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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
PubMed2004

Optical methods--quantitative light fluorescence.

Considerable research during the past two decades has focused upon the development of new technologies for the detection of dental caries. Of these technologies, the method that has been most extensively studied is based upon the indirectly assessed changes in the fluorescence of enamel associated with the loss of mineral. The purpose of this presentation was to review the available information regarding the use of this technology, commonly known as quantitative light fluorescence, for caries detection, particularly early caries detection, and the potential for the routine use of this technology in clinical caries trials. This technology is unique in its ability to measure small changes in the mineral content of enamel lesions quantitatively. The results of recent small-scale clinical trials have indicated that the impact of caries-preventive measures can be determined within a six-month period. With current hardware and software refinements and the results of long-term clinical validation studies that are in progress, it may be that this technology will be the future method of choice for caries clinical trials.

Clinical Trials as Topic↗
PubMed2002

Dental fluorosis: variability among different inbred mouse strains.

Concurrent with the decline in dental caries has been an increase in the prevalence of dental fluorosis, a side-effect of exposure to greater than optimal levels of fluoride during amelogenesis. The mechanisms that underlie the pathogenesis of dental fluorosis are not known. We hypothesize that genetic determinants influence an individual's susceptibility or resistance to develop dental fluorosis. We tested this hypothesis using a mouse model system (continuous eruption of the incisors) where genotype, age, gender, food, housing, and drinking water fluoride level can be rigorously controlled. Examination of 12 inbred strains of mice showed differences in dental fluorosis susceptibility/resistance. The A/J mouse strain is highly susceptible, with a rapid onset and severe development of dental fluorosis compared with that in the other strains tested, whereas the 129P3/J mouse strain is least affected, with minimal dental fluorosis. These observations support the contribution of a genetic component in the pathogenesis of dental fluorosis.

Analysis of Variance↗
PubMed2001

Emerging methods of caries diagnosis.

Current diagnostic tools used in dental caries detection are not sensitive enough to diagnose the disease process in its early stages and, frequently, once a diagnosis is made, restoration is the only effective means of treatment. The purpose of this review was to systematically assess the available literature for evidence to determine if emerging diagnostic methods for dental caries are more efficient than traditional methods for detecting and monitoring the progress of caries in permanent and primary teeth. Inclusion and exclusion criteria were established preceding the literature search. Included articles were grouped by type of emerging technology and study design. The types of emerging technologies included laser fluorescence, light fluorescence, digital imaging fiber optic transillumination, and ultrasound. Primarily on the basis of in vitro and preclinical data, some of the reviewed methodologies showed promising results for the detection and monitoring of early caries lesions. However, very little clinical data are available to validate these emerging technologies. It was concluded that, although significant promise is apparent with these technologies, there is not enough evidence available at this time for any of the reviewed diagnostic techniques to be recommended as a substitute for traditional diagnostic techniques.

Databases, Bibliographic↗
PubMed2001

Problem-based learning and the dental school library.

A major curriculum revision involving the utilization of problem-based learning was implemented at Indiana University School of Dentistry in the summer of 1997. Two of the main goals of this new student-centered curriculum were to promote critical thinking skills and to encourage a desire for lifelong learning, both of which were anticipated to increase student use of the library. This study examined circulation at the library for three years immediately prior to, and for three years immediately following, the curricular change. Results show that library circulation has increased significantly since the pedagogical change. This suggests that students in the new curriculum place more emphasis on the library as a learning resource than did their traditional curriculum counterparts.

Analysis of Variance↗
PubMed2000

An In vitro microbial-caries model used to study the efficacy of antibodies to Streptococcus mutans surface proteins in preventing dental caries.

