3D printing of ultra-thin veneers made of lithium disilicate using the LCM method in a digital workflow: A feasibility study.

OBJECTIVE: This article highlights the feasibility of the additive fabrication of ultra-thin veneers made of lithium disilicate using the lithography-based ceramic manufacturing (LCM) method. CLINICAL CONSIDERATIONS: An esthetical appealing restoration of anterior teeth with thin ceramic veneers is considered one of the ultimate challenges in restorative dental prosthetics. These sophisticated restorations can be fabricated in different ways. Both analog and digital subtractive manufacturing processes have been used to date. Either of the methods is highly demanding for the dental technician and dental engineering due to the required low ceramic layer thickness. CONCLUSION: Modern additive manufacturing methods, for example LCM technology, enable the production of ultra-thin lithium disilicate veneers with layer thicknesses of down to 0.2 mm and could therefore represent a viable alternative for this indication in the future. CLINICAL SIGNIFICANCE: Digital technologies can help streamline workflows, make the outcome more predictable and reproducible, and even further optimize therapeutic restorative options such as highly esthetic veneers for anterior teeth. The reduced material thickness allows for a true non-prep solution or minimally invasive preparation.

Digital implant planning and guided implant surgery - workflow and reliability.

Modern oral implantology and implant prosthetics depend on comprehensive diagnostics and precise planning to ensure the desired outcome and meet the patient's and the dentist's expectations. In this context, digital implant planning and guided implant surgery based on three-dimensional radiographic data and the digitised intraoral surfaces can be of excellent service. They provide valuable information and permit stringent backward planning to optimise the implantological and prosthetic result, improving the safety and efficiency of the surgical procedure and rendering the restorative outcome more predictable in terms of function, biology and aesthetics. However, template-guided implant surgery carries its own specific risks in terms of manufacturing inaccuracies and application errors. These possible sources of error must be recognised and carefully considered in order to avoid adverse consequences.

Real-time observation of interfering crystal electrons in high-harmonic generation.

Acceleration and collision of particles has been a key strategy for exploring the texture of matter. Strong light waves can control and recollide electronic wavepackets, generating high-harmonic radiation that encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of high-harmonic generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems, and provides hope for compact solid-state attosecond sources and electronics at optical frequencies. Yet the underlying quantum motion has not so far been observable in real time. Here we study high-harmonic generation in a bulk solid directly in the time domain, and reveal a new kind of strong-field excitation in the crystal. Unlike established atomic sources, our solid emits high-harmonic radiation as a sequence of subcycle bursts that coincide temporally with the field crests of one polarity of the driving terahertz waveform. We show that these features are characteristic of a non-perturbative quantum interference process that involves electrons from multiple valence bands. These results identify key mechanisms for future solid-state attosecond sources and next-generation light-wave electronics. The new quantum interference process justifies the hope for all-optical band-structure reconstruction and lays the foundation for possible quantum logic operations at optical clock rates.

[Optic neuropathy after retrobulbar neuritis in multiple sclerosis: are optical coherence tomography and magnetic resonance imaging useful and necessary follow-up parameters?]. / Optikusneuropathie nach Retrobulbärneuritis bei Multipler Sklerose : Sind OCT und cMRT hilfreiche Verlaufsparameter?

BACKGROUND: This study evaluated whether progressive optic neuropathy (ON) is commonly found after retrobulbar neuritis and whether optical coherence tomography (OCT) is a useful tool for follow-up of patients with multiple sclerosis (MS). METHODS: An observational study of 86 MS patients (currently treated with immunomodulation) with a past medical history of ON was carried out. Patients were assessed in 2010 and 2012 using the expanded disability status scale (EDSS), visual acuity, visual evoked potentials (VEP) and OCT but magnetic resonance imaging (MRI) was performed only in 2012. RESULTS: In this study 16 men and 70 women with a mean age of 41.6 and 43.8 years, respectively, were evaluated (28 patients post bilateral and 58 patients post unilateral ON including 114 eyes post-ON and 58 eyes without previous ON). Visual acuity and VEPs improved or remained the same over the study period. Visual acuity, VEPs, retinal nerve fiber layer (RNFL) thickness and macular volume were significantly worse in eyes post-ON compared to eyes without previous ON. The RNFL significantly decreased over the study period in eyes post-ON from an average of 79.9 ± 13.3 µm to 77.0 ± 12.9 µm (p < 0.0001) and eyes without previous ON from 89.5 ± 12.9 µm to 86.0 ± 12.5 µm (p < 0.0001). The number of VEPs and RNFL thickness were significantly correlated with visual acuity in all eyes. In patients after unilateral ON the brain atrophy parameters corpus callosum index (CCI) and cella media index (CMI) were negatively correlated with the EDSS. CONCLUSION: Initially MS often begins with an episode of ON which can be stabilized by immunomodulation. A mild progressive ON was generally detectable in this study but severe progressive ON was rarely observed. The OCT measurements showed no better correlation than the VEPs with visual acuity; however, OCT can be applied for confirmation of atypical ON. The corpus callosum index seems to be best associated with the degree of disability while, as already described in the literature, the number of T2 lesions is not well correlated with disability, probably due to the small-world network function of the brain and the position of the lesions in areas with no clinical relevance.

