Cyclic Loading Effect on Color Stability of Unshaded versus Shaded Zirconia.

STATEMENT OF PROBLEM: Shaded versions of dental zirconia may improve initial color matching to teeth, but might change color with cyclic mechanical loading. PURPOSE: The purpose of this study was to measure the color of unshaded and shaded zirconia dental ceramic before and after cyclic mechanical loading and calculate color differences (ΔE). MATERIAL AND METHODS: Disk-shaped specimens (N = 30, Nobel Procera, 0.8 mm thick, 12 mm diameter) of unshaded or shaded zirconia (intrinsically shaded by small oxide modifications) were fabricated by the Nobel Biocare using standard CAD-CAM processing. Milled surfaces were polished. CIE L*a*b* values were measured (Konica Minolta spectrophotometer) before and after mechanical cycling (custom modified Leinfelder test machine, biaxial flexure loading, load = 80 N × 500,000 cycles, dry), and L*a*b* individual differences and ΔE color differences were calculated and compared (ANOVA, p < 0.05). RESULTS: Mean L*a*b* values for the unshaded group before (U1 = 86.165, -0.887, 0.372) and after (U2 = 84.860, -0.805, 0.097) cyclic loading were compared to the shaded group before (S1 = 75.281, -0.679, 23.251) and after (S2 = 74.961, -1.233, 22.439) cyclic loading. All color variables for both unshaded and shaded groups were significantly different between before and after cyclic loading (p < .004) except for the L* value of the shaded group. The ΔE for unshaded (1.441 ± 0.495) versus shaded (1.252 ± 0.363) were statistically different but clinically the change would not be detectable at this point. CONCLUSIONS: The color of the unshaded and shaded zirconia specimens was influenced by cyclic loading (p < 0.05). Color changes were detectable but small at levels up to 500,000 cycles, and remained clinically acceptable at that point. CLINICAL SIGNIFICANCE: It is important to acknowledge any possible color changes that might occur in zirconia restorations, especially in the esthetic zone. Minor color changes that are individually imperceptible to the human eye within different restorative components may be compounded to produce clinically significant color change that is not aesthetically acceptable.

Composition, phase analysis, biaxial flexural strength, and fatigue of unshaded versus shaded Procera zirconia ceramic.

STATEMENT OF THE PROBLEM: Recent interest in shaded zirconia has raised questions about the relative stability of the tetragonal phase after colorant oxide additions. PURPOSE: The purpose of this in vitro study was to evaluate the effects of fatigue cycling on the stability of a commercially available dental zirconia (Procera) in both unshaded and shaded compositions by measuring the change in biaxial flexural strength (BFS) after 500 000 cycles at 80-N loads and in phase composition as detected by x-ray diffraction (XRD). MATERIAL AND METHODS: Partially stabilized zirconia disks (NobelProcera) were fabricated in unshaded and shaded forms (12 mm diameter × 0.8 mm thick). Specimens were analyzed by energy-dispersive x-ray spectroscopy (EDS) and by wavelength-dispersive x-ray spectroscopy (WDS) for oxide compositions which indicated the presence of small amounts of Fe-O (0.13 ±0.10 wt %) in the shaded specimens. XRD focused on the tetragonal (T) and monoclinic (M) peaks in the 20 to 40 degrees 2θ range. The disks were polished on 1 side, cyclically loaded (80N, 500 000 cycles, custom 4-station fatigue test machine), and tested for residual BFS after cycling. Unshaded (U) and shaded groups (S) were compared before (U1, S1) and after (U2, S2) load cycling with XRD and residual BFS. RESULTS: Residual BFS (MPa) for specimens before (U1=856 ±99 versus S1= 842 ±40) and after fatigue (U2=772 ±65 versus S2= 718 ±68) were statistically different (U1 versus U2; S1 versus S2; U2 versus S2, P<.05). The XRD of U1 and S1 specimens revealed tetragonal and cubic zirconia. U2 and S2 specimens contained tetragonal zirconia, with the initial appearance of small amounts of monoclinic zirconia after fatigue cycling. Monoclinic detection was measured on the tension side of the tested specimens and varied between tests at the center and radially at 4 mm. CONCLUSIONS: The results indicated shaded materials more readily transform the tetragonal to the monoclinic phase during load cycling than unshaded ones. However, extrapolating the effects of any shortening of the service life of zirconia compositions is difficult. The potential mitigating effects of other factors such as the thermal postprocessing of porcelain veneers, stains on zirconia, or effects of water have yet to be investigated.