The first step for a pathogenic bacterium to initiate infection is via attachment (i.e., through surface determinants) to a suitable receptor. An in vitro microbial artificial-mouth model was used to test the efficacy of polyclonal antibodies to Streptococcus mutans cell surface proteins (CsAb) and a cell surface 59-kDa protein (59Ab) in preventing S. mutans colonization and carious lesion formation. In study 1, groups of 12 human teeth specimens were inoculated with S. mutans, which were incubated with different concentrations of CsAb (A1 [positive control], sterile saline, no antibody; A2, 0.007 mg of antibody protein/ml; and A3, 0.7 mg of antibody protein/ml) for 1 h at 37 degrees C. The negative control group (B1) was not infected and was incubated with Trypticase soy broth (TSB) without dextrose supplemented with 5% sucrose (TSBS). In study 2, the same study design was used except that 59Ab was used instead of CsAb, normal rabbit serum was used in the positive control group (A1), and TSB supplemented with 1% glucose was used as the nutrient to control for sucrose-dependent colonization. All groups were exposed for 4 days to circulating cycles of TSBS and TSB (study 1 and study 2, respectively; 30 min each, three times per day) and a mineral washing solution (21 h per day). Prior to each nutrient cycle, 1 ml of the appropriate CsAb or 59Ab solution was administered to each group and allowed to mix for 30 min before cycling was resumed. Data obtained by confocal laser scanning microscopy demonstrated the presence of a significantly smaller (P < 0.05) lesion area and a smaller total lesion fluorescence in group A3 than in group A1 for both studies. In study 1, group A2 had significantly smaller values than A1 for lesion depth and area. There were no significant differences between groups A2 and A3 for lesion area or between groups A1 and A2 for total lesion fluorescence. In study 2, there were no significant differences among groups A1 and A2 for lesion depth or between groups A2 and A3 for all of the parameters studied. In both studies, there were no significant differences between S. mutans plaque CFU numbers among any of the groups. These studies demonstrated the efficacy of CsAb and 59Ab in reducing primary caries development in this model, although the underlying mechanism remains unclear.

Antibodies, Viral↗
PubMed2000

Direct digital radiography for caries detection and analysis.

Recent developments in the field of electronic imaging have provided a new set of imaging tools for intra-oral imaging and clinical diagnosis. In this chapter, we review the general structure and characteristics of image sensors used in digital radiography and their application for clinical caries detection and analysis. An overview of the literature, comparing the diagnostic accuracy of digital and film-based radiography and the impact of image-processing methods, is provided. We also describe several approaches for quantitative assessment of radiographic images for caries detection and assessment. Examples include digital subtraction radiography, and 2-D and 3-D density profiling. To increase the accuracy and reduce observer variability the use of 3-D imaging and computer-aided diagnosis is presented as future direction for clinical caries diagnosis.

Dental Caries↗
PubMed2000

Current status of caries prevention.

The use of fluoride in water, professional topical applications, and dentifrices has resulted in a pronounced decline in dental caries. However, caries continues to afflict more 90% of the US population. Preventing and controlling dental caries requires the use of innovative measures to address the causes and reverse the caries process. This article provides an overview of the current strategies for the prevention of dental caries, the rationale for their use, and their relative efficacy.

Cariostatic Agents↗
PubMed1999

Fluoride intake from foods, beverages and dentifrice by young children in communities with negligibly and optimally fluoridated water: a pilot study.

UNLABELLED: While the level of fluoride intake that affords optimal cariostatic efficacy without causing dental fluorosis is not precisely known, it has been suggested that the threshold of fluoride exposure above which fluorosis may occur is between 0.05 and 0.07 mg/kg/day. OBJECTIVE: To monitor and compare fluoride intake from diet and dentifrice use (theoretical F: 0.10-0.11%) by three groups of 16- to 40-month-old children: two groups living in the negligibly water-fluoridated communities of San Juan, Puerto Rico, and Connersville, Indiana, and the third group residing in the optimally water-fluoridated region of Indianapolis, Indiana. METHODS: Fluoride intake from diet was monitored by the "duplicate plate" method, and fluoride ingested from dentifrice was determined by subtracting the amount of fluoride recovered after brushing from the amount originally placed on the child's toothbrush. RESULTS: The mean combined amount of fluoride ingested daily by children living in the negligibly fluoridated communities was not significantly different from that ingested by children in the fluoridated community. The major component of fluoride ingested by children in the negligibly fluoridated communities came from fluoridated dentifrice, and in the fluoridated area children ingested as much fluoride from toothpaste as they did from beverages. In San Juan mean daily fluoride intake was within the estimated range for safe fluoride exposure; however, in the "halo" community of Connersville and in Indianapolis, daily fluoride ingested by many of the children may have exceeded this level. CONCLUSION: Attention needs to be given, in negligibly water-fluoridated as well as in optimally water-fluoridated communities, to reducing the daily intake of fluoride by young children in order to avoid putting them at risk of developing dental fluorosis.

