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Biomedical subjects

F F Feagin

Publications and source records attributed to F F Feagin.

At least 19 recordsLinked to original sources
PubMed1994

Air-rotor stripping and enamel demineralization in vitro.

This investigation sought to evaluate the effects of air-rotor stripping on the susceptibility of human enamel to demineralization using an in vitro caries model. Crowns of extracted premolar teeth were abraded (0.5 mm) on one proximal surface by air-rotor stripping. The teeth were placed in a demineralizing gel and removed at various intervals up to 336 hours. Lesion depth and mineral content on the abraded and intact surfaces was measured with contact microradiography and computerized image analysis (double window technique). For each time interval measured, lesion depth was greater (p < 0.05) on the abraded surfaces and mineral density was significantly less (p < 0.05). In a second experiment, the effect of fluoride supplements (dentifrice or topical gel) were examined on abraded and intact enamel surfaces that were exposed to the acid gel for 192 hours. The data showed that fluoride treatments significantly reduced lesion penetration on intact and abraded surfaces compared with a no fluoride group. Lesion depth on the abraded, fluoride treated surfaces was significantly greater (p < 0.05) than on the intact untreated surfaces. No significant differences (p < 0.05) were apparent between the fluoride treatment groups with respect to lesion depth and mineral density within the lesion. These results suggest that air-rotor stripping significantly increases the susceptibility of proximal enamel surfaces to demineralization. As a result, the clinician should use caution in the application of this technique until the long-term effects on caries susceptibility have been determined.

Acidulated Phosphate Fluoride↗
PubMed1993

In vitro demineralization by strains of Actinomyces viscosus and Streptococcus sobrinus of sound and demineralized root surfaces.

Root sections were inoculated with one of two strains of Actinomyces viscosus or a strain of Streptococcus sobrinus and then incubated for 9 days in Trypticase soy broth (TSB) containing 0.25% glucose or TSB supplemented with 0.25% sucrose (TSB+S). Lesion progression was measured from microradiographs. One section from each group was examined with a transmission electron microscope. Lesion progression was associated with a fall in the pH of the medium. However, lesion progression was not correlated with the mean 48-hour pH of the medium. In both TSB and TSB + S, lesion progression with A. viscosus was significantly greater than in the S. sobrinus group. However, the mean 48-hour pH value in TSB + S was lower than that in the S. sobrinus group. Plaque formation in TSB was, subjectively, least in the S. sobrinus group. Examination of transmission electron micrographs revealed bacteria penetrating the surfaces of the sections and extending into the lesion in the A. viscosus groups but not in the S. sobrinus group. This in vitro bacterial plaque model of root caries may be suitable for investigations of the bacterial etiology of root-surface caries and the virulence factors associated with pathogenicity.

Actinomyces viscosus↗
PubMed1992

Comparison of phosphoprotein isolated from mature and immature human tooth roots.

Mature (average patient age = 29.5 yr, closed apical foramen) and immature (average patient age = 17.5 yr, open apical foramen) root shards were placed in dialysis tubing and demineralized to completion using either 10% disodium EDTA plus protease inhibitors or 0.6 N HCl. The demineralized shards were re-extracted (five times) with 0.05 M tris-HCl, 1.0 M NaCl and then collagenase digested. No major differences were observed in chromatograms of extracts, re-extracts or collagenase digests from root shards demineralized in either way. In contrast, chromatograms of immature and mature roots showed qualitative differences. Chromatograms of mature roots demineralized in either way showed broader protein peaks and less organic phosphorus than those from immature tooth roots. A distinct band amid degraded phosphoprotein (150 K) was found in SDS-PAGE gels (7.5%) from EDTA-extracted immature tooth roots but not from mature tooth roots. Electroelution of this band revealed a typical phosphoprotein amino-acid profile containing increased aspartic acid and serine residues. Comparison of the total phosphoprotein and amino acid composition of extracts, re-extracts and collagenase digests revealed that phosphoprotein, serine and to a lesser extent aspartic acid were recovered in greater quantities from immature roots than mature tooth roots. These data suggest that the degree of maturation is crucial to the isolation of an intact phosphoprotein and provides additional evidence that human dentine phosphoprotein undergoes amino acid compositional changes during maturation.

Adolescent↗
PubMed1992

Computer-based image analysis of natural approximal caries on radiographic films.

