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L R Martins

Publications and source records attributed to L R Martins.

At least 19 recordsLinked to original sources
PubMed2001

The influence of tubule density and area of solid dentin on bond strength of two adhesive systems to dentin.

PURPOSE: To determine the correlation between the tubule density (TD) and the area occupied by solid dentin (ASD) with the bond strength of one conventional and one self-etching adhesive system to dentin. MATERIALS AND METHODS: The crown of extracted human third molars was transversally sectioned with a diamond saw to expose either superficial, middle, or deep dentin. The three groups of dentin surfaces were randomly divided and bonded with either Clearfil Liner Bond 2V (LB) or Prime & Bond 2.1 (PB) adhesive systems according to manufacturer's directions. Resin composite buildup crowns (10.0 mm high) were incrementally constructed on the bonded surfaces and the teeth stored in water at 37 degrees C. After 24 h of storage, the teeth were vertically, serially sectioned in both x and y directions to obtain several bonded sticks of approximately 0.7 mm2 cross-sectional area. Each stick was tested in tension in a EMIC DL-500 tester at 0.5 mm/min until failure. After testing, the dentin side of the fractured specimen was gently abraded with a 1000-grit SiC paper, etched with 37% phosphoric acid for 15 s and allowed to air dry. SEM micrographs at 1000x and 4000x magnification were taken to permit calculation of the TD (number of tubules/mm2) and ASD (% of total area) at the site of fracture. Correlation between TD and ASD with the bond strength data was performed by linear regression. All statistical analysis was done with alpha = 0.05. RESULTS: Overall bond strength (MPa) for LB was 26.0 +/- 10.2, and 42.6 +/- 15.2 for PB. There was a significant direct relationship between bond strength and ASD for both materials (r2 = 0.20, p < 0.05 and r2 = 0.66, p < 0.01, respectively for LB and PB). PB bond strength dropped significantly as the TD increased (r2 = 0.63, p < 0.05), while LB was not sensitive to TD (r2 = 0.05, p > 0.05). Mean bond strength of PB was significantly higher than LB for both superficial and middle dentin (p < 0.05), while there was no significant difference for deep dentin (p > 0.05). CONCLUSION: Regional variations in TD and ASD may modify bond strength of both conventional and self-etching adhesive systems. Bonding sites with larger ASD seem to yield higher bond strengths regardless of the type of adhesive system used.

Acetone↗
PubMed2000

Increased hip bone mineral density in a woman with gluteal silicon implant.

Conditions and artifacts such as aortic calcification, osteophytes, hip prostheses, and metallic objects can mislead the results of dual energy X-ray absorptiometry (DXA) scanning of the spine and hip. Gluteal silicon implants increasingly are being used for aesthetic purposes by women in Brazil, some of whom are at an age of high risk for the development of postmenopausal osteoporosis. We herein report a case of a woman whose hip bone mineral density by DXA clearly increased after the placement of bilateral gluteal implants of silicon. This case demonstrates the importance of inquiring about the presence of this artifact to avoid unnecessary evaluation of hip bone densitometry in these situations.

Absorptiometry, Photon↗
PubMed1995

[Diagnosis using nuclear medicine of anterior descending artery stenosis in patients with left bundle branch block].

PURPOSE: To evaluate septal perfusion and contractility in patients with left bundle branch block (LBBB). METHODS: Twenty patients were submitted to myocardial scintigraphy with Tecnecium-99m isontrile after exercise and dipyridamole infusion. The septal contractility was observed during the radionuclide ventriculography. All patients were submitted to coronariography. RESULTS: Twenty patients were studied and 17 (85%) had a normal left anterior descending (LAD) artery. Nine (53%) patients had abnormalities in septal perfusion after the exercise and 2 (12%) after dipyridamole infusion. All patients had abnormalities in septal contractility during the radionuclide ventriculography. CONCLUSION: The myocardial scintigraphy after dipyridamole infusion showed better specificity in the diagnosis of a LAD lesion. The radionuclide ventriculography was an efficient method to evaluate the septal contraction abnormalities in patients with LBBB.

Bundle-Branch Block↗
PubMed1985

Lung inhalation scintigraphy: development of a new aerosol system.

A new technique for lung inhalation scintigraphy is reported, developing a new aerosol system, based on the original system of Taplin [1]. With two small compact polypropylene reservoirs, this 99Tcm DTPA technique allowed continuous breathing during the inhalation period. This system proved to be a useful alternative to that using radioactive gases and the system of Taplin, due to its low cost and the ease with which several projections may be obtained.

Adult↗
PubMedDate not supplied

Aortic root dimension measurement by first-pass radionuclide angiography.

A method for measuring the ascending aortic cross-sectional dimension is reported. First-pass radionuclide angiocardiography was performed in 53 patients with various cardiac diseases. The number of pixels from superior vena cava/right atrium junction to the main pulmonary artery were counted horizontally and converted to distance in centimeters. Aortic root size was also measured in these patients by M-mode echocardiography performed within 6 months of the radionuclide study. The two methods were compared by regression analysis. The correlation coefficient between the methods was 0.76, and the standard deviation of the regression was 0.23 cm. This radionuclide method has an accuracy which can be clinically useful for size assessment of the ascending aorta.

Adult↗