Analysis of Variance↗
PubMed1999

Intranasal immunization against dental caries with a Streptococcus mutans-enriched fimbrial preparation.

Streptococcus mutans has been identified as the major etiological agent of human dental caries. The first step in the initiation of infection by this pathogenic bacterium is its attachment (i.e., through bacterial surface proteins such as glucosyltransferases, P1, glucan-binding proteins, and fimbriae) to a suitable receptor. It is hypothesized that a mucosal vaccine against a combination of S. mutans surface proteins would protect against dental caries by inducing specific salivary immunoglobulin A (IgA) antibodies which may reduce bacterial pathogenesis and adhesion to the tooth surface by affecting several adhesins simultaneously. Conventional Sprague-Dawley rats, infected with S. mutans at 18 to 20 days of age, were intranasally immunized with a mixture of S. mutans surface proteins, enriched for fimbriae and conjugated with cholera toxin B subunit (CTB) plus free cholera toxin (CT) at 13, 15, 22, 29, and 36 days of age (group A). Control rats were either not immunized (group B) or immunized with adjuvant alone (CTB and CT [group C]). At the termination of the study (when rats were 46 days of age), immunized animals (group A) had significantly (P < 0.05) higher salivary IgA and serum IgG antibody responses to the mixture of surface proteins and to whole bacterial cells than did the other two groups (B and C). No significant differences were found in the average numbers of recovered S. mutans cells among groups. However, statistically fewer smooth-surface enamel lesions (buccal and lingual) were detected in the immunized group than in the two other groups. Therefore, a mixture of S. mutans surface proteins, enriched with fimbria components, appears to be a promising immunogen candidate for a mucosal vaccine against dental caries.

Administration, Intranasal↗
PubMed1999

Caries-preventive effects of sodium and amine fluoride dentifrices.

PURPOSE: To determine the comparative effects of sodium (NaF) and amine fluoride dentifrices, as well as the effect of different silica abrasives used in NaF dentifrices, on caries formation in rats. MATERIALS AND METHODS: Harlan Sprague Dawley mixed sex, weanling, littermate rats were fed a cariogenic diet and inoculated with S. sobrinus strain 6715 to induce caries formation. The dentifrices evaluated contained 0.31% NaF with precipitated silica I as the abrasive system; 0.31% NaF with sodium bicarbonate and hydrated silica; placebo; amine fluoride (0.14%) containing silica (Elmex); 0.31% NaF with precipitated silica II (Sensodyne F); and 0.31% NaF with hydrated silica. Dentifrice slurries were administered 7 days per week for 3 weeks at which time the animals were euthanized and the hemijaws removed, coded and stained with a murexide solution. The recovery of S. sobrinus after the 3-week study clearly showed that all of the six groups were infected with S. sobrinus. The Keyes scoring method was then used to assess the caries formation within the six groups. RESULTS: Caries scores showed that all five experimental fluoride dentifrices were equally efficacious statistically in reducing caries formation when compared to the placebo with reductions ranging from 26 to 43%.

Amines↗
PubMed1999

Dental caries diagnosis.