This paper reports on the development of computer software for automatic detection and measurement of approximal caries lesions on digital images obtained from radiographic films. If the program detects a lesion, it defines the lesion's border and measures and reports these lesion parameters: percent mineralization, area, maximum enamel penetration, and mean enamel penetration. Two experiments are reported; both were conducted with the use of extracted human premolar teeth. In the first experiment, thin sections were obtained from 13 approximal surfaces with caries lesions. Microradiographs were made of the sections, and software measurements of the lesions were obtained from the microradiographs. The software was able to separate the lesions into two groups: those that had penetrated less than 100% of the enamel and those that had penetrated 100% of the enamel. The software measurements agreed with evaluation of lesion penetration by polarized light microscopy of the thin sections. In the second experiment, simulated clinical radiographs were made of 16 approximal surfaces, 12 with lesions and four without. Thin sections were obtained for microradiography. Software was used for automatic detection and measurement of the lesions on both types of film. The ability of the software to detect the lesions on the clinical films was compared with that of 10 experienced clinicians. Correlations of the same parameter from the two types of radiographic films were statistically significant, 0.86 less than or equal to r less than or equal to 0.95 and p less than 0.05. The coefficients of variation were low for both microradiographs, 0.4-2.3%, and for clinical films, 0.7-8.5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1991

Effects of phosphoprotein moieties on the remineralization of human root caries.

The noncollagenous proteins, especially phosphoprotein, have been shown to modulate biomineralization. The objective of this study was to investigate the remineralization potential of human tooth root organic matrices which did or did not contain soluble non-collagenous proteins including phosphoprotein. Human tooth roots were completely demineralized using conditions that either removed or did not remove soluble phosphoprotein and were then subjected to remineralization conditions. Removal of soluble phosphoprotein resulted in remineralization while no remineralization occurred in tooth roots that still contained soluble phosphoprotein. Transmission electron microscopy and microradiography demonstrated that demineralized cementum did not remineralize under any of the conditions used in this study. Collagenase digestion of demineralized and salt-reextracted tooth root organic matrices revealed that a nonsoluble phosphoprotein was present in the matrices. Amino acid analysis and SDS-PAGE showed that this nonsoluble phosphoprotein was similar in composition to the soluble phosphoprotein. This work suggests that the removal of soluble, noncollagenous proteins, especially phosphoprotein from root caries lesions, may enhance their remineralization potential.

Amino Acids↗
PubMed1990

Phosphoprotein extraction from the dentine/cementum complex of human tooth roots.

Root shards were placed in dialysis tubing and demineralized to completion in either 10% disodium EDTA, pH 7.4, 0.6 M HCl, 0.1 M HCl, 0.5 M acetic or 75 mM-25 mM lactic-acetic acids. The demineralized shards were then re-extracted with 0.05 M tris-HCl, 1.0 M NaCl. DEAE chromatography revealed that the major peak of the 0.6 M CHl and EDTA extracts contained organic phosphorus, whereas much less organic phosphorus was found in the major peak of the 0.1 M HCl extract. Analysis of the re-extracts gave a pattern opposite to that obtained from the initial extractions. Measurements of protein and organic phosphorus released during extraction and re-extraction confirmed these results. Staining of SDS-PAGE gels for phosphoprotein with Stains-All resulted in a blue smear in fractions containing organic phosphorus. Thus the extraction of phosphoproteins from human tooth roots differed depending upon the demineralizing conditions. This ability to remove phosphoprotein differentially will allow further investigation of the role of phosphoprotein in mineralization and remineralization.

Acetates↗
PubMed1990

Quantitative radiographic measurement of dentinal lesions.

The purpose of this investigation was the comparison of the precision and accuracy of two reference ramp techniques for the quantification of radiographic density changes in teeth. Radiographs (65 kVp, 10 ma, 1 s, and intra-oral ultraspeed film) of transverse sections from extracted permanent human molars were made before and after dentinal lesions were created. Each radiograph contained the image of a tooth section and the aluminum reference ramp. Method A used the image of the ramp on both the before- and after-lesion radiographs, and method B used the image of the ramp only on the before-lesion radiograph. Three groups of lesions (0.525-mm diameter, n = 11; 0.675-mm diameter, n = 9; and the 0.525-mm holes enlarged to 0.675 mm) were measured radiographically by each technique and by direct planimetry of the lesions. Radiographic method B produced results in close agreement with the planimetric measurements. Method B differentiated (p less than 0.05) between groups that had a mean planimetric size difference of 0.10 mm (equivalent to a change in density difference of 0.6%). These density change measurements are in absolute units of mm of aluminum that can be compared between lesions and between samples. This technique may prove useful for the quantification of changes in mineral density of caries lesions detectable in longitudinal radiographic records.

Dental Caries↗
PubMed1989

Caries on root surfaces exposed following gingivectomy in conventional rats infected with Streptococcus sobrinus and Actinomyces viscosus.

