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Biomedical subjects

J Wirz

Publications and source records attributed to J Wirz.

At least 19 recordsLinked to original sources
PubMed1979

[Dental reconstruction with non-precious metal screws and posts].

A short review of the current methods for restoring destroyed dental crowns by mechanical retentive elements. The causes leading to failure in such restorations are mentioned in a short review of literature. Main causes are corrosive changes in posts and screws anchored in root canals. This is why a special chapter deals with the problem of corrosion. A systematic enumeration of various corrosions in posts and screws is illustrated by a choice of clinical and radiological illustrations. The author's own metallurgical analytic investigations of the posts and screws available commercially allow to divide them into 4 typical nonprecious metal groups: Inox steel, cromium nickel steel, cromium nickel molybdene steel and brass alloys. The reasons for resistance to corrosion lie in the different metallographic structures and processing methods. Further investigations are finished and will be published later in this journal.

Chemical Phenomena↗
PubMed1978

[Gamma-2-free amalgams: effect of technic (trituration) on physical properties].

The goal of investigation was to find the physical data, viz. changes of volume, pressure resistance after 1 and 24 hours, creep value of gamma-2-free amalgams (dispersion type), to compare the values to each other and to those of conventional amalgams. On the whole, gamma-2-free amalgams are superior to the conventional products. The pressure resistance after 1 hour is considerably higher, and the creep values are significantly lower. Furthermore, it could be proven that a mixing unit of high RPM was able to improve the quality still more. The best results were found with Amalcap non-gamma 2 and Dispersalloy evenly, both premeasured in capsules and triturated in the Silamat unit. Similar data were found with Dispersalloy tablets, mixed in the Diomat II unit at 3000 RPM. Before clinical long-range examinations can be obtained, judgment of quality cannot be passed.

Dental Amalgam↗
PubMed1978

[Long-term experience in endosseous endodontic implantation].

The results of 9 years experience with transfixed abutment-teeth for bar-joint dentures in the lower jaw were collected. The method has been slightly altered since the beginning, and these changes are described in order to complete earlier publications: there are special chapters dealing with the implant-material Syntacoben, which is used in human and veterinary medecine mainly, and with the transfixation technique. By measuring the tooth mobility over a period of 20 months in a group of subjects, one has shown that the stabilisation (4.5 +/- 1.0.10(-2) mm) of loosened lower anterior abutment teeth combined with a bar-joint denture is lasting, even under masticatory pressure. The long-term results (mean wearing-time is 5.5 years) are gathered in a summarized survey. In 62 patients with 100 transfixed abutment-teeth (making a total of 159 abutment-teeth) there was a success of 62%, 15% partial success, and 23% failure. 5 success-cases are also radiologically shown. Within strict indications, transfixation can be recommended today to the practitioner.

Bone Screws↗
PubMed1977

[Lead content in alginates].

Alginates containing a high level of lead may lead to health damages in dentists and their personnel. Walter and Söremark have pointed out these hazards. The author's investigations with the Perkin-Elmer absorption-photospectrometer shall show how high the lead content of the 25 brands of alginate sold in this country is. Ca 37, Protex and Algihard S contain sizeable amounts of lead. Recommendations are given towards the protection of dentist and assistant.

Alginates↗
PubMed1977

[Mercury vapors in dental practice].

Mercury as a hazard to health for dental office personnel and patients has been discussed for a long time. With the efforts of ecology in this country it was necessary to examine the situation again. 32 dental offices of a Swiss town of 90000 inhabitants were examined regarding their air contamination with mercury. A relationship was determined between dosage, working method, cleaning methods and texture of office floors. The results were not alarming. If specific rules are observed, mercury is no hazard for either dental personnel or patient.

Dental Amalgam↗
PubMed1976

[Materials-testing research on hard and high strength dental plasters].

Types of III and IV dental plasters (ADA specifications No. 25) are used for making working models for clinical and laboratory purposes. 14 plaster products of these two types were examined for their physical properties and compared to the specifications, namely of setting time, volume changes, resistance to pressure and accuracy of detail. Additionally the values of surface hardness, bending strength and resistance to scraping were examined. Accordingly, three products were attributed to special stone (specification No IV): Duricap red (predosed capsule), Glastone, and Vel Mix Stone.

Calcium Sulfate↗