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Biomedical subjects

G K Stookey

Publications and source records attributed to G K Stookey.

At least 19 recordsLinked to original sources
PubMed1992

Sample size considerations in designing studies with intra-oral models.

Especially during recent years, the use of pre-clinical models for predicting the efficacy of fluoride systems has assumed greater importance within the scientific community. Originally utilized primarily to screen experimental fluoride delivery systems, preclinical models are now being considered as predictors of clinical efficacy in lieu of controlled clinical caries trials. Of the various preclinical models presently available, human intra-oral models have the greatest potential for reflecting intended usage conditions and therefore may be the most meaningful models for predicting clinical efficacy. However, only with the proper consideration of numerous critical variables can studies using intra-oral models be appropriately designed to achieve the desired objectives. Clearly, these models must provide relevant information in a manner which reflects clinically established cariostatic activity and be capable of detecting established differences in the amount of cariostatic activity, i.e., dose-response effects. Three sources of variation must be considered before an appropriate study design and sample size can be chosen. Based on fluoride uptake data from an intra-oral model with proximally-located enamel specimens, estimates of variation among subjects, within subjects, and among specimens within subjects were obtained. Multiple specimens per panelist do not affect the first two sources of variation. Thus, the number of panelists, and not the number of specimens, is of primary importance when pre-test data are used to choose the appropriate study design and calculate the required sample size.

Adult↗
PubMed1992

Reactor paper concerning patient selection and appliance design in intra-oral models.

Patient selection and appliance design are important factors in the development of intra-oral models. Adults, rather than children, are recommended as panelists due to their similarity to children in response to fluoride for caries prevention, greater likelihood of compliance with all study requirements, and greater availability for appointments. It may be desirable for additional factors--including the presence of cariogenic micro-organisms and the characteristics of their saliva with regard to remineralization--to be used in the selection of panelists. Cross-over test designs may be desirable to minimize the impact of these variables as well as of dietary differences. Appliances should be designed to approximate the normal oral conditions to the maximum extent possible. Intra-oral models should be capable not only of detecting the effects of clinically-proven fluoride treatments but also of detecting fluoride dosage responses.

Adult↗
PubMed1991

Use of an in vitro model to assess the effects of APF gel treatment on the staining potential of dental porcelain.

Porcelains and resin composites exposed to acidulated phosphate fluorides (APF) have been reported to result in increased roughness, loss of weight, and loss of specular reflectance (gloss). Six samples of five commercial porcelains were subjected to five four-minute treatments with APF gels. Samples were then subjected to a nine-day cyclic staining procedure that utilized a tea, coffee, and mucin mixture. Changes in reflectance were then measured by means of a Minolta Chromameter (CR121) and converted to CIE L* a* b* values at illuminant D65 against a white background. delta L*, delta a*, delta b*, and delta E values were calculated. There was a substantial decrease in the L* value (lightness) for all porcelains. The average L* value for APF-treated and then stained porcelains was 43.6, for the stained-untreated samples, 48.2, and for untreated-unstained porcelain, 53.5. For three of the five porcelains, the differences in L* between treated and untreated stained porcelains were statistically significant. Changes in a* and b* values were also found to be consistent with but not as large as the changes in L*.

Acidulated Phosphate Fluoride↗
PubMed1991

Effect of zinc upon cell attachment and proliferation on periodontally-diseased root surfaces.

The purpose of this study was to determine the effect of zinc ions on fibroblast attachment to periodontally-diseased root surfaces in vitro. Extracted periodontally-diseased teeth were treated with 0.5% ZnCl2 by iontophoresis at 0.5 mA for 2 to 6 minutes. Control groups were untreated diseased and untreated healthy teeth. Sections of the root underlying the pocket were cut from the diseased teeth. The specimens were incubated for 18 hours with L929 mouse fibroblasts, then transferred and incubated in cell-free medium for 48 hours. Cell attachment was evaluated by cell counts and scanning electron microscopy (SEM). Root surfaces were sampled with an acid-etch technique and zinc was measured with an atomic absorption spectrophotometer. Two samples from each group were examined for cell attachment with SEM. Data were analyzed using the appropriate statistical methods. The results showed that diseased, untreated root surfaces had significantly fewer cells attached; however, zinc iontophoresis did not significantly improve cell attachment to the diseased root surfaces. Zinc analysis showed that diseased, untreated root surfaces had a higher zinc content than healthy ones. SEM examination showed striking differences in cell attachment to healthy versus diseased root surfaces. The data indicated that zinc iontophoresis did not significantly enhance cell attachment to root surfaces of diseased teeth.

Cell Adhesion↗
PubMed1991

Absence of sustained effects of acute fluoride exposure on cyclic AMP levels in the adult rat.