Extremely Nonperturbative Nonlinearities in GaAs Driven by Atomically Strong Terahertz Fields in Gold Metamaterials.

Terahertz near fields of gold metamaterials resonant at a frequency of 0.88 THz allow us to enter an extreme limit of nonperturbative ultrafast terahertz electronics: Fields reaching a ponderomotive energy in the keV range are exploited to drive nondestructive, quasistatic interband tunneling and impact ionization in undoped bulk GaAs, injecting electron-hole plasmas with densities in excess of 10^{19} cm^{-3}. This process causes bright luminescence at energies up to 0.5 eV above the band gap and induces a complete switch-off of the metamaterial resonance accompanied by self-amplitude-modulation of transmitted few-cycle terahertz transients. Our results pave the way towards highly nonlinear terahertz optics and optoelectronic nanocircuitry with subpicosecond switching times.

Rapid-scan acousto-optical delay line with 34 kHz scan rate and 15 as precision.

An optical fast scan delay exploiting the near-collinear interaction between a train of ultrashort optical pulses and an acoustic wave propagating in a birefringent crystal is introduced. In combination with a femtosecond Er:fiber laser, the scheme is shown to delay few femtosecond pulses by up to 6 ps with a precision of 15 as. A resolution of 5 fs is obtained for a single sweep at a repetition rate of 34 kHz. This value can be improved to 39 as for multiple scans at a total rate of 0.3 kHz.

Nonperturbative interband response of a bulk InSb semiconductor driven off resonantly by terahertz electromagnetic few-cycle pulses.

Intense multiterahertz pulses are used to study the coherent nonlinear response of bulk InSb by means of field-resolved four-wave mixing spectroscopy. At amplitudes above 5 MV/cm the signals show a clear temporal substructure which is unexpected in perturbative nonlinear optics. Simulations based on a model of a two-level quantum system demonstrate that in spite of the strongly off-resonant character of the excitation the high-field few-cycle pulses drive the interband resonances into a nonperturbative regime of Rabi flopping. The rotating wave approximation breaks down in this case and the system reaches a complete population inversion.

Ultrashort pulse characterization with a terahertz streak camera.

A phase-locked terahertz transient is exploited as an ultrafast phase gate for femtosecond optical pulses. We directly map out the group delay dispersion of a low-power near-infrared pulse by measuring the electro-optically induced polarization rotation as a function of wavelength. Our experiment covers the spectral window from 1.0 to 1.4 µm and reaches a temporal precision better than 1 fs. A quantitative analysis of the detector response confirms that this streaking technique requires no reconstruction algorithm and is also well suited for the characterization of pulses spanning more than one optical octave.

Single-cycle multiterahertz transients with peak fields above 10 MV/cm.

Phase-locked single-cycle transients with frequency components between 1 and 60THz and peak fields of up to 12MV/cm are generated as the idler wave of a parametric amplifier. To achieve broadband conversion in GaSe nonlinear crystals, we match the group velocities of signal and idler components. The influence of group-velocity dispersion is minimized by long-wavelength pumping at 1.18mum. Free-space electro-optic sampling monitors the multiterahertz waveforms with direct field resolution.

[Angiosarcoma of the temporal bone]. / Angiosarkom des Os temporale.

Angiosarcoma of the temporal bone is an extremely rare malignant tumor, which originates from vascular endothelium. We describe a case of a 57-year-old woman, initially presenting with progressive hearing loss, otorrhea as well as facial palsy diagnosed as a mastoiditis elsewhere. After subtotal mastoidectomy histological examination revealed an angiosarcoma of the mastoid. Since the tumor was not completely removed lateral petrosectomy and postoperative radiotherapy were performed. Afterwards the patient developed local recurrence with intracerebral tumor extension. During palliative polychemotherapy the patient developed a pneumonia and deceased. In this manuscript the morphology, imaging characteristics and current treatment options of angiosarcomas of the lateral skull base are reviewed and discussed.

