Quantitative evaluation of dental abfraction and attrition using a swept-source optical coherence tomography system

A fast swept-source optical coherence tomography (SS-OCT) system is employed to acquire volumes of dental tissue, in order to monitor the temporal evolution of dental wear. An imaging method is developed to evaluate the volume of tissue lost in ex vivo artificially induced abfractions and attritions. The minimal volume (measured in air) that our system could measure is 2352 ìm3. A volume of 25,000 A-scans is collected in 2.5 s. All these recommend the SS-OCT method as a valuable tool for dynamic evaluation of the abfraction and attrition with remarkable potential for clinical use. © The Authors

3D reconstructions of resin dental fillings based on en face OCT images

Optical tomographic techniques are of particular importance in the medical imaging field, because these techniques can provide non-invasive diagnostic images. In the present study, en-face optical coherence tomography (efOCT) was used as a non-invasive high resolution imaging method for supplying the necessary information on the quality of dental hard tissues and coronal composite resin fillings. Teeth after being subject to several treatment methods are imaged in order to asses the material defects and micro-leakage of tooth-filling interface as well as to evaluate the quality of dental hard tissue. C-scan and B-scan OCT images are acquired from a large range of samples. Based on such images, 3D reconstructions were assembled, which lead to a better view of the investigated areas. Cracks and voids in the dental structures as well as material defects and gaps at the interfaces are clearly exposed. The advantages of the OCT imaging method consist in non-invasiveness and high resolution. The en-face OCT offers the user the possibility of rapidly acquiring sequential B-scans and C-scans by switching the instrument between the two regimes. Sequential and rapid switching between the en-face regime and the cross-section regime, specific for the en-face OCT systems, represent a significant advantage in the process of non-invasive imaging, as images with different orientations can be obtained using the same system, during the same imaging event. 3D reconstructions of volumes allow evaluation and localization of defects in the samples. By importing such data into numerical simulation software can provide answers on the behavior of the investigated structures

Plastination biopsy samples from the central nervous system as a solution for time domain optical coherence tomography noninvasive investigation method

A biopsy sample that was taken from neurosurgery then introduced into the solution of formaldehyde was examined with Time Domain optical coherence tomography. The results are inconclusive and so that preserving was accomplished by plastination the tissue sample in which the degree of rigidity of the sample is controlled without destroying the tissue

Optical imaging of oral squamous cell carcinoma using optical coherence tomography and micro CT

Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cancer. Early detection is a cornerstone to improve survival and to reduce diagnostic delay. We propose optical coherence tomography (OCT), as a non-invasive diagnosis method. OCT represents a new high-resolution optical technique that permits 3D, real-time imaging of near surface abnormalities in complex tissues. In the present study half of the excisional biopsy was directed to the pathologist and the other half was assigned for OCT and Micro-CT investigation. For the OCT imaging it was used an OCT prototype (1300 nm), Synchrotron Radiation Micro-CT and histopathology validated the results. Areas of OSCC of the buccal mucosa were identified in the OCT images by the disruption of the basement membrane, an epithelial layer that was highly variable in thickness, with areas of erosion, extensive epithelial down-growth and invasion into the sub-epithelial layers. In this respect, OCT seems to be a highly promising imaging modality. © (2014) Trans Tech Publications, Switzerland

Optical investigations of various polymeric materials used in dental technology

Dental prosthetic restorations have to satisfy high stress as well as aesthetic requirements. In order to avoid deficiencies of dental prostheses, several alternative systems and procedures were imagined, directly related to the material used and also to the manufacturing technology. Increasing the biomechanical comportment of polymeric materials implies fiber reinforcing. The different fibers reinforcing products made very difficult the evaluation of their performances and biomechanical properties analysis. There are several known methods which are used to assess the quality of dental prostheses, but most are invasive. These lead to the destruction of the samples and often no conclusion could be drawn in the investigated areas of interest. Using a time domain en-face OCT system, we have recently demonstrated real time thorough evaluation of quality of various dental treatments. The aim of this study was to assess the quality of various polymeric materials used in dental technology and to validate the en face OCT imagistic evaluation of polymeric dental prostheses by using scanning electron microscopy (SEM) and microcomputer tomography (μCT). SEM investigations evidenced the nonlinear aspect of the interface between the polymeric material and the fiber reinforcement and materials defects in some samples. The results obtained by microCT revealed also some defects inside the polymeric materials and at the interfaces with the fiber reinforcement. The advantages of the OCT method consist in non-invasiveness and high resolution. In addition, en face OCT investigations permit visualization of the more complex stratified structure at the interface between the polymeric material and the fiber reinforcement

