bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Salivary Flow Rate on Diffusion of Potassium Chloride from Artificial Plaque at Different Sites in the Mouth
Authors: Lecomte P. , Dawes C.
Published: November 2010

The rate at which substances diffuse from dental plaque influences the rate of clearance of acid and bacterial toxins from plaque into saliva. The aim of this study was to compare the rates of clearance of potassium chloride, as a model substance, from artificial plaque of 3-, 4-, and 6-mm-diameter, positioned bilaterally at different locations in the mouth. The diffusant was KCl (1 mol/L) in a 1.0% agarose matrix, placed in wells 1.5 mm deep, in small acrylic devices 3 mm thick, which could be fastened to the teeth with dental floss and removed after different time periods. The half-time for clearance was determined from the best-fitting least-squares line of the potassium concentration remaining in the gel plotted against the square root of time. For 14 subjects, half-times for the lower anterior lingual and upper posterior lingual regions averaged about 2.5 times greater than those for clearance into a large, stirred volume in vitro, whereas those for the upper and lower anterior buccal regions averaged about 12.8 times greater. This difference may be due to the fact that anterior buccal sites are exposed only to minor rather than to major salivary gland secretions. When salivary flow was stimulated by the sucking of sour lemon drops, all in vivo half-times were reduced by about one-half. The half-times were also directly related to the surface areas of the chambers, which implies that rates of diffusion from plaque of substances such as acid or bacterial toxins are inversely related to the surface area of the plaque at a particular site.
Cost-effectiveness Analysis of Periodontal Disease Control
Authors: Antczak-Bouckoms A.A. , Weinstein M.C.
Published: November 2010

Cost-effectiveness analysis was used to evaluate alternative methods of periodontal disease control. The alternatives considered included non-surgical and surgical procedures as well as the use of antimicrobial agents. Data on costs were obtained from American Dental Association publications of average charges for periodontal services. The concept of quality-adjusted tooth-years (QATYs) was developed to provide an outcome measure which could be compared across treatments. The conclusions of this analysis are as follows: (1) Conservative non-surgical treatments for periodontal disease control not only have costs lower than surgical alternatives, as would be expected, but also maximize expected quality-adjusted tooth-years over a wide range of estimates; (2) antimicrobial therapy used as an adjunct to non-surgical treatment is likely to be both effective and cost-effective; and (3) quality of tooth-years is a critical consideration in the determination of outcome of periodontal treatment. For example, when tooth-years are not adjusted for quality, differences between treatments are diminished, and surgical treatment becomes as good as or better than more conservative treatments for some levels of disease severity-
The Use of Saturated DCPD in Remineralization of Artificial Caries Lesions in vitro
Authors: Wefel J.S. , Harless J.D.
Published: November 2010

Dicalcium phosphate dihydrate (DCPD) may play a significant role in the caries lesion since it is a stable calcium phosphate phase under acidic conditions. The reaction of DCPD and fluoride, forming fluor-apatite (FAP), may provide a potentially promising treatment regimen for remineralization of caries lesions in vivo. The purpose of this study was to determine whether a two-step DCPD and inorganic wash with fluoride can remineralize artificial caries-like lesions in vitro. We used the single-section technique to facilitate quantitation of the same tissue before and after the experimental regimen. The two-step remineralizing treatment was repeated three times and consisted of a two-minute saturated DCPD treatment (pH 2.1) followed by a 24-hour inorganic wash. Lesion parameters were recorded before and after treatment by the taking of polarized light photomicrographs of each section after imbibition in several media. The changes in the tissue following treatment were expressed as a percent change in the area of the initial pre-treatment lesion. Significant reductions (p < 0. 02) in lesion pore volume were observed in all aqueous media examined. In the lesions after imbibition in quinoline, remineralization was also apparent from the significant increase in the area of the dark zone following treatment. This two-step DCPD treatment appears to remineralize artificial caries-like lesions effectively, but additional work is needed to determine whether it affords any protection against subsequent cariogenic challenges.
The Effect of Baseline Lesion Mineral Loss on in situ Remineralization
Authors: Strang R. , Damato F.A. , Creanor S.L. , Stephen K.W.
Published: November 2010

