Ultra-translucent zirconia processing and aging effect on microstructural, optical, and mechanical properties.

OBJECTIVES: To evaluate the effect of the ceramic processing and aging method on the microstructure, optical, and mechanical properties of a third generation ultra-translucent zirconia, yttria partially stabilized zirconia (5Y-PSZ). METHODS: In-house discs were obtained through uniaxial and isostatic pressing an ultra-translucent Y-PSZ powder and sintering at 1450 °C for 2 h. As control, a commercial disc was milled from pre-sintered blocks fabricated with the same 5Y-PSZ powder through isostatic pressing and sintered under the same protocol. Discs were allocated into three groups according to aging condition as immediate (non-aged) and aged using autoclave or hydrothermal reactor at 134ºC for 20 h at 2.2 bar. Crystalline content and microstructure were evaluated using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Optical properties were determined using reflectance data to calculate the contrast ratio (CR) and translucency parameter (TP). Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength tests. RESULTS: XRD spectra revealed a prevalence of cubic (70%) and tetragonal (30%) phases, and the SEM images showed a dense fully crystalline ceramic matrix for both materials. Crystalline content and microstructure of the in-house and commercial 5Y-PSZs were not affected by aging. As-sintered 5Y-PSZs demonstrated similar CR (~0.6) and TP (~18) values, as well as Vickers hardness (~14 GPa) and fracture toughness (~3.8 Mpa.m1/2), with no significant alteration after both aging methods. In-house and commercial Y-PSZs Weibull moduli ranged from 3.0 to 5.3. 5Y-PSZ processing methods resulted in similar characteristic strength after sintering (592-618 Mpa). While commercial 5Y-PSZ showed no significant influence of aging on strength, hydrothermal reactor aging significantly decreased the in-house Y-PSZ characteristic strength (474 Mpa). Both 5Y-PSZs demonstrated high reliability up to 300-Mpa strength missions, with no detrimental effect of aging (88-100%). SIGNIFICANCE: Irrespective of the processing method, ultra-translucent 5Y-PSZ showed high aging resistance and translucency stability, as well as strength corresponding to the indication up to short-span anterior prostheses.

Physicochemical and mechanical characterization of a fiber-reinforced composite used as frameworks of implant-supported prostheses.

OBJECTIVES: To characterize the physicochemical and mechanical properties of a milled fiber-reinforced composite (FRC) for implant-supported fixed dental prostheses (FDPs). METHODS: For FRC characterization, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction, Fourier-transformed infrared spectrometry, simultaneous thermogravimetric analysis and differential scanning calorimetry were performed. For fatigue testing, 3-unit FRC frameworks were fabricated with conventional (9 mm2 connector area) and modified designs (12 mm2 connector area and 2.5 mm-height lingual extension). A hybrid resin composite was veneered onto the frameworks. FDPs were subjected to step-stress accelerated-life fatigue testing until fracture or suspension. Use level probability Weibull curves at 300 N were plotted and the reliability for 100,000 cycles at 300, 600 and 800 N was calculated. Fractographic analysis was performed by stereomicroscope and SEM. RESULTS: The FRC consisted of an epoxy resin (∼25%) matrix reinforced with inorganic particles and glass fibers (∼75%). Multi-layer continuous regular-geometry fibers were densely arranged in a parallel and bidirectional fashion in the resin matrix. Fatigue analysis demonstrated high probability of survival (99%) for FDPs at 300 N, irrespective of framework design. Conventional FDPs showed a progressive decrease in the reliability at 600 (84%) and 800 N (19%), whereas modified FDPs reliability significantly reduced only at 800 N (75%). The chief failure modes for FRC FDPs were cohesive fracture of the veneering composite on lower loads and adhesive fracture of the veneering composite at higher loads. SIGNIFICANCE: Milled epoxy resin matrix reinforced with glass fibers composite resulted in high probability of survival in the implant-supported prosthesis scenario.

Metastasis of breast cancer to major duodenal papilla.

Metastasis is an infrequent cause of tumor involvement of the major duodenal papilla and of cholestasis. We report a case of obstructive jaundice due to a metastatic breast carcinoma to the major duodenal papilla, and assess curative and palliative treatment that interventional endoscopy can offer.

Metastasis of breast cancer to major duodenal papilla / Metástasis del cáncer de mama a la papila mayor duodenal

Metastasis is an infrequent cause of tumor involvement of the major duodenal papilla and of cholestasis. We report a case of obstructive jaundice due to a metastatic breast carcinoma to the major duodenal papilla, and assess curative and palliative treatment that interventional endoscopy can offer.

La metástasis es una causa infrecuente de compromiso de la papila mayor y colestasis. Reportamos una causa rara de ictericia causada por metástasis de cáncer de mama en la papilla mayor duodenal.

O uso da tomografia cone beam no auxílio ao diagnóstico e planejamento de cirúrgia periapical: relato de caso clínico / The use of cone-beam volumetric tomography to help diagnose and plan a periapical surgery: clinical case report

O diagnóstico e o planejamento das intervenções são fundamentais na execução de um tratamento cirúrgico. Um método rotineiramente usado para auxiliar no diagnóstico de lesões periapicais é a radiografia periapical, porém, com essa técnica, estruturas anatômicas tridimensionais são comprimidas em imagens bidimensionais, resultando em superposição de estruturas de interesse diagnóstico. Este artigo relata um caso clínico de um paciente que apresentava uma lesão cística, de dimensões expressivas, na região anterior da maxila cuja cirurgia foi planejada e executada após a visualização das margens da lesão por imagens de tomografia computadorizada Cone Beam (TCCB). Dessa forma, foi possível concluir que a TCCB constitui-se como um método preciso para auxiliar no diagnóstico, propiciando uma maior exatidão no planejamento, pois permite a visualização tridimensional das estruturas.

The diagnosis and planning of interventions are vital for the execution of a surgical treatment. A method used routinely to help diagnose periapical lesions is the periapical radiography. However, with this technique, three-dimensional anatomic structures are compressed into two-dimensional images resulting in the superposition of structures of diagnostic interest. This article reports the clinical case of a patient who presented a cystic lesion of expressive dimensions in the anterior region of the maxilla, and whose surgery was planned and performed after visualization of the lesions? margins by means of Cone Beam Computed Tomography (CBCT). Thus, it is possible to determine that CBCT constitutes a precise method to help diagnosis, providing better accuracy for planning as it allows the three-dimensional visualization of structures.

Fibromatose gengival anatômica: caso clínico / Anatomical gingival fibromatosis: a clinical case

As fibromatoses gengivais são lesões proliferativas, não neoplásicas, raras na cavidade bucal, sendo caracterizadas por um aumento gengival lento e progressivo. Podem ser classificadas em hereditária, irritativa, medicamentosa e anatômica. Este artigo relata o caso clínico de um paciente de 56 anos que apresentou hiperplasia gengival da região de molares ao tuber da maxila estendendo-se para porção posterior do palato, bilateralmente, com maior envolvimento do lado direito. Essa lesão caracterizava-se por superfície lisa, consistente a manipulação, não pediculada e de coloração rosa-pálido. O tratamento consistiu de orientação da higienização bucal ao paciente, e caso a lesão afetasse a fonação e/ou a mastigação, poderia se considerar a possibilidade de correção cirúrgica.