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Biomedical subjects

B Kordass

Publications and source records attributed to B Kordass.

At least 19 recordsLinked to original sources
PubMed2006

Concept and development of a computerized positioning of prosthetic teeth for complete dentures.

To date, CAD/CAM technology has made no noteworthy inroads into removable dentures. We want to present a new area of application for this in our study. Models of the maxilla and edentulous mandible were 3D scanned. The software detects and automatically reconstructs the reference structures that are anatomically important for the set-up of artificial teeth, such as the alveolar ridge centerlines and the interalveolar relations between the alveolar ridges. In a further step, the occlusal plane is semiautomatically defined and the front dental arch is designed. After these design features have been determined, artificial teeth are selected from a database and set up automatically. The dental technician can assess the esthetics and function of the suggested dental set-up on the computer screen and make slight corrections if necessary. Summarizing: The interplay of hardware and software components within on integrated solution including conversion of the "virtual" into a real positioning of prosthetic teeth is presented.

Alveolar Process↗
PubMed2006

Optimization of the static occlusion by "occlusal surface settling" in the Cerec 3D software.

The adjustment of the static occlusion can be automated in computer-based systems. The Cerec 3D software makes it possible to take preformed occlusal surfaces from a database and adapt them to the antagonist. In this adaptation (settling), the CAD occlusal surface "settles" as whole or each cusp individually into the occlusal surface of the antagonist until stable occlusion is reached. Two occlusal surface shapes were compared: Vita Physiodens and Lee Culp. An index was formed from the number, quality, and position of the occlusal contacts for 35 model cases (25 molars, 10 premolars). With regard to the settling of the total occlusal surfaces, there were no differences between the two occlusal surface shapes. In "cusp settling" of the molars, Vita Physiodens performed significantly better. In the comparison of the 1st with the 3rd settling process, significant improvements occurred the 3rd time in many cases when settling individual cusps, but in clearly fewer cases in the settling process of the total occlusal surface. The Lee Culp tooth occlusion improved especially after the 3rd settling process of individual cusps. It is therefore expedient to combine both settling versions with one another.

Bicuspid↗
PubMed2006

Comparison of the contact surface pattern between virtual and milled Cerec 3D full-ceramic crowns.

PURPOSE: The objective of this study was to compare resulting contact point patterns in the context of crown production with the Cerec 3D system. The contact surface patterns of full-ceramic crowns milled with the Cerec 3D system were examined for agreement with the corresponding virtually produced crowns. MATERIALS AND METHODS: The agreement was determined with regard to the parameters number, size, position, and shape. Twenty-eight models were mounted centrally in a mechanical articulator. In these model cases, at least one second premolar and one first molar in the maxilla and mandible had to be prepared for crown production (preparation). A total of 50 teeth was prepared. Crowns were then designed with the aid of the Cerec 3D system. The crown designs were milled and integrated in the model. Silicone bite registrations, the contact point patterns of which were compared with the virtually designed crowns, were produced in static occlusion in the region of the crowns. Different evaluation methods were used for the comparison. RESULTS: There was an agreement of 78% with regard to number, 76% in terms of localization, 65% regarding size, and 65% in terms of shape. CONCLUSION: It was thus confirmed that very good, highly reproducible results can be achieved with the Cerec 3D system.

Bicuspid↗
PubMed2006

Clinical reproducibility of GEDAS--"Greifswald Digital Analyzing System" for displaying occlusal contact patterns.

The clinical display of the occlusal contact points is an essential part of the quality control of restorative work. Normally, articulating paper of different colors, occlusion foil or special waxes are used for this. A possible digital method has to date been to display the contact points and their distribution using a pressure sensor foil (T-Scan system). Occlusion bites in a silicone material are also possible alternatives. The Greifswald Digital Analyzing System (GEDAS) displays the strength, extent and localization of static contacts in intercuspation (IP) based on digitized silicone registrations. In 10 completely dentulous test persons (age 23 to 29 years), with 3 different examiners as well as 2 examination times spaced 14 days apart, the intraindividual reproducibility of the contact relations resulted in kappa values of 0.92, 0.96 and 0.99, and the interindividual reproducibility was between 0.90 and 1.00. Different versions of the GEDAS software are presented, including explanation and discussion of the possibilities of use.

