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Biomedical subjects

L R Manson-Hing

Publications and source records attributed to L R Manson-Hing.

At least 19 recordsLinked to original sources
PubMed1990

Evaluation of alveolar bone in relation to nutritional status during pregnancy.

Demand for nutrients necessary for the formation of mineralized tissues increases dramatically during pregnancy to meet fetal requirements. The purpose of this clinical study was to identify short-term effects of pregnancy and dietary intakes of calcium, phosphorus, protein, and vitamin C on radiographic density and alveolar crest morphology of the mandible. Seventy-six subjects between ten and 20 weeks' gestational age were recruited from the Jefferson County, Alabama, Department of Health maternity clinic. Initially, an evaluation of their diet was done, and a single periapical radiograph was taken in the canine-premolar region of the mandible. A final evaluation of the diet and a periapical radiograph of the same teeth were obtained at a time as close to the expected date of delivery as possible. Dietary evaluation consisted of a 24-hour recall history and a food-frequency history at the two visits. Radiographs were made with a bite-block film-holding system with occlusal registration in acrylic for reproduction of projection geometry at the two visits. An aluminum stepwedge was incorporated for densitometric standardization. Measurements of plaque, and bleeding and pocket-depth probing were recorded for control of local effects on alveolar change. Standard statistical procedures of regression determined correlation of 12 nutrients and periodontal variables with bone density change and with alveolar crest morphology change. Vitamin C intakes (24-hour recall) showed a positive correlation (p = 0.033) with bone density change, and calcium intakes (24-hour recall) showed a negative, but not significant, correlation (p = 0.058) with bone density change, contributed particularly by subjects with the highest calcium intakes. The strongest relation with alveolar crest morphology change was the interproximal pocket-depth change (p = 0.086).

Adult↗
PubMed1987

Comparison of focal trough dimensions and form by resolution measurements in panoramic radiography.

Panoramic focal trough dimensions affect both the number of patient structures seen in radiographs and the margin of error possible when positioning a patient to take a radiograph. This study compares the dimensions, or size, and position, or form, of the focal troughs of four machines by resolution measurements. There is a continued need for technicians to position the patient's anterior teeth accurately in the zones of sharpness of these machines, but the widths of the sharpness zones show an increase in dimensions over older panoramic machines.

Equipment Design↗
PubMed1986

The horizontal plane in patient positioning for panoramic radiography.

The average angles between the horizontal and occlusal planes and the ala-tragus and orbito-meatal lines were measured for 96 patients in a panoramic x-ray machine. The angles required to produce clinically acceptable radiographs are described. Some operator judgment is required when positioning each patient's head for radiographs of optimum quality.

Adolescent↗
PubMed1986

The accuracy of an x-ray film quality-assurance step-wedge test.

The accuracy of an aluminum step-wedge quality-assurance test for machine and processor in dental radiography was determined. The clinical radiographic density range accepted by twenty dentists was similar to eight steps of an aluminum step-wedge test object, with dentists using six or seven steps. The test used a two-step density shift to detect and separate changes in both x-ray machine and film processing before radiographic quality becomes clinically unacceptable. Measured latent image fading of test films stored for months was small and did not affect the test performance. The accuracy of the step-wedge test in detecting eighteen machine and film-processing variables was measured with a densitometer. Possible comparisons with measurements made by an accepted densitometric method used in medical radiography showed similar results. The test can be used in lieu of more costly, time-consuming tests.

Absorptiometry, Photon↗
PubMed1985

A stepwedge quality assurance test for machine and processor in dental radiography.

A quick, inexpensive quality assurance test for clinical dental radiography is described. Data on operator error in matching test radiographs and the use of the test in some radiographic facilities for 3 years indicate that the test can be useful in monitoring film processing and X-ray machine output in clinical practice.

Quality Control↗
PubMed1982

A study of the zone of sharpness of three panoramic x-ray machines and the effect of screen speed on the sharpness zone.

Sharpness zones of the Orthopantomograph-5, Autopan, and Panorex were delineated with the use of a standard multiline test object at 1.7 line pairs per millimeter. In addition, Panorex zones made with medium- and high-speed screens were compared. The focal troughs of all machines covered most tooth positions. The Autopan and Orthopantomograph troughs were narrow anteriorly, while the Panorex trough was not close to the condyle posteriorly. There was little difference between focal troughs produced with the use of high- and medium-speed screens.

Radiographic Image Enhancement↗
PubMed1981

Effect of radiographic technique upon prediction of tooth length in intraoral radiography.

Evaluation of the effect of radiographic technique upon the prediction of tooth lengths for all major types of teeth indicated the following: 1. The paralleling technique using the Rinn XCP film holder, the paralleling technique using the hemostat with bite block, and the bisecting-the-angle technique using the Rinn XCP film holder were the most accurate systems. 2. There were no significant differences among the three most accurate techniques. 3. The paralleling technique using a 16-inch tube-to-patient distance was more accurate than the bisecting-the-angle technique using an 8-inch tube-to-patient distance. 4. A beam-guiding film holder produced a more accurate radiographic image than the other film holders used in the study. 5. For the buccal roots of maxillary molars, the bisecting-the-angle technique using the Rinn XCP film holder produced the least mean difference between radiographic image and tooth length. 6. The accuracy of predicting the length of mandibular molar teeth from the diagnostic radiograph was not affected by radiographic technique.

Humans↗
PubMed1980

What's the angle: a study of the angle bisected in intraoral radiography.

Intraoral radiographs were made via the bisecting-the-angle technique on patients of different ages, sexes, and races. The tooth-film angles for various areas of the mouth were measured and found to be close to 30 degrees for all areas of the mouth except the mandibular posterior regions. The study was conducted to assist in quick positioning of the x-ray beam in difficult cases.

Adolescent↗
PubMed1979

Evaluation of new radiographic screens for intraoral radiography.

The ability of screen-films to depict dental structures utilizing the parameters used in intraoral radiography is investigated. The resolution and contrast of a variety of screen-film combinations are determined. Radiographs made on a phantom and patient are evaluated by observers. Some film-screen combinations produce radiographs with qualities similar to conventional intraoral films and with less radiation.

Adult↗
PubMed1979

A study of the quality of duplicated radiographs.

The resolution, contrast, and clinical appearance of radiographs and duplicate radiographs made with two types of duplicating film were compared. Duplicating conditions evaluated were type and shape of light, light-film distance, type of exposure surface, and developer temperature. Major observations were as follows: both Kodak and DuPont films produced clinically acceptable duplicates; Kodak film was faster; DuPont film responded better in incandescent photoflood light than Kodak film; clear glass with appropriate light-film distance was the best exposure surface.

Absorptiometry, Photon↗