Dynamics of composite polymerization mediates the development of cuspal strain.

OBJECTIVES: In the current study, we used electronic speckle pattern interferometry (ESPI) to measure tooth deformation in response to polymerization of five resin composites with a range of polymerization shrinkage. Our hypothesis was that composites with higher polymerization shrinkage should cause more cuspal strain as measured by ESPI. METHODS: Standardized MOD cavities were prepared and placed into the ESPI apparatus before the cavities were filled with composites (n=10). The ESPI apparatus was constructed to measure the out-of-plane displacement of the lingual cusps of the teeth during the polymerization of the restorative material. A thermocouple was attached to the specimen to monitor thermal changes throughout the polymerization process. RESULTS: Experiments with empty preparations demonstrated that the ESPI technique was temporally responsive and sensitive to dimensional changes. However, the correlation between polymerization shrinkage of composite resins and ESPI-measured tooth deformation was not straightforward. In particular, a flowable material did not deform the tooth significantly more that a conventional hybrid. Further, an experimental silorane material (with the lowest axial shrinkage) induced the least tooth deformation. SIGNIFICANCE: We concluded that ESPI is a viable method for assessing cuspal strain induced by shrinkage of bonded composite restorations, but that polymerization shrinkage data may overestimate shrinkage-induced tooth deformation. The rate of polymerization shrinkage appeared to mediate the development of cuspal strain.

Prevalencia de leishmaniasis visceral Humana y canina en la ciudad de Lambaré, Paraguay / Humana and canine visceral leishmaniasis in Lambaré city, Paraguay

Estudio de una muestra representiva y aleatoria de la población de perros de toda la ciudad de Lambaré, para determinar la prevalencia de los casos de LV canina y a la búsqueda activa de personas de la misma ciudad, consideradas con riesgo de contagio para LV, a fin de determinar la ocurrencia de casos de LV en humanos, un total de 348 muestras de sangre canina y 930 personas fueron analizadas analizadas

Digital subtraction arthrography of the prosthetic hip.

Digital subtraction techniques are easily adapted to the evaluation of loosening in total hip prostheses, allowing real time review of injection dynamics and data manipulation after the study. We have successfully used both standard radiographic and digital imaging techniques in the evaluation of 15 prosthetic hip joints. The digital results are comparable to and often better than those of standard radiographic techniques for the evaluation of loosening in total hip prostheses.

Craniofacial mucormycosis: assessment with CT.

Computed tomographic (CT) scans of ten patients with rhinocerebral mucormycosis were reviewed. Early paranasal sinus involvement appeared as mucosal thickening on CT scans, usually without air/fluid levels. Recognition as mucormycosis was facilitated by knowledge of the clinical setting or by identification of invasive disease. Evidence of bone destruction on CT scans was seen in only two patients, was a late finding, and usually was absent despite deep extension of disease beyond the bony confines of the paranasal sinus. Five cases had intracranial involvement, either as fungal abscess or infarction. Intracranial mucormycosis usually involved the base of the brain and cerebellum following invasion of the infratemporal fossa or orbit. Intracerebral fungal abscess appeared as low-density masses on CT scans, with variable peripheral enhancement and little surrounding vasogenic edema. Identification of a rim of spared cortex was useful in distinguishing infection from bland infarct. Serial CT scans were also useful in assessing response to hyperbaric oxygen treatment, surgery, and chemotherapy.

Chronic tension pneumothorax presumably due to a "ball valve" bronchopleural fistula.

We have described an unusual variant of bronchopleural fistula whose ball valve characteristics led to a chronic tension pneumothorax without fluid collection in a postpneumonectomy space.

Accuracy of ultrasound in fetal femur length determination. Ultrasound phantom study.

An ultrasound phantom was constructed simulating fetal femurs in amniotic fluid. Bones of 26, 36, 50, 58, and 70 mm, representative of gestational ages ranging from 17 to 36 weeks, were scanned with mechanical sector, phased sector, and linear array systems (ATL, Diasonics, Acuson, and GE). Measurements were made with the bone in both a horizontal and nearly vertical orientation at 5, 10, and 15 cm from the transducer. The ultrasound measurements were compared with the true bone length. With bones in a nearly vertical orientation (parallel to the ultrasound beam) the ultrasound measurements corresponded more closely to the true bone length regardless of the type of equipment or distance from the transducer. The wide aperture linear system was most accurate with no measurable difference from the actual bone length and a mechanical sector scanner had the largest error which was 6 mm. In the horizontal position (perpendicular to the beam) the smallest errors occurred when the bone was in the focal zone. This ranged from no error for the wide aperture linear array to 8 mm for the mechanical sector scanner. When the bone was not in the focal zone the error ranged from 8 to 26 mm for the mechanical sector scanner. Errors in ultrasound-measured femur lengths can be shown to result from the focal characteristics of the equipment as well as the orientation and distance of the bone from the transducer. These differences can produce errors in estimation of gestational age as large as ten weeks.

Computed tomography of axial skeletal osteoid osteomas.

Five cases of axial skeletal osteoid osteomas were viewed with particular attention to the role of computed tomography (CT) as a key diagnostic tool in the evaluation of osteoid osteoma. The complex anatomy of the axial skeleton can make the diagnosis of osteoid osteoma extremely difficult on routine films or tomograms, and the lesion often is well delineated only on CT scans. As complete surgical excision of this benign bony tumor is curative, precise anatomic localization is essential to the surgeon. The unique cross-sectional display of CT of the axial skeleton provides the surgeon with the exact location and extent of the lesion, which may allow a more limited surgical resection of the involved bone by defining the optimal surgical approach or procedure. Conventional radiographs were normal in all patients. Bone scans were positive when obtained and were useful in localizing the lesion and directing CT to the appropriate level. In all five cases CT was of proven value in accurately demonstrating the location, nidus, and other characteristic diagnostic radiographic features of osteoid osteoma.

Primary lower extremity lymphedema: CT diagnosis.

The CT findings of two cases of primary lymphedema of the lower extremities are presented. CT showed a coarse, nonenhancing, reticular pattern in an enlarged subcutaneous compartment. CT excluded the diagnosis of secondary lymphedema from an obstructing mass by demonstrating a normal retroperitoneum and pelvis. The CT findings are correlated with pedal lymphangiograms.