AN AUTOMATED DENTAL CARIES DETECTION AND SCORING SYSTEM FOR OPTIC IMAGES OF TOOTH OCCLUSAL SURFACE

Dental caries are one of the most prevalent chronic diseases. Worldwide 60 to 90 percent of school children and nearly 100 percent of adults experienced dental caries. The management of dental caries demands detection of carious lesions at early stages. The research of designing diagnostic tools in caries has been at peak for the last decade. This research aims to design an automated system to detect and score dental caries according to the International Caries Detection and Assessment System (ICDAS) guidelines using the optical images of the occlusal tooth surface. There have been numerous works that address the problem of caries detection by using new imaging technologies or advanced measurements. However, no such study has been done to detect and score caries with the use of optical images of the tooth surface. The aim of this dissertation is to develop image processing and machine learning algorithms to address the problem of detection and scoring the caries by the use of optical image of the tooth surface

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

3D imaging of proximal caries in posterior teeth using optical coherence tomography

Optical 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

An evaluation of computer-based radiographic methods in estimating dental caries and periodontal diseases

Reductions in dental diseases have resulted in a need for more accurate diagnostic and monitoring methods. The purpose of this study was to 1) identify the best diagnostic technique, 2) investigate the main factors which limit its validity and reliabilty and 3) devise methods to improve its reliability and 4) investigate ways of automating its use for general dental practice. From the literature review radiography was identified as the best current method with regard to validity, reliability, production of stable objective data and ease of use. However, irradiation geometry variations between serial films and subjective measurement errors were its principle limitations. Although an accurate semi-automatic caries measuring system exists, it is unsuitable for general practice due to lengthy operator interaction. A series of computer-based experiments were devised to evaluate further the digital subtraction radiography technique (DSR); develop a new method using stored regions of interest (ROI) to reduce subjective measurement errors; investigate the feasibility of completely automatic image analysis. In addition, an in vitro caries experiment was designed to demonstrate the effects of irradiation geometry variation on lesion size and caries scores. The results demonstrated that small variations in irradiation geometry can change radiographic scores. Misalignment of subsequent films beneath a video camera can cause significant errors in the DSR technique. The stored ROI method reduced cement-enamel junction to alveolar crest measurement errors to standard deviation 0.15mm. A fully automatic method for recognising teeth and bone crests was demonstrated. It was concluded that 1) radiography is currently the technique of choice, 2) a new significant methodological error for DSR has been demonstrated, 3) the subjective ROI method produced lower intra- and inter-examiner measurement errors compared to similar methods, 4) routine use of automatic methods may be feasible and should be investigated further and 5) standardised irradiation geometry is essential

Investigating the ultrastructure of enamel white spot lesions (WSL) using Optical Coherence Tomography at different length scales

White spot lesion (WSL) is the clinical presentation of early caries, which is a demineralisation that occurs at subsurface level, with a well-mineralised surface layer enclosing the lesion. Early diagnosis and treatment of WSL is crucial to prevent further destruction of tooth structure. The aim of this research is to investigate the potential of optical coherence tomography (OCT) to be used as an adjunct diagnostic clinical tool to evaluate the severity of such lesions. This research also compared the OCT outputs with traditional histology, X-ray Microtomography (XMT), Synchrotron X-ray Diffraction (SXRD) and Scanning Electron microscope (SEM). All specimens were collected from patients undergoing dental treatment at Eastman Dental Hospital with informed consent following ethical approvall. Initially, Artificial WSLs were induced on sound enamel surfaces using a buffered methylcellulose gel system at pH 4.6 for 7 and 14 days. Type-matched native WSL and healthy control teeth were selected based on ICDAS for comparison. Imaging of samples was obtained using OCT of whole teeth and by polarised microscopy, SXRD, XMT and SEM of polished 250 μm thick sections. Polarised microscope, XMT and SEM confirmed the findings of the OCT results. Images showed that the more back scattered signals recorded, the deeper the destruction throughout enamel thickness. SXRD results showed changes in enamel texture, which was interpreted from measuring crystallite orientations and lattice parameter. SXRD result showed some correlation with OCT images, however more investigation is required to confirm the findings. In conclusion, the variations observed in the back-scattered light in OCT experiment were because of mineral density variation within enamel structure, as well as the changes in prismatic structure and may be related to crystallite texture and orientation. OCT has shown to be a reliable non-destructive technique, that can investigate the internal structure, by measuring the back-scattered light from materials such as enamel and dentine. In healthy samples, OCT B-scans showed a homogenous pattern of scattering intensity throughout enamel structure, indicating healthy structure, while in both natural and induced white spot lesions, a non homogenous scattering intensity was observed, indicating changes in enamel structure

A Comparison of the Clinical Axial Extension of Class II Carious Lesions with Different Diagnostic Images

[null]Master of ScienceRestorative DentistryUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/91025/1/Bin-Shuwaish_Mohammed_SH-THESIS-FINAL.pd