Pediococcus pentosaceus Endocarditis in a Patient With Recent Transcatheter Aortic Valve Implantation and Liver Cirrhosis: A Case Report and Review of the Literature.

Transcatheter aortic valve implantation (TAVI) is increasingly being used in the management of severe aortic stenosis, mainly in older and/or medically compromised patients, due to its minimally invasive nature. As in any valve replacement procedure, endocarditis is a recognized complication, more so in TAVI patients, in whom comorbidities are highly prevalent. We report the case of a 70-year-old male with a history of liver cirrhosis and a recent TAVI, who presented with recurrent fever and sustainedPediococcus pentosaceus bacteremia. The diagnosis of endocarditis was delayed, as the microorganism was initially discarded as a contaminant, given that Pediococci are rarely described as human pathogens. However, in cirrhotic patients, microbiota may cause intermittent bacteremia and thereby affect prosthetic valves. Transthoracic echocardiography was not helpful in validating the diagnosis, as is often the case in TAVI patients. Transesophageal echocardiography was deemed perilous, due to esophageal varices complicating the underlying cirrhosis. Therefore, endocarditis diagnosis was based on sustained bacteremia and Duke's criteria, including the presence of high fever, a predisposing cardiac lesion, splenic infarction, and the exclusion of an alternative diagnosis. Moreover, cirrhosis enhanced the side effects of treatment and led to the need for regimen changes and prolonged hospitalization. Given the precariousness of the situation, confirmation of treatment success by 2-deoxy-2-[fluorine-18]fluoro-D-glucose positron emission tomography-computed tomography (18F-FDG PET-CT) scan was sought. This is the first reported case of Pediococcus TAVI endocarditis in a cirrhotic patient, highlighting the unique challenges in the diagnosis and management of TAVI endocarditis in patients with co-existing conditions.

Left bundle branch area pacing versus conventional pacing in patients with advanced atrioventricular conduction abnormalities: a prospective cohort study.

BACKGROUND: Left bundle branch area pacing (LBBAP) is an emerging pacing method that may prevent the deleterious effects of right ventricular pacing. The aim of this study is to compare the effects of LBBAP with right ventricular septal pacing (RVSP) in patients with advanced atrioventricular conduction abnormalities and preserved left ventricular ejection fraction. METHODS: The effect of pacing was evaluated by echocardiographic indices of dyssynchrony, including global myocardial work efficiency (GWE) and peak systolic dispersion (PSD). The primary endpoint was GWE postprocedural, at 3, 6, and 12 months after the procedure. RESULTS: Twenty patients received LBBAP and 18 RVSP. Complete follow-up was accomplished in 37 patients (97.4%) due to the death of a patient (RVSP arm) from nonrelated cause. GWE was significantly increased in the group of LBBAP compared to RVSP at all time points (90.8% in LBBAP versus 85.8% in RVSP group at 12 months, p = 0.01). PSD was numerically lower in the LBBAP arm at all time points, yet not statistically significant (56.4 msec in LBBP versus 65.1 msec in RVSP arm at 12 months, p = 0.178). The implantation time was increased (median 93 min in LBBAP versus 45 min in RVSP group, p < 0.01), along with fluoroscopy time and dose area product (DAP), in the arm of LBBAP. There were no severe perioperative acute complications in either group. CONCLUSIONS: LBBAP is an emerging and safe technique for patients with a pacing indication. Despite the longer procedural and fluoroscopy time, as well as higher DAP, LBBAP seems to offer better left ventricular synchrony compared to RVSP, according to GWE measurements.

Material options for restoring intentionally misaligned implants on maxillary edentulous arch: a clinical report.

