1. Articles in category: Dentistry

    1-24 of 531 1 2 3 4 ... 21 22 23 »
    1. Monitoring fatigue damage in different CAD/CAM materials: A new approach with optical coherence tomography.

      Monitoring fatigue damage in different CAD/CAM materials: A new approach with optical coherence tomography.

      Purpose: To investigate fatigue damage over time, monolithic posterior computer-aided-designed/computer-aided-manufactured (CAD/CAM) crowns were artificially aged in a mouth-motion-simulator, and damage was monitored with optical coherence tomography (OCT). Methods: Forty-eight crowns were milled of six different CAD/CAM-materials (n=8), including 3Y-TZP (Lava Plus,‘3Y’), 4Y-PSZ (Pritidentamultidisc,‘4Y’), 5Y-PSZ (Prettauanterior,‘5Y’), zirconia-reinforced lithium silicate (CeltraDuo,‘ZLS’), hybrid ceramic (Vita Enamic,‘VE’),and resin composite (BrilliantCrios,‘COM’), and were adhesively luted on CAD/CAM-milled human molars. Specimens were artificially aged in a mouth-motion-simulator (50-500N, 2Hz, 37°C) for a period of 1 million cycles. Before loading and every 250,000 ...

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    2. Influence of tissue fixation on depth-resolved birefringence of oral cavity tissue samples

      Influence of tissue fixation on depth-resolved birefringence of oral cavity tissue samples

      Significance: To advance our understanding of the contrast observed when imaging with polarization-sensitive optical coherence tomography (PS-OCT) and its correlation with oral cancerous pathologies, a detailed comparison with histology provided via ex vivo fixed tissue is required. The effects of tissue fixation, however, on such polarization-based contrast have not yet been investigated. Aim: A study was performed to assess the impact of tissue fixation on depth-resolved (i.e., local) birefringence measured with PS-OCT. Approach: A PS-OCT system based on depth-encoded polarization multiplexing and polarization-diverse detection was used to measure the Jones matrix of a sample. A wide variety of ex ...

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    3. Sorptivity of water in enamel for categorizing caries lesions

      Sorptivity of water in enamel for categorizing caries lesions

      Objective The aim of this research was to determine the association between sorptivity of water and the state of mineralization in carious enamel of different stages of severity. Methods As a preliminary work, water droplets of 1.5 μL were placed on the surfaces of hydroxyapatite (HA) discs of different densities. The water droplet profile was dynamically recorded every second over a period of 10 s using a contact angle meter to determine the relationship between sorptivity and density. To measure and calculate sorptivity on enamel surfaces, varnish was painted on the labial surface of 96 extracted caries-free human teeth ...

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    4. University of California at San Francisco Receives NIH Grant for Infrared Methods for Lesion Activity Assessment

      University of California at San Francisco Receives NIH Grant for Infrared Methods for Lesion Activity Assessment

      University of California at San Francisco Receives a 2020 NIH Grant for $45,564 for Infrared Methods for Lesion Activity Assessment. The principal investigator is Nai-Yaun Chang. Below is a summary of the proposed work. The overall objective of this proposed research is to develop methods for the clinical assessment of lesion structure and activity. Improved imaging technologies employing non-ionizing radiation will significantly improve caries diagnosis and management. It is not sufficient to simply detect carious lesions, methods are needed to assess the activity of the lesion and determine if chemical intervention is needed. The central hypothesis underlying this proposal ...

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    5. Fracture resistance of extensive bulk-fill composite restorations after selective caries removal

      Fracture resistance of extensive bulk-fill composite restorations after selective caries removal

      This study evaluated the effect of selective carious tissue removal on the fracture strength and failure mode of composite restorations in molars presenting only the buccal cusps. Deep cavities were prepared on the occlusal surface, and the lingual cusps were removed. Carious lesions in the middle of the pulpal wall were artificially induced with acetic acid (pH = 4.5) for 35 days. The demineralized dentin was left intact or was completely removed prior to restoration with a bulk-fill composite (n = 10). Images of the specimens were obtained by optical coherence tomography (OCT) before and after the caries induction/removal. The ...

