Deutsche zahnarztliche Zeitschrift最新文献

The purpose of this investigation was to evaluate the precision of optical impressio obtained with the Cerec-device. Cerec provides a linear correlation between z-data and altitude (r = 1), one bit representing 49 microns. Repeated measurements deliver pixel-z-data within a range of +/- 49 microns and surfaceaverages (484 pixel) within +/- 5 microns. Deviations occur near areas with parallel orientation to the direction of measurement.

Tooth migration into jaw segments where granular hydroxy apatite had been implanted was studied in rats. To prevent premature contact with the ceramic granules, tooth germs were completely removed in the animals at the age of 10 days. Tooth root contact with the ceramo-osseous complex as a result of physiological tooth migration had deleterious effects. In the light of these findings the implantation of granular hydroxy apatite in the vicinity of tooth roots is not advisable.

For testing the reliability of caries epidemiologic data a group of 273 children, aged 7 to 15 years, was examined by two dentists. A second group of children was investigated twice by one examiner at an interval of two weeks. Neither an inter-examiner nor an intra-examiner comparison of these data did indicate any statistically significant differences in caries incidence.

Dental amalgam has been considered to have adverse side effects on the immune system. There are controversial reports, which indicate an increase as well as a decrease in peripheral blood lymphocyte counts due to amalgam fillings. We investigated 2 groups of patients: one group was treated with amalgam restorations for the first time. In the other group all previous amalgam fillings were removed. Before and after treatment we determined the absolute and relative numbers of granulocytes, lymphocytes, monocytes, T cells, B cells, suppressor T cells, helper T cells and NK cells. In addition, functional investigations of T cells were performed. In conclusion, we could not find any effect of amalgam restorations on the immune system regarding the investigated parameters.

Over 7 days specimens of 5 gamma 2-free Amalgams were stored in KSCN-containing and KSCN-free lactic acid-salt solution. After 1, 4 and 7 days samples of the solution were analyzed for their mercury contents using inductively coupled plasma atom emission spectroscopy. In KSCN-containing solution the release of mercury was 45.4 micrograms, in KSCN-free solution it was 70.7 micrograms/50 mm2. KSCN, a part of natural saliva, has the effect of inhibiting corrosion.

40 periodontal defects with probing depths of 5 mm in 10 patients were treated with a conventional flap or with the "papilla preservation flap". In addition, half of the defects received granular hydroxyapatite. In terms of pocket depth and probing attachment-level no significant differences were seen between the 4 groups after 3 and 6 months. Regarding the development of gingival recession, however, the papilla preservation technique has significant advantages and showed better aesthetic results.

In a 5-year longitudinal study we assessed the amount and frequency of gingival recessions in relation to the width of the keratinized gingiva and the already existing recessions in two groups (each n = 15). Group I (dental students) had nearly no recessions and group II (patients) had exposed roots on 24% of their teeth. In both groups there existed no correlation between the width of the keratinized gingiva or, respectively the existing recessions and the recessions occurring. Only 36 sites had a recession greater than or equal to 1 mm, these were accumulated in just a few probands.

Probing depth (PD) is measured at 2, 4 or 6 sites per tooth. We sought to ascertain whether or not more measurements increase the sensitivity of assessing the severity of periodontitis. 2 probings compared with 4 probings per tooth resulted in 68% sensitivity for PD greater than 2 mm and 77% for PD greater than 4 mm. The mesio-buccal PD explains only 16% of the variance of the buccal/oral PD. Comprehensive examination of pockets should consist of a minimum of 4 probings per tooth.

After immersion of unpolished and polished high copper amalgam in saliva with different pH values for up to 12 weeks, the elements mercury, tin, copper, silver and antimony were analysed in the solution. Unpolished amalgam corroded more than polished amalgam. Corrosion increased with the time of immersion and the acidity of the solution. The values calculated to a maximum of clinical application not imply any toxicologic risk.