The effect of baseline lesion mineral loss on the remineralization of enamel lesions by a sodium fluoride dentifrice was studied in situ by means of an appliance carrying enamel sections. Artificial lesions of various sizes were created, by means of acidified gelatin, and were then mounted on the appliances of five volunteers. Each brushed twice daily for two min with a 1000 ppm F sodium fluoride dentifrice. Measurements of mineral content were made at baseline and at weekly intervals by microradiographic/microdensitometric techniques. Data from all five volunteers showed a linear increase in remineralization rate with increasing lesion size. Thus, in studies which compare the effects of different remineralizing formulations, care must be taken to ensure that initial lesion sizes are matched, or that the results are expressed as a percentage change in mineral content.
The Ultrastructure of Human Dental Enamel Heat-treated in the Temperature Range 200°C to 600°C
Authors: Palamara J. , Phakey P.P. , Rachinger W.A. , Orams H.J.
Published: November 2010

Heating enamel in the temperature range 200°C to 600°C resulted in poor crystal packing due to void formation, permanent change in the sign of its birefizngence (from negative to positive) in some areas, and an altered crystal morphology. Transmission electron microscopy of enamel heated in the temperature range 200°C to 400°C revealed that the distinction between the positively birefringent regions and the negatively birefringent regions (which were present up to 350°C and occasionally up to 400°C) at the tooth's surface was due to the greater volume of intra- and inter-crystalline voids within the positively birefringent regions. There was a significant increase in void volume at 400°C, and above this all of the enamel was positively birefringent and opaque. Large remineralized crystals of β-tricalcium phosphate (β-TCP) phase (whitlockite) were initially formed at 400°C, and their size and number increased at 500°C and above_ Both the greater solubility of β-TCP crystals and the increased surface area due to the presence of voids would increase the rate of demineralization of heat-treated enamel.
Experimental Masticatory Muscle Pain
Authors: Bowley J.F. , Gale E.N.
Published: November 2010

Ten female subjects with no history of temporomandibular disorders performed five exercises designed to induce masticatory muscle pain. Three of the exercises were replications of Christensen's tooth-clenching (1970) and tooth-grinding (1971) studies and Scott and Lundeen's mandibular protrusion (1980) study. The other two exercises were designed to induce specific unilateral masticatory muscle pain. The amount of muscle pain as well as the time of onset and the duration were assessed by a clinical palpation exam and a pain questionnaire.

These five pain-inducing methods did not consistently produce masticatory muscle pain in non-pain subjects. However, certain individuals appeared to be very susceptible to developing pain during or after most of the exercises. These susceptible individuals demonstrated a bilateral muscle pain pattern after the unilaterally stressful exercises. None of the five exercises produced a statistically significant amount of site-specific masticatory muscle pain as determined by either the palpation examination or the pain questionnaire, even when the exercise was intended to produce such specificity. The fact that some subjects did develop masticatory muscle pain is indicative that muscle exercise and fatigue may lead to TMD-like symptoms.
The Activity of Glucosyltransferase Adsorbed onto Saliva-coated Hydroxyapatite
Authors: Schilling K.M. , Bowen W.H.
Published: November 2010