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    6. Diagnostic Accuracy of 870-nm Spectral-Domain OCT with Enhanced Depth Imaging for the Detection of Caries beneath Ceramics

      Diagnostic Accuracy of 870-nm Spectral-Domain OCT with Enhanced Depth Imaging for the Detection of Caries beneath Ceramics

      Abstract Objectives To evaluate the diagnostic accuracy of optical coherence tomography (OCT) for the non-invasive detection of caries adjacent to ceramic materials. Methods Disks made from five ceramic materials (hybrid ceramic, feldspathic ceramic, zirconia-reinforced lithium silicate, lithium disilicate, and high-translucent zirconia) were ground to the recommended material thickness for single crown restorations and laminated with a 100 µm thick layer of one of three adhesive cements. The disks were fixed to extracted human molars with or without carious lesions of one of three standardized sizes. A total of 240 stacks of cross-sectional scans obtained using an 870-nm SD-OCT with enhanced ...

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    7. Fabrication of Dental Crown by Optical Coherence Tomography: A Pilot Study

      Fabrication of Dental Crown by Optical Coherence Tomography: A Pilot Study

      Digital impressions have been studied for better gingival retraction in including the under subgingival finish line condition. Here, we employed swept-source optical coherence tomography (SS-OCT) of 1310 nm wavelength, which is capable of noninvasive, high-resolution, and high-speed, to discern the utilization-possibility for supporting the fabrication of the dental crown. A three-dimensional (3D) abutment was used at the 0.5 mm of the subgingival finish line below the level of the gingiva. The SS-OCT system scanned a field of view of 10 mm × 10 mm using the 3D working model by the depth-directional three focal points. The obtained 1500 images of ...

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    8. OCT evaluation of orthodontic surface sealants: a 12-month follow-up randomized clinical trial

      OCT evaluation of orthodontic surface sealants: a 12-month follow-up randomized clinical trial

      Objectives The aim of this single-center randomized controlled trial (NCT03753256) was to assess orthodontic surface sealant layer thickness and integrity in vivo during a 12-month follow-up by optical coherence tomography (OCT). Materials and methods Using a split-mouth design, quadrants of 20 patients treated with fixed orthodontic appliances were included. Quadrants were randomly assigned to the sealants Pro Seal® (PS) or Opal® Seal™ (OS). OCT scans were performed immediately after the application of the sealants and after 3, 6, 9, and 12 months. Sealant layer thicknesses and their integrity were determined at 5 regions of interest (ROIs) known for high risks ...

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    9. Assessment of the Inner Surface Roughness of 3D Printed Dental Crowns via Optical Coherence Tomography Using a Roughness Quantification Algorithm

      Assessment of the Inner Surface Roughness of 3D Printed Dental Crowns via Optical Coherence Tomography Using a Roughness Quantification Algorithm

      Abstract: Dental crowns are used to restore decayed or chipped teeth, where their surfaces play a key role in this restoration process, as they affect the fitting and stable bonding of the prostheses. The surface texture of crowns can interfere with this restoration process, therefore the measurement of their inner surface roughness is very important but difficult to achieve using conventional imaging methods. In this study, the inner surfaces of dental crowns were three-dimensionally (3D) visualized using swept-source optical coherence tomography (SS-OCT) system. Nine crowns were fabricated with a commercial 3D printer using three different hatching methods (one-way, cross, and ...

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    10. Comparative evaluation of interfacial gaps at the dentin-restorative interface using different bulk fill composites through optical coherence tomography

      Comparative evaluation of interfacial gaps at the dentin-restorative interface using different bulk fill composites through optical coherence tomography

      ABSTRACT: The main problem faced by composites is polymerization shrinkage and stresses which depends on multiple factors such as the configuration factor, composition of resin composites, material properties, various incremental placement techniques and different modes of curing. The aim of this in-vitro study was to evaluate interfacial gaps at dentin- restorative interface with different Bulk-fill composites using a new non-invasive technique, optical coherence tomography (OCT). Our null hypothesis was that there would be no difference in marginal adaptation to the cavity floor between different bulk fill resin composites.

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    11. IDENTIFICATION OF CARIOUS LESIONS IN ENAMEL USING OPTICAL COHERENCE TOMOGRAPHY

      IDENTIFICATION OF CARIOUS LESIONS IN ENAMEL USING OPTICAL COHERENCE TOMOGRAPHY

      The aim of this research was to asses wether OCT could be used for early detection of carious/ demineralised lesions in enamel. If application of Optical coherence tomography (OCT) could be used in early, chair-side detection of caries and therefore initiate the prompt treatment strategies required. 10 extracted teeth were selected with no visible carious lesion. All teeth were scanned using Xray Microtomography (XMT). Four teeth were found with areas of demineralisation which were not visible to the naked eye. The same lesions were then scanned using OCT. SAM software was used to analyse the depth of penetration. OCTview software ...

