PubMed Health⌕ Search

Biomedical subjects

M Augthun

Publications and source records attributed to M Augthun.

28 records · Page 2Linked to original sources
PubMed1989

[Dicor glass ceramic crowns].

Within a period of 36 months 103 Dicor glass ceramic crowns have been inserted. Total loss of function occurred in 8 of the restored teeth in the form of loss, partial or total fracture of the crown. In 15 cases a partial loss of function was observed due to esthetic damage, abrasions or cement washouts. Before treatment 73 teeth had been sensitive on probing, after restoration 4 of them required endodontic treatment. Many of the reasons for loss of function could be found. These results suggest that, although sensitive to technical errors, this technique provides highly qualified single tooth restaurations.

Ceramics↗
PubMed1989

[Mathematical simulation of the cooling and solidifying process in improving the quality of dental castings].

CASTS-3D (Computer Aided Solidification Technologies) is a FEM software system for the simulation of heat transfer, melt flow and solidification problems for foundry purposes. This software system may basically be applied to dental castings as well--especially if the FEM software system is optimized and exact data on the thermophysical properties of the dental alloys are provided.

Computer Simulation↗
PubMedDate not supplied

Anterior disc displacement without reduction in the temporomandibular joint: MRI and associated clinical findings.

To determine the value of MRI in temporomandibular joint (TMJ) disorders, the data of MRI-proven anterior disc dislocation without reduction (ADWOR) were correlated with clinical history and clinical data. MRI demonstrated degenerative bony changes and a reduced sagittal diameter of the condyle, a variable degree of disc deformation, and a thinned bilaminar zone in each of the joints with ADWOR, which clearly differed from patients with anterior disc dislocation with reduction (ADWR) (P = .01) and normal disc position (NDP) (P < .001). Of 59 patients and 83 TMJs that had been investigated in a 2-year period, as shown by MRI, 22 patients (27 TMJs) had ADWOR (32%), 16 joints had NDP (19%), and 40 patients had ADWR (49%). In patients with ADWOR, the clinical history revealed pain in either of the joints and/or cervical or masticatory muscles in 25 (93%) joints. Clinical investigation revealed various abnormalities in 22 joints; five of those presented without any pathologic clinical finding. Mouth opening was unlimited in nine patients (47%), palpation of the muscles of mastication was painless in 13 patients (52%), and joint noises during mouth opening or closing were noted in 14 patients (56%). According to clinical histories, four patients were suspected to have become symptomatic only after dental treatment. ADWOR is difficult to diagnose with clinical methods alone. The indication for MRI evaluation of the TMJ should be extended for asymptomatic patients with a history of limitation in mouth opening and pathologic x-ray morphology of the condyle. Because symptoms may arise after dental treatment in these patients, aggravation of internal derangement may be avoided by careful handling.

Adult↗
PubMedDate not supplied

Fracture resistance of lithium disilicate-, alumina-, and zirconia-based three-unit fixed partial dentures: a laboratory study.

PURPOSE: The purpose of this study was to determine the fracture resistance of three-unit fixed partial dentures (FPD) made of new core ceramics. MATERIALS AND METHODS: A base metal three-unit master FPD model with a maxillary premolar and molar abutment was made. Tooth preparation showed 0.8-mm circumferential and 1.5-mm occlusal reduction and a chamfer margin design. FPDs were constructed with a uniform 0.8-mm-thick core ceramic and a porcelain veneer layer. In-Ceram Alumina, In-Ceram Zirconia, and DC-Zirkon core ceramics were machined by a computer-aided design/manufacturing system, whereas IPS Empress 2 core ceramic was indirectly built up using the fabrication technology of waxing and heat pressing. FPDs of IPS Empress were heat pressed as complete restorations without core material. To ensure standardized dimensions, the FPDs were controlled at different points. All FPDs were cemented with ZnPO4 on the master model and loaded on a universal testing machine until failure. The failure load and mode of failure were recorded. RESULTS: The highest failure loads, exceeding 2,000 N, were associated with FPDs of DC-Zirkon. FPDs of IPS Empress and In-Ceram Alumina showed the lowest failure loads, below 1,000 N, whereas intermediate values were observed for FPDs of IPS Empress 2 and In-Ceram Zirconia. Differences in mean values were statistically significant. CONCLUSION: The high fracture resistance evaluated for FPDs made of DC-Zirkon underscores the remarkable mechanical properties of high-performance ceramic, which could be useful for highly loaded all-ceramic restorations, especially in the molar region.

Aluminum Oxide↗
PubMedDate not supplied

Healing of bone defects in combination with immediate implants using the membrane technique.

Twenty Brånemark implants were placed with membranes (Gore-Tex Augmentation Material) as immediate or delayed implants in the extraction sockets of 15 patients. Membrane perforations through the mucous membrane occurred in 10 patients after 6 to 24 weeks and once after 2 weeks. Histologic examination of 15 tissue samples taken when the membrane was removed showed genuine bone regeneration in three patients, connective tissue regeneration with intermittent bone regeneration in eight patients, purely fibrous healing in two patients, and inflammatory granulation tissue in two patients. The high proportion of membrane perforations with immediate implants should be taken into account in the assessment and clinical application of this therapy principle.

Alveolar Process↗
PubMedDate not supplied

The influence of spruing technique on the development of tension in a cast partial denture framework.

Distortions of cast removable partial denture frameworks result more from the method of sprue connection than from other variables in the investment and mold preparation. A standard test pattern and optical measuring equipment were used to evaluate residual casting stresses. Based on the data obtained from the initial study, modified removable partial framework patterns were made and cast under varying conditions. The use of a dorsal spruing technique and a box-type casting flask resulted in less distortion than use of the conventional vertical sprue attachment and investing in a ring flask. Dorsal spruing and use of a box-type casting flask reduced the deformation of a cast partial denture framework in the area of the palatal bar and retentive elements up to 0.3 mm. Such a tension-free casting method means a better fit of the partial framework on the master cast and intraorally.

Dental Casting Investment↗
PubMedDate not supplied

Microbial findings of deep peri-implant bone defects.

The objective of this study was to examine inflammatory tissue in deep peri-implant bone pockets (> 5 mm) for anaerobic bacteria colonization. The peri-implant inflammatory tissue of bone defects from 12 edentulous patients with 18 unsuccessful implants (IMZ type) was removed after surgical opening of the defects. After grinding the tissue with glass beads in nutrient solution, an aliquot of the suspension was plated and incubated on appropriate culture media. The quantitative and qualitative distribution of bacteria as a function of the tissue dry weight was determined (cell count/mg dry weight). The mean total cell count was 67 x 10(3) cells/mg dry weight. The following bacteria dominated: species of the family Bacteroidaceae (Prevotella intermedia, Prevotella buccae, Prevotella oralis, Prevotella melaninogenica, Prevotella denticola); Actinobacillus actinomycetemcomitans; Fusobacterium nucleatum; Capnocytophaga spp; and Eikenella corrodens. Bacteroidaceae and Actinobacillus actinomycetemcomitans were found particularly frequently. The increased colonization of these bacteria in deep peri-implant bone pockets is consistent with the currently held view of advanced periodontal lesions, whereby certain pathogens grow at a disproportionate rate in comparison with the total bacteria count under specific circumstances.

Aged↗