This study aimed to determine physical and kinetic properties of glucosyltransferase (GTF) adsorbed onto hydroxyapatite (HA) surfaces. For development of a solid-phase enzyme assay, 4.0-mg samples of washed HA powder were exposed to centrifuged whole saliva (WSHA) or buffer, and subsequently exposed to a GTF solution. The activities of GTF adsorbed to HA and that remaining in solution were measured. WSHA was more effective in adsorbing GTF than was naked HA. Enzyme activity on the surface of WSHA was enhanced; more activity was detected on WSHA than was apparently removed from solution. A similar effect was observed when GTF was adsorbed to naked HA from a mixture with lysozyme or saliva; however, no enhancement was seen when GTF was adsorbed from a mixture with albumin. Compared with GTF in solution, adsorbed GTF displayed activity over a much wider range of pH values. Temperature-activity profiles indicated that GTF adsorbed to surfaces had a lower temperature optimum (40°C) than did soluble enzyme (45°C), and that the bound enzyme was more resistant to adverse effects of heat at elevated temperatures. The majority of glucan made by GTF adsorbed to parotid saliva-coated HA remained attached to the surface. The activity of lysozyme adsorbed to HA was reduced by adsorption of GTF to the same surface and was almost completely abolished by formation of glucans by the adsorbed GTF. These results suggest that soluble bacterial enzymes found in saliva can be incorporated into pellicle, interact with host-derived molecules on the surfaces of teeth, express enzymatic activity, and potentially influence the biological properties of pellicle.
Reliability of Visual Analog and Verbal Descriptor Scales for "Objective" Measurement of Temporomandibular Disorder Pain
Authors: Le Resche L. , Burgess J. , Dworkin S.F.
Published: November 2010

Eight dentists viewed standardized videotapes showing palpations of the temporomandibular joint and muscles of mastication and recorded their judgments concerning the amount of pain the patient was experiencing. Judgments were recorded using a four-point verbal descriptor scale (VDS) ("none", "mild", "moderate", "severe "pain) or a 100-mm visual analog scale (VAS) anchored with the terms "no pain" and "worst pain possible". Test/re-test reliability over a one-week period and interjudge reliabilities were calculated for each scale; reliabilities of the two scales were directly compared based on the statistical equivalence of weighted kappa and the Intraclass Correlation Coefficient.

Neither scale showed satisfactory reliability. Median test/re-test reliabilities were k = 0.590 for the VDS and r = 0.822 for the VAS. Interjudge reliabilities averaged k = 0.394 for the VDS and r = 0. 735 for the VAS. Direct comparison of reliabilities for the two scales showed no clear advantage for either scale. The marginal reliabilities of these scales, when used by dentists to quantify the patient's pain, suggest that neither scale should be regarded as an "objective" pain measure.
Comparison of two Scoring Methods for Root Surface Caries in Hamsters
Authors: Firestone A.R. , Feagin F.F. , Graves C.N. , Stookey G.K. , Rodlun C. , Warrick J.
Published: November 2010

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.
A Preliminary Report of Long-term Elimination of Detectable Mutans Streptococci in Man
Authors: Sandham H.J. , Brown J. , Phillips H.I. , Chan K.H.
Published: November 2010

Application of an antimicrobial varnish to the teeth of 33 adult volunteers resulted in the elimination of detectable mutans streptococci from the saliva of 21 of them for a mean period of 34.6 weeks (range, 4 to 89 weeks) without additional treatment. The mean number of applications of varnish required for elimination was 3.14 (range, 1 to 5). Extensive examination of 10 subjects made free of mutans streptococci on the basis of saliva examination revealed no detectable mutans streptococci in their dental plaque. In 14 of the subjects in whom mutans streptococci were eliminated, they subsequently re-appeared after a mean period of 22.7 weeks (range, 4 to 71 weeks). Four out of the five recurrences that were treated were eliminated with only one additional varnish application. The treatment failed to provide long-term elimination of detectable mutans streptococci in 12 of the 33 treated subjects. No serious adverse reactions were observed in any of the treated subjects. The results indicate that it is possible to eliminate mutans streptococci from man in a safe and effective manner.
Analysis of the Buffering Systems in Dental Plaque
Authors: Shellis R.P. , Dibdin G.H.
Published: November 2010

