[Experimental studies on the systemic toxicity of dental alloys free of precious metals]. / Experimentelle Untersuchungen zur systemischen Toxizität edelmetallfreier Dentallegierungen.

The systemic toxicity of five non-precious dental alloys was evaluated by help of an animal study. The pulverized dental alloys, filled in gelatine capsules, were orally administered to laboratory rats using a special esophageal application device. For each alloy examined randomized groups of ten experimental animals and ten control animals were used. For a period of seven days the experimental animals received daily 1000 mg alloy powder per kilogram body-weight. The animals of the control groups received daily empty gelatine capsules (placebo application). After two weeks all animals were killed and autopsies of the animals were performed. Histopathologic examinations of the lungs, kidneys, liver, small intestine and large intestine of all animals were done. With statistic significance (p less than 0.001) rats whom nickel-chromium alloys were administered orally showed serious pathologic reactions more frequently than placebo-treated control animals. Nickel-chromium alloys containing beryllium and/or gallium caused the strongest organic lesions. In contrary to this a dental cobalt-chromium alloy showed a very low systemic toxicity. The results of the study underline that preclinical toxicity testing of dental alloys is necessary in order to avoid systemic toxic lesions in man.

[Histocompatibility of implant materials--animal model criteria and findings]. / Histokompatibilität von Implantatwerkstoffen.

The histocompatibility of the dental implant materials titanium and aluminium-oxideceramics was examined with the aid of quantitative histomorphometry and semiquantitative histopathologic methods after intramuscular and subcutaneous implantation in rabbits and guinea-pigs. Of each material cylindrical and spindel-shaped specimens with rough and smooth surface conditions were implanted for different implant periods (1, 2, 4, 8, 12 weeks). The local tissue reactions caused by the implant materials showed significant differences. Cylindrical implants and/or implants with a rough surface produced, with statistical significance (p less than or equal to 0.001) the strongest tissue reactions (foreign body reactions). Contrary to this, spindel-shaped and smooth titanium- and Al2O3-ceramic-implants elicited bland tissue reactions. In these cases we found a significant increase in subcapsular adipose tissue (p less than or equal to 0.001) and significantly less thickness of the connective tissue capsule (p less than or equal to 0.001).

[Biocompatibility of precious metal dental alloys]. / Zur Gewebeverträglichkeit von Edelmetall-Dentallegierungen.

The local toxicity of three dental gold alloys was examined by help of intramuscular implantation tests in rabbits. For each alloy implantation periods of 1, 2, 4, 8, and 12 weeks were used. The local tissue reactions (foreign body reactions) were judged and graded by use of quantitative histomorphometry. Furthermore specific cellular parameters were examined with semiquantitative histopathologic methods to get an toxicity index for each material. The local tissue reactions caused by the implanted dental alloys were judged in relation to those, caused by biological inert materials (titanium, aluminum-oxide-ceramics) respectively materials with well-known toxic potential (polyvinyl-chloride with toxic aids), after intramuscular implantation in the same animals. Significant differences were found in the tissue reactions caused by the dental gold alloys; an gold alloy with lower noble metal content elicited stronger tissue reactions than both gold alloys with high noble metal content did.

[Histomorphometrical studies on the histocompatibility of dental alloys]. / Histomorphometrische Untersuchung der Gewebeverträglichkeit dentaler Legierungen.

The local toxicity (histocompatibility) of 12 dental casting alloys was examined with the aid of quantitative histomorphometry after intramuscular implantation in rabbits. For each alloy examined and each implantation period (2, 4, 8, 12 weeks) two rabbits were used. In each animal eight grooved cylindrical implants of the same alloy were installed in the left paravertebral muscle. Histomorphometric measurements of the thickness of the connective tissue encapsulating the implant were carried out to assess the degree of foreign body reactions caused by the alloys. Histomorphometry revealed significant differences in the thickness of the soft tissue capsule in relation to the length of the implantation period. The study also demonstrated significant differences in capsule thickness for the different dental alloys at equal implantation periods. Quantitative histomorphometry of the thickness of the connective tissue capsule around intramuscularly implanted dental alloys proved to be suitable for examining the histocompatibility of those materials.

[Biocompatibility of dental materials: Part 2. Materials with mucosal contact]. / Biokomatibilitat zahnarztlicher Materialien: Teil II. Materialien mit Schleimhautkontakt.

Dental materials which are supposed to contact the oral, mucous membranes during their intended dental use may affect our patients health in different ways. Their local and systemic toxicity, and their allergenic and tumorigenic potential are reviewed and methods of biocompatibility testing discussed. Special emphasis is placed on impression materials, denture base resins and dental alloys.

Release and detection of dental corrosion products in vivo: development of an experimental model in rabbits.

An experimental animal model was developed to investigate the release of metal ions from nonprecious dental alloys. Cast specimens of five Ni-Cr-alloys and Co-Cr-alloys were implanted intramuscularly in rabbits for periods of 2, 4, 8, and 12 weeks. The concentrations of nickel, chromium, cobalt, and molybdenum in the implant-loaded muscles were determined by electrothermal atomic absorption spectrometry (AAS) and neutron activation analysis (NAA). Reference muscle samples of each animal were analyzed to determine the individual control values. Significant increases in the tissue concentrations of these metals occurred in the immediate vicinity of the implants. Concentration gradients of the corrosion products were found between the implant contact tissue and the implant periphery (p less than 0.001). Tissue concentrations of nickel and chromium correlated (r less than 0.7). Microprobe analysis before and after implantation of the alloy specimens indicated an even corrosive loss of the alloy surfaces and changes in the surface element distributions. Advantages and limitations of this animal model are discussed, as well as its application in future studies.

Comparative study of clinical examination, occlusal analysis and new radiological imaging procedures in patients with functional TMJ disorders.

A comparative study was made in fifty-three patients with functional diseases of the stomatognathic system and twelve healthy probands by means of anamnestic exploration, clinical examination, occlusal analysis, computed tomography (CT) and magnetic resonance imaging (MRI). Connections between functional and structural changes of the diseased stomatognathic system were found. The results showed the possibilities and applications of CT and MRI as supplementary diagnostic methods in the diagnosis of functional TMJ disorders.