Deutsche zahnarztliche Zeitschrift最新文献

BOP (Biocompatible Osteoconductive Polymer) shows no cytotoxicity in vitro. After six months of subcutaneous implantation in mice a weak cellular tissue reaction is seen histologically. The hard tissue reaction after six months of implantation in fractured tibia bone shows less connective tissue between the implant material BOP and bone.

A 0.25 N hinged constant force probe (Borodontic) and two inflexible probes (WHO, PCP-11) were used for probing. The mean probing depth differences between WHO and Borodontic as well as between Borodontic and PCP-11 were significant. Deepest probing levels were found with WHO and shallowest levels with Borodontic. Also, the pockets in patients with higher sulcus bleeding index presented shallower probing levels with Borodontic than the other probes.

A total of 107 bonded bridges could be re-evaluated after a mean period of 2.3 years and a maximum of 5 years. The preparation of mechanical retentive aids, such as grooves and bores resulted in a significant reduction of failure rates after one year. Electrolytical etching or silicoating of the CoCr restorations failed to have any effect on the failure rates of those bridges that were provided with adequate mechanical retention.

In this study the influence of physically different titanium implant surfaces (smooth, rough-textured, porous-coated) on osseointegration was examined. Embryonic chick calvarial osteoblasts were cultured on the various titanium disks in vitro. Synthesis of extracellular matrix and mineralization were evaluated. Osteoblasts cultured on rough-textured and porous-coated titanium disks exhibited substantially higher rates of bone-specific extracellular matrix synthesis (collagen) and subsequent mineralization than the osteoblasts on smooth titanium disks or plastic tissue culture dishes as controls. From this it can be concluded that porous or rough titanium implant surfaces may act like "natural" substrates permiting microscopic tissue/cell ingrowth and thus improving clinical implant fixation.

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).

Light curing composite resins became the preferred material in treating carious or traumatic lesions of anterior teeth. Attempts to improve the properties of these materials lead to the development of hybrid composites with an amount of anorganic fillers of more than 80 weight %. It was the purpose of this study to investigate whether composites with higher amounts of anorganic filler show better properties than those with lower amounts of filler. Eight commercial and two experimental composites have been tested for their resistance to abrasion by simulated toothbrushing, polymerization shrinkage, water sorption, porosity, and surface quality. The results showed no correlation between the amount of anorganic filler on the one hand and tested properties on the other. The amount of anorganic filler is no quality criterium per se, the properties of a composite are rather influenced by composition and quality of the organic matrix, even if the amount of anorganic fillers increases to more than 80 weight %.

Hormonal changes occuring during pregnancy are known to induce periodontal changes and may therefore influence preexisting periodontal diseases negatively. Since glycosaminoglycans (GAG) and collagen are the principal constituents of the matrix, the influence of progesterone on their synthesis was chosen as an assay system. Confluent human gingival fibroblast cultures grown under standard conditions were preincubated with progesterone levels ranging from 0.05 to 0.5 microgram/ml for 48h before GAG synthesis was assayed by incorporation of 14C-glucosamine. The GAG fraction was detemined by ion-exchange-chromatography and fractionated precipitation. Collagen-synthesis was monitored by 14C-proline-incorporation. Progesterone concentrations corresponding to those seen in the third trimenon of pregnancy were able to lower GAG-synthesis; the synthesis of all GAG-species was affected in a similar way. Collagen synthesis was only affected by unphysiologicaly high hormone doses. The observed clinical changes may therefore be due to the influence of progesterone on GAG synthesis.

Endosseous implantation procedures are used in dentistry with ever increasing frequency. For an assessment of the role of dental implantology within the specialities of dentistry, 2000 physicians and dentist in the FRG were surveyed. The article reports data on physicians/dentists involved in implantology, the frequency of insertions of endosseous implants, the popularity of implant systems, implantological methods applied, successes, failures and indications.

The German Society for Prosthodontics and Material Sciences is turning 40 years this year. This event is reason enough to look back and remember its stages in development.

Although the use of osseointegrated Brånemark implants is associated with a high success rate, late losses of primarily osseointegrated implants have been observed again and again. In this study 50 patients were evaluated to clarify the effects of abutment position on late losses. The results have shown that implant position is less important for the loss of implants than other parameters such as healing disorders or poor oral hygiene.