Without major bone grafting procedures, anatomic challenges may dictate less than ideal implant placement. When surgical correction is impossible, it may be possible to place implants on an angle and use angled abutments to compensate. This article presents 2 patient treatments where angled abutments were used to facilitate the fabrication of an implant-supported fixed complete-arch prosthesis. In both scenarios the supporting bars for the prostheses were milled in titanium. Soft tissue shaded ceramic was used to simulate the soft tissues for one patient and soft tissue shaded composite resin was used for the second. The prostheses were completed by cementing 12 individual crowns on each bar.

Randomized comparison of Glidesheath Slender with conventional 5Fr arterial sheaths for coronary angiography through the distal radial artery.

BACKGROUND: The potential benefits of the thin-walled 5F Glidesheath Slender sheath in the distal transradial access (dTRA) have not been investigated. This study aimed to compare the Glidesheath Slender versus conventional 5Fr arterial sheaths in patients undergoing diagnostic coronary angiography (CAG) through the dTRA. METHODS: A total of 352 consecutive patients with an indication for CAG were randomized (1:1) to Glidesheath Slender 5Fr versus a conventional 5Fr arterial sheath for dTRA. The primary endpoint was the rate of successful hemostasis at 30 minutes after sheath removal. Follow-up ultrasound of the right radial and distal radial artery was performed 7-10 days after the procedure. RESULTS: After exclusion of patients where a 6Fr sheath or crossover of access site was required, 108 patients in the Glidesheath Slender and 105 patients in the conventional 5Fr arterial sheath group were included in the analysis. The crossover rate to conventional radial access and the rate of successful hemostasis at 30 minutes after sheath removal were similar between the two groups (18.9% in the Glidesheath slender vs. 22% in the control group; P=0.460, and 62% vs. 51.4%; P=0.118, respectively). The level of pain associated with the procedure was significantly lower in the Glidesheath Slender group (2.69 vs. 3.29 in the control group; P=0.02). No significant difference was recorded between the two groups in the rate of access-related complications. CONCLUSIONS: Use of Glidesheath Slender for dTRA did not increase the rate of early hemostasis compared with conventional arterial sheath.

High Frequency of Post-Transfusion Microchimerism Among Multi-Transfused Beta-Thalassemic Patients.

BACKGROUND: Transfusion-associated microchimerism implies the presence of allogeneic hematopoietic cells in an individual, following the transfusion of a blood product. It is a transfusion-related adverse effect/long-term consequence, which has not been well-investigated among regularly transfused patients with thalassemia. PATIENTS AND METHODS: We investigated 64 regularly transfused, homozygous ß-thalassemic patients and 21 never-transfused healthy volunteer blood donors (controls) for the presence of microchimerism in their sera, using real-time PCR targeting circulating allogeneic, both, Human Leukocyte Antigen-DR isotype (HLA-DR) and non-HLA alleles. The investigation was longitudinally repeated in patient subsets for more than 2 years. Results were correlated with clinical and laboratory parameters, peripheral blood lymphocyte immunophenotype, blood storage time, and donor's gender to identify potential contributing factors for microchimerism generation. RESULTS: Overall, microchimerism was detected in 52 of the 64 patients (81.2%) and in 6 of the 21 controls (28.5%, p = 0.0001). Forty-four patients (68.7%) exhibited long-term microchimerism (persisted for more than 6 months), confirmed at all time-points investigated. Microchimerism was more frequent among elderly, women, splenectomized and more heavily transfused patients, and among those who exhibit higher serum ferritin levels. In these patients, a distinct descending pattern of CD16dim+CD56dim+ natural killer (NK)-cells (p < 0.001) and an ascending pattern of CD4+CD25brightCD127- regulatory T-cells (p = 0.022) for increasing allelic burden were noticed, suggesting the establishment of recipient immune tolerance against the donor-derived chimeric alleles. Both splenectomized and non-splenectomized thalassemic patients exhibited the same trend. The storage time of transfused blood products and donor/gender mismatch had no impact on the development of microchimerism. DISCUSSION-CONCLUSIVE REMARKS: Transfusion-associated microchimerism appears to be a very common complication among multi-transfused thalassemic patients. The potential clinical consequences of this phenomenon remain as yet unclear. Immune tolerance attributed to disease itself and to repeated transfusions might at least in part explain its appearance.

