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Biomedical subjects

I V Wagner

Publications and source records attributed to I V Wagner.

At least 19 recordsLinked to original sources
PubMed1995

IT-based evaluation and automatic improvement of the quality of intraoral radiographs.

The quality of intraoral radiographs made in dental practices is too often not adequate for diagnostic purposes. This necessitates standardized measures for the quality of intraoral radiographs and controlled techniques for automatic image improvement. For the evaluation of the quality of digitized intraoral radiographs the authors have defined two parameters which enable the measurement of radiographic image quality with regard to contrast and gray value distribution. A two-dimensional feature space based on these parameters is used for separation of images with 'good diagnostic quality' from images with 'insufficient diagnostic quality'. Specific image improvement techniques based on piecewise linear gray scale transformation allow the automatic improvement of over- and under-exposed radiographs as well as the automatic improvement of suspected pathological regions of interest.

Humans↗
PubMed1995

Three-dimensional visualization of the mandible: a new method for presenting the periodontal status and diseases.

A three-dimensional representation of an ideal human jaw was reconstructed from a series of 178 digitized photographic cross-sections. The two-dimensional images were taken from the slices of an artificial skull and have been digitized by means of a high resolution scanner with a spatial resolution of 860 dots per inch. On the basis of that sequence of cross-sections, a semi-automatic segmentation algorithm was developed to reduce the information to a quadriliteral surface-representation of the teeth and the bone. An algorithm was developed which simulates the individual pathology of a patient both on the basis of the findings stored in this patient's dental record and by using the representation of the reference jaw. The results of the modeling module were automatically prepared for rendering with visualization tools compatible to the RenderMan standard. This new method of presenting periodontal situations in especially helpful for the diagnostic support of periodontologists and for dental educational purposes.

Gingiva↗
PubMed1995

Quality assurance in oral radiography: computer-based methods for assessment and controlled improvement of intraoral radiographs.

The reported poor diagnostic quality of 30-50% of all radiographs made in dental practices suggests the need for standardized quality measures and appropriate image improvement procedures. We propose a new method to evaluate the quality of digital/digitized radiographs using feature vectors. This method assures the separation of over- and under-exposed radiographs from well exposed ones as clusters of "good image quality" and "poor image quality" in the resulting feature space. Automatic image improvement is accomplished by adaptive, piece-wise linear grayvalue transformation with regard to the image quality being measured. In particular, our method automatically detects grayvalue intervals which are likely to represent relevant diagnostic information as well as grayvalue intervals which are irrelevant for diagnostic purposes. Based on those intervals, a piece-wise linear grayvalue mapping function is calculated. These procedures may be used both on whole images and for the interactive improvement of suspected pathological regions of interest. Actual image quality is indicated by the simultaneous display of the defined cluster of "good image quality" and the position of the image within the feature space for visual control.

Quality Assurance, Health Care↗
PubMed1995

A virtual reality environment for enhanced oral implantology.

The quality of clinical decision making is limited by the performance of human cognitive processing of complex visual information. In the field of oral implantology, treatment planning is still based on the holistic interpretation and mental reconstruction of cross sectional 2d-image data. This surpasses widely human cognitive competence and hampers treatment planning in three dimensions that are essential in implantology. To overcome these problems, a virtual reality environment for enhanced treatment planning in oral implantology is presented, which provides a fully three-dimensional perception of an individual clinical situation. It enables the clinician to perceive and handle the objects of her work in a virtual world as needed for the task of diagnosis and treatment. Human visual decoding effort is thus reduced, and estimating the real position and orientation of implants during planning is enabled in any direction. Immersive three-dimensional perception is achieved by hybrid stereoscopic rendering techniques combined with large screen projections. The virtual world in which treatment planning takes place allows the clinician to move and interact with the individual anatomy simultaneously with three degrees of freedom. A set of virtual tools enables the clinician to perform a virtual treatment "in advance." The design and placement of implants, as it is interactively controlled by the clinician, is simulated in real-time. Thus the results of actions become immediately visible and provide visible feedback for interactive adjustment. In addition, the presented virtual reality environment for oral implant treatment planning includes algorithms for detection of inappropriate treatment in the concerned bone regions, according to the current design of the implant. These algorithms take both the individual properties of a patient's bone and the type of implants used into account.

Computer Simulation↗
PubMed1991

[Restorative materials and initial pellicle formation].

Information concerning initial pellicle forming (dental cuticle) are possible via contact-angle determination. Not only the type of the restorative material but also its surface processing (structure) influence the initial forming of the pellicle. The higher the surface energy of a material, the more complete and quicker the masking of the surface by the initial pellicle.

Dental Deposits↗
PubMed1991

Computer based decision support in dentistry.

Work analyses in dental practices have revealed a need for improvements especially in regard to patient dental record, decision support for diagnosis and therapy and patient recall. An adequate decision support for diagnosis, therapy and prevention requires the use of the most advanced methods of informatics and computer bases interactive multimedia technology as well as of advanced human-computer interface techniques.

Appointments and Schedules↗
PubMed1989

[The porosity, microhardness, roughness and internal stresses of PMMA base materials in relation to their isolation. 1. Porosity and microhardness].

Selected material properties of hot and cold polymerized denture basic materials (polymethylmethacrylate) were investigated after different methods of isolation: alginate, tin foil and silicone. Both tin foil and silicone isolation the handling of which is much easier result in a decreased portion of porosities and an increased microhardness in the PMMA.

Dental Materials↗
PubMed1989

[Porosity, microhardness, roughness and internal stresses of PMMA base materials depending on the isolation method. 2. Roughness and internal stresses].

In the present paper hot and cold polymerized denture basic materials were investigated after isolation by means of alginate, tin foil and silicone. Measurements of roughness and internal stresses after polymerization show that the advantages of a silicone isolation correspond to those of a tin foil isolation, where the clinically important smoothing effect of a silicone isolation is convincing using simple laboratory handling.

Dental Materials↗