Current methods to measure the of strength of the musculus orbicularis oculi are limited by high proneness to examiner error or by their complex and impracticable set-ups. Our aim was to develop a simple and practicable method to measure eye lid power via video analysis. 50 healthy subjects were included. A deformable single use lid speculum was used. Forced maximum lid closure was recorded via a video slit lamp. Analysis of the video data was performed with open source tracking software. The maximum and minimum distances of the inserted lid speculum were detected. The rigidity and mechanical characteristics of the lid speculum were tested separately. In this way, lid power could be determined by analysis of the maximum compression of the lid speculum. To explore the impact of age and sex on eye lid power, Pearson's correlation coefficient was evaluated. ICC (intra class correlation) was analysed as a measure of reliability. In three repeated measurements in 9 subjects, an ICC of α = 0.91 was detected. With 50 healthy subjects, the range of lid power was 0.62 - 4.72 N. No correlation was found between the age of the subjects and eyelid power (Pearson's correlation coefficient = 0.054). A weak correlation was found between the sex of the subjects and eyelid power. For female subjects, the mean power was 1.82 N and for male subjects 2.58 N (Pearson's correlation coefficient = 0.428). A test series of 50 healthy subjects exhibited a wide range of lid power. The wide range makes it difficult to distinguish between pathological and normal eyelid power. The major application field of the method may therefore be in inner-individual measurements of known eyelid pathologies, such as paresis of the facial nerve or ocular myasthenia.
Titanium and titanium alloys are common used materials for dental implants, however they have biological limitations for oral use. Ceramics meet the demands of biocompatibility, but their susceptibility to implant fracture is increased. Therefore, a combination of both materials could be an advantage for dental implants. Therefore, a new hybrid implant combining titanium and ceramic components by glass solder fixation was introduced. The aim of the present study was to investigate the static and dynamic mechanical properties of such hybrid implants. Two different types of hybrid implants were tested, which consisted of a metallic inlay made of titanium grade 4 or grade 5 (primec GmbH) fixed in a thin modified Cercon ceramic (yttrium stabilized zirconium dioxide) shell with a diameter of 4.3 mm (DeguDent GmbH) via glass solder and a titanium abutment fixed with an abutment screw. For each group n = 4 were tested according to DIN EN ISO 14801. The static tests were performed displacement-controlled until implant failure with 0.2 mm/s and the dynamic tests with sinusoidal load levels of 20 to 200 N and 24 to 240 N until failure or 5x10 6 run out cycles. The Cercon ceramic implant with the Ti grade 5 abutment showed higher fracture loads (298 N ± 42 N) in the static tests compared to the implants with the Ti grade 4 (262 N ± 22 N). During dynamic testing two specimens of both groups reached 5x10 6 cycles at the load level of 200 N. At the higher load level one specimen with the Ti grade 5 reached the required cycles, none with the Ti grade 4. The tested hybrid implants showed favourable static and dynamic failure loads comparable to other titanium or ceramic dental implants. Further research has to be performed to determine the in vivo performance of hybrid implants.
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