A semi-micro method was used for investigation of the buffering properties of whole plaque, plaque fluid, and washed plaque bacteria. Artifacts associated with titration of samples containing live bacteria were noted and their effects estimated. All three sample types showed minimal buffering in the region of neutrality, with much stronger buffering in the regions pH 4-5.5 and pH 8-9. For the range pH 4-7, almost 90% of the total buffer capacity of plaque appeared to be accounted for by macromolecules of bacterial cell walls and plaque matrix. Extracellular buffers in plaque fluid removable by centrifugation contributed up to 11%. These buffers (probably soluble proteins, peptides, organic acids, and phosphate) are, potentially at least, capable of exchange with saliva. In vitro, bicarbonate (dissolved in the extracellular fluid) contributed only 2-5% of total buffering; there was no evidence of formation of carbamino compounds. However, in vivo, salivary bicarbonate may be important as a continually replenished source of additional buffering.
Effects of Inorganic Orthophosphate and Pyrophosphate on Dissolution of Calcium Fluoride in Water
Authors: Lagerlöf F. , Saxegaard E. , Barkvoll P. , Rølla G.
Published: November 2010

Calcium and fluoride release from excess solid calcium fluoride was monitored for 15-30 min in aqueous solutions containing various concentrations of inorganic orthophosphate and pyrophosphate. Low concentrations of these ions (1-10 μmol/L) considerably inhibited the rate of dissolution of calcium fluoride. This inhibition was pH-dependent, being reduced at pH values below 5. It is suggested that a reduced calcium fluoride dissolution rate, in the presence of phosphate, can account for the relatively slow loss of calcium fluoride from dental enamel observed in recent clinical studies. It also appears that calcium fluoride coated with phosphate may provide a pH-controlled slow release of fluoride that may be of clinical significance and a major component of the cariostatic mechanism of topically applied fluoride.
Comparison of in vivo vs. in vitro Bonding of Composite Resin to the Dentin of Canine Teeth
Authors: Pashley E.L. , Tao L. , Mackert J.R. , Pashlety D.H.
Published: November 2010

Dogs were utilized in a study to compare the bond strengths of dentin bonding agents made to dentin in vivo and then again in vitro in the same teeth 30 min, one day, one week, and one month post-extraction. No statistically significant differences were observed between bonds made in vivo and those made in vitro at any time period. Contamination of the dentin surfaces with blood or saliva lowered the bond strengths, but these could be restored to control values by re-surfacing of the dentin with a bur.
An in vivo Study of Microhardness and Fluoride Uptake in Partially Demineralized Human Enamel Covered by Plaque
Authors: Reintsema H. , Arends J.
Published: November 2010

In this investigation, microhardness changes in partially demineralized human enamel were studied after in vivo use of fluoridated toothpaste systems. Flattened enamel specimens were demineralized in vitro and subsequently positioned in approximal positions in the prostheses of 27 participants for three weeks; the samples were plaque-covered in vivo. After brushing for one week with a non-fluoridated paste to achieve an in vivo equilibrium, participants brushed with an assigned product for a two-week period. This test was a six-way cross-over design which used randomization of subjects. Five fluoridated and one non-fluoridated paste were tested. Knoop hardness measurements were carried out on sound and on in vitro demineralized enamel, and after in vivo exposure of the enamel to the dentifrice treatments. The results showed that during the two weeks of in vivo exposure to the fluoride products, net rehardening of the demineralized enamel did not occur, and no correlation was observed between fluoride uptake into the demineralized enamel and changes in microhardness.

