The Use of Optical Coherence Tomography in Dental Diagnostics: a State-of-the-Art Review

Optical coherence tomography provides sections of tissues in a noncontact and noninvasive manner. The device measures the time delay and intensity of the light scattered or reflected from biological tissues, which results in tomographic imaging of their internal structure. This is achieved by scanning tissues at a resolution ranging from 1 to 15 μm. OCT enables real-time in situ imaging of tissues without the need for biopsy, histological procedures, or the use of X-rays, so it can be used in many fields of medicine. Its properties are not only particularly used in ophthalmology, in the diagnosis of all layers of the retina, but also increasingly in cardiology, gastroenterology, pulmonology, oncology, and dermatology. The basic properties of OCT, that is, noninvasiveness and low wattage of the used light, have also been appreciated in analytical technology by conservators, who use it to identify the quality and age of paintings, ceramics, or glass. Recently, the OCT technique of visualization is being tested in different fields of dentistry, which is depicted in the article

Optical coherence tomography in the detection and diagnosis of dental enamel demineralisation areas

A cárie dentária e a erosão dentária são os principais problemas em odontologia. O diagnóstico correto, especialmente em lesões precoces, é vital para o plano de tratamento adequado. O exame visual-tátil e a radiografia dentária são os métodos mais utilizados para esse fim. A tomografia de coerência óptica (OCT) é outro método imagiológico capaz de melhorar o exame visual-tátil no diagnóstico de lesões em esmalte. A sensibilidade do instrumento é muito alta, geralmente mais de 90% e a especificidade normalmente acima de 95%. Utiliza o princípio da interferometria óptica com uma fonte de luz a emitir no infravermelho próximo (comprimento de onda na região de 1300 nm). Um software de processamento de imagens adequado pode melhorar a produção de imagens, incluir zonas colorimétricas e produzir uma imagem-3D, reduzindo a subjetividade na interpretação. Por não utilizar radiação ionizante e obter uma imagem nítida em tempo real, pode ser um bom substituto para a radiografia dentária em caso de avaliação diagnóstica de esmalte e dentina dentários.The dental caries and dental erosion are the major dental problems in dentistry. The correct diagnosis, especially in early lesions, is vital for the proper treatment plan. Visualtactile examination and dental radiography are the most used methods for this purpose. The optical coherence tomography (OCT) is another imaging tool with the capability to improve the visual-tactile examination in enamel diagnostic. The instrument sensitivity is very high, usually more than 90% as the specificity is usually higher than 95%. It uses the principle of optical interferometry with an optical source emitting in the near-infrared (wavelength close to 1300 nm). Proper processing image software can improve the imaging production and present a 3D-image as reduces subjectivity with a colorimetric presentation. As it not use ionising radiation and offers a clear image production in real time, can be a good substitute to dental radiography in case of enamel and outer dentin diagnostic assessment

The Use of Optical Coherence Tomography as a Diagnostic Tool for Dental Caries

Dental caries is one of the most common human diseases, 60-90% of school children world-wide have dental cavities. Severity can vary, from early demineralisation, which preventive measures can improve, to cavitation, leading to fillings. Different diagnostic tools are available, such as clinical examination, radiographic investigation and Enhanced Visual examination/In-ternational Caries Detection and Assessment System (ICDAS). To date, there is no universal diagnostic tool that can be used to detect carious lesions at the very early stages. Optical Coherence Tomography (OCT) is a non-invasive and ionising radiation free technique that has been used in dentistry, but not to diagnose caries. // The aim of this research was to investigate the use of OCT imaging in dentistry as a routine, and adjunct clinical diagnostic tool for dental caries, by developing standardised markers for each ICDAS score, and to compare the results with conventional clinical methods i.e. radio-graphs and ICDAS. In addition, markers in the OCT scan and scattering profile intensity plots for both sound and carious affected teeth were determined, to aid diagnosis. // All specimens were collected from patients undergoing dental treatment at Eastman Dental Hospital. Extracted human primary and permanent teeth (N>180) with varying caries severity were collected under ethical approval, after obtaining informed consent according to the inclu-sion and exclusion criteria. Photographic and radiographic images of tooth samples were taken and categorised according to the ICDAS system. Samples were then imaged using OCT (VivoSight OCT Scanner) with each lesion scanned separately (N>200). The scattering inten-sity profiles were plotted. In healthy samples, OCT B-scans showed a homogenous pattern of scattering intensity throughout enamel structure indicating healthy structure while in carious teeth, a non-homogenous scattering intensity was observed indicating changes in enamel structure. // Different scattering intensity profiles for each ICDAS score were observed, and empirical markers were developed for each score. This led to establishing scattering fingerprints for each type of ICDAS lesion. A multi-assessor’s analysis, followed by a kappa analysis, was carried to evaluate the selectivity and accuracy of the makers. The results showed moderate to substantial strength of agreement in both intra-rater and inter-rater reliability. // In conclusion, OCT has been shown to be a safe, useful, reliable and non-destructive tech-nique that can investigate the internal structure by measuring the back-scattered light from enamel and dentine. OCT provides an understanding of the lesion in terms of depth and ex-tent, therefore helping in predicting the lesion’s prognosis, which is not found in conventional methods. In addition, OCT helps to differentiate between carious and sound teeth, and addi-tionally between different ICDAS scores. The definition of specific scattering markers for each type of caries lesions will enable us to bring this technique one-step closer to the clinic