Previously published results from studies of the in vivo effects of fluoride on cyclic AMP are contradictory. Because of the important physiological role of cyclic AMP as a "second messenger" in numerous metabolic processes, it was important to clarify the effect of fluoride on cyclic AMP. This study was designed to monitor cyclic AMP levels in the plasma, liver and kidney of rats at intervals of 0.5, 4 and 24 hours following acute intraperitoneal or intubated treatment with a single dose of 15 mg fluoride/kg and to relate cyclic AMP levels to plasma and tissue fluoride concentrations determined at the same time.

Animals↗
PubMed1990

Evaluation of mutagenicity of restorative dental materials using the Ames Salmonella/microsome test.

Compounds of five commercially available dental material kits were examined for mutagenic potential by use of the Ames Salmonella/microsome test. Dimethyl sulfoxide (DMSO) was used as the solvent for all materials, except MONO-LOK2 Primer and Right-On Activator, which were dissolved in 95% ethanol. The Tenure, Fuji, and Gluma materials were initially screened at 2 mg (solids) or 2 microL (liquids) per plate, without S9 (Aroclor 1254-induced rat liver microsomes), and dose-response studies were conducted for those materials showing potential mutagenicity. The components of three dental kits, MONO-LOK2, Right-On, and Gluma, were further examined, both with and without S9 activation, at doses of 0.2, 4, 20, 100, 500, and 2500 micrograms (nL for liquid components) per plate. The data showed no mutagenic potential for the components of Fuji Glass Ionomer (Type III), Tenure Dentin Bonding System, and MONO-LOK2 kits, or Right-On Paste. However, Gluma 3, a component of the Gluma/Lumifor Bonding System, exhibited mutagenic activity in a dose-response manner. The mutagenicity of Gluma 3 was demonstrated in repeated experiments. Gluma 4 and the resin of the Gluma dental kit, as well as Right-On Activator, caused a slight increase in the number of revertants, and judgment regarding their mutagenicity could not be made conclusively. The results of this study indicate that some commercial dental materials may not have been adequately tested for mutagenicity, and that a reliable test program for evaluation of mutagenicity of dental materials is needed so that their safe use in dental practice can be ensured.

Aldehydes↗
PubMed1990

Critical evaluation of the composition and use of topical fluorides.

This report reviews the current status of various topical fluoride systems commonly used for caries prevention; these systems include professional fluoride applications, prophylaxis pastes, varnishes, rinses, gels, and dentifrices. Although the cariostatic benefits of professional applications are well-established from early studies, the magnitude of benefit relative to other preventive measures needs to be re-assessed under current conditions. Significant cariostatic benefits from fluoride prophylaxis pastes remain to be established, as does the relative efficacy of fluoride varnishes in comparison with other fluoride measures. The established cariostatic activity of fluoride rinses with supervised usage needs confirmation under normal home usage conditions. There is inadequate evidence to justify either increasing or decreasing the concentration of fluoride in conventional dentifrices whose efficacy is well-established. Based on limited clinical data and supportive laboratory data, fluoride appears to be effective for preventing root-surface caries.

Dental Caries↗
PubMed1990

Effect of sorbitol gum chewing on plaque pH response after ingesting snacks containing predominantly sucrose or starch.

The purpose of this study was to determine the effect of chewing a sorbitol gum (Trident) for 10 minutes on interproximal plaque pH changes following ingestion of selected sucrose- or starch-containing foods. The snacks containing predominantly sucrose (and/or simple sugars) were chocolate bar, cream-filled cupcakes, cream-filled sandwich cookie, cherry pie and raisins. The snacks containing predominantly starch were oat cereal, granola bars, pretzels, potato chips and corn chips. Plaque pH responses were monitored using an indwelling wire-telemetry system in five adult panelists. The test design involved two sets of 5 x 5 Latin square randomization in which each set consisted of two series of tests. In the first series of tests, the fasted, resting plaque pH was recorded for 5 minutes, panelists ingested the designated snacks for 2 minutes, and the pH response was monitored for the remainder of a 2-hour period. In the second series of tests, the same procedure was followed through the snack ingestion. After the pH response to the snack was monitored for 15 minutes, the panelists were asked to chew one stick of sorbitol gum for 10 minutes and the pH response was then monitored for the balance of the 2-hour period. Results indicated that both the sugar- and starch-containing snacks tested in this study caused significant decreases in interproximal plaque pH. Chewing a sorbitol gum after ingestion of the snacks significantly reduced the demineralizing potential of the plaque. The chewing of sorbitol gum following the ingestion of snacks can be recommended as an adjunct to other caries-preventive oral hygiene measures.

Chewing Gum↗
PubMed1990

The impact of chewing sugarless gum on the acidogenicity of fast-food meals.

