Dental Diagnosis and Treatment Assessments: Between X-rays Radiography and Optical Coherence Tomography

A correct diagnosis in dental medicine is typically provided only after clinical and radiological evaluations. They are also required for treatment assessments. The aim of this study is to establish the boundaries from which a modern, although established, imaging technique, Optical Coherence Tomography (OCT), is more suitable than the common X-ray radiography to assess dental issues and treatments. The most common methods for daily-basis clinical imaging are utilized in this study for extracted teeth (but also for other dental samples and materials), i.e., panoramic, intraoral radiography, and three-dimensional (3D) cone beam computed tomography (CBCT). The advantages of using OCT as an imaging method in dentistry are discussed, with a focus on its superior image resolution. Drawbacks related to its limited penetration depth and Field-of-View (FOV) are pointed out. High-quality radiological investigations are performed, measurements are done, and data collected. The same teeth and samples are also imaged (mostly) with an in-house developed Swept Source (SS)-OCT system, Master-Slave enhanced. Some of the OCT investigations employed two other in-house developed OCT systems, Spectral Domain (SD) and Time Domain (TD). Dedicated toolbars from Romexis software (Planmeca, Helsinki, Finland) are used to perform measurements using both radiography and OCT. Clinical conclusions are drawn from the investigations. Upsides and downsides of the two medical imaging techniques are concluded for each type of considered diagnosis. For treatment assessments, it is concluded that OCT is more appropriate than radiography in all applications, except bone-related investigations and periodontitis that demand data from higher-penetration depths than possible with the current level of OCT technology. View Full-Tex

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

Optical Coherence Tomography Investigations and Modeling of the Sintering of Ceramic Crowns

Dental prostheses are sintered in ovens that sometimes suffer from a loss of calibration. This can lead to variations of the sintering temperature outside the range recommended by the manufacturer. Stress and even fractures in dental ceramics may occur, and this leads to the necessity to rebuild the dental construct. The aim of this work is to monitor the quality of sintering processes using an established biomedical imaging technique—optical coherence tomography (OCT). Conventional current procedures imply the fabrication of supplemental samples that add to the expenses and are only evaluated visually. To our knowledge, we were the first to propose the use of OCT, a non-destructive method that brings objectivity for such assessments, focusing, in a previous study, on metal ceramic dental prostheses. Here, a different material, pressed ceramics, is considered, while we propose a quantitative assessment of the results—using reflectivity profiles of en-face (i.e., constant-depth) OCT images of sintered samples. The results for both the pressed ceramics and metal ceramics prostheses are discussed by obtaining the analytic functions of their reflectivity profiles. A multi-parametric analysis demonstrates the best parameter to characterize the loss of calibration of dental ovens. Rules-of-thumb are extracted; producing dental prostheses with defects can thus be avoide

Optimization of X-ray Investigations in Dentistry Using Optical Coherence Tomography

The most common imaging technique for dental diagnoses and treatment monitoring is X-ray imaging, which evolved from the first intraoral radiographs to high-quality three-dimensional (3D) Cone Beam Computed Tomography (CBCT). Other imaging techniques have shown potential, such as Optical Coherence Tomography (OCT).We have recently reported on the boundaries of these two types of techniques, regarding. the dental fields where each one is more appropriate or where they should be both used. The aim of the present study is to explore the unique capabilities of the OCT technique to optimize X-ray units imaging (i.e., in terms of image resolution, radiation dose, or contrast). Two types of commercially available and widely used X-ray units are considered. To adjust their parameters, a protocol is developed to employ OCT images of dental conditions that are documented on high (i.e., less than 10 �m) resolution OCT images (both B-scans/cross sections and 3D reconstructions) but are hardly identified on the 200 to 75 �m resolution panoramic or CBCT radiographs. The optimized calibration of the X-ray unit includes choosing appropriate values for the anode voltage and current intensity of the X-ray tube, as well as the patient’s positioning, in order to reach the highest possible X-rays resolution at a radiation dose that is safe for the patient. The optimization protocol is developed in vitro on OCT images of extracted teeth and is further applied in vivo for each type of dental investigation. Optimized radiographic results are compared with un-optimized previously performed radiographs. Also, we show that OCT can permit a rigorous comparison between two (types of) X-ray units. In conclusion, high-quality dental images are possible using low radiation doses if an optimized protocol, developed using OCT, is applied for each type of dental investigation. Also, there are situations when the X-ray technology has drawbacks for dental diagnosis or treatment assessment. In such situations, OCT proves capable to provide qualitative images