The Greek way to the Register: the establishment and operation of the Register for Clinical Chemists-Clinical Biochemists in Greece.

In Greece, there is no officially organized training in clinical chemistry for scientists. The Greek Society of Clinical Chemistry-Clinical Biochemistry (GSCC-CB), following the encouragement of the EC4/RC decided to organize a voluntary Register for specialists in clinical chemistry. The following criteria for registration were defined: 1) University degree in Chemistry, Biochemistry, Biology, Medicine, Pharmacy or other relevant subject. 2) A total of 9 years of university studies and postgraduate specialization in clinical chemistry-clinical biochemistry. 3) A minimum of 4 years of postgraduate specialization in clinical chemistry-clinical biochemistry on the job. 4) The candidate must be practicing clinical chemistry-clinical biochemistry in a laboratory in a medical environment in Greece. The postgraduate specialization in clinical chemistry-clinical biochemistry includes the laboratory training and the theoretical education. The laboratory training is organized by the GSCC-CB according to the Professional Training Dossier. The theoretical education was organized in a series of 18 "Seminars" which was the content of the "Educational program" of the GSCC-CB. Successful completion of the Educational program leads to a Certificate of Competence. The Greek Register has gained equivalence with the EC4 Register and it has 218 members, more than 80 of whom are European clinical chemists.

Nonrigid connection of tooth with implants in the esthetic zone with a ceramic restoration: a clinical report.

Restoring edentulous areas with fixed prostheses can be challenging, especially when key abutment teeth are missing and implant placement is not an option. Sometimes, clinicians are faced with situations where teeth have to be connected with implants even though long-term prognosis of those connections may be questionable. This clinical report presents a connection of 2 implants with 1 tooth in the esthetic zone with a nonrigid connection. Two zirconia custom abutments and 1 zirconia coping definitively cemented on the tooth were used. A zirconia superstructure, veneered with porcelain, was cemented with provisional cement on the abutments and the coping.

Translucency of shaded zirconia core material.

STATEMENT OF PROBLEM: With the development of various zirconia core shades, questions arise regarding the effect of the shaded zirconia on the translucency of ceramic crowns. PURPOSE: The purpose of this study was to investigate the translucency of the 3 Procera Zirconia shaded core materials. The hypothesis was that differences exist in the translucency of various shaded zirconia cores. MATERIAL AND METHODS: Disk-shaped (0.6 ± 0.01 × 12 mm) zirconia core (Procera Zirconia) specimens (n=90) were fabricated by the manufacturer using a CAD/CAM process. The disks were fabricated in 3 groups according to shade (light, medium, intense) (n=30). A spectrophotometer was used to measure contrast ratio (CR) which is indicative of translucency. One-way ANOVA was conducted to determine significant differences among the shades (α=.05). RESULTS: A significant difference in translucency between the light and intense shades (P=.030) and the medium and intense shades (P<.001) was observed. There was no significant difference between the light and medium shades (P=.15). CONCLUSIONS: Shaded zirconia is partially translucent. In addition, significant differences in translucency measurements were identified between specific shades.

Maxillary implant-supported bar overdenture and mandibular implant-retained fixed denture using CAD/CAM technology and 3-D design software: a clinical report.

The implant-supported bar overdenture and the implant-retained fixed complete denture are appropriate treatment choices for patients with inadequate bone volume in the posterior maxilla and mandible, respectively. Computer-aided design/computer-aided manufacturing (CAD/CAM) technology has broadened the scope and application of those treatment options, allowing for prosthodontically-driven implant placement and ideal substructure design for optimal esthetics and biomechanics. This report describes the fabrication of a maxillary implant-supported milled titanium bar with attachments and an overdenture, and a mandibular implant-retained fixed complete denture with milled titanium substructure.