The objective of this study was to evaluate the effect of chewing sorbitol gum on plaque pH following the ingestion of acidogenic fast-food meals. Plaque pH response was monitored using an indwelling wire-telemetry system in five adult panelists. From a pilot study with 12 fast-food meals, the most acidogenic breakfast, lunch and dinner were selected for this study. In the first test, the fasted, resting plaque pH was recorded for 5 minutes; panelists ingested the selected meals for 10 minutes, rinsed thoroughly with 50 ml of tap water, and the pH response was monitored for the remainder of a 2-hour period. In the second test series, the same procedures were followed through the post-meal ingestion rinse. After the pH response to the meal was monitored for 5 minutes, the panelists chewed a sorbitol gum for 15 minutes in their usual manner and the panelists were encouraged to move the gum around their mouth, however, it appeared as if they favored the side of their mouth without the partial denture. The pH response was monitored for the balance of the 2-hour period. All panelists ate the test foods, with and without the chewing gum, according to a randomized-block test design. The results indicated that the use of sorbitol gum significantly raised the plaque pH, prevented the subsequent pH drops after the fast-food meal ingestion and reduced the pH curve area under 5.5.

Chewing Gum↗
PubMed1989

Encouraging primary care physicians to help smokers quit. A randomized, controlled trial.

STUDY OBJECTIVE: To increase the effect that primary care physicians have on their patients who smoke. DESIGN: Randomized, controlled trial with 112 general internists and their patients who smoke. PATIENTS: Sample of 1420 patients from a general medicine clinic of a city-county teaching hospital, who smoke at least one cigarette a day and were recruited regardless of their interest in quitting smoking. INTERVENTIONS: Physicians were randomly assigned to one of four groups: participants who received a protocol for smoking management and a lecture on the consequences and management of smoking (control); in addition, had nicotine gum freely available to patients (gum); had stickers attached to their smokers' charts (reminder); or had both gum and reminders (both). MEASUREMENTS AND MAIN RESULTS: The percentage of patients with a return visit at 6 months who quit smoking (alveolar carbon monoxide of less than nine parts per million) was 1.3% (control), 7.7% (gum), 7.0% (reminders), and 6.3% (both). At 1 year the percentages were 2.7%, 8.8%, 15.0%, and 9.6%, respectively. Subsequent pairwise comparisons showed that the three intervention groups were not significantly different, but that each was significantly different from the control group (P less than 0.05). Physicians in all three intervention groups spent significantly more time than did the physicians in the control group counseling their patients about smoking. CONCLUSIONS: The availability of nicotine gum or labeling the charts of smokers can help primary care physicians increase their success rates two- to six-fold in helping patients quit smoking. If all primary care physicians used these procedures, they could help an additional 2 million smokers quit.

Adult↗
PubMed1989

Effects of molybdenum on human enamel fluoride uptake and experimental rat dental caries.

The addition of high concentrations of molybdenum to a topically applied sodium fluoride solution did not result in a statistically significant increase in fluoride uptake into subsurface lesions in human enamel when compared to that after treatment with fluoride alone in vitro. The addition of 3000 parts/10(6) molybdenum to a 1000 parts/10(6) fluoride topical solution had no impact in vivo on the cariostatic activity of topically applied fluoride in rats.

Analysis of Variance↗
PubMed1989

Genotoxic evaluation of chronic fluoride exposure: sister-chromatid exchange study.

As part of a continuing investigation, this study was conducted to examine the genotoxic effects of chronic exposure to sodium fluoride (NaF) in drinking water on the frequency of sister-chromatid exchange (SCE) in the bone-marrow cells of male Chinese hamsters. Animals at about 3 weeks of age were randomly assigned to 6 groups, each with at least 3 hamsters, and were maintained on a low fluoride diet (less than 0.2 ppm F) throughout the experiment. At 4 weeks of age, the animals in groups I-V began to receive drinking water containing fluoride at concentrations of 0, 1, 10, 50 and 75 ppm, respectively. Group VI was treated with cyclophosphamide and served as the positive control. The animals were sacrificed at 24 weeks of age by cervical dislocation. The humeri and plasma were analyzed for fluoride content, which was found to increase with the increase in fluoride concentration in drinking water. Slides of chromosomes from bone-marrow cells were prepared and blindly examined for the frequency of SCE. The mean scores of SCE for the hamsters receiving drinking water containing F concentrations up to 75 ppm for 21 weeks ranged from 4.28 to 6.28 per cell, and were not significantly different from those of the negative controls (4.60-5.44/cell). The results indicated that chronic fluoride exposure had no effect on the frequency of SCE in Chinese hamster bone-marrow cells under the conditions of the present investigation.

Animals↗
PubMed1989

Genotoxic evaluation of chronic fluoride exposure: micronucleus and sperm morphology studies.