Adult↗
PubMed2006

Analysis of the variability of occlusal function patterns in masticatory movement--use of the GEMAS software.

Individual masticatory patterns are similar to chaotic tangles of tortuous paths and are characterized by variability. The analysis of such masticatory patterns is therefore difficult. The new GEMAS software--Greifswald Movement Analyzing System--with which the variability of the masticatory function can be examined, is presented. Intersecting planes are placed through the orbit of the chewing cycles with which it is possible to wonder from the intercuspal position up to the maximum mouth-opening position of the masticatory pattern. The opening and closing points are displayed in different colors. Zones where masticatory paths converge or diverge can be determined, including the fan or funnel-shaped entering and exiting movements close to the centric position and the extent of their spread. A special diagram visualizes the rhythmic sequence of entering and subsequent exiting movement. The relation between restricted variability or monotony and forms of disease of the masticatory system is indicated by reference to case examples. The more monotonous or stereotyped the chewing cycles are, the higher is the risk of permanent wear of anatomical structures. Attention should therefore also be paid to variability in the individual occlusal surface design of dental restorations.

Data Display↗
PubMed2004

DentSim - a future teaching option for dentists.

Apart from a requirement to acquire more and more academic knowledge, during their training, dental students need to acquire a full range of highly precise manual and technical skills, including excellent hand/eye coordination, to enable them to visualize and understand how to prepare cavities, prior to placing restorations. Furthermore, unlike medical students, dental students are in the position of administering treatment to patients very early in their training. The increasing academic workload means that these skills have to be mastered in a short space of time. This you will gain in the future only through the use of effective methods of the educations - for example by the use of the computer-assisted dental simulators (DentSim/DenX), which serves the visual-, audio- and practical learning channel simultaneously. Unlike the conventional phantom heads, the DentSim-unit has the following advantages - the acquisition of knowledge takes place in a multimedia learning environment with a high audio-visual content and degree of interaction and complexity, - problem-oriented learning takes place through clinically relevant work, - individual students can work to personalized programs through the digital tutor function, - two-dimensional knowledge is transferred into three-dimensional spatial work, - three-dimensional preparations can be easily analysed by two-dimensional error analysis, - all preparation exercises are recorded for error and effectiveness analysis. Apart from student training, the computer-assisted simulators can also be used for the evaluation of the effectiveness or the quality control of various teaching methods in the context of Evidence Based Dental Education.

Computer Simulation↗
PubMed2003

The virtual articulator: development and evaluation.

The accuracy, reliability, and reproducibility of the virtual articulator as applied in functional diagnostics are examined. Its potential in planning and simulating orthodontic treatment is also explored.

Dental Articulators↗
PubMed2002

Quantification of gingival edema using a new 3-D laser scanning method.

OBJECTIVES: The aim of the study was to investigate the suitability of measuring volume differences in the gingival tissue for monitoring changes in the inflammatory status of the gingiva. MATERIALS AND METHODS: Data for this investigation were obtained from a mouthrinse evaluation which was performed as a 4-week, double-blind, placebo-controlled, cross-over study in which localised experimental gingivitis was induced. 24 volunteers were enrolled in the study. Only the data from the placebo period of each subject were used in the current investigation. During the plaque accumulation periods, plaque guards were worn during routine performance of oral hygiene measures to prevent any plaque removal from the experimental area (1st and 2nd premolars and molars in one upper quadrant). Clinical examinations with assessment of plaque and gingivitis were performed on days 0, 4, 7, 14, 21, 28 and 42. Volume differences in the gingival papillae were determined between day 0 and days 21, 28, and 42, and between days 28 and 42 by taking measurements from replicas of the respective clinical situations using a 3-D laser scanner and reference-free automated 3-D superimposition software. Data were analysed with the Wilcoxon signed ranks test. RESULTS: Plaque accumulation in the experimental area resulted in a highly significant increase (p<0.001) of inflammation of the gingival papillae. The mean (standard deviation) papillary GI at baseline was 0.23 (0.34) as compared to 1.22 (0.27) and 1.2 (0.31) on days 21 and 28, respectively. The mean increase in volume of all papillae as compared to baseline was 25,478 micrometer3 after 21 days and 24,210 micrometer3 after 28 days. After resuming a normal oral hygiene regimen, mean volume of the papillae decreased between days 28 and 42 by 19,250 micrometer3. CONCLUSION: With this novel method, gingival papillary edema can be quantified in vivo from replicas of the clinical situation.

