MDPIActa Medica Okayama1996-19441482021Assessment of Demineralization Inhibition Effects of Dentin Desensitizers Using Swept-Source Optical Coherence Tomography1876ENKumikoMatsuzakiDepartment of Operative Dentistry, Field of Study of Biofunctional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesYasushiShimadaDepartment of Operative Dentistry, Field of Study of Biofunctional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesYasuoShinnoDepartment of Operative Dentistry, Field of Study of Biofunctional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesSerinaOnoDepartment of Operative Dentistry, Field of Study of Biofunctional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesKozoYamajiDepartment of Operative Dentistry, Field of Study of Biofunctional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesNaokoOharaDepartment of Operative Dentistry, Field of Study of Biofunctional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesAlirezaSadrBiomimetics Biomaterials Biophotonics Biomechanics & Technology Laboratory, Department of Restorative Dentistry, University of WashingtonYasunoriSumiCenter of Advanced Medicine for Dental and Oral Diseases, Department for Advanced Dental Research, National Center for Geriatrics and Ger OntologyJunjiTagamiDepartment of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityMasahiroYoshiyamaDepartment of Operative Dentistry, Field of Study of Biofunctional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesThe purpose of this study was to evaluate the mechanism of action and the inhibiting effects of two types of desensitizers against dentin demineralization using pre-demineralized hypersensitivity tooth model in vitro. In this study, we confirmed that a hypersensitivity tooth model from our preliminary experiment could be prepared by immersing dentin discs in an acetic acid-based solution with pH 5.0 for three days. Dentin discs with three days of demineralization were prepared and applied by one of the desensitizers containing calcium fluoro-alumino-silicate glass (Nanoseal, NS) or fluoro-zinc-silicate glass (Caredyne Shield, CS), followed by an additional three days of demineralization. Dentin discs for three days of demineralization (de3) and six days of demineralization (de6) without the desensitizers were also prepared. The dentin discs after the experimental protocol were scanned using swept-source optical coherence tomography (SS-OCT) to image the cross-sectional (2D) view of the samples and evaluate the SS-OCT signal. The signal intensity profiles of SS-OCT from the region of interest of 300, 500, and 700 mu m in depth were obtained to calculate the integrated signal intensity and signal attenuation coefficient. The morphological differences and remaining chemical elements of the dentin discs were also analyzed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. SS-OCT images of CS and NS groups showed no obvious differences between the groups. However, SS-OCT signal profiles for both the CS and NS groups showed smaller attenuation coefficients and larger integrated signal intensities than those of the de6 group. Reactional deposits of the desensitizers even after the additional three days of demineralization were observed on the dentin surface in NS group, whereas remnants containing Zn were detected within the dentinal tubules in CS group. Consequently, both CS and NS groups showed inhibition effects against the additional three days of demineralization in this study. Our findings demonstrate that SS-OCT signal analysis can be used to monitor the dentin demineralization and inhibition effects of desensitizers against dentin demineralization in vitro.No potential conflict of interest relevant to this article was reported.ELSEVIER SCI LTDActa Medica Okayama1882-76165612020Evaluation of dental caries, tooth crack, and age-related changes in tooth structure using optical coherence tomography109118ENYasushiShimadaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama UniversityMasahiroYoshiyamaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama UniversityJunjiTagamiDepartment of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityYasunoriSumiDepartment for Advanced Dental Research, Center of Advanced Medicine for Dental and Oral Diseases, National Center for Geriatrics and GerontologyOptical coherence tomography (OCT) is an imaging technique that can visualize the internal biological structure without X-ray exposure. Swept-source OCT (SS-OCT) is one of the latest version of OCT, wherein the light source is a tunable laser that sweeps near-infrared wavelength light to achieve real-time imaging. The imaging depth of OCT is highly influenced by the