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Biomedical subjects

C M Russell

Publications and source records attributed to C M Russell.

At least 91 records · Page 5Linked to original sources
PubMed1988

Clinical and chemical properties of a novel mucosal bioadhesive agent.

Through clinical observations and known chemical properties, this series of studies delineates properties of a new bioadhesive agent available commercially (Zilactin). Using a previously published protocol, we determined that the duration of the film formed on mucosa was not altered after exposure to extremes in temperatures encountered in drinking hot and cold liquids. In addition, through dissection of the agent into several component parts, we were able to determine a specific role for each of the acidic ingredients. It is clear that the solubility of hydroxypropyl cellulose (Klucel) is altered by esterification of the polymer by tannic and salicylic acids and that boric acid effectively crosslinks these to form Zilactin's characteristic clinical film. Other fine points of the chemical reactions are detailed. These studies are intended to serve as a foundation for the future manipulation and application of this agent in oral mucosal diseases.

Adhesiveness↗
PubMed1988

Effect of coefficient of thermal expansion on microleakage.

This study examines the relationship between thermal coefficient of expansion and microleakage. Six restorative materials with varying coefficients of thermal expansion were thermocycled in basic fuschin dye and compared for relative microleakage. The use of dental restorative materials with low coefficients of thermal expansion such as glass ionomer can control microleakage.

Acrylic Resins↗
PubMed1987

Tensile bond strengths of orthodontic bonding resins and attachments to etched enamel.

The purpose of this in vitro study was to determine the tensile bond strengths (TBS) of several orthodontic bonding systems and orthodontic brackets to enamel surfaces exposed to different etching procedures. The TBS of four bonding systems were determined by a test method developed by Kemper and Kilian. Twelve test specimens were prepared for each procedure. The test system was modified to determine the TBS of orthodontic brackets bonded to enamel surfaces by six bonding procedures and the TBS were evaluated 15 minutes and 24 hours after specimen preparation. The specimens were loaded to failure in an Instron machine operated at a crosshead speed of 0.02 inch/min. The TBS were expressed in MN.m-2. The TBS of the four bonding systems to etched enamel were not significantly different (P = 0.2528). The TBS of bonded brackets determined 24 hours after specimen preparation were not significantly different than the TBS recorded after 15 minutes except for brackets bonded with Lee Cleanse and Bond I to enamel surfaces etched with 15% H3PO4 for 30 seconds. The TBS of brackets to enamel etched with 15% H3PO4 for 30 seconds were not significantly different from the TBS to enamel surfaces etched with 5% H3PO4 for 15 seconds except for brackets bonded with Lee Cleanse and Bond II and tested 24 hours after bonding.

Acid Etching, Dental↗
PubMed1982

Locus of control and expectancy in electromyographic biofeedback.

From a subject pool of 226 psychology students, 16 external and 16 internal subjects, as determined by the Nowicki-Strickland Locus of Control Scale, were randomly assigned to either a positive or a negative expectancy group (n = 8). In Session I all subjects were asked to relax their frontalis muscle using auditory proportional biofeedback over 8 subsequent 3-min trials. The procedure was repeated during Session II except for the inclusion of a verbal expectation which suggested subjects' likelihood or non-likelihood of achieving further muscle relaxation. Results indicated that externals with positive expectancy had significantly higher levels of tension than internals with positive expectancy. No difference between externals and internals in the negative expectancy condition were observed. Results are interpreted to indicate that cognitive set affected the perception of performance ability with externals being disrupted by comments suggesting positive expectancies.

Attitude↗
PubMedDate not supplied

Dental caries and fluorosis among children in a rural Georgia area.

PURPOSE: This IRB-approved study compared the caries experience, fluorosis prevalence, and plaque and salivary fluoride concentrations ([F]) in middle school (MS; N = 51) and elementary school (ES; N = 144) children residing in nonfluoridated and fluoridated communities in rural Georgia. All participants were exposed to fluoridated water at school (0.5-1.2 ppm), some received that level at home, and others received home water with < 0.1 ppm F. METHODS: Subjects' parents completed a questionnaire regarding fluoride exposure. Children were examined at school by two calibrated dentists. RESULTS: No significant differences were seen in DMFS+dfs between children with or without fluoridated home water, nor for those with or without fluorosis. MS children with non-fluoridated home water had lower mean salivary [F] values than MS children with fluoridated home water. No differences were found among MS and ES children in mean plaque [F] for those with or without fluorosis. CONCLUSIONS: Home water fluoridation had little effect on the variables measured. These findings appear to be due to fluoride exposure from fluoridated dentifrices, fluoridated drinking water at school, and the fluoride "halo" effect.

Child↗
PubMedDate not supplied

Comparison of direct digital and conventional radiography for the detection of proximal surface caries in the mixed dentition.

PURPOSE: The aim of this study was to compare the performance of direct digital radiography and traditional dental radiography for the detection of proximal surface dental caries in the mixed dentition. METHODS: 15 quadrants of extracted teeth, arranged from the primary canine to permanent first molar, were imaged using direct digital (Schick Technologies, Long Island City, NY, USA) and conventional films (D-speed and E-speed Plus; Eastman Kodak Co., Rochester, NY, USA). Five pediatric dentists viewed the images and scored the 270 proximal surfaces for presence of caries on a 5 point scale and extent of caries on a 4 point scale. The teeth were sectioned and viewed microscopically to determine the gold standard. Receiver operating characteristic (ROC) analysis and analysis of variance (ANOVA) were used to evaluate the viewer's performance for detecting proximal caries using the 3 different image receptor types. RESULTS: Experienced examiners were significantly more accurate in diagnosis of proximal surface caries using either D-speed or E-speed Plus films than they were using the direct digital receptor. The mean areas under the ROC curve (Az) for the viewers were 0.7595 for D-speed film, 0.7557 for E-speed Plus film, and 0.5928 for the direct digital receptor. The results also indicated that selected viewers' accuracy increased when viewing the direct digital images a second time. CONCLUSION: CCD based direct digital radiography was not as accurate as conventional film images for the purpose of diagnosing proximal surface caries in the mixed dentition. However, the results imply that with increased experience, direct digital images may be as accurate as conventional film based images for diagnosis.

Analysis of Variance↗
PubMedDate not supplied

Enamel uptake and patient exposure to fluoride: comparison of APF gel and foam.

This crossover study with 46 child dental patients compared two topical APF products, a gel and a foam, with respect to the amounts of product and fluoride (F) applied, salivary F concentrations, and enamel F uptake. Half the subjects were treated for 4 min with the gel first and the other half with the foam. After approximately 16 days, each patient received a second treatment using the other product. An acid-etch enamel biopsy was performed and whole saliva samples were collected before and after each treatment. Significantly less F was applied to the teeth and retained by the subjects when the APF foam was used. Salivary F concentrations after treatment with the gel were higher than after treatment with the foam. The differences in enamel F uptake at both 15 min and 16 days after the APF applications, however, were not significant. We concluded that: 1) the two products are equivalent with respect to enamel F uptake; 2) only about one-fifth as much of the foam product is required for adequate coverage of the teeth, which significantly reduces F exposure and retention by the patient.

Acidulated Phosphate Fluoride↗