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Biomedical subjects

P R Patel

Publications and source records attributed to P R Patel.

30 records · Page 2Linked to original sources
PubMed1979

Linear dimensional change of copper-rich dental amalgam.

Copper-rich amalgams made from alloy mixtures have large expansions in air at 105 +/- 2 weeks that range from 100 to 194 micrometers/cm at 60 C, from 36 to 101 micrometers/cm at 37 C, and from 14 to 44 micrometers/cm at 23 C on unrestricted 8- x 4-mm cylinders (Dispersalloy, Micro II, and Optaloy II). Other copper-rich amalgams made from one alloy usually had a slight shrinkages at the three temperatures with an exception, a slight expansion of 12 micrometers/cm at 60 C (Aristaloy CR, Indilogy non-zinc, Sybraloy, and Tytin). Dimensional changes during hardening ranged,on the average, from -3 to +19 micrometers/cm when measured by ADA Specification methods and from -2 to +25 micrometers/cm when measured by an indirect method. The clinical significance of the foregoing findings is unknown; nor is a relationship known among dimensional change of unrestricted specimens, dimensional change of restricted specimens, creep value, and clinical behavior of amalgams generally. In specific instances, however, a relationship is sometimes shown.

Chemical Phenomena↗
PubMedDate not supplied

The spinoglenoid ligament and its relationship to the suprascapular nerve.

Entrapment of the suprascapular nerve by the inferior transverse scapular ligament or spinoglenoid ligament (SGL) has been discussed frequently in the literature, but it has not been well documented anatomically. Therefore the mechanism of entrapment is not well understood. When isolated atrophy and denervation of the infraspinatus muscle have been noted, compression of the muscle's motor branch at the spinoglenoid notch has been implicated. This anatomic and morphologic study investigates the role of the SGL in entrapment neuropathy of the infraspinatus. We used 23 shoulders from 19 cadavers, 5 women (8 shoulders) and 14 men (15 shoulders), with a mean age of 67.9 (54 to 78) years. The presence or absence of the SGL was noted. The length, width, and orientation of the SGL; size and shape of the tunnel to the infraspinatus fossa; and distance of the notch to the posterior glenoid rim were determined. The SGL was present in 14 (60.8%) shoulders, 5 (36%) women and 9 (64%) men. The SGL was wider at the superior entrance of the tunnel and fanned and twisted toward the inferior aspect. In all specimens the SGL fibers inserted into the posterior shoulder capsule. The mean length for the upper part of the SGL was 17.5 +/- 2.6 mm in men and 15.8 +/- 1.8 mm in women, and the lower part was 14.1 +/- 2.4 mm and 12.9 +/- 1.8 mm, respectively. The widths of the SGL at the origin of the scapular spine were 12.2 +/- 3.9 mm for men and 10.4 +/- 2.7 mm for women, whereas the insertion site widths were 15.8 +/- 2.2 mm for men, and 16.1 +/- 3.8 mm for women. The midportion width of the SGL was 6.8 +/- 1.9 mm in men and 5.8 +/- 2.1 mm in women. During cross-body adduction and internal rotation of the glenohumeral joint, the interaction of the SGL and the posterior capsule resulted in a tightening of the SGL. The suprascapular nerve moved laterally and stretched underneath the SGL in this position.

Aged↗
PubMedDate not supplied

Formation of Ca HPO4-2H2O from enamel mineral and its relationship to caries mechanism.

Tooth enamel, when treated with dilute H3P94 solutions, dissolved incongruently with formation of large CaHPO4-2HO2O crystals. Equilibrated solutions were saturated with respect to Ca5(PO4)3OH, probably an impure, defective apatite. The CaHPO4-2H2O crystals formed at considerably higher pH values than expected becuase of enhanced solubility of the apatitic phase in enamel. Pyolysis of carious enamel revealed the presence of acidic calcium phosphate presumed to be CaHPO4-2H2O.

Calcium↗
PubMedDate not supplied

Thermodynamic solubility product of human tooth enamel: powdered sample.

Solubility of human dental enamel in H3PO4 was studied in the pH range of 4.5 to 7.6. Thermodynamic solubility of the enamel mineral was calculated in terms of the ion activity product, (Ca2+)5(PO43-)3(OH-), for hydroxyapatite. The solubility product varied from 7.2 times 10(-53) to 6.4 times 10(-58) mol9 liter-9 depending on the cumulative amount of the dissolution of the solid in a series of repetitive sequences of solubility experiments.

Calcium Phosphates↗
PubMedDate not supplied

The use of magnetic resonance imaging in the diagnosis of lumbar disc disease.

Low back pain is a common malady, affecting up to 80% of adults at some time. Our diagnostic capabilities have been markedly improved with the introduction and evolution of magnetic resonance imaging. MRI is an accurate modality in the diagnosis of disc herniation, as well as recurrent disc herniation, degenerative disc disease, and other abnormalities that may present as back pain.

Adult↗