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Biomedical subjects

K P Lange

Publications and source records attributed to K P Lange.

At least 19 recordsLinked to original sources
PubMed2001

Plaque formation on surface modified dental implants. An in vitro study.

Bacterial adhesion on titanium implant surfaces has a strong influence on healing and long-term outcome of dental implants. Parameters like surface roughness and chemical composition of the implant surface were found to have a significant impact on plaque formation. The purpose of this study was to evaluate the influence of two physical hard coatings on bacterial adhesion in comparison with control surfaces of equivalent roughness. Two members of the oral microflora, Streptococcus mutans and Streptococcus sanguis were used. Commercially pure titanium discs were modified using four different surface treatments: physical vapour deposition (PVD) with either titanium nitride (TiN) or zirconium nitride (ZrN), thermal oxidation and structuring with laser radiation. Polished titanium surfaces were used as controls. Surface topography was examined by SEM and estimation of surface roughness was done using a contact stylus profilometer. Contact angle measurements were carried out to calculate surface energy. Titanium discs were incubated in the respective bacterial cell suspension for one hour and single colonies formed by adhering bacteria were counted by fluorescence microscopy. Contact angle measurements showed no significant differences between the surface modifications. The surface roughness (Ra) of all surfaces examined was between 0.14 and 1.00 microm. A significant reduction of the number of adherent bacteria was observed on inherently stable titanium hard materials such as TiN and ZrN and thermically oxidated titanium surfaces compared to polished titanium. In conclusion, physical modification of titanium implant surfaces such as coating with TiN or ZrN may reduce bacterial adherence and hence improve clinical results.

Bacterial Adhesion↗
PubMed1997

Contact activation of plasmatic coagulation on polymeric membranes measured by the activity of kallikrein in heparinized plasma.

Kallikrein is involved in the generation of bradykinin during extracorporal circulation, that is believed to play an important role in cases of anaphylactic shock during hemodialysis. Therefore, a method for the assessment of kallikrein generation was developed, based on the chromogenic substrate S-2302. Comparison of kallikrein-like activity on glass using citrate or heparinized plasma demonstrated enhanced activity in the presence of heparin. The applicability of the assay, and the time course of kallikrein generation was demonstrated with glass and cuprophan. Membranes based on pure polyacrylonitrile, or its copolymers differing in their content of acrylic acid, 2-hydroxyethyl acrylate, and allylsulphonate were investigated with respect to kallikrein-like activity, and physicochemical surface properties. It was found that high content in 2-hydroxyethyl acrylate, and acrylic acid caused a substantial activation of the contact system while low content in allylsulphonate (less than 2 mol%) did not result in enhanced kallikrein-like activity. The activating materials were characterized to be highly wettable, and had the most negative zeta potentials.

Acrylates↗
PubMed1991

[The marginal periodontium on osseointegrated implants--literature review and own investigations. 2. Own investigations].

19 IMZ-implants with a medium age of incorporation of 10.5 months were examined at four sites concerning their periimplantary situation. Gingival index, bleeding on probing, pocket depth and composition of subgingival plaque corresponded in 67% of the examined sites with periodontal health. Favourable correlations were stated between the values of plaque index and of the bleeding on probing as well as between the wide of fixed gingiva and the dimension of gingival recession. Compared to bridge constructions more unfavourable results concerning the amount of plaque and clinical criteria of the gingival margin were observed in case of mucosal fixed prostheses.

Adult↗
PubMed1991

[Infrared casting temperature control of the induction centrifuge casting exemplary in the non-precious dental alloy Wiron 88].

A temperature-dependent, IR-controlled casting technology for the non-precious dental alloy Wiron 88 (Bego) is presented and compared with a traditional procedure. The new casting allows the production of cast objects with favourable and reproducible material properties. Compared with the commonly used technology hardness, grain size and susceptibility to corrosion could be reduced. Texture after casting was found to be homogeneous. The procedure presented meets the requirements for a modern casting technology and be adapted to older automatic casating devices.

Aluminum↗
PubMed1991

[The ceramic system In-Ceram in the prosthetic dentistry--clinical and experimental results].

The ceramic system In-Ceram is a metal-free method to manufacture ceramic crowns and bridges. The metal framework is replaced by a sintered, glass infiltrated aluminium oxide substructure of high strength. Due to improved material properties the implementation of ceramic dental restorations allows a wider range of application. The paper presents own clinical experiences as well as recommendations concerning the dimensions of the aluminium oxide substructure.

Aluminum Oxide↗
PubMed1991

[Reexamination of cantilever bridges-a cross-section study].

In the present study reexaminations of 28 cantilever bridges and 26 conventional bridges were carried out. The aim was to evaluate the periodontal conditions and to give recommendations for use. Parameters were PI, GI, tooth mobility, pocket depth, gingival recession and BOP. Deducing from the results, which were statistical analysed, we recommend the cantilever bridges by right using. Special attention should be directed to antagonistical dentition.

Analysis of Variance↗
PubMed1991

[Investigations on secondary emission of metallic implant materials Ti and Ta following radiation].

Two implant materials, titanium and tantalum, were investigated for their electron emission in response to therapeutic tumor irradiation and were compared, in this context, to a substance equivalent to bone. The reaction of titanium was found to be similar to that of bone, whereas substantive increase in radiation was caused by tantalum which, consequently, should be removed from the radiation field.

Bone and Bones↗
PubMed1990

[The microstructure and corrosive properties of the nonferrous casting alloys Gisadent NCA, NCS 1 and KCM 83 before and after casting].

Nonprecious alloys (NEM) applied in dental practice often show widely differing material properties after casting. This is caused by subjective and objective differences in manufacturing of these alloys with a given technology as well as by varying composition and structure of the alloys within and in between different lots. For homogeneous composition of crude specimens technologically caused variance of casting condition itself leads to considerable differentiation of casting results. If the original state of crude alloy forms is very different then there will be a levelling out and/or increase of scattering of material parameters after casting. Optimized computed-controlled casting technology in combination with defined muffle ring size could result in reproducible casting results.

Chromium Alloys↗