Indirect Restorative Polymeric Dental Materials

The current chapter, entitled “Indirect restorative polymeric dental materials,” is dedicated to one class of dental materials with wide indications in dental medicine. The chapter is an overview of polymeric resin composites dedicated to indirect restauration currently used and latest avail resin composite and polymers in dentistry. This chapter includes chemical composition, indications, light-curing mechanism and physical and mechanical properties of indirect conventional and new polymeric materials. Important aspects about resin composites are related to clinical and physical properties such as light-curing, aesthetics, wear rates and biocompatibility. The accuracy and longevity of indirect composite restorations depend on choosing the right material according to clinical requirements, material’s properties, and behaviour in the oral cavity and clinical indications. The chemical composition of resin composite, curing mechanism and advantages of these materials are presented in Introduction. The second section is dedicated to structure and composition of indirect polymers, indirect resin composites, first and second generation of indirect resin composites and their indications. Section 3 describes the structure and composition of high-performance hybrid polymers, hybrid ceramic and high-performance polymers, and poly ether ketone ketone dedicated to different processing technologies

Optoelectronic evaluation of indirect dental veneers interfaces

Dental indirect veneers have become the most functional and cost-effective method for providing high-aesthetic results whenever smile design enhancement is required. Yet, clinical failures have been reported due to the detachment of the veneers from the dental hard tissues, as well as to chipping and microleakage. Many experimental studies have been conducted in order to identify clinical and technical solutions for enhancing the adhesive and biomechanical properties of the veneers, by promoting the same classical, linear marginal contour of these particular indirect restorations. Thus, the aim of this study is to develop a novel design of the veneers deemed to augment the interfacial adhesive forces and, furthermore, to investigate the bonded interfaces by using optical coherence tomography

New ways of combating demineralization: link between classic and allopathic medicine

Prevention and allopathic medicine gained attention, since it is possible for dentists to prevent demineralization, using plants and natural substances with well-known efficacy. The purpose of this study was to present new methods for teeth remineralization. It was made a selection of 10 extracted teeth, maintained in physiological serum, with no color fading, decay or demineralization. It was induced demineralization, with ortho-phosphoric acid (concentration 45 %), for one minute. The probes were visually and with optical coherence tomography (OCT) inspected. The natural product and the bonding with additional nanoparticles of argent were created and applied on the demineralization zone of the both groups of teeth. Each tooth in the first group had one plain surface demineralized. The second group of teeth had a cavity prepared on one of each tooth’s side. The pastes were applied on the demineralized surfaces and in the demineralized cavities for two minutes. After time expired, the pasta applied on the first group of teeth was washed away; the bonding above the second group of teeth was light cured. The probes were again visually and with OCT inspected. It was observed an improvement in remineralizing the white marks on plain surfaces and in the created cavities, the OCT being able to detect different levels of remineralization. The efficacy of natural pasta depends on the time it is applied and the concentration of the different main substances. Also, the type of surface, plain or occlusal facets, may influence the substances’ penetration ability. The non-invasive specific feature of these products, low costs and safety are strong positive aspects of this method of remineralization. However, the natural process of remineralization is a long-lasting one; perfecting the main substances in order to accelerate the process, in addition to several in vivo studies would be necessary to be fulfilled

Investigation of firing temperature variation in ovens for ceramic-fused-to-metal dental prostheses using swept source optical coherence tomography

One of the most common fabrication techniques for dental ceramics is sintering, a process of heating of the ceramic to ensure densification. This occurs by viscous flow when the firing temperature is reached. Acceptable restorations require the alloy and ceramic to be chemically, thermally, mechanically, and aesthetically compatible. Thermal and mechanical compatibility include a fusing temperature of ceramic that does not cause distortion of the metal substructure. Decalibration of ovens used for firing of the ceramic layers for metal ceramic dental prostheses leads to stress and cracks in the veneering material, and ultimately to the failure of the restoration. 25 metal ceramic prostheses were made for this study. They were divided in five groups, each sintered at a different temperature: a group at the temperature prescribed by the producer, two groups at lower and two groups at higher temperatures set in the ceramic oven. An established noninvasive biomedical imaging method, swept source (SS) optical coherence tomography (OCT) was employed, in order to evaluate the modifications induced when using temperatures different from those prescribed for firing the samples. A quantitative assessment of the probes is performed by en-face OCT images, taken at constant depths inside the samples. The differences in granulation, thus in reflectivity allow for extracting rules-of-thumb to evaluate fast, by using only the prostheses currently produced the current calibration of the ceramic oven. OCT imaging can allow quick identification of the oven decalibration, to avoid producing dental prostheses with defects