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    12. Detection of Artificial Tooth Cracks based on Optical Coherence Tomography

      Detection of Artificial Tooth Cracks based on Optical Coherence Tomography

      Due to the hidden symptoms of the tooth cracks, the existing imaging technologies have problems of insufficient resolution and inaccurate detection. In this paper, a swept-source OCT system is designed, which is suitable for the full crown scanning of different kinds of teeth. And the artificial tooth-cracked model is prepared by the temperature difference method, the tooth cracks tomographic images of incisors, premolars and molars under different preparation conditions were obtained by the swept-source OCT. The experimental results show that the swept-source OCT system can image different grades of tooth cracks and monitor the progress of cracks. At the same ...

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    13. Effect of Pretreatment and Activation Mode on the Interfacial Adaptation of Nanoceramic Resin Inlay and Self-adhesive Resin Cementv

      Effect of Pretreatment and Activation Mode on the Interfacial Adaptation of Nanoceramic Resin Inlay and Self-adhesive Resin Cementv

      Objectives The first objective of this study was to determine if the luting material used for resin nanoceramic inlay affects interfacial adaptation. The second was to investigate whether pretreatment and the adhesive curing method before cementation affects interfacial adaptation. The final objective was to compare activation modes of luting material. Methods Class I cavities were prepared on extracted human third molars. Resin nanoceramic inlays were fabricated using Lava Ultimate CAD/CAM block (3 M). For the control groups, inlays were cemented using Panavia V5 (Kuraray Noritake). For the experimental groups, teeth were randomly divided into five experimental groups with four ...

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    14. Evaluation of Neurodegenerative and Inflammatory Processes in Temporomandibular Joint Disorders Using Optical Coherence Tomography

      Evaluation of Neurodegenerative and Inflammatory Processes in Temporomandibular Joint Disorders Using Optical Coherence Tomography

      Introduction: Temporomandibular joint disorders (TMD) is a process with systemic effects rather than local effects. The purpose of this study is to examine the retinal layer structure using optical coherence tomography (OCT) method in order to detect possible degenerative and inflammatory process in patients with TMD. Material and Methods: 35 healthy controls and 34 TMD patients were evaluated bilaterally in this study. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL) and choroidal thickness were analyzed using OCT. Results: When TMD patients were compared with healthy controls, GCL and IPL volumes and RNFL thickness decreased ...

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    15. Correlation between Lesion Progression and Depolarization Assessed by Polarization-Sensitive Optical Coherence Tomography

      Correlation between Lesion Progression and Depolarization Assessed by Polarization-Sensitive Optical Coherence Tomography

      The detection of early stages of caries is still one of the major challenges in preservative dentistry. Since it is known from polarized light microscopy (PLM) that intrinsic enamel birefringence is affected by demineralization, polarization-sensitive optical coherence tomography (PSOCT) could facilitate the noninvasive detection and assessment of early carious lesions. The present study aims to correlate enamel lesion progression and depolarization measurements based on PSOCT in an artificial demineralization model. A total of 18 enamel slabs were prepared from bovine incisor teeth and demineralized in an acetic buffer solution for up to 49 days. The degree of polarization (DOP)—indicating ...

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    16. Non‐invasive multimodal imaging by integrating optical coherence tomography with autofluorescence imaging for dental applications

      Non‐invasive multimodal imaging by integrating optical coherence tomography with autofluorescence imaging for dental applications

      We report the development of an integrated multi‐functional imaging system capable of providing anatomical (optical coherence tomography, OCT), functional (OCT angiography, OCTA) and molecular imaging (light‐induced autofluorescence, LIAF) for in vivo dental applications. Blue excitation light (405 nm) was used for LIAF imaging, while the OCT was powered by a 1310 nm swept laser source. A red‐green‐blue (RGB) digital camera, with a 450 nm cut‐on broad‐band optical filter, was used for LIAF detection. The exciting light source and camera were integrated directly with the OCT scanning probe. The integrated system used two non‐invasive ...

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    17. Diagnosis of Occlusal Caries with Dynamic Slicing of 3D Optical Coherence Tomography Images

      Diagnosis of Occlusal Caries with Dynamic Slicing of 3D Optical Coherence Tomography Images

      Detecting 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 ...

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    18. Effect of Light Irradiation Condition on Gap Formation Under Polymeric Dental Restoration; OCT study

      Effect of Light Irradiation Condition on Gap Formation Under Polymeric Dental Restoration; OCT study

      Objective To investigate the effect of two light-curing systems; quartz tungsten-halogen (QTH) and light-emitting diode (LED), and irradiation time on interfacial gap formation of dental composite resin restorations bonded with an adhesive resin using optical coherence tomography (OCT). Materials and Methods Forty cavities were prepared in extracted human molar teeth and divided into four groups (n = 10) based on the type of light curing system QTH (LITEX 680A) and LED (Demi Plus) and curing duration (10 s or 40 s). A single-step self-etching dental adhesive (Tetric® N-Bond; Ivoclar Vivadent AG, Schaan, FL, Liechtenstein) was applied and polymerized with QTH for ...

