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Biomedical subjects

G Arnetzl

Publications and source records attributed to G Arnetzl.

13 recordsLinked to original sources

PREPassistant: a system for evaluating tooth preparations.

Learning the widely differing forms of tooth preparation, especially in restorative dentistry, places high demands on both trainees and instructors with regard to precision, reproducibility, assessment, evaluation and three-dimensional conceptualization. In the past, evaluation of such preparations has been against subjective parameters and their interpretation by the assessor (usually the instructor). The use of CAD systems in teaching seminars and courses allows an objective assessment of tooth preparations and offers the trainee the possibility of measuring him/herself against a standard, of detecting errors, and of achieving perfection in the required tasks. The PREPassistant system described in this article is one such CAD-assisted learning system. It is recommended both for students in dental schools and for the continuing education of established dentists. Its strengths are that it produces a design for a tooth preparation, enables exact comparison with an ideal preparation, detects errors, and promotes improvements and perfection.

Computer Systems↗

Functional quality of molar crown occlusal surfaces in the different design modes of Cerec 2.

The goal of the present study was to objectify whether the design modes of "Correlation", "Function", and "Extrapolation" of the Cerec 2 system are suitable for generating a functionally perfect occlusal surface of a first mandibular molar crown. For this purpose, an occlusal surface was waxed up according to the biomechanical concept of MH Polz, and this served as the reference occlusal surface. Four different Cerec 2 comparison crowns (produced in the laboratory, Extrapolation mode, Correlation mode, Function mode) were produced and the positions of the cusps were measured. It was shown that the Correlation mode delivers the most accurate results, and the manually produced occlusal surface also showed good results. The occlusal surfaces of the crowns produced according to the Extrapolation and Function mode were clearly inferior.

Ceramics↗

Residual dentin thickness after 1.2-mm shoulder preparation for Cerec crowns.

Since the introduction of crown software for Cerec, it has been possible to produce full-ceramic crown restorations. Despite the excellent material quality of industrially made ceramic blocks and the good clinical long-term success of these ceramics in inlay- and onlay preparations, extended preparation with high loss of dental tissue is incident to crown restorations, which may endanger the vitality of the respective tooth. The aim of this experimental study was to determine the residual dentin thickness after preparation of an extended circular shoulder in the molar and premolar region. On extracted human molars and premolars, 1.2-mm-wide circular shoulders with rounded inner edges were prepared, and the thickness of the residual dentin wall was measured under a microscope. Using this preparation method, it was found that only the group of maxillary molars showed an average residual dentin thickness of more than 0.7 mm.

Bicuspid↗

[Clinical results and material behavior of composite, ceramic and gold inlays].

Laboratory-manufactured gold, ceramic and composite inlays were compared with the CAD/CAM produced CEREC inlay experimentally and clinically. The following systems were examined: Dicor, Optec, Hi-Ceram, Du-Ceram, Cerec, Kulzer, Coltene, SR-Isosit composite inlays, and gold inlays (Degulor C) with adhesive fixation (group I) and with zinc oxide phosphate cement (group II). In the clinical trial inlays in 270 teeth were re-evaluated in a total of 73 patients after 2.3 to 5 years. After 3 years the results obtained with Optec, Hi-Ceram and the Coltene composite inlay were less favorable than those of other systems--statistically however, this difference was of rather low significance (p less than 0.05). Fractures of ceramic inlays occurred in 6 cases within 8 months. 10 failures of ceramic and composite inlays were due to secondary caries.

Composite Resins↗

[Preparation of root canals with the Excalibur in comparison with manual instrumentation, Endocursor and Intra-Endokopf].

64 curved root canals of acrylic models were instrumented from two experienced operators with Endocursor, Excalibur, Intra-Endokopf 3LDSY and by manual. A significant influence on the form of the root canal preparation had the factors instrument type, operator and the interferences between operator and instrument. The time of root canal preparation had a significant influence in the middle and coronal third of the root only. The best results are achieved by ideal combination of operator and instrument. With the Excalibur it is possible, to make a sparing and careful instrumentation. The excellent calibration guide is very helpful.

Dental Cavity Preparation↗

[Caries status and periodontal health in 6- to 10-year old elementary school children in Graz compared to Swiss, Swedish and WHO principles].

In a complete survey, 7500 primary pupils in Graz aged between six and ten years were examined for caries and periodontal health. Comparison with the DMF-T values of primary school pupils in Switzerland and Sweden indicated that considerable efforts are required in Austria if preventive dental health education is to achieve the standard status it has enjoyed for years in the other countries mentioned.

Austria↗

[Periodontal aspects of care of partially edentulous jaws].

After an initial periodontal therapy to reduce bleeding a pocket depth and after reaching an AOI below 30% it is possible to make an apical reposition-flap. It is apt to supragingivalize the margins of restorations of fractured teeth or in case of subgingival lesions or preparation margins. In combination with a good recall-system thus the prognosis of periodontal treatment can be optimized.

Denture, Partial, Removable↗

[Periodontal aspects of removable partial dentures].

Periodontal pre-treatment of patients receiving partial dentures should involve three phases: initial therapy; periodontal surgery; home care. For periodontal surgery and/or prosthodontic treatment using precision materials, e.g. telescope retainers, the API (approximal plaque index) should not exceed 30%. To prevent further loss of gingival attachment due to iatrogenic irritation by the dentures preparation of abutments should consistently the para- or supragingival. In patients with few residual teeth telescope retainers, which can be cemented for definitive fit if indicated, are the treatment of choice.

Dental Abutments↗