International Journal of Computerized Dentistry, 02/2005

Computer graphics is here to stay and spreading. This article intends to be nothing more than a brief introduction of this new tool in the field of dentistry. We hope that our colleagues will welcome this new development and recognize it as an opportunity to make contact with the basic sciences. Keywords: crown preparation, vector graphics, parametric polynomial, interpolation, approximation, C2- continuity

Introduction: The teaching of manual skills and competencies is among the most time-consuming aspects of oral health-care education, especially when large groups of students are involved. Video has been repeatedly used as an educational tool with varying results. Purpose: The present study aimed to investigate theeffectiveness ofacomputer-based video support system during practical training ofmanual skills and competencies related to periodontal treatment. Materials and Methods: Eighty-four students were randomized into 9 groups: 5 experimental and 4 control groups. The control groups received instruction in the use of scaling and root planing instruments during a 7-hour seminar, and 2 hours of manual practice. The experimental groups received the same instruction, but in addition had access to a computer-based video support system, the Visual Training System (VTS), during practical training. During the 2-hour long practice session, all students practiced 21 different procedures, which were video recorded. The videos were later evaluated by an independent observer. Results: On the whole, the students in the experimental group performed significantly better than their colleagues in the control group. Specifically, the groups that utilized the VTS video support performed significantly better in 9 of the 21 procedures tested. Conclusion: These results suggest that this computer-based video support can be an effective aid in the teaching of manual skills related to oral health care. Keywords: dental education, effectiveness of teaching, effectiveness of learning, periodontology, psychomotor skills, video support

In the 1990s, there was great optimism due to the development of devices for measuring tooth shade. The frequently not so simple, visual determination of the shade of a tooth was to be done with the aid of a device which recognizes the shade and describes it accurately by reference to a color chart. However, the skepticism towards such devices was also great. It is known that the color effect frequently differs strongly when comparing a tooth from the shade guide with a metal ceramic crown, despite identical shade designation. Anyone who considers visual shade determination to be inadequate and places his hopes in digital shade matching devices will be disappointed. It is the shade-generating structures of the metal ceramic and frequently of the veneer layers that turn out to be too thin which, despite correct shade selection, cause a different color perception. Such problems have been reduced decisively with the development of fracture- proof hard porcelain caps (Vita In- Ceram) with optical characteristics similar to teeth. In addition, the Vita System 3D-Master tooth shade system developed in 1998 by Vita in cooperation with Dr. Hall from Australia, leads the practitioner to a better understanding of the primary tooth shade characteristics of "brightness (value)", "color intensity (chroma)" and "color (wave length of the visible light, hue)". These two innovations allow a more accurate estimate of the basic shade of a natural tooth (reference tooth) and the imitation in the laboratory of its natural, shade-generating structures. If digital shade measurement supplements the visual shade estimate, then a further improvement can be expected - especially in the recognition of the basic shade. Qualitative descriptions of subjective shade measurement of a natural tooth and of its imitation in the dental laboratory by ceramics can be found frequently in professional journals and publications. With digital tooth shade matching devices, which apart from the color code of the color chart also reproduce exact, colorimetric values, such work processes can be recorded quantitatively and objectively. Reports about this type of controlled shade determination and generation are found rarely in the literature, which is surprising in view of the large number of tooth shade matching devices and dental ceramic systems available. In the present paper, the influence of the individual ceramic layers on color perception is measured and described under standardized conditions. The creation of the basic shade as it results from the composition of the various ceramic layers is traced with a spectrophotometer. The Vita In-Ceram Alumina infiltration ceramic and the VitaVM7 veneer ceramic were selected as the ceramic system. MHTSpectroShade and Vita Easyshade were used as shade matching devices. Keywords: In-Ceram, all-ceramic, veneering ceramic, Vita VM7, tooth shades, digital color measurement

It is necessary for orthodontists to collect and analyze the patients' photographic data. By conventional methods, these photo data were commonly saved on film, which were frail and often resulted in data loss. Furthermore, it is not convenient for the orthodontists to consult and study these data during clinical research. A critical problem thus arises in managing these photo data scientifically. The computer technique and picture processing method were employed in the present study to establish the Photo Management System for Orthodontics (PMSO), which makes the administration of patients' photo data more scientific, convenient, and effective than before. This system is characterized as follows: 1. Clinical orthodontists designed and programmed the system, which is "close to clinical reality and serves the clinic". Orthodontists can easily use it without any training course. 2. The images can be imported from many devices, such as digital cameras, scanners, and electronic data storage media such as floppy disks. 3. Even two groups of photos (four images) could be displayed in the same window for comparison and study. This function allows orthodontists to easily observe the differences in the same patient's photos at different stages, which is important to obtain comprehensive knowledge of the patient. 4. The network technique makes it possible for the photos to be shared. The orthodontists can get the patients' photos through the network without going to the radiology department or the imaging room. 5. It is helpful for orthodontic research since the photos can be exported easily in different ways. 6. This is shared software; orthodontists can use it for free. Keywords: orthodontics, photo management, image processing, photo grouping, clinical application

An innovative extension of performance in the area of single crown production is presented. Prefabricated crown blanks with color layering are inserted in the row of teeth with specially developed software and adapted apically to the stump with a CAM milling program. Keywords: prefabricated crown blanks, semi-finished product, CAD/CAM crown, plastic jacket crown, layering-induced esthetic effect, Cerec, inLab