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Biomedical subjects

R Biffar

Publications and source records attributed to R Biffar.

At least 19 recordsLinked to original sources
PubMed2004

Dental nomograms for benchmarking based on the study of health in Pomerania data set.

AIM: Benchmarking is a means of setting goals or targets. On an oral health level, it denotes retaining more teeth and/or improving the quality of life. The goal of this pilot investigation was to assess whether the data generated by a population-based study (SHIP 0) can be used as a benchmark data set to characterize different practice profiles. MATERIAL AND METHODS: The data collected in the population-based study SHIP (n=4310) in eastern Germany were used to generate nomograms of tooth loss, attachment loss, and probing depth. The nomograms included twelve 5-year age strata (20-79 years) presented as quartiles, and additional percentiles of the dental parameters for each age group. Cross-sectional data from a conventional dental office (n=186) and from a periodontology unit (n=130, Greifswald) in the study region as well as longitudinal data set of a another periodontology unit (n=135, Kiel) were utilized in order to verify whether the given practice profile was accurately reflected by the nomogram. RESULTS: In terms of tooth loss, the data from the conventional dental office agree with the median from the nomogram. For attachment loss and probing depth, some age groups yielded slight but not uniform deviations from the median. Cross-sectional data from the periodontology unit Greifswald showed attachment loss higher than the median in younger but not in older age groups. The probing depth was uniformly less than the median and tended toward the 25th percentile with increasing age. The longitudinal data of the Unit of Periodontology in Kiel showed a pronounced trend towards higher percentiles of residual teeth, meaning that the patients retained more teeth. CONCLUSION: The profile of the Pomeranian dental office does not deviate noticeably from the population-based nomograms. The higher attachment loss of the Unit of Periodontology in Greifswald in younger age strata clearly reflects their selection because of periodontal disease; the combination of higher attachment loss and decreased probing depth may reflect the success of the treatment. The tendency of attachment loss towards the median with increasing age may indicate that the Unit of Periodontology in Greifswald does not fulfill its function as a special care unit in the older subjects. The longitudinal data set of the Unit of Periodontology in Kiel impressively reflects the potential of population-based data sets as a means for benchmarking. Thus, nomograms can help to determine the practice profile, potentially yielding benefits for the dentist, health insurance company, or--as in the case of the special care unit--public health research.

Adult↗
PubMed1996

Hydrothermal ceramic for porcelain-fused-to-metal crowns: an initial experience report from clinical practice.

The development of hydrothermal ceramics was an important requirement for fusing hydrolysis-resistant ceramics to precious metal alloys with low melting interval. Clinical findings since 1992 confirm the wide range of application of these metal-ceramic restorations in dentistry. Initial problems concerning temperature regulation of the ceramic ovens were rectified by checking and adjusting them for lower sintering temperatures. The golden yellow color is only one advantage of the ceramic-veneered alloy. Other advantages include its nonporous, smooth surface, translucence, and suitability for use in all types of dental restorations and reconstructions. Hydrothermal ceramic veneers thus can help to substantially reduce the number of different alloys used in a patient's mouth.

Crowns↗
PubMed1991

[Clinical post-treatment evaluation of powder metallurgically produced tooth replacements].

258 units of fixed crowns and inlays, produced with the powder metallurgic Degusint-System (Degussa), were clinically evaluated 6 and 12 months after insertion. Periodontal examinations, especially of the crevicular fluid flow, failed to show higher amounts of marginal inflammation due to the subgingival localization of the margins of fixed sintermetallic restorations compared with reference teeth of the same individual. Plaque accumulations during the wearing period were quite the same as those observed with crowns.

Crowns↗
PubMed1991

[Dimensional stability of alginate impressions after immersion disinfection with Impresept].

With an experimental design near clinical conditions the alginates Alginoplast, Blend-a-print, Blue-print, Palgaflex and Xantalgin were examined under the influence of the disinfection with Impresept (Espe). The absolute means of the differences between models from disinfected or nondisinfected impressions reached from 0.05%lin to 0.19%lin. In comparison to the specific tolerances of the materials the influence of Impresept on the dimension stability is not important.