As with any disease process, the early initiation of therapy for dental caries is often the most effective means to ensure resolution. However, for any therapy to be effective, early diagnosis is paramount to success. Unfortunately, current tools used in dental caries detection are not sensitive enough to diagnose the disease process in its early stages and, frequently, once a diagnosis is made restoration is the only effective means of treatment. Quantitative light-induced fluorescence, electrical conductance measurements, direct digital radiography, and direct fiber optic transillumination are methods that may offer promise as effective tools in diagnosing early dental caries. This article describes some of the research that has been performed to make these methods a reality.

Dental Caries↗
PubMed1999

Preventing dental calculus formation in lemurs (Lemur catta, Eulemur fulvus collaris) and baboons (Papio cynocephalus).

The prevention of calculus accumulation in exotic animals is a relatively unexplored topic. A 6-mo study in ring-tailed lemurs (Lemur catta) and collared lemurs (Eulemur fulvus collaris) and two studies in baboons (Papio cynocephalus) (7.5 wks and 6.5 mo) tested the benefits of a primate diet coated with 0.6% sodium hexametaphosphate (HMP) in controlling calculus in these species using a sequential crossover design. The control regimen was an identical, but non-HMP-coated, dry primate chow. At study initiation, the primates were given a thorough dental prophylaxis and provided with the control diet or experimental diet. At the conclusion of the test period, the animals were anesthetized and examined for clinical calculus independently by two examiners. The animals were then given another dental prophylaxis, provided the alternate ration, and the foregoing procedures were repeated. When the animals were provided the HMP-coated diet, significant reductions in calculus formation of 48-62% were observed in the lemurs and the baboons. No clinically significant changes were observed in body weights or in blood chemistry values as a result of ingestion of the HMP-coated regimen.

Animal Feed↗
PubMed1998

Chronic fluoride exposure does not cause detrimental, extraskeletal effects in nutritionally deficient rats.

On the basis of observations that endemic fluorosis occurs more often in malnourished populations, a series of studies tested the hypothesis that deficient dietary intake of calcium, protein or energy affects fluoride metabolism so that the margin of safe fluoride exposure may be reduced. The objective of the investigation was to determine whether changes in fluoride metabolism in nutritionally deficient rats resulted in manifestation of any extraskeletal toxic fluoride effects not observed in healthy animals. This investigation included two studies, one that monitored the effect of calcium deficiency on the effects of chronic fluoride exposure, and a second study that observed fluoride effects in rats that were deficient either in protein or in energy and total nutrient intake. Control and experimental rats received drinking water containing 0, 0.26 (5), 0.79 (15) or 2.63 (50) mmol fluoride/L (mg/L) for 16 or 48 wk. Control rats were fed optimal diets and experimental rats were fed diets deficient in calcium (Study 1) or protein (Study 2). An additional group of experimental rats (Study 2) was provided with a restricted amount of diet; thus these rats were deficient in energy and total nutrient intake. The intake, excretion and retention of fluoride were monitored; after the rats were killed, tissue fluoride levels and biochemical markers of tissue function were analyzed. Bone marrow cells were harvested from some of the rats, after 48 wk of treatment, for determining the frequency of sister chromatid exchange, a marker of genetic damage. Although there were significant differences among fluoride treatment groups in fluoride excretion and retention that resulted in significantly greater fluoride levels in tissues of the experimental rats, we were unable to detect any harmful, extraskeletal biochemical, physiologic or genetic effects of fluoride in the nutritionally deficient rats.

Animals↗
PubMed1998

Severe dental fluorosis in a Tanzanian population consuming water with negligible fluoride concentration.