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    19. Evaluation of Crack Formation and Propagation with Ultrasonic Root-End Preparation and Obturation Using a Digital Microscope and Optical Coherence Tomography

      Evaluation of Crack Formation and Propagation with Ultrasonic Root-End Preparation and Obturation Using a Digital Microscope and Optical Coherence Tomography

      Objective . This study is aimed at determining (1) the effect of root-end resection, ultrasonic root-end preparation, and root-end filling on the incidence of crack formation and propagation by using a digital microscope (DM) and optical coherence tomography (OCT) and (2) the performance of OCT on the detection of cracks by comparing with microcomputed tomography (micro-CT) as a reference standard. Methodology . Thirty extracted lower incisors were endodontically treated and subjected to root-end resection and ultrasonic root-end cavity preparation. Then, the teeth were divided into three groups ( , each), and the root-end cavity was either left unfilled or filled with mineral trioxide aggregate ...

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    20. Optical coherence tomography for orthodontic aligners

      Optical coherence tomography for orthodontic aligners

      Methods and apparatuses for 3D imaging (including 3D optical coherence tomography imaging) to measure the shape of orthodontic aligners, teeth, and other oral structures simultaneously, in-vivo or in-vitro. These methods and apparatuses may be used to determine contact locations of aligners with teeth and/or teeth with other teeth with very high precision, including determining the size of gaps where they are not in contact. These measurements may be used design, modify or replace an aligner and/or to verify aligner fit. 3D models of the whole aligner and teeth may be generated.

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    21. Demineralization detection in orthodontics using an ophthalmic optical coherence tomography device equipped with a multicolor fluorescence module

      Demineralization detection in orthodontics using an ophthalmic optical coherence tomography device equipped with a multicolor fluorescence module

      Objectives Demineralizations such as white spot lesions are among the most prevalent side effects during orthodontic treatment. Fluorescence devices, including quantitative light-induced fluorescence (QLF), exploiting the intrinsic fluorescence of enamel and teeth and most recently optical coherence tomography (OCT) were introduced for early demineralization detection. In addition to near-infrared OCT scanning, multicolor modules allow for imaging with different laser wavelengths and the detection of reflective- and fluorescent light. The aim of this study was to evaluate a modified multicolor ophthalmic OCT device for the detection of early carious lesions in vitro and in vivo. Materials and methods Twenty-seven extracted lesion ...

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    22. EVALUATION OF POROSITY AND BIOFILM FORMATION IN RELINE RESINS THROUGH OPTICAL COHERENCE TOMOGRAPHY

      EVALUATION OF POROSITY AND BIOFILM FORMATION IN RELINE RESINS THROUGH OPTICAL COHERENCE TOMOGRAPHY

      Objective To evaluate the porosity and adhesion of mixed colony microorganisms in reline resins by means of optical coherence tomography (OCT). Study Design Two commercial brands of reline resins (Soft-Comfort and Coe-Comfort) were used, divided into 2 groups, and 10 samples were made for each group. Samples were submitted to OCT scanning before and after 96 hours inoculation with Candida albicans . The OCT images were composed of 2000 columns and 512 lines, obtained from a commercial model, Callisto SD-OCT (Thorlabs, USA), operating at 930 nm of central wavelength and 7 μm of axial resolution in the air. After the images ...

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    23. The Use of Optical Coherence Tomography as a Diagnostic Tool for Dental Caries (Thesis)

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

      Dental caries is one of the most common human diseases, 60-90% of school children worldwide 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/International 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 ...

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    24. OCT-Based Periodontal Inspection Framework

      OCT-Based Periodontal Inspection Framework

      Periodontal diagnosis requires discovery of the relations among teeth, gingiva (i.e., gums), and alveolar bones, but alveolar bones are inside gingiva and not visible for inspection. Traditional probe examination causes pain, and X-ray based examination is not suited for frequent inspection. This work develops an automatic non-invasive periodontal inspection framework based on gum penetrative Optical Coherence Tomography (OCT), which can be frequently applied without high radiation. We sum up interference responses of all penetration depths for all shooting directions respectively to form the shooting amplitude projection. Because the reaching interference strength decays exponentially with tissues’ penetration depth, this projection ...

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