To study the ability of bacteria associated with coronal caries to initiate root surface caries, a rat model was used. Root surfaces were exposed by gingivectomy in rats fed a caries-promoting diet and orally inoculated with either Actinomyces viscosus M-100, Streptococcus sobrinus (mutans) 6715, or both. A fourth group received a diet containing antibiotics. The animals were sacrificed 64 days following the gingivectomy performed on the right molar quadrants. Gingivectomy significantly increased exposed lingual root length and root caries incidence. There were no caries on non-gingivectomy root surfaces. Root surface caries incidence in the groups inoculated with A. viscosus and A. viscosus plus S. sobrinus did not differ. For both these groups, root caries incidence was significantly greater than that for the group inoculated with S. sobrinus alone. Root caries incidence in this latter group did not differ from that in the control group.

Actinomyces↗
PubMed1988

A method of semi-quantitative microradiographic analysis of root surface lesion remineralization.

The purpose of this study was to present a modified photometer based digital analysis system for image enhanced microradiographic semi-quantitation of reactions of demineralization and remineralization of root surface lesions. The system was used to determine effects of fluoride on abraded root surface dentin in vitro. Lesions of 30-40 micron depth were produced during 18 h exposure of 180 micron thick single sections in solution of 3 mM Ca (Ca/P 1.67) and 30 mM lactic acid at pH 5.1. Mean mineral content of the lesions was 32% relative to adjacent sound dentin. Exposure of 20 h in the same acid with 5 mM Ca (Ca/P 1.67) and 0.12 mM NaF at pH 6.1 restored the mean mineral content to 76% of normal and increased the resistance of the lesions to demineralization. Remineralization and subsequent demineralization characteristics indicated the growth of fluorapatites on residual minerals in the dentin lesions. The microradiographic analysis system proved to be sensitive and critical in these studies.

Densitometry↗
PubMed1988

Evaluation of the effects of F in acidified gelatin gel on root surface lesion development in vitro.

Oral exposed, natural root surfaces of extracted human teeth were subjected to artificial lesion formation in gels of dialyzed gelatin that contained 75 mM lactic and 25 mM acetic acid and 1, 3, 10, 32, 100, 320, 550, or 1,000 mg F/l at pH 4.3-4.4 and at 36 degrees C. Ca and PO4 demineralization per square millimeter exposed surface and lesion depth decreased with increased F concentrations, except for the levels above 320 mg/l. Quantitative microradiographic image analyses showed that the mean percent mineral content of the entire lesions relative to the adjacent sound tissue was constant at about 64% for the F levels less than 320 mg/l. F above 3 mg/l changed the mineral density profile of the lesions by eliminating subsurface lamination. This showed that sufficient F incorporated at the site of demineralization prevented lesion progression and that the best effect would be obtained for F levels between 100 and 320 mg/l. Higher levels of F may also prove to be beneficial by providing labile F from CaF2 formed in the root surface.

Acids↗
PubMed1988

Comparison of two scoring methods for root surface caries in hamsters.

The aim of this investigation was to compare two methods of scoring root surface caries in hamster teeth. The experimental material was mandibles from hamsters which had been infected with Actinomyces viscosus, fed a caries-promoting diet, and received either 0, 1, 10, or 25 ppm fluoride in the drinking water during an 18-week experimental period (Stookey, 1986). Root surface caries on the lingual surfaces of mandibular first molars was scored according to the grid method of Doff et al. (1977) and by the quantitative planimetric method of Firestone et al. (1986). Data from both methods confirmed that 25 and 10 ppm fluoride were significantly more caries-inhibitory than 1 ppm fluoride, which, in turn, significantly reduced root surface caries compared with the 0 ppm control group. Correlation coefficients for caries scores (0.92) and ranking of the scores (0.88) for each animal between the two methods were highly significant (p < 0.0001). The planimetric measurement of root surface caries in hamsters was as sensitive as the grid-scoring method.

Animals↗
PubMed1988

The effects of different levels of dietary sucrose on root caries subsequent to gingivectomy in conventional rats infected with Actinomyces viscosus M-100.

Three groups of weanling, Sprague-Dawley-derived rats were inoculated with Actinomyces viscosus M-100 and fed powdered diet containing either 67%, 5%, or 0% confectioner's sugar. Two further groups were fed diet containing 5% confectioner's sugar and inoculated with Streptococcus sobrinus 6715 or S. sobrinus 6715 plus A. viscosus M-100. The most coronal 1 mm of gingiva was removed from maxillary and mandibular right molar quadrants (gingivectomy), and the animals re-inoculated following gingivectomy. The animals were killed 64 days following gingivectomy, and the lingual surface of mandibular first molar roots was measured for exposed root-surface area and root caries. In the groups of rats infected with A. viscosus M-100, root caries area was significantly greater in the group fed diet containing 67% confectioner's sugar. Sucrose level did not significantly affect the amount of exposed lingual first molar root area regardless of whether the tooth had been subjected to a gingivectomy. In the groups of rats receiving diet containing 5% confectioner's sugar, there were no significant differences in root caries area or exposed root-surface area, regardless of the infection status of the animals. In the rat model presented here, a high level of dietary sucrose was a necessary condition for the initiation of root caries in the absence of other readily fermentable carbohydrates.