That we failed to observe rehardening may be due to the fact that the duration of this study was too short for any net remineralization to have occurred, especially because the samples were constantly covered with plaque. Other possibilities, such as the type and/or severity of the lesions used in this study, may account for the lack of rehardening.
In vitro Bonding of Prosthodontic Adhesives to Dental Alloys
Authors: Watanabe F. , Powers J.M. , Lorey R.E.
Published: November 2010

In vitro tensile bond strengths were determined for three adhesive cements and two resin-bonded bridge cements to two alloys, each prepared by two methods: sandblasted Ni-Cr-Be alloy (I), electro-etched Ni-Cr-Be alloy (II), sandblasted Type IV gold alloy (III), and tin-plated Type IV gold alloy (IV). Storage conditions of 24 hours at 37°C and 30 days at 70°C were evaluated. The highest bond strengths were obtained for the electro-etched Ni-Cr-Be alloy, and all bond failures were cohesive. At both 24 hours and 30 days, the adhesive cements had the highest bond strengths to the other alloy/surface preparations (I, III, and IV). The adhesive cements usually failed cohesively under these conditions, whereas the resin-bonded bridge cements failed adhesively at the cement-alloy interface. Storage for 30 days at 70°C caused average decreases of 30%, 5%, 15%, and 32% for allay/surface preparations I to IV, respectively.
Taurodontism in 47,XXY Males: An Effect of the Extra X Chromosome on Root Development
Authors: Varrela J. , Alvesalo L.
Published: November 2010

Effects of an extra X chromosome on root development were studied in males with a 47, XXY chromosome constitution. Occurrence of taurodontism in the permanent molars of the lower jaw was noted from orthopantomograms of 30 Finnish 47,XXY males, 16 of their first-degree relatives, and a sample of 157 normal males and females. Nine, or 30%, or the 47, XXY males had at least one mandibular molar which was classified as taurodont. Only hypotaurodont teeth were found, and the teeth affected were all either second or third molars. None of the control relatives showed taurodontism. In the population sample, four individuals, or 2.5%, had taurodont teeth. A change in the mitotic activity of the cells of the developing teeth is one possible factor that can affect root formation leading to the development of taurodontism.
Abrasion Biopsy in Studies of Mineral Density of Experimental Enamel Lesions
Authors: Ikemi T. , Koulourides T.
Published: November 2010

The profile of mineral density of experimental enamel lesions was determined by means of sampling with a new abrasion biopsy technique. Three types of lesions were produced on bovine enamel slabs: (1) pre-softened in lactic acid buffer for 16 hr; (2) pre-softened and exposed to a test for acid resistance for seven days; and (3) pre-softened, exposed to the seven-day Intra-oral Cariogenicity Test with extra-oral immersions in 1000 ppm F solutions for one min twice daily (ICT/F), plus the seven-day test for acid resistance. Lesions were assessed with measurements of surface microhardness, microradiography of thin sections, and abrasion biopsy. For abrasion biopsy of the experzmental lesions, 15 parallel layers of approximately 10 μm each were abraded simultaneously with reference slabs of sound enamel on strips of lapping film. The depth of abrasion for each sample was calculated from the phosphorus content of the reference sample. Exposure to the ICT/F formed an acid-resistant zone within the lesion which diminished the microhardness change, although it did not have an appreciable effect on the total lesion depth as assessed with microradiography; abrasion biopsy indicated the formation of a mineral-dense zone within the lesion. This recently-developed technique of abrasion biopsy of experimental lesions offers the opportunity to link the composition of the lesion to controlled experimental conditions which will improve our understanding of demineralizing and remineralizing reactions on a standard tooth substrate.
Ion-translocating Properties of Calcifiable Proteolipids
Authors: Swain L.D. , Boyan B.D.
Published: November 2010

