Microstructure of veneered zirconia after surface treatments: A TEM study

Objective

Clinical studies reveal that veneer chipping is one major problem associated with zirconia based dental restorations, the underlying mechanisms being still investigated. We semi-quantitatively analyzed the effects of different surface treatments (thermal etching, 35/105 μm sandblasting and coarse bur drilling (150 μm)) on the microstructure of a zirconia veneered dental ceramic.

Methods

The relative monoclinic content on zirconia surfaces was determined using X-ray diffraction (XRD). The microstructure at the zirconia–veneer interface has thereafter been investigated using transmission electron microscopy (TEM). Selected area electron diffraction (SAED) was used to qualitatively assess the depth of the stress-induced phase transformation.

Results

Sandblasting or bur drilling significantly roughened the zirconia surface. A reverse transformation of already transformed monoclinic zirconia grains back into the tetragonal polymorph has been observed after thermal veneering treatment. In TEM, the mechanically treated samples revealed a highly damaged area of 1–3 μm from the interface. The presence of monoclinic phase in veneered zirconia samples has been observed in SAED up to depths of 4 μm (35 μm sandblasted), 11 μm (105 μm sandblasted) and 9 μm (150 μm diamond drilled) below the interface.

Significance

Regardless of the treatment protocol and produced roughness, the veneering ceramic perfectly sealed the zirconia surface. XRD showed an increased amount of monoclinic phase on the surface treated zirconia. However after thermal treatment, the monoclinic phase was re-transformed into the tetragonal polymorph. TEM/SAED analysis has found indication for a greater extend of the monoclinic transformation into the bulk zirconia compared to the treatment related defective zone depth.     

Tantalum(v) 1,3-propanediolate β-diketonate solution as a precursor to sol–gel derived,metal oxide thin films

Tantalum oxide is ubiquitous in everyday life, from capacitors in electronics to ion conductors for electrochromic windows and electrochemical storage devices. Investigations into sol–gel deposition of tantalum oxide, and its sister niobium oxide, has accelerated since the 1980s and continues to this day. The aim of this study is to synthesize a near UV sensitive, air stable, and low toxicity tantalum sol–gel precursor solution for metal oxide thin films – these attributes promise to reduce manufacturing costs and allow for facile mass production. By utilizing 1D and 2D nuclear magnetic resonance, this study shows that by removing ethanol from the precursor solution at a relatively low temperature and pressure, decomposition of the photosensitive complex can be minimized while obtaining a precursor solution with sufficient stability for storage and processing in the atmosphere. The solution described herein is further modified for inkjet printing, where multiple material characterization techniques demonstrate that the solution can be utilized in low temperature, photochemical solution deposition of tantalum oxide, which is likely amorphous. Tested substrates include amorphous silica, crystalline silicon wafer, and gold/titanium/PET foil. The hope is that these results may spark future investigations into electronic, optical, and biomedical device fabrication with tantalum oxide, and potentially niobium oxide, based films using the proposed synthesis method.

Synthesis of tantalum(v) 1,3-propanediolate β-diketonate solution and use in photochemical solution deposition to form tantalum oxide films.     

Medium-term results after complex intra-articular fractures of the tibial plateau

Background

To present the medium-term results of intra-articular, bicondylar AO/OTA classification type C fractures of the tibial plateau in a retrospective study at a level-1 trauma center in 22 patients with 23 fractures.

Methods

Demographic data for the patients and details of current clinical and radiological follow-up findings were obtained to assess range of motion, clinical stability and alignment of the knee, and posttraumatic arthrosis (Kellgren/Lawrence score). Functional outcomes were assessed using the Lysholm score, Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) form.

Results

Patients’ mean age was 46 years (range 20–67 years). Leading causes of the fractures were high-energy traffic accidents and falls. There were seven C1, seven C2, and nine C3 fractures. ORIF was performed in 20 patients; in two patients an external fixator and in one patient cannulated screws alone were used. In 13/22 patients, an angle-stable locking plate (Less Invasive Stabilization System, LISS©) was used for osteosynthesis. The mean follow-up period was 67 months (range 36–109 months). The overall complication rate was 39.1 %, including four infections and four cases of pseudarthrosis (17.4 %). The average flexion of the injured knee was significantly lower in comparison with the contralateral side (124.9° vs. 135.2°). Knee stability did not differ statistically significantly. Current radiographs revealed no signs of posttraumatic arthrosis in 30.4 % of cases, mild signs in 34.8 %, clear signs in 26.1 %, and severe signs in 13 % using the Kellgren and Lawrence scale. The average Lysholm score was 66.2 points, and the average KOOS score was 67.84. One patient was in category A, and 2 were in category B in the IKDC overall categories, whereas 5 patients were in category C and 14 were even in category D.

Conclusions

Complex articular tibial plateau fractures are associated with a high rate of complications, continue to have a severe impact on function in the injured knee, lead to early post-traumatic arthrosis, and result in long-lasting subjective symptoms for the patients.     

Results of dynamic pedobarography following surgically treated intra-articular calcaneal fractures

Objective

To investigate the clinical outcome and gait analysis findings by dynamic pedobarography in patients following surgically treated single, closed, dislocated intra-articular calcaneal fractures.

