[The influence of macro- and microstructure on the surface wettability and retention properties of endodontic posts in vitro]. / Der Einfluss der Makro- und Mikrostruktur auf die Benetzungs- und Retentionseigenschaften von Wurzelkanalstiften in vitro.

Aesthetical and biomechanical requirements on fiber-reinforced endodontic posts play an important role in clinical application. Leading to a long-term clinical success, post systems must ensure an adequate force transmission and optimal retention behavior into the root channel. The aim of this study was to determine the microstructure and morphology of commonly used fiber reinforced endodontic posts in vitro. Post-specific fiber diameter, fiber arrangement over the cross-sections and length, and fiber-matrix ratio could be associated with mechanical properties, such as three-point bending strength and structure modulus. Furthermore, our investigation focused on the quantification of the wettability of the post surface. By using a modified contact-angle measurement, the meniscus on the post surface was characterized. In additional investigations, posts were inserted in artificial root channels and the extraction force was measured. The results show a strong correlation between the extraction force and the wettability of the post surface.

[Drug release of coated dental implant neck region to improve tissue integration]. / Pharmakafreisetzende biodegradierbare Polymerbeschichtung von dentalen Titanimplantaten zur Verbesserung der Weichgewebsintegration.

In order to improve tissue integration, the neck region of dental implants was coated with the biodegradable polymer poly (L-lactide) incorporating tetracycline, ibuprofen and the combination of both drugs using a solvent dip-coating process. Metallographic analysis, light microscopy and electron microscopy were used to detect the thickness range and the surface characteristics of the coatings. Cytotoxicity was evaluated using the tetrazolium colorimetric method with the fibroblast cell line L929. The in vitro drug release was measured in isotonic sodium chloride solution by UV spectroscopy. To explore if drug release is concentration-dependent, the total amount of drug was varied in the coating (20% wt, 30% wt and 40% wt). The results showed a continuous release of the embedded drugs in relevant dosage over a period of 6 months. In contrast to high tetracycline concentrations, high ibuprofen concentrations resulted in a decreased metabolic activity of the L929 fibroblasts.

[Intraoral diagnostics using confocal laser scanning microscopy]. / Intraorale Diagnostik mittels konfokaler Laser-Scanning-Mikroskopie.

The aim of this study was to analyze and evaluate the oral mucosa and the surface constitution of dental materials to display the characteristics and the behaviour of dental composites concerning the margin fit. Therefore, the gingiva and composite restorations of 45 patients aged 17-69 years were examined with a new digital confocal laser scanning microscope developed in Rostock. The device works in contact with the surface of the examination region using a water immersion objective and a diode laser with a wavelength of 670 nm. As a result of a PMMA-Cap with a thickness of 0.5 mm, we can create images with exact depth information and of very good quality. The epithelium of the gingiva with its cellular and subcellular structures could be observed up to a depth of 200 microm. Also, papillary crests, blood vessels and even the blood flow were visible. An inflammation of the gingiva could be verified because of the existence of inflammatory cells. The enamel and dental restorations could be observed up to a depth of 80 microm and allowed the evaluation of the margin fit. Confocal laser scanning microscopy seems to be suitable for the non-invasive examination of oral mucosa and dental materials in vivo.