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Biomedical subjects

R J Nicholson

Publications and source records attributed to R J Nicholson.

18 recordsLinked to original sources
PubMed1987

An evaluation of xeroradiographs and radiographs in length determination in endodontics.

Twelve block sections of mandibles containing incisors, canines, premolars, and molars were dissected from human cadavers (total, 26 teeth). Endodontic access was achieved, and a No. 10 k-type endodontic file was inserted to a point approximately 1 to 2 mm short of the radiographic apex. By securing the mandible and Rinn instrument with plaster mounts, exposures were made from identical angles and film and jaw placement remained constant in both techniques. Conventional film images were recorded on Kodak Ultraspeed film with six to eight impulses. Xeroradiographic images were recorded with four to five impulses. Radiographs and xeroradiographs were evaluated with the use of light from a masked viewbox. A magnifying glass was used to evaluate visualization of the following entities: the root apex; the periodontal ligament; the trabecular pattern; and the measuring instruments. The images were examined and categorized by three examiners, who used the following scores: 3, optimal for diagnostic information; 2, adequate for diagnostic information; 1, poor but providing diagnostic information; and 0, unacceptably poor. In all categories examined, the information provided by xeroradiographs was significantly greater than that provided by conventional radiographs (p less than .05). In terms of diagnostic value and lower patient dose, xeroradiographs are preferred to conventional radiographs.

Dental Pulp Cavity↗
PubMed1978

Human blood pressure and pulse rate response to racemic epinephrine retraction cord.

1. The pulse rate of patients after application of racemic epinephrine-impregnated retraction cords depends more on the level of anxiety and stress than on the level of the epinephrine. 2. Blood pressure is elevated by placement of racemic epinephrine-impregnated retraction cords upon an exposed vascular bed or lacerated tissue. 3. Four percent racemic epinephrine-impregnated retraction cords cause less elevation of blood pressure than 8% racemic epinephrine cords. 4. Although the elevations in blood pressure from 8% cord occur within a narrow range, this range may be hazardous to cardiac patients. Therefore, 4% racemic epinephrine cord should be used. 5. A desirable amount of tissue retraction is produced by 4% racemic epinephrine cord. 6. Dry cords do not provide adequate retraction of tissue and are contraindicated for tissue-retraction purposes.

Adult↗
PubMed1976

Direct and indirect pulp capping.

Cavity disinfection, indirect pulp capping, and direct pulp capping have been discussed in light of present day knowledge of the biology of the pulp. A format has been presented to the restorative dentist which has had long-standing clinical acceptance based on some scientific data and clinical evidence to substantiate the treatment radionale.

Calcium Hydroxide↗
PubMed1975

Comparison of tissue response between a synthetic gutta-percha and a natural gutta-percha endodontic filler.

Biologic acceptance is one of several criteria that must be met by an endodontic filling material. The purpose fo this experiment was to compare a new filling material consisting of a synthetic gutta-percha with a standard material consisting of natural gutta-percha. Each sample, being an endodontic point, contained a quantity of fillers. The materials were implanted subcutaneously in male white rats. The histologic appearance was essentially identical for both materials.

Animals↗
PubMedDate not supplied

Trabecular bone mineral density in idiopathic scoliosis.

The association of idiopathic scoliosis with an osteoporotic state has been indicated previously. The present study compared the trabecular bone mineral densities of 44 adolescent idiopathic scoliotic girls with 44 age-, weight-, sex-, and race-matched controls. Their lumbar spine and femoral neck bone mineral densities were evaluated using dual-photon absorptiometry. Radiographs and scoliotic curve data were also obtained for the experimental group. The scoliotic subjects exhibited significantly lower lumbar and femoral neck bone mineral densities than the control subjects. No effect was found with respect to treatment, degree, or progression of curvature. The results of this study indicate that there is a generalized state of osteoporosis in idiopathic scoliotic girls when compared with matched controls.

Adolescent↗