A technique for indirect fabrication of a complete-arch, implant-supported, fixed provisional restoration from a radiographic template.

This article describes an alternative technique for the fabrication of a complete-arch, implant-supported, cement-retained, fixed provisional restoration. The definitive cast is fabricated from the surgical guide and the provisional restoration is fabricated indirectly from the radiographic guide. This technique is an easy and time-saving procedure to fabricate an interim prosthesis for immediate or delayed loading of implants.

Restoring implants in the esthetic zone after sculpting and capturing the periimplant tissues in rest position: a clinical report.

Obtaining an accurate representation of the soft tissue contours developed around an implant in the esthetic zone is crucial to the success of a restoration. The technique presented emphasizes "guiding" of the soft tissue by modifying a provisional restoration to obtain an emergence profile that appears natural and blends with the gingival contour of the adjacent teeth. The technique provides an accurate impression of the soft tissue through the intraoral use of autopolymerized acrylic resin supported by the impression coping and vinyl polylsiloxane impression material. The eventual restoration uses an esthetic zirconia custom abutment and an implant-supported single crown to fulfill the esthetic and functional expectations of the patient and the provider.

The organization of an educational program for specialists in clinical chemistry by the Greek Society of Clinical Chemistry-Clinical Biochemistry.

In Greece, there is no officially organized training in clinical chemistry for scientists. The Greek Society of Clinical Chemistry-Clinical Biochemistry decided to organize an intensive educational program of 18 seminars on clinical chemistry content as it is described in the EC4 Syllabus. The duration of each seminar was about 6 hours and consisted of 6 to 9 lectures. At the end of each seminar there was a voluntary written examination, comprised of 24 multiple choice questions. Successful completion of the Educational program was leading to a Certificate of Competence. Two cycles of the 18 seminars were performed: 1st cycle from October 2003 to December 2005 and 2nd cycle from March 2005 to October 2007. One hundred eighty nine colleagues was the mean attendance per seminar for the seminars of the 1st cycle and 38 colleagues for the seminars of the 2nd cycle. The mean participation to the examination for each seminar was almost 80% for the 1st cycle and 68% for the 2nd cycle. More than 80% of the participants performed Good or Very good in the examination in both cycles. It is estimated that more than 40% of the scientists who practice Clinical Chemistry in Greece, participated to this educational activity. This program is now provided as an e-learning application, and it is open for all scientists who want to follow the discipline of clinical chemistry.

Correlation between increased serum sFas levels and microalbuminuria in type 1 diabetic patients.

OBJECTIVE: The aim of this study was to elucidate if apoptosis dysregulation is present in type 1 diabetic patients with microalbuminuria. SUBJECTS AND METHODS: The following variables were determined in 29 type 1 diabetic patients: the duration of diabetes, soluble Fas (sFas), Bcl-2, hemoglobin A(1c) levels, glomerular filtration rate (GFR) and microalbuminuria, using the urine albumin to urine creatinine ratio (ACR). Age and gender were assessed and patients were categorized into two groups, according to their ACR: the microalbuminuric (MA) group with an ACR > or =30 mg/g, and the normoalbuminuric (NA) group with an ACR <30 mg/g. RESULTS: The differences between the two groups regarding sFas, Bcl-2 and GFR were not statistically significant. However, in the MA group, a significant positive relationship between sFas and ACR was observed (r = 0.736, p = 0.015). Dividing patients into two subgroups--mild versus severe (ACR > or =150 mg/g) microalbuminuric patients--significant differences in sFas (60.4 vs. 87.2 pg/ml; p = 0.047) and GFR (113 vs. 69.5 ml min(-1) 1.73 m(-2); p = 0.021) were observed, whereas in Bcl-2, the difference was not significant (77.96 vs. 71.13 ng/ml). CONCLUSIONS: At the early stages of diabetic nephropathy in type 1 diabetic patients, there seems to be a dysregulation of apoptosis, as expressed by enhanced sFas levels, leading to the speculation that the prevalence of antiapoptotic mechanisms (sFas) may promote mesangial proliferation.