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Biomedical subjects

J R Strub

Publications and source records attributed to J R Strub.

At least 19 recordsLinked to original sources
PubMed1992

[Severe atrophy of the alveolar ridge in edentulous patients. Combined treatment using bone grafts and screw implants].

In cases of advanced alveolar ridge atrophy, when the bone available for endosseous implants is not sufficient, endosseous implants are combined with augmentation of the alveolar ridge by means of autologous bone transplants. Depending on the type of atrophy found, the authors use three different surgical procedures: onlay technique, sandwich technique and alveolar extension technique. In all cases functional loading of the implants was performed by way of an entirely implant-supported bridgework. Results to date indicate that initial postoperative resorption is followed by a virtual standstill once the implants have been loaded.

Alveolar Process↗
PubMed1991

[Tensile strength of the bond to In-ceram after varying modes of surface conditioning].

The tensile bond strengths of six different resin-bonding-systems to the aluminium oxide ceramic In-Ceram were tested. The samples were stored in artificial saliva (37 degrees C) up to 150 days and thermocycled (5 degrees-55 degrees C, 18,750 cycles). After sandblasting or silicoating of In-Ceram the tensile bond strength of the modified Bis-GMA resin Panavia-Ex showed no significant changes within this observation period. Using the conventional Bis-GMA resin Microfill-pontic, silicoating In-Ceram with the Rocatec-system resulted in a better bond strength than the use of a silane. The used etching procedure with boiling 70% sulphuric acid was proven to be unsuitable for a long-term stable bond.

Acid Etching, Dental↗
PubMed1991

[Texture formation of the dental ceramic core material In-Ceram and thermal expansion of its individual components].

Electron microscopic investigations of the core material In-Ceram show how its texture is formed. While these are processed the Al2O3 crystallites turn idiomorphic. Etching the material with sulphuric acid selectively dissolves the glassy phase and reveals the crystallites. The chemical composition of the two components of the core material is determined by microprobe analysis. While the crystallites are pure Al2O3, the glass consists of La2O3, SiO2, Al2O3 and CaO. Measurements of the thermal expansions of the glass and the Al2O3 frame show the value for the glass to be 5.1% lower than that of the Al2O3 frame. This results in internal pressure and contributes to the high strength of the material.

Aluminum Oxide↗
PubMed1990

[Resin bonding bridges--state of the art].

Adhesive fixed partial denture (FPD) technology has gradually become viable in recent years, suitable for use in general dental practice. The most important prerequisites for success are patient selection and meticulous production techniques. Indications and limits of this technique are evaluated on the basis of the current state of the art. Initial preprosthetic treatment and clinical procedures are described. Research that has been done so far appears to demonstrate that adhesive FPDs are compatible with healthy periodontal tissues, even though some over-contouring of the adhesive tabs on the abutment teeth seems to be unavoidable. First clinical long-term studies have shown, however, that the failure rate of adhesive FPDs is higher than with conventional crown and bridge techniques. Porcelain-fused-to-metal FPDs on pure titanium frames and full ceramic FPDs are new developments in adhesive FPD technology which are not yet fit for use in dental practice.

Acid Etching, Dental↗
PubMed1990

[Optimizing the bond between metal and bonding agent in bonded restorations using a simplified silicoating procedure].

The tensile bond strengths of five different resinbonding-systems to a Co-Cr-alloy (Dentitan) are tested. The samples were stored in artificial saliva (37 degrees C) up to 150 days and thermocycled (5 degrees-55 degrees C, 18,750 cycles). In contrast to micromechanical bonding-systems, mechanical-chemical ones showed no significant changes in tensile bonding strength during this observation period. The tribochemical silicoating procedure (Rocatec) seems to be suitable for Co-Cr-alloys used in resin-bonded restorations.

Chromium Alloys↗
PubMed1990

[Chemical and thermal compatibility of all-ceramic systems].

The chemical and thermal compatibility of the all-ceramic systems Vitadur-N, Hi-Ceram and In-Ceram as well as the combinations of Dicor with Vitadur-N, Dicor with NBK 1000 and Dicor with Vivodent, respectively, were investigated by means of electronmicroscopy and microprobe measurements at the interface of each compound, and thermomechanical analyses of the components were performed. The results show good contact at the interface of all combinations investigated. No evidence was found for diffusion at the interface except in the In-Ceram system, were a migration of K+ from Vitadur-N dentine into the glassy phase of In-Ceram occurs. The thermomechanical analyses showed a good thermal compatibility of all compounds investigated.

Biocompatible Materials↗
PubMed1989

Prevalence of Bacteroides forsythus and Bacteroides gingivalis in subgingival plaque of prosthodontically treated patients on short recall.

The prevalence of Bacteroides forsythus and Bacteroides gingivalis in subgingival plaque of patients on short recall was analyzed in relation to the probing depth of the test sites. The subjects had excellent oral hygiene and therefore were unlikely to suffer from active periodontal destruction. Sixty-four subgingival plaque samples, taken from gingival or periodontal pockets with probing depths ranging from 1 to 8 mm, were quantitatively assessed for the presence of the two species using species-specific monoclonal antibodies in conjunction with a very sensitive indirect immunofluorescence technique. Both organisms were encountered in probes from sites as shallow as 2 mm, but the percentage of positive samples clearly rose in relation to the probing depth of the test sites. Overall, B. forsythus was found to colonize lesions earlier, that is at smaller probing depths, than B. gingivalis. Interestingly, whenever a sample was found to be positive for B. gingivalis it was also positive for B. forsythus. The numbers of B. forsythus and B. gingivalis and the total bacterial cell number found in the pockets were significantly correlated to the probing depth. However, with advancing probing depth the increase of the total cell numbers of the two Bacteroides species was considerably more pronounced than the increase of the total subgingival plaque cell number. The recall interval neither affected the frequency of sites positive for B. forsythus or B. gingivalis nor influenced significantly the proportions of the two species in subgingival plaque.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