De novo formation of calcium hydroxyapatite in biological systems occurs on membrane surfaces through specific interactions of Ca, Pi, phospholipids, calcifiable proteolipids, and ion flux to and from the nucleating site. This paper reports an in vitro model demonstrating an ion transport function for calcifiable proteolipid. Bacterionema matruchotii proteolipid was incubated with a radiolabeled H+ -channel inhibitor, 14C-dicyclohexyl-carbodiimide, and binding characterized by displacement studies with DCCD or ethyldimethylaminopropylcarbodiimide. A carboxyl binding site was suggested by displacement of DCCD by the nucleophile, glycine ethyl ester. The displacement studies indicated that proteolipid bound DCCD via carboxyl group interaction in a hydrophobic region of the protein. SDS-polyacrylamide gel electrophoresis showed that all label was associated with a single band of 8500 Mr. No non-specific binding of 14C-DCCD to phospholipids occurred, since all bound label was associated with protein following Sephadex LH-20 chromatography of crude proteolipid. Phospholipid liposomes were prepared containing bacteriorhodopsin and proteolipid or proteolipid-14C-DCCD, via cholate dialysis. Transmembrane pH changes established by the bacteriorhodopsin H+ pump were measured in the presence and absence of added proteolipid. Proteolipid had an effect similar to those of uncouplers such as tetraphenylboron. Both the rate and extent of proton translocation increased following addition of proteolipid to BR-liposomes. 14C-DCCD abolished the proteolipid-augmented ion transport. When tetraphenylboron was used to abolish the transmembrane electrical potential, calcifiable proteolipid did not augment proton transport. These data suggest that calcifiable proteolipids may function as an ionophore during membrane-initiated calcification.
Effect of Fluoride in the Apatitic Lattice on Adsorption of Enamel Proteins onto Calcium Apatites
Authors: Tanabe T. , Aoba T. , Moreno E.C. , Fukae M.
Published: November 2010

The selective adsorption of enamel proteins onto crystalline calcium apatites having different specific surface areas and various degrees of fluoride substitution was investigated. The proteins were obtained from the outer (close to the ameloblast) layer of secretory enamel of porcine permanent incisors. The adsorption of the enamel proteins was not affected markedly by the variation of specific surface area of the hydroxyapatites used as adsorbents, but it was enhanced substantially with increasing fluoride content in the crystalline lattice. Through the use of SDS- and two-dimensional polyacrylamide gel electrophoresis, it was shown that the originally secreted amelogenin (25 kd) as well as 60-90-kd and 5-6-kd molecules adsorbed most selectively onto the hydroxyapatites and that additional moieties having 21-23-kd and 14-18-kd molecular masses commenced to adsorb onto the apatitic surfaces with increasing degrees of fluoride substitution in the lattice. In contrast, the 20-kd amelogenin, a product partially degraded from the 25-kd amelogenin, showed no significant adsorption, even onto the fluoridated apatites. These results suggest that the retention of proteinaceous matrix in the developing enamel might be affected by the nature of the forming crystals.
Cross-sectional Analysis of Serum Antibody to Oral Streptococcal Antigens in Children
Authors: Luo Z. , Smith D.J. , Taubman M.A. , King W.F.
Published: November 2010

Antibodies to S. salivarius, S. sanguis, and S. mutans cells and to glucosyltransferases (GTF) prepared from these micro-organisms were measured in the sera of 133 infants and children by enzyme-linked immunosorbent assay (ELISA). IgG antibody activity to each cell type and GTF was present at birth (presumably derived from maternal transfer) and declined significantly thereafter. IgG antibody levels to S. salivarius and S. sanguis were next detected in young children (2 to < 3 yr group). However, an increase in IgG antibody to S. mutans cells was not seen until children were older ( 4 to < 8 yr group), possibly reflecting the later colonization of this organism. In contrast, IgG antibody to GTF of all three streptococcal species remained at low levels throughout the first four years of life. IgG antibody to S. mutans GTF was then the first to appear ( 4 to < 8 yr group). Serum IgA antibodies to all GTFs were not detected until after this time. Fifteen sera were used to develop IgG immunoblots with the GTF antigens. Some positive sera (7/12) demonstrated reaction(s) with GTF from each of the three streptococcal species. Individual sera showed IgG antibody bands to GTF from several serotypes of the mutans streptococci. No immunoblot reaction was observed with GTF and sera (3) from the four-to-seven-year and younger age groups. These results indicate the presence of serum antibody to bacteria and bacterial products associated with plaque formation very early in life and during and after the pre-adolescent years. The potential exists for this serum antibody to modulate bacterial colonization or accumulation in the oral cavity.
Electrophoretic Heterogeneity of Lipopolysaccharides of Actinobacillus actinomycetemcomitans
Authors: Hoover C.I.
Published: November 2010