translucency of the medium. The medium that does not transmit light and the deeper structure beyond the range of light penetration depth are not relevant for OCT imaging. In OCT, sound enamel is almost transparent at the OCT wavelength range, and enamel and dentin can be distinguished from each other as the dentin-enamel junction (DEJ) appears as a dark border. Demineralized enamel and dentin are imaged as bright zones because of the formation of numerous micro-porosities where the backscatter of OCT signal is increased. In cavitated caries at interproximal or occlusal hidden zone, the upper margin of the cavity reflects the signal showing a distinct bright border in the SS-OCT image. SS-OCT is capable of determining crack penetration depth even when the cracks extended beyond the DEJ. SS-OCT has a high degree of sensitivity and specificity for the detection of dental caries and tooth cracks. SS-OCT is also capable of detecting non-carious cervical lesions and occlusal tooth wear in cross-sectional views to estimate the amount of tooth structure loss.No potential conflict of interest relevant to this article was reported.ElsevierActa Medica Okayama1882-76165612020Evaluation of dental caries, tooth crack, and age-related changes in tooth structure using optical coherence tomography109118ENYasushiShimadaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama UniversityMasahiroYoshiyamaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama UniversityJunjiTagamiDepartment of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityYasunoriSumiDepartment for Advanced Dental Research, Center of Advanced Medicine for Dental and Oral Diseases, National Center for Geriatrics and GerontologyOptical coherence tomography (OCT) is an imaging technique that can visualize the internal biological structure without X-ray exposure. Swept-source OCT (SS-OCT) is one of the latest version of OCT, wherein the light source is a tunable laser that sweeps near-infrared wavelength light to achieve real-time imaging. The imaging depth of OCT is highly influenced by the translucency of the medium. The medium that does not transmit light and the deeper structure beyond the range of light penetration depth are not relevant for OCT imaging. In OCT, sound enamel is almost transparent at the OCT wavelength range, and enamel and dentin can be distinguished from each other as the dentin–enamel junction (DEJ) appears as a dark border. Demineralized enamel and dentin are imaged as bright zones because of the formation of numerous micro-porosities where the backscatter of OCT signal is increased. In cavitated caries at interproximal or occlusal hidden zone, the upper margin of the cavity reflects the signal showing a distinct bright border in the SS-OCT image. SS-OCT is capable of determining crack penetration depth even when the cracks extended beyond the DEJ. SS-OCT has a high degree of sensitivity and specificity for the detection of dental caries and tooth cracks. SS-OCT is also capable of detecting non-carious cervical lesions and occlusal tooth wear in cross-sectional views to estimate the amount of tooth structure loss.No potential conflict of interest relevant to this article was reported.MDPIActa Medica Okayama1424-822020212020Diagnosis of Occlusal Tooth Wear Using 3D Imaging of Optical Coherence Tomography Ex Vivo6016ENMisaKashiwaDepartment of Cariology and Operative Dentistry Department, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityYasushiShimadaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityAlirezaSadrDepartment of Cariology and Operative Dentistry Department, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityMasahiroYoshiyamaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityYasunoriSumiCenter of Advanced Medicine for Dental and Oral Diseases, Department for Advanced Dental Research, National Center for Geriatrics and GerontologyJunjiTagamiDepartment of Cariology and Operative Dentistry Department, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityThe aim of this study was to assess the utility of 3D imaging of optical coherence tomography (OCT) for the diagnosis of occlusal tooth wear ex vivo. Sixty-three extracted human molars with or without visible tooth wear were collected to take digital intraoral radiography and 3D OCT images. The degree of tooth wear was evaluated by 12 examiners and scored using 4-rank scale: 1-slight enamel wear; 2-distinct enamel wear; 3-tooth wear with slight dentin exposure; 4-tooth wear with distinct involvement of dentin. The degree of tooth wear was validated by the histological view of confocal laser scanning microscopy (CLSM). The sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic analysis were calculated. Diagnostic accuracy was compared with the agreement with CLSM observation using weighted kappa. The results were statistically analyzed at a significance level of alpha = 0.05. Three-dimensional OCT showed significantly higher sensitivity (p < 0.05) for all the diagnostic thresholds of enamel wear and dentin exposure than digital radiography (0.82, 0.85, and 0.79 vs. 0.56, 0.52, and 0.57, respectively). Three-dimensional OCT showed higher AUC and kappa coefficients than digital radiography (p < 0.05), where mean AUC and Kappa values were 0.95 and 0.76 for OCT and 0.92 and 0.47 for radiography, respectively. No significant difference of specificity was observed (p > 0.05). Three-dimensional OCT could visualize and estimate the degree of tooth wear and detect the dentin exposure at the tooth wear surface accurately and reproducibly. Consequently, a new guideline for tooth wear assessment can be proposed using OCT.No potential conflict of interest relevant to this article was reported.Nature ResearchActa Medica Okayama2045-232210120203D imaging of proximal caries in posterior teeth using optical coherence tomography15754ENYasushiShimadaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityMichael F.BurrowFaculty of Dentistry, The University of Hong Kong, Prince Philip Dental HospitalKazuyukiArakiDepartment of Oral Diagnostic Sciences, Division of Radiology, Showa University School of DentistryYuanZhouDepartment of Preventive Dentistry, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of MedicineKeiichiHosakaDepartment of Cariology and Operative Dentistry, Graduate School of Medical and Dental SciencesAlirezaSadrDepartment of Restorative Dentistry, University of Washington School of DentistryMasahiroYoshiyamaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityTakashiMiyazakiDepartment of Conservative Dentistry, Division of Biomaterials and Engineering, Showa University School of DentistryYasunoriSumiDepartment for Advanced Dental Research, Center of Advanced Medicine for Dental and Oral Diseases, National Center for Geriatrics and GerontologyJunjiTagamiDepartment of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityOptical coherence tomography (OCT) can create cross-sectional images of tooth without X-ray exposure. This study aimed to investigate the diagnostic accuracy of 3D imaging of OCT for proximal caries in posterior teeth. Thirty-six human molar teeth with 51 proximal surfaces visibly 6 intact, 16 slightly demineralized, and 29 distinct carious changes were mounted to take digital radiographs and 3D OCT images. The sensitivity, specificity and area under the receiver operating characteristic curve (AUC) for the diagnosis of enamel caries and dentin caries were calculated to quantify the diagnostic ability of 3D OCT in comparison with digital radiography. Diagnostic accuracy was evaluated by the agreement with histology using weighted Kappa. OCT showed significantly higher sensitivity, AUC and Kappa values than radiography. OCT can be a safer option for the diagnosis of proximal caries in posterior teeth that can be applied to the patients without X-ray exposure.No potential conflict of interest relevant to this article was reported.MDPIActa Medica Okayama1424-82202062020Diagnosis of Occlusal Caries with Dynamic Slicing of 3D Optical Coherence Tomography Images1659ENMinh N.LuongDepartment of Restorative Dentistry, University of WashingtonYasushiShimadaGraduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityKazuyukiArakiDivision of Radiology, Department of Oral Diagnostic Sciences, Showa University School of DentistryMasahiroYoshiyamaGraduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityJunjiTagamiDepartment of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityAlirezaSadrDepartment of Restorative Dentistry, University of WashingtonDetecting the extent of occlusal caries is a clinically important but challenging task required for treatment decision making. The aim of this study was to assess the diagnostic power of 3D swept-source optical coherence tomography (OCT) for evaluation of occlusal caries in comparison with X-ray radiography. Extracted human molars not exhibiting American Dental Association (ADA) criteria advanced caries were mounted in a silicone block and digital dental radiographs were captured from the buccal side. Subsequently, occlusal surfaces were scanned with a prototype Yoshida Dental OCT. Thirteen examiners evaluated the presence and extent of caries on radiographs and dynamically sliced 3D OCT video images, using a 4 level scale-0: intact; 1: enamel demineralization without cavitation; 2: enamel caries with cavitation; 3: dentin caries