Optical imaging of oral pathological tissue using optical coherence tomography and synchrotron radiation computed microtomography

The efforts aimed at early diagnosis of oral cancer should be prioritized towards developing a new screening instrument, based on optical coherence tomography (OCT), to be used directly intraorally, able to perform a fast, real time, 3D and non-invasive diagnosis of oral malignancies. The first step in this direction would be to optimize the OCT image interpretation of oral tissues. Therefore we propose plastination as a tissue preparation method that better preserves three-dimensional structure for study by new optical imaging techniques. The OCT and the synchrotron radiation computed microtomography (micro-CT) were employed for tissue sample analyze. For validating the OCT results we used the gold standard diagnostic procedure for any suspicious lesion - histopathology. This is a preliminary study of comparing features provided by OCT and Micro-CT. In the conditions of the present study, OCT proves to be a highly promising imaging modality. The use of x-ray based topographic imaging of small biological samples has been limited by the low intrinsic x-ray absorption of non-mineralized tissue and the lack of established contrast agents. Plastination can be used to enhance optical imagies of oral soft tissue samples. © 2013 OSA-SPIE

Time domain optical coherence tomography evaluation of polymeric fixed partial prostheses

Polymeric fixed partial prosthesis represents an important part of the prosthetic treatment. Their presence in the oral cavity could lead to fracture them and to alter the final prosthetic treatment. Time Domain Optical Coherence Tomography can be used as a noninvasive evaluation method and 3D reconstructions which could generate a real forecast on those prosthesis in the oral cavity environment

Defectoscopy of denture polymers

When making a denture, a removable partial prosthesis or a removable orthodontic appliance, long term preservation of structure and function require that potential irritating effects are kept at minimum. Polymer manufacturing technology with optimal properties and the material type are essential for a successful treatment. Increasing the biomechanical comportment of polymeric materials implies fiber reinforcing. The different fibers reinforcing products made very difficult the evaluation of their performances and biomechanical properties analysis. The aim of this study was to assess the quality of various polymeric materials used in dental technology and to validate the en face OCT defectoscopic evaluation of polymeric dental prostheses by using scanning electron microscopy (SEM). SEM investigations evidenced the nonlinear aspect of the interface between the polymeric material and the fiber reinforcement and materials defects in some samples. The advantages of the OCT method consist in non-invasiveness and high resolution. In addition, en face OCT investigations permit visualization of the more complex stratified structure at the interface between the polymeric material and the fiber reinforcement

Time domain optical coherence tomography evaluation of the human skin

The aim of this study is to evaluate the normal skin by using the optical coherence tomography in Time Domain Mode. In conclusion, the optical coherence tomography could act as a valuable technique to be used for a better evaluation of the skin

Evaluation of metal-polymeric fixed partial prosthesis using optical coherence tomography

Metal-Polymeric fixed partial prosthesis is the usual prosthetic treatment for many dental patients. However, during the mastication the polymeric component of the prosthesis is fractured and will be lost. This fracture is caused by the material defects or by the fracture lines trapped inside the esthetic components of the prosthesis. This will finally lead to the failure of the prosthetic treatment. Nowadays, there is no method of identification and forecast for the materials defects of the polymeric materials. The aim of this paper is to demonstrate the capability of Optical Coherence Tomography (OCT) as a non-invasive clinical method that can be used for the evaluation of metal-polymeric fixed partial prostheses. Twenty metal-polymeric fixed partial prostheses were used for this study. The esthetic component of the prostheses has been Adoro (Ivoclar). Optical investigations of the metal prostheses have revealed no material defects or fracture lines. All the prostheses were temporary cemented in the oral cavities of the patients for six month. The non-invasive method used for the investigations was OCT working in Time Domain mode at 1300 nm. The evaluations of the prostheses were performed before and after their cementation in the patient mouths. All the imagistic results were performed in 2D and than in 3D, after the reconstruction. The results obtained after the OCT evaluation allowed for the identification of 4 metal-polymeric fixed partial prostheses with material defects immediately after finishing the technological procedures. After 6 month in the oral environment other 3 fixed partial prostheses revealed fracture lines. In conclusion, OCT proved to be a valuable tool for the noninvasive evaluation of the metal-polymeric fixed partial prostheses. © 2013 SPIE