Actinomyces↗
PubMed1987

In vitro caries-like lesion production by Streptococcus mutans and Actinomyces viscosus using sucrose and starch.

We investigated the formation of caries-like lesions on root and enamel sections by S. mutans and A. viscosus when grown in four different carbohydrate substrates. The substrates were: sucrose, starch + alpha-amylase, and a combination of starch and sucrose with and without alpha-amylase. Twenty-four sections with exposed windows on both the root and enamel surfaces were exposed to the individual bacterial species in each of the four substrates for three weeks. At three weeks, the sections were removed and lesion depths measured. When grown in sucrose alone, S. mutans produced significantly deeper lesions in both root and enamel surfaces when compared with A. viscosus. However, S. mutans failed to produce lesions when grown in "limited" sucrose with starch added, whereas A. viscosus in this same substrate produced lesions in the enamel and root surfaces. A viscosus also produced either similar or significantly deeper lesions in both root and enamel surfaces, when compared with S. mutans grown in the two substrates with amylase. Thus, under these in vitro conditions, it was demonstrated that A. viscosus could utilize starch, whereas utilization of starch by S. mutans was alpha-amylase-dependent.

Actinomyces↗
PubMed1987

Root surface caries subsequent to gingivectomy in rats inoculated with Streptococcus sobrinus (mutans) and Actinomyces viscosus.

We studied the effect of oral infection with cariogenic micro-organisms on alveolar bone loss and root surface caries subsequent to gingivectomy in rats. Thirty-six rats were fed diet MIT 200 (67% sucrose); one-half, the controls, had antibiotics added to the diet. At ages 18, 19, and 21 days, the experimental group was orally infected with streptomycin-resistant Streptococcus sobrinus (mutans) 6715 and Actinomyces viscosus M-100. At age 30 days, all animals were subjected to a gingivectomy on maxillary and mandibular left quadrants. The experimental group was re-inoculated at age 36 days. Animals were killed seven weeks after surgery. Jaws were stained, and planimetric measurements of exposed root surface area and caries on lingual/palatal surfaces of 1st and 2nd molars were made from video images with a computer/digitizer. Compared with the non-operated contralateral quadrants, gingivectomy significantly increased exposed root surface area in the maxilla and in the mandible in both the control and experimental groups. Oral inoculation significantly increased exposed root surface in mandibular (but not maxillary) quadrants which had received a gingivectomy, but had no effect on non-gingivectomized quadrants. There was no caries in the control group, whereas ten rats in the experimental group had root surface caries lesions, all in quadrants which had received a gingivectomy. This rat model should prove useful in further studies of root surface caries.

Actinomyces↗
PubMed1986

Fluoride distribution in enamel after in vitro caries-like lesion formation.

Using a microdissection technique to obtain samples from carious and adjacent sound enamel, we compared the fluoride concentrations in surface and subsurface enamel. Undialyzed and dialyzed gels were used to create lesions with and without negatively birefringent surface zones, respectively. The fluoride concentration in the surface enamel of the lesions was always greater than that in the corresponding sound enamel, as was the subsurface fluoride concentrations of caries lesions compared with adjacent sound enamel at the same depth.

Dental Caries↗
PubMed1984

Mineral flux of surface enamel and root surfaces in acidified gelatin gels.

Gels of crude gelatin were dialyzed to eliminate fluoride, and then acidified with 75 mM lactic and 25 mM acetic acid at pH 4.2 and interfaced with enamel and root surfaces in gel-surface ratio of 0.2 ml/0.15 cm2. Enamel and root surface to gel mineral flux was reduced by initial inclusion of 0.5 and 1.0 mM fluoride with 2.5 mM calcium and 1.5 mM phosphate in gels at pH 4.2. Inclusion of 0.25 mM fluoride in the gels without added mineral ions had no effect in the first 22-day interface. The 0.25, 0.5 and 1.0 mM fluoride remarkably increased remineralization in a second 12-day interface. This indicated that the first fluoride exposure initiated formation of fluorapatites in the enamel which required a lower degree of gel saturation for enhanced remineralization in the second acid exposure. Fluoride had the same effect, but greater effectiveness on enamel than root-surface remineralization. Gels of crude gelatin may contain sufficient mineral ions to alter remineralization-demineralization of enamel and root surface.

Acetates↗