with or without cavitation. Sensitivity, specificity and area under operating characteristic curves (Az) were statistically analyzed (alpha = 0.05). Reliability analysis showed an excellent agreement among the 13 examiners for both methods. The OCT presented a significantly higher sensitivity and Az value for the detection of caries compared to radiographs (p < 0.05). Radiography showed especially low sensitivity for dentin caries (0-2 versus 3). Dynamic slicing of 3D OCT volumes is a powerful adjunct tool to visual inspection to diagnose the dentin occlusal caries in vitro.No potential conflict of interest relevant to this article was reported.Japanese Society for Dental Materials and DevicesActa Medica Okayama0287-4547383852019The Effect of Flowable Composite Lining and Dentin Location on Microtensile Bond Strength and Internal Fracture Formation798805ENNaoKominamiDepartment of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityYasushiShimadaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University.KeiichiHosakaDepartment of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityMinh Nguyet LuongDepartment of Restorative Dentistry and Endodontics, Faculty of Odonto-Stomatology, University of Medicine and Pharmacy at Ho Chi Minh CityMasahiroYoshiyamaDepartment of Operative Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University.AlirezaSadrBiomimetics Biomaterials Biophotonics & Technology Laboratory, Department of Restorative Dentistry, University of Washington School of DentistryYasunoriSumiNational Center for Geriatrics and Gerontology, Department of Advanced Dental Research, Center of Advanced Medicine for Dental and Oral DiseaseJunjiTagamiThe objective of this study was to determine the effect of flowable composite lining and dentin location on internal dentin fracture formation in the microtensile bond strength (MTBS) test using swept-source optical coherence tomography (SS-OCT). MTBS test beams (1.0×1.0 mm) were prepared from human superficial and deep dentin, which was bonded with a self-etch adhesive (Clearfil SE Bond) and hybrid composite resin (Clearfil AP-X), with or without flowable lining (Clearfil Majesty ES-Flow). We tested 4 groups according to placement technique (with vs. without flowable liner) and dentin (superficial vs. deep) locations. Cross-sectional 2D images of the bonded interface were obtained before and after the MTBS test. Internal dentin fracture after MTBT was observed as a bright zone in SS-OCT. Flowable lining significantly reduced internal fracture formation in dentin (p<0.05). Dentin location significantly influenced MTBS (p<0.05), and this was reduced by flowable lining usage.No potential conflict of interest relevant to this article was reported.Japanese Society for Dental Materials and DevicesActa Medica Okayama0287-45473852019Cavity Adaptation of Composite Restorations Prepared at Crown and Root: Optical Assessment Using SS-OCT779789ENRima Zakzuk AlshahniCariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityYasushiShimadaDepartment of Operative Dentistry, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical SciencesYuanZhouCariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental UniversityMasahiroYoshiyamaDepartment of Operative Dentistry, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical SciencesAlirezaSadrDepartment of Restorative Dentistry, University of Washington, School of DentistryYasunoriSumiDivision of Oral and Dental Surgery, Department of Advanced Medicine, National Center for Geriatrics and Gerontology, National Hospital for Geriatric MedicineJunjiTagamiCariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University Evaluation of gap formation at the interfaces of a two-step self-etching adhesive with/without pre-etching was performed using sweptsource optical coherence tomography (SS-OCT). Round cavities were prepared in bovine incisors at the middle (MC) and cervical (CC) thirds of the crown and the cervical third of the root (CR). Clearfil SE bond was directly applied to one group (SE) and another (PA) was pretreated with K-etchant gel. Following restoration by flowable composite resin, the teeth were thermally challenged and stored for 2 months. Interfacial gaps observed in the cross-sectional OCT images were analyzed and the bottom cavities exhibited increased gaps compared to the margin and dentin-enamel junction (DEJ). The CR site had a larger gap than at MC and CC in the SE group. DEJ separation at the MC was significantly smaller than that at CC in both groups. Therefore, gap formation depends on the cavity region, location, and bonding protocol.No potential conflict of interest relevant to this article was reported.