Adult↗
PubMed1999

The temporomandibular joint in video motion--noninvasive image techniques to present the functional anatomy.

The presentation of the functional anatomy of the temporomandibular joint (TMJ) is involved with difficulties if dynamic aspects are to be of prime interest, and it should be demonstrated with the highest resolution. Usually noninvasive techniques like MRI and sonography are available for presenting functionality of the temporomandibular joint in video motion. Such images reflect the functional anatomy much better than single pictures of figures could do. In combination with computer aided records of the condyle movements the video motion of MR and sonographical images represent tools for better understanding the relationships between functional or dysfunctional patterns and the morphological or dysmorphological shape and structure of the temporomandibular joint. The possibilities of such tools will be explained and discussed in detail relating, in addition, to loading effects caused by transmitted occlusal pressure onto the joint compartments. If pressure occurs the condyle slides mainly more or less retrocranially whereas the articular disc takes up a more displaced position and a deformed shape. In a few extreme cases the disc prolapses out of the joint space. These video pictures offer new aspects for the diagnosis of the disc-condyle stability and can also be used for explicit educational programs on the complex dysfunction-dysmorphology-relationship of temporomandibular diseases.

Humans↗
PubMed1997

[Craniomandibular disorders. Conception of a screening method for patients with chronic head and facial pain].

Craniomandibular disorders are suggested to be responsible for many cases of chronic pain of the head and face. The assessment of dysfunctional factors in diseases of chronic head and facial pain normally requires special knowledge and equipment for the diagnosis and therapy of stomatognathic dysfunction. However, the first signs can be evaluated rather well without using complete equipment, which is not always available in general practice. It is therefore important that general practitioners have a simple, time-efficient method of routine screening based on sufficient methods and tests. Thus, we would like to present a questionnaire consisting of ten points that cover the valid elements of complete stomatognathic assessment. Answering these questions reveals signs of dysfunctional components of craniomandibular disorders, which indicate a dysfunction diagnosis and even better, consultation with a specialist.

English Abstract↗
PubMed1990

[Functional value of hyperbalance for function course in temporomandibular joint].

The resulting effects of excursive attrition contacts on balanced side are pointed out. In a case report new ultrasonic recordings of TMJ movements with MT 1602 system are described to demonstrate the influence of overbalanced contacts on the axiographic track of TMJ condyle. Characteristic changes of the axiographic path results and are discussed as distraction effects of TMJ condyle.

Adult↗
PubMed1990

[Follow-up study of accuracy of fit of crowns, prepared for phantom head under practice conditions].

Mesial, distal, oral and vestibular measurement of fissure spaces in 39 crowns and 51 bridges (divided with interlock-connection) made in the context of propedeutic instruction showed a mean marginal discrepancy of 62-90 microns in a range of 30-160 microns. A simple method to evaluate the fissure space was described. In actually discussion the results would be helpful to determine criterions for quality on fixed restorations.

Crowns↗
PubMed1990

[Perspectives of a function study of the TMJ with magnetic resonance imaging].

Magnetic resonance imaging of the temporomandibular joint is usefull in the examination of the stomatognathic system. In order to visualize the components of the temporomandibular joint during dynamic jaw movement and to improve the diagnostic accuracy of temporomandibular joint disorders we present remedies for magnetic resonance imaging and discuss their possibilities and limits how you can stabilize the jaw in an interesting functional position during examination period.

Humans↗