OBJECTIVES: To identify risk factors for dental fluorosis that cannot be explained by drinking water fluoride concentration alone. METHODS: Two hundred eighty-four Tanzanian children ages 9 to 19 (mean 14.0+/-SD 1.69), who were lifetime residents at differing altitudes (Chanika, 100 m; Rundugai, 840 m; and Kibosho, 1,463 m; Sites 1, 2, and 3 respectively) were examined for dental fluorosis and caries. They were interviewed about their food habits, environmental characteristics and use of a fluoride-containing food tenderizer known locally as magadi. Meal, urine, water and magadi samples supplied by the participants were analyzed for fluoride content. Urine samples were also analyzed for creatinine concentration. Four magadi samples from Sites 1 and 3 were analyzed for complete element composition. RESULTS: Of the 13 water samples from Site 2, 10 contained > or =4 mg/L F, ranging from 1.26 to 12.36 mg/L with a mean+/-SD of 5.72+/-4.71 mg/L. Sites 1 and 3 had negligible water fluoride of 0.05+/-0.05 and 0.18+/-0.32 mg/L respectively. Mean TFI fluorosis scores (range 0-9) for Site 2 were high: 4.44+/-1.68. In Sites 1 and 3, which both had negligible water fluoride, fluorosis scores varied dramatically: Site 1 mean maximum TFI was 0.01+/-0.07 and Site 3 TFI was 4.39+/-1.52. Mean DMFS was 1.39+/-2.45, 0.15+/-0.73 and 0.19+/-0.61 at Sites 1, 2, and 3, respectively. There were no restorations present. Urinary fluoride values were 0.52+/-0.70, 4.34+/-7.62, and 1.43+/-1.80 mg/L F at Sites 1, 2, and 3, respectively. Mean urinary fluoride values at Site 3 were within the normal urinary fluoride reference value range in spite of pervasive severe pitting fluorosis. Meal and magadi analyses revealed widely varied fluoride concentrations. Concentrations ranged from 0.01 to 22.04 mg/L F for meals and from 189 to 83211 mg/L F for magadi. Complete element analysis revealed the presence of aluminum, iron, magnesium, manganese, strontium and titanium in four magadi samples. There were much higher concentrations of these elements in samples from Site 3, which was at the highest altitude and had severe enamel disturbances in spite of negligible water fluoride concentration. An analysis of covariance model supported the research hypothesis that the three communities differed significantly in mean fluorosis scores (P<0.0001). Controlling for urinary fluoride concentration and urinary fluoride:urinary creatinine ratio, location appeared to significantly affect fluorosis severity. Urinary fluoride:urinary creatinine ratio had a stronger correlation than urinary fluoride concentration with mean TFI fluorosis scores (r=0.43 vs r= 0.25). CONCLUSIONS: The severity of enamel disturbances at Site 3 (1463 m) was not consistent with the low fluoride concentration in drinking water, and was more severe than would be expected from the subjects' normal urinary fluoride values. Location, fluoride in magadi, other elements found in magadi, and malnutrition are variables which may be contributing to the severity of dental enamel disturbances occurring in Site 3. Altitude was a variable which differentiated the locations.

Adolescent↗
PubMed1998

Laser fluorescence detection of demineralization in artificial occlusal fissures.

Laser fluorescence (LF) has been used previously to detect early smooth-surface lesions. Although its use for detection of occlusal demineralization has been implicated, it has not been demonstrated. The aim of this study was to determine whether LF could detect demineralization in the base of artificial fissures. To employ LF for detection of occlusal demineralization an apparatus was devised to direct laser light into fissures and simultaneously detect fluorescence from the base of the fissures. Three groups (n = 40/group) of differing fissure types were prepared (straight wall, converging and diverging wall) with either a sound or lesioned base. One half of each group was examined with LF and dye-enhanced LF (DELF); the other half was examined with LF, exposed to plaque, examined with LF and DELF, air-polished and examined with DELF. All images were scored twice as either (1) carious; (2) sound, or (3) undetermined, by a group of 3 examiners. For fissures without plaque, the average sensitivity was higher for DELF (0.76) than for LF (0.54) (p < 0.05). Likewise, the average specificity was higher for DELF (0.64) than for LF (0.29) (p < 0.05). In the presence of plaque, sensitivity was higher for DELF (0.91) compared to LF (0.43); however, specificity was lower for DELF (0.05) compared to LF (0.55). When the fissures were air-polished and then examined with DELF, sensitivity averaged 0.82 (p < 0.05), and specificity increased consistently (average 0.51, p < 0.05). It was concluded that, in the absence of plaque, DELF was a better diagnostic tool than LF for detection of demineralization in artificial fissures.