OCT for non-destructive examination of the internal biological structures of mosquito specimen

The Study of mosquitoes and their behavioral analysis are of crucial importance to control the alarmingly increasing mosquito-borne diseases. Conventional imaging techniques use either dissection, exogenous contrast agents. Non-destructive imaging techniques, like x-ray and microcomputed tomography uses ionizing radiations. Hence, a non-destructive and real-time imaging technique which can obtain high resolution images to study the anatomical features of mosquito specimen can greatly aid researchers for mosquito studies. In this study, the three-dimensional imaging capabilities of optical coherence tomography (OCT) for structural analysis of Anopheles sinensis mosquitoes has been demonstrated. The anatomical features of An. sinensis head, thorax, and abdomen regions along with internal morphological structures like foregut, midgut, and hindgut were studied using OCT imaging. Two-dimensional (2D) and three-dimensional (3D) OCT images along with histology images were helpful for the anatomical analysis of the mosquito specimens. From the concurred results and by exhibiting this as an initial study, the applicability of OCT in future entomological researches related to mosquitoes and changes in its anatomical structure is demonstrated

Optical Methods in Sensing and Imaging for Medical and Biological Applications

The recent advances in optical sources and detectors have opened up new opportunities for sensing and imaging techniques which can be successfully used in biomedical and healthcare applications. This book, entitled ‘Optical Methods in Sensing and Imaging for Medical and Biological Applications’, focuses on various aspects of the research and development related to these areas. The book will be a valuable source of information presenting the recent advances in optical methods and novel techniques, as well as their applications in the fields of biomedicine and healthcare, to anyone interested in this subject

Effects of Temperature Variations during Sintering of Metal Ceramic Tooth Prostheses Investigated Non-Destructively with Optical Coherence Tomography

Calibration loss of ovens used in sintering metal ceramic prostheses leads to stress and 18 cracks in the material of the prostheses fabricated, and ultimately to failure of the dental treatment. 19 Periodic calibration may not be sufficient to prevent such consequences. Evaluation methods based 20 on firing supplemental control samples are subjective, time consuming, and rely entirely on the 21 technician’s skills. The aim of this study was to propose an alternative procedure for such 22 evaluations. Fifty prostheses were sintered in a ceramic oven at a temperature lower, equal or 23 larger than the temperature prescribed by the manufacturer. A non-destructive imaging method, 24 swept source (SS) optical coherence tomography (OCT) was used to evaluate comparatively the 25 internal structure of prostheses so fabricated. A quantitative assessment procedure is proposed, 26 based on en-face OCT images acquired at similar depths inside the samples. Differences in 27 granulation and reflectivity depending on the oven temperature are used to establish 28 rules-of-thumb on judging the correct calibration of the oven. OCT evaluations, made on a regular 29 basis allow an easy and objective monitoring of correct settings in the sintering process. This 30 method can serve rapid identificatio

Effects of Temperature Variations during Sintering of Metal Ceramic Tooth Prostheses Investigated Non-Destructively with Optical Coherence Tomography

Calibration loss of ovens used in sintering metal ceramic prostheses leads to stress and 18 cracks in the material of the prostheses fabricated, and ultimately to failure of the dental treatment. 19 Periodic calibration may not be sufficient to prevent such consequences. Evaluation methods based 20 on firing supplemental control samples are subjective, time consuming, and rely entirely on the 21 technician’s skills. The aim of this study was to propose an alternative procedure for such 22 evaluations. Fifty prostheses were sintered in a ceramic oven at a temperature lower, equal or 23 larger than the temperature prescribed by the manufacturer. A non-destructive imaging method, 24 swept source (SS) optical coherence tomography (OCT) was used to evaluate comparatively the 25 internal structure of prostheses so fabricated. A quantitative assessment procedure is proposed, 26 based on en-face OCT images acquired at similar depths inside the samples. Differences in 27 granulation and reflectivity depending on the oven temperature are used to establish 28 rules-of-thumb on judging the correct calibration of the oven. OCT evaluations, made on a regular 29 basis allow an easy and objective monitoring of correct settings in the sintering process. This 30 method can serve rapid identificatio