Alginates↗
PubMed1990

[Deformation of crown margins by porcelain fusion].

This study attempted to measure marginal distortion of the porcelain-bonded-to-metal restoration due to porcelain fusion, 40 crowns were made of a PdAg-alloy on two dies with different extensions of the bevelled shoulder preparations. Only four crowns fit on the original dies after the firing procedure. Dimensional changes within oxide bake as well as dentine and glaze bakes could be achieved. Crowns with extended vestibular margins showed a higher amount of relative distortion. In a second simple experiment dimensional changes caused by the PFM-process could be found for other Au- and Pd-based alloys too.

Crowns↗
PubMed1990

[Clinical application of powder metallurgically produced crowns].

The clinical applicability of a newly developed powder metalurgic procedure (Degusint/Degussa) for the production of crowns and bridges is evaluated in a controlled clinical study. Until now 366 units ranging from occlusal inlays to four-unit ceramometallic bridges were incorporated. In a total of 15,000 marginal gap measurements, medians of 22 microns (Degusint G) and 26 microns (Degusint U) were found, with 95.4% or 94.0% respectively of the values ranging below 70 microns. The PFM-process increases the marginal gap from median 27 microns to 33 microns. With uniform pore distribution mean values from 90.3% to 92.4% of the theoretical density were reached using the available powder compositions. Compared with cast fixed prostheses no differences in intraoral behaviour could be noticed up to now.

Crowns↗
PubMed1989

[Accuracy of fit of veneer crowns with ceramic shoulders].

Two different types of special ceramic shoulder powders were used for veneering 40 casted crowns. A total of 2400 measurements of the marginal defects provide information on the marginal qualities of the facially butted porcelain margins. Surfaces and shapes of the margins were compared by SEM and metallographic sections. Vita shoulder porcelain, with glazed surfaces and rounded edges of the facial margins, shows poor marginal adaptation. The veneers made of Ducera shoulder porcelain exhibit minor facial openings and high form stability during sintering. The higher content of aluminum oxide in this porcelain powder reduces sintering shrinkage but, at the same time, produces a rough surface. The use of a new experimental liquid failed to improve the results.

Aluminum Oxide↗
PubMed1989

[Effects of mold preheating temperatures and the time of melt casting on the structure of cast denture frameworks].

At casting temperatures of 1330 degrees to 1530 degrees C and preheating temperatures of 900 degrees to 1100 degrees C, 28 cast denture frameworks were manufactured using the cobalt chromium alloy Biosil f (Degussa). The inner defects were detected by X-ray defectoscopy and the grain numbers of clasp, connector and basis elements determined by metallography. The best results for compact castings were observed at a temperature range of 1410 degrees to 1480 degrees C. Casting previous to the melting of the last alloy cube results in a structure of clasps and connectors with 100-200 grains/mm2 and a high amount of defects; exceeding the liquidus temperature of 1380 degrees C produces grain numbers of 20-30/mm2, while a casting temperature of 1530 degrees C results in 3-5/mm2. Overheating of the melt, also in connection with low preheating temperatures, is probably a cause for the premature loss of clasp retention and fracture of many denture frameworks.

Dental Alloys↗
PubMed1989

[Effects of different tray types on the resulting impression].

In addition to the impression material the type of the used impression tray influences the accurat dimensional transfer of the teeth position to the master cast. In total 80 impressions were taken from models of the upper- and lower jaw by using condensation silicone, hydrocolloid, solid and perforated stock trays and acrylic custom trays. After that the casts were measured. The highest conformity with the original could be achieved with a hydrocolloid stock tray. The custom tray for the upper jaw showed short differences to the original model. By using a custom tray for the lower jaw higher dimensional changes occurred. Besides the different impression material thickness, distorsions of the trays should be discussed.

Dental Impression Materials↗