The purpose of this study was to investigate the genotoxic effects of chronic fluoride exposure on mammalian cells in vivo by use of the mouse bone-marrow micronucleus test and the sperm morphology methodology. Mice of genotype B6C3F1 were obtained at weaning and maintained on a low-fluoride diet (less than 0.2 ppm F) ad libitum throughout the experiment. The animals were randomly assigned to seven groups and given fluoride (as sodium fluoride) in concentrations ranging from 1.0 to 75 ppm in the drinking water. Negative (distilled water) and positive (cyclophosphamide) controls were included. After a 21-week treatment period, the animals were killed by cervical dislocation, and blood was obtained by cardiac puncture. Slides of femur marrow cells were prepared and blindly examined for the frequency of micronucleated polychromatic erythrocytes (MN-PCE). Slides of sperm from the cauda epididymides of the male mice were also prepared and similarly examined for morphological abnormalities. Weight of the testes was recorded, and the plasma, humeri, testes, and carcasses were saved for fluoride analyses. Analyses of bone and plasma fluoride confirmed the effective absorption of fluoride following ingestion. The frequency of MN-PCE, the count of abnormal sperm, and the weight of the testes for mice chronically exposed to fluoride, in doses ranging from approximately 0.3 to 23 mg/kg/day, were not significantly different from those of the negative control animals. The results of this study support the view that fluoride has no genotoxic effects.

Animals↗
PubMed1989

Helping smokers quit: a randomized controlled trial with private practice dentists.

Fifty private practitioners and their office staff members were randomly assigned to one of four groups: participants received a protocol for smoking management and a lecture on the consequences and management of smoking, or in addition, had nicotine gum freely available to patients, had stickers attached to their charts, or had gum and reminders. The percentage of patients in each group who had quit smoking a year later was 7.7, 16.3, 8.6, and 16.9, respectively, indicating a significant main effect for the gum conditions. The availability of nicotine gum also significantly increased the amount of time that patients reported they received smoking cessation counseling from the dentists and office staff.

Adult↗
PubMed1989

Clinical effect of a sanguinaria dentifrice on plaque and gingivitis in adults.

A clinical trial was conducted to evaluate the effects of a sanguinaria-zinc chloride dentifrice on the prevention of plaque formation and gingivitis. A total of 59 young adults, 18 to 30 years of age, either performed supervised brushing with a 0.075% sanguinaria-0.05% zinc chloride dentifrice, a 0.24% sodium fluoride dentifrice, or rinsed daily with a 0.05% NaF solution. Clinical evaluations for plaque and gingivitis were performed after 7, 14, and 21 days of the test regimen. After 21 days, all subjects resumed twice daily supervised brushing and flossing and post-test evaluations were conducted after two weeks. The results showed that after 7, 14, and 21 days both groups using dentifrices had significantly less plaque and gingivitis than the group using the rinse, and there were no significant differences between the two groups using either the sanguinaria-ZnCl2 or the NaF dentifrices.

Adolescent↗
PubMed1988

Overreporting of smokeless tobacco use by adolescent males.

This study evaluates the impact of a pipeline assessment (salivary cotinine determination) on the accuracy of self-reported use of cigarettes and smokeless tobacco by 160 rural seventh- and eighth-grade males ranging in age from 12 to 16. Half of them were randomly assigned to complete a questionnaire on tobacco use prior to revealing the biochemical validation materials and collecting samples. The others had the samples collected prior to receiving and completing the questionnaires. The questionnaire-first group reported significantly greater smokeless tobacco use than did the pipeline-first group. Only for the latter were their self-reports significantly corroborated by the cotinine results. These results suggest that the utilization of a biochemical pipeline not only can improve self-reported tobacco use but also may help identify perceptions about the social desirability of using harmful substances.

Adolescent↗
PubMed1988

Genotoxic effects of fluoride: a controversial issue.

Fluoride is an element which is widely distributed in our environment. Its cariostatic efficacy has been well documented, and numerous studies indicate that at a concentration of 1 ppm in water, fluoride is beneficial for caries prevention and does not appear to exacerbate any diseases. Currently, more than half the American population is consuming naturally or artificially fluoridated water and efforts are being made to increase this proportion significantly. In addition, the multiple use of fluoride for dental caries prevention is clearly increasing. It is a common practice to use fluoride in a variety of delivery systems, including dentifrices, mouthrinses, pediatric supplements, and professional or self-applied topical solutions or gels as well as dental restorative materials. These dental products may contain fluoride in concentrations as high as 12,300 ppm. Increasing exposure of the population to fluoride has raised questions about the safety of this measure and has established the need for objective reappraisal. In particular, interest has developed regarding the genotoxic effects of fluoride. Unfortunately, there is, at present, only a limited amount of information available concerning the potential genotoxic effects of fluoride, and the results that have been published are contradictory and often very confusing. A review of the literature clearly indicates the importance of, and necessity for, clarifying the conflicts and controversies regarding this important issue.

Animals↗