Three-dimensional computed display of otosurgical operation sites by spiral CT.

We studied the usefulness of spiral CT for preoperative information on the individual anatomy of the temporal bone in a computed three-dimensional (3D) display. In 87 patients with various otological diseases, 3D reconstructions were performed based on spiral high-resolution CT (HR-CT) by volume-rendering on an independent work-station. The positions of the ossicles, facial nerve, labyrinth and vestibular aqueduct relative to reference points were comprehensively demonstrated by thresholding or interactive segmentation. Spiral CT enables 3D display of otosurgical operation sites in a shorter scan time than conventional CT. 3D reconstructions improve the surgeon's understanding of individual anatomy and thus help in surgical planning. This is particularly important for surgery of temporal bone tumours, middle ear deformities, cochlear implants and saccotomy.

Anatomy of the temporal bone: detailed three-dimensional display based on image data from high-resolution helical CT: a preliminary report.

Our purpose was to demonstrate the application of helical computed tomography (CT) for computer graphics of the normal temporal bone with special regard to inner ear structures. Three-dimensional reconstruction of temporal bones was performed from helical CT data on 41 patients with various otologic diseases. Image postprocessing was carried out on an independent work station. In contrast to former surface-rendered three-dimensional visualizations of the temporal bone, a volumetric-rendering algorithm was used. This technique allows automated segmentation, thresholding, and simultaneous visualization of different planes (cube-cutting) in near-real time. We were able to demonstrate the three-dimensional display of the labyrinth during clinical routine. Anatomic details (internal auditory canal, cochlea, vestibulum, semicircular canals, distal part of the vestibular aqueduct, complete ossicular chain, fallopian canal, internal carotid canal) were comprehensively demonstrated by interactive segmentation or thresholding. Difficulties were found in three-dimensional delineation of the complete vestibular and cochlear aqueduct, as well as the modiolus. Initial experience with an advanced helical CT-based three-dimensional display showed excellent images of temporal bone anatomy. Validation studies with correlative histologic sections and surgical dissections remain to be done.

[3-dimensional imaging of temporal bone structures using spiral CT. Initial results in normal temporal bone anatomy]. / Die dreidimensionale Darstellung von Felsenbeinstrukturen mittels Spiral-CT. Erste Ergebnisse bei normaler Felsenbeinanatomie.

3D reconstruction of the temporal bone using spiral CT techniques was performed in 51 patients with various otological diseases during routine clinical work evaluation. The 3D display was optimized by a reduced study time and improved detail accuracy by special algorithms. We were able to demonstrate comprehensively in a 3D mode the normal anatomy of the inner ear and adjacent middle ear structures, such as the modiolus of the cochlea, the semicircular canals, the cochlear and vestibular aqueduct and the ossicles. We suggest routine 3D delineation of the substructures of the temporal bone prior to otologic surgery to provide the surgeon with a 3D view of individual anatomy and specific otosurgical sites.

[Psychological development up to the 1st year following acute myocardial infarct in relation to physical and social rehabilitation]. / Die psychische Entwicklung bis zum ersten Jahr nach akutem Myokardinfarkt in Abhängigkeit vom Stand der physischen und sozialen Rehabilitation.

In 64 patients with definitive myocardial infarction the development of the neurotic-functional disturbances up to the 12th month after myocardial infarction depending upon the duration of the rehabilitation phase I, the physical functional capacity, the cardiovascular morbidity and the professional rehabilitation was examined by means of the standardized questionnaire of complaints and the questionnaire of behaviour after Hess and Höck. The great proportion of psychic disturbances (questionnaire of complaints = 39%, questionnaire of behaviour = 33%) after admission of the patients from the intensive care unit had reduced spontaneously by 1/3 both in a 5-6 weeks and in a 3 weeks duration of the phase I without fully decreasing to the level of the average population. In these cases patients with low watt energy up to the 3rd month showed more frequently neuroses, whereas cardiovascular complications, the enlargement of the left ventricle and the unsolved situation of the professional rehabilitation increased the number of neuroses in rehabilitands in phase III. The investigations confirmed the connection of physical and social with psychic rehabilitation, particularly the use of the further shortening of the early mobilisation in suitable patients for their psychic stability. But the results of the study also emphasize the necessity of the early beginning psychotherapy, in order to prevent neurotic developments after myocardial infarction.