Influence of Abutment Design on Stiffness, Strength, and Failure of Implant-Supported Monolithic Resin Nano Ceramic (RNC) Crowns

BACKGROUND Recent technical development allows the digital manufacturing of monolithic reconstructions with high-performance materials. For implant-supported crowns, the fixation requires an abutment design onto which the reconstruction can be bonded. PURPOSE The aim of this laboratory investigation was to analyze stiffness, strength, and failure modes of implant-supported, computer-assisted design and computer-aided manufacturing (CAD/CAM)-generated resin nano ceramic (RNC) crowns bonded to three different titanium abutments. MATERIALS AND METHODS Eighteen monolithic RNC crowns were produced and loaded in a universal testing machine under quasi-static condition according to DIN ISO 14801. With regard to the type of titanium abutment, three groups were defined: (1) prefabricated cementable standard; (2) CAD/CAM-constructed individualized; and (3) novel prefabricated bonding base. Stiffness and strength were measured and analyzed statistically with Wilcoxon rank sum test. Sections of the specimens were examined microscopically. RESULTS Stiffness demonstrated high stability for all specimens loaded in the physiological loading range with means and standard deviations of 1,579 ± 120 N/mm (group A), 1,733 ± 89 N/mm (group B), and 1,704 ± 162 N/mm (group C). Mean strength of the novel prefabricated bonding base (group C) was 17% lower than of the two other groups. Plastic deformations were detectable for all implant-abutment crown connections. CONCLUSIONS Monolithic implant crowns made of RNC seem to represent a feasible and stable prosthetic construction under laboratory testing conditions with strength higher than the average occlusal force, independent of the different abutment designs used in this investigation.

Endothelial progenitor cells as a biological marker of peripheral artery disease.

The role of endothelial progenitor cells (EPCs) in peripheral artery disease (PAD) remains unclear. We hypothesized that EPC mobilization and function play a central role in the development of endothelial dysfunction and directly influence the degree of atherosclerotic burden in peripheral artery vessels. The number of circulating EPCs, defined as CD34(+)/KDR(+) cells, were assessed by flow cytometry in 91 subjects classified according to a predefined sample size of 31 non-diabetic PAD patients, 30 diabetic PAD patients, and 30 healthy volunteers. Both PAD groups had undergone endovascular treatment in the past. As a functional parameter, EPC colony-forming units were determined ex vivo. Apart from a broad laboratory analysis, a series of clinical measures using the ankle-brachial index (ABI), flow-mediated dilatation (FMD) and carotid intima-media thickness (cIMT) were investigated. A significant reduction of EPC counts and proliferation indices in both PAD groups compared to healthy subjects were observed. Low EPC number and pathological findings in the clinical assessment were strongly correlated to the group allocation. Multivariate statistical analysis revealed these findings to be independent predictors of disease appearance. Linear regression analysis showed the ABI to be a predictor of circulating EPC number (p=0.02). Moreover, the functionality of EPCs was correlated by linear regression (p=0.017) to cIMT. The influence of diabetes mellitus on EPCs in our study has to be considered marginal in already disease-affected patients. This study demonstrated that EPCs could predict the prevalence and severity of symptomatic PAD, with ABI as the determinant of the state of EPC populations in disease-affected groups.

The CLIF Consortium Acute Decompensation score (CLIF-C ADs) for prognosis of hospitalised cirrhotic patients without acute-on-chronic liver failure

BACKGROUND & AIMS Cirrhotic patients with acute decompensation frequently develop acute-on-chronic liver failure (ACLF), which is associated with high mortality rates. Recently, a specific score for these patients has been developed using the CANONIC study database. The aims of this study were to develop and validate the CLIF-C AD score, a specific prognostic score for hospitalised cirrhotic patients with acute decompensation (AD), but without ACLF, and to compare this with the Child-Pugh, MELD, and MELD-Na scores. METHODS The derivation set included 1016 CANONIC study patients without ACLF. Proportional hazards models considering liver transplantation as a competing risk were used to identify score parameters. Estimated coefficients were used as relative weights to compute the CLIF-C ADs. External validation was performed in 225 cirrhotic AD patients. CLIF-C ADs was also tested for sequential use. RESULTS Age, serum sodium, white-cell count, creatinine and INR were selected as the best predictors of mortality. The C-index for prediction of mortality was better for CLIF-C ADs compared with Child-Pugh, MELD, and MELD-Nas at predicting 3- and 12-month mortality in the derivation, internal validation and the external dataset. CLIF-C ADs improved in its ability to predict 3-month mortality using data from days 2, 3-7, and 8-15 (C-index: 0.72, 0.75, and 0.77 respectively). CONCLUSIONS The new CLIF-C ADs is more accurate than other liver scores in predicting prognosis in hospitalised cirrhotic patients without ACLF. CLIF-C ADs therefore may be used to identify a high-risk cohort for intensive management and a low-risk group that may be discharged early.