Animals↗
PubMed1998

An in vitro comparison between laser fluorescence and visual examination for detection of demineralization in occlusal pits and fissures.

It has been demonstrated that when excited by laser light carious enamel appears dark compared to luminescent sound enamel. The aim of this study was to compare the sensitivity and specificity of visual exams (V), laser fluorescence (LF) and dye-enhanced LF (DELF) for detecting demineralization in occlusal pits and fissures. The actual presence of lesions was determined by subsequent confocal laser microscopy (CM), which was compared to histology (H). Independent clinical examiners visually graded three sites on occlusal surfaces of extracted, human premolars as sound or carious and also rated the color of each graded site as: 0 = same as surrounding enamel; 1 = white; 2 = light brown, or 3 = brown/dark brown. An argon laser was used to illuminate the teeth for LF and DELF; the images were captured with a CCD camera and then analyzed. DELF images were captured after the teeth had been exposed to 0.075% sodium fluorescein. Sections were then cut from each specimen and analyzed by CM and H for the presence or absence of caries. Results showed that DELF (0.72) was significantly more sensitive (p<0.05) than LF (0.49) and V (0.03) for detecting caries, but there were no significant differences among the methods in specificity (V 1.00; LF 0.67; DELF 0.60). When color was used as an indication of caries in V (VC, sensitivity 0.47; specificity 0.70), V exams were not different from LF. The area under the ROC curve, using H as the gold standard and CM as the test, was 0.78. Results indicated that DELF was the best diagnostic tool and that VC and LF were equally effective as diagnostic methods, when color of fissures was included as an indication of demineralization in the visual exam.

Argon↗
PubMed1998

Measurement of enamel remineralization using microradiography and confocal microscopy. A correlational study.

Tooth minerals are lost and regained constantly in a normal, human oral environment. Different methods have been developed to measure this gain and loss in enamel minerals; however, these methods deal with different problems, such as being time consuming or involving the use of X-rays. The aim of this study was to determine if remineralization measured in a thin enamel section (TS) by transversal microradiography (MR) can be reliably monitored by measuring lesion parameters (area, total and average dye fluorescence) on the same TS or on half a tooth (HT) with confocal laser scanning microscopy (CLSM). Thirty-six human enamel specimens were demineralized for 96h, and then half of each specimen was covered with an acid-resistant nail varnish. Specimens were divided into three groups (12/group) and subjected for 20 days to a cyclic remineralization regimen with consisted daily of a 4-hour acid challenge, four 1-min treatment periods with 0, 250 or 1,100 ppm F dentifrice slurries (1:2; dentifrice:water) and 20 h in pooled, human saliva, at room temperature. Specimens were cut and analyzed by MR, then stained with a fluorescent dye (0.1mM rhodamine B) for 1 h and analyzed using CLSM. Both MR and CLSM detected significantly greater remineralization (p<0.05) in the specimens treated with the fluoride-containing dentifrices than in the specimens treated with 0 ppm F. Significant differences were detected between specimens treated witht the fluoride-containing dentifrices by MR and CLSM (HT area and total fluorescence). Statistically significant (p<0.05) Pearson correlation coefficients were calculated between the MR and CLSM data: difference in MR mineral content (DeltaM) versus HT lesion area = 0.71; DeltaM versus HT total fluorescence = 0.70; DeltaM versus HT average fluorescence = 0.61; DeltaM versus TS lesion area = 0.88; DeltaM versus TS total fluorescence = 0.63, and DeltaM versus TS average fluorescence = 0.40. It is concluded that confocal microscopy in either TS or HT may provide valid surrogates (area and total fluorescence) for MR measurements in enamel remineralization studies.

Analysis of Variance↗