は光干渉断層計(OCT)を用いた齲蝕の診断精度の検証を目的とし，in vitro および in vivo 実験を行った．平滑面齲蝕，咬合面齲蝕，隣接面齲蝕ならびにコンポジットレジン修復の窩底部の 齲蝕に対する SS-OCT の感度，特異度，受信者動作特性曲線の面積を計測し，視診または X 線写真の結果と比較し た．SS-OCT の断層画像では，齲蝕病変部を輝度の上昇によって表示することができた．厚さ 2 mm までのコンポジ ットレジン修復窩底部の齲蝕も明るく表示され，健全な窩底象牙質と区別することができた． キーワード：齲蝕，光干渉断層計(OCT) ，診断 AbstractDetection of carious lesions remains to be diagnostically challenging, dentists need an imaging technology that can noninvasively and reliably quantify the extent of caries. Dental radiographs do not have the sensitivity for early lesions, and by the time the lesions are radiolucent they have often progressed well into dentin. The aim of this study was to determine the diagnostic accuracy of optical coherent tomography (OCT) in detecting and estimating the depth of dental caries in vitro and in vivo. 19The sensitivity, specificity and area under the receiver operating characteristic curve (Az) of swept-source (SS-) OCT for the detection of smooth surface caries, occlusal caries, proximal caries, and caries under the composite restorations were calculated and compared with visual inspection or radiography.SS-OCT could demonstrate the cross-sectional image of caries as highlighted zone in tomogram. The caries under the composite up to 2 mm thickness also appeared as bright zone that was clearly distinguished from intact dentin.