Design

Retrospective single-center study with 26 patients. The average follow-up period was 34 months (range 18–61 months). We used the Zwipp score and a score based on a visual analog scale (VAS) to assess the subjective and objective clinical outcome. Dynamic pedobarography (EMED-M, 38 × 42 cm, four sensors per square centimeter, 50 Hz; Novel GmbH., Munich, Germany) was performed to retrieve gait patterns. Analysis was performed using the Emed-Software (Novel GmbH., Munich, Germany).

Results

For the Zwipp score (±200 points), the average was +54.4 points (±48.2); for the VAS score (0–100 points), the average was 58.3 points (±24.3). There was limited mobility in the upper and lower ankle joint. Pedobarography showed a clearly disturbed gait with increased pressure for the fractured side (157 vs. 119 kPa) in the midfoot region (71.8 vs. 68 kPa) and under fifth metatarsal bone (234 vs. 160 kPa). The gait line was lateralized. The force–time-integral (fractured vs. healthy side) showed significant differences for the medial (18 vs. 7 N s) and lateral (61 vs. 36 N s) midfoot region.

Conclusions

We found only an average clinical outcome and clear pathological gait patterns in our cohort with lateralization of the gait line.     

Radiographic detection and characteristic patterns of residual excess cement associated with cement-retained implant restorations: a clinical report

Residual excess cement (REC) is a common complication of cement-retained prostheses and has been linked to periimplant disease. Removal of the cement residue may result in resolution of the issue if addressed early in the disease process. However, this is dependent upon the ability to locate and adequately remove the foreign material. This series of patient scenarios describes the ability to detect REC by using dental radiography. Characteristics related to cements and flow patterns specific to implants are addressed.     

Exercise Reveals the Interrelation of Physical Fitness,Inflammatory Response,Psychopathology, and Autonomic Function in Patients With Schizophrenia

Maintaining and improving fitness are associated with a lower risk of premature death from cardiovascular disease. Patients with schizophrenia are known to exercise less and have poorer health behaviors than average. Physical fitness and physiological regulation during exercise tasks have not been investigated to date among patients with schizophrenia. We studied autonomic modulation in a stepwise exhaustion protocol in 23 patients with schizophrenia and in matched controls, using spirometry and lactate diagnostics. Parameters of physical capacity were determined at the aerobic, anaerobic, and vagal thresholds (VT), as well as for peak output. VT was correlated with psychopathology, as assessed by the Positive and Negative Syndrome Scale, with the inflammatory markers IL-1β, IL-6, and TNF-α and with peak output. The MANOVA for heart and breathing rates, as well as for vagal modulation and complexity behavior of heart rate, indicated a profound lack of vagal modulation at all intensity levels, even after the covariate carbon monoxide concentration was introduced as a measure of smoking behavior. Significantly decreased physical capacity was demonstrated at the aerobic, anaerobic, and VT in patients. After the exercise task, reduced vagal modulation in patients correlated negatively with positive symptoms and with levels of IL-6 and TNF-α. This study shows decreased physical capacity in patients with schizophrenia. Upcoming intervention studies need to take into account the autonomic imbalance, which might predispose patients to arrhythmias during exercise. Results of inflammatory parameters are suggestive of a reduced activity of the anti-inflammatory cholinergic pathway in patients, leading to a pro-inflammatory state.Key words: heart rate, physical exercise, respiration, schizophrenia, vagal threshold, cardiac death, inflammation, physical fitness     

Functional neuroimaging studies of bipolar disorder: Examining the wide clinical spectrum in the search for disease endophenotypes

Bipolar disorder (BP) is among the top ten most disabling illnesses worldwide. This review includes findings from recent studies employing functional neuroimaging to examine functional abnormalities in neural systems underlying core domains of the psychopathology in BP: emotion processing, emotion regulation and executive control, and common comorbid features of BP, that are relevant to the wide spectrum of BP rather than focused on the more traditional BPI subtype, and that may facilitate future identification of diagnostically-relevant biomarkers of the disorder. In addition, an emerging number of studies are reviewed that demonstrate the use of neuroimaging to elucidate biomarkers whose identification may help to (1) identify at-risk individuals who will subsequently develop the illness to facilitate early intervention, (2) identify targets for treatment and markers of treatment response. The use of newer neuroimaging techniques and potential confounds of psychotropic medication upon neuroimaging findings in BP are also examined. These approaches will help to improve diagnosis and the mental well-being of all individuals with BP.     

Long‐term course of substantia nigra hyperechogenicity in Parkinson's disease

A hyperechogenicity of the (SN+) in transcranial sonography corroborates the diagnosis of idiopathic Parkinson's disease (iPD). Although it is thought to represent a biomarker of the disease that is independent of disease severity and progression, differing results have been reported describing a positive correlation of the size and advancing clinical stage. In 50 parkinsonian patients, transcranial ultrasound and clinical examination was performed twice with a mean time interval of 6.4 years. SN+ did not change in size significantly between the first and second examination, whereas clinical parkinsonian symptoms—as determined by the motor part of the UPDRS—significantly worsened (P < 0.001). We found a highly significant intraindividual correlation in SN+ sizes between both examinations (P < 0.001). The size of SN+ did not correlate with the UPDRS part III at the time of first or second ultrasound examination. Progression of motor symptoms between the first and second investigation did not correlate with the size of SN+ at baseline. Furthermore, even in the subgroup of patients with an interval of ≥8 years between examinations, there was no significant change in SN+ size. SN+ represents a largely stable biomarker in iPD and does not reflect disease progression. The size of SN+ does not predict the further course of the disease. © 2012 Movement Disorder Society