Electrophoretic banding patterns of lipopolysaccharides (LPS), as observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), have proved to be useful in studies relating LPS structure to virulence and as epidemiological markers. In this report, LPS of Actinobacillus actinomycetemcomitans from outer membrane fractions and hot phenol-water extracts were analyzed by SDS-PAGE and LPS-specific silver-staining techniques. Both intra- and inter-strain heterogeneity of A. actinomycetemcomitans LPS was observed. Twelve strains of A. actinomycetemcomitans, representative of the three described serotypes, were assigned to LPS subtypes based on the relative mobility of their most rapidly migrating LPS band. All three serotype a strains (29523, aB75, and GA3), two (29524 and SAC11A) of five serotype b strains, and two (aB67 and SAC5A) of four serotype c strains were assigned to LPS subtype I. The three remaining serotype b strains (29522, Y4, and JP2) were assigned to LPS subtype II, and the remaining two serotype c strains (SAC6A and SAC12A) were assigned to LPS subtype III. LPS subtyping may serve as an adjunct or alternative to serotyping in epidemiological studies.
Mineral Density and Fluoride Content of in vitro Remineralized Lesions
Authors: Jima Y. , Koulourides T.
Published: November 2010

This in vitro investigation studied the remineralization of experimental caries lesions in bovine enamel by use of three methods: (1) surface microhardness, (2) microradiography, and (3) abrasion biopsy for mineral density and fluoride content. The lesions were produced by a two-day exposure to 0.01 mol/L lactic acidlsodium hydroxide buffer partially saturated with 3.0 mmol/L Ca, 1.8 mmol/L P, in 1% CMC, at pH 4.0 and 37°C. The lesions were exposed to a remineralizing solution containing 3.0 mmol/L Ca, 1.8 mmol/L P, and 3 ppm F in 1% CMC at pH 7.0 and 37°C for two, six, and ten days, with solution changes every two days. The data derived from the three methods are presented in sequence from the baseline and at days two, six, and ten of the remineralizing treatment. Microhardness measurements showed hardness recoveries of 35.9, 78.9, and 87.5%, respectively. Microradiography suggested complete recovery with the ten-day remineralization. Abrasion biopsy of successive 10-μm layers to a depth of 100 μm indicated 15.2, 39.8, and 68.8% mineral density recoveries, with fluoride content of the surface layer increasing from a baseline of 300 ppm to 4600, 9000, and 9800 ppm F for the 2, 6, 10 days of remineralization, respectively. Subsequent acid-etching of thin sections from the ten-day-remineralized specimens showed that the fluoride-enriched remineralized area was more resistant to acid dissolution than was the underlying nonnal enamel.
Microleakage in Class II Composite Restorations Bonded to Dentin Using Thermal and Load Cycling
Authors: Darbyshire P.A. , Messer L.B. , Douglas W.H.
Published: November 2010

The effectiveness of a dentin-bonding agent (DBA) and a glass-ionomer cement liner (GIC) in reducing the marginal microleakage at the cervical margin of Class II posterior composite restorations was examined. The effect of load cycling on microleakage of this type of restoration was evaluated.

The Class II cavities were prepared in extracted human pre-molar teeth, with the cervical margins finished approximately 1 mm below the CFJ. Combinations of DBA, GIC, and control (no liner) were used as mediators between resin and dentin. All restorations were placed incrementally with a 40-second cure per increment and finished with high-speed diamond burs. Half the samples of each treatment group received cyclical axial loading and half did not. All samples were thermocycled at 5° and 55°C for 500 cycles of one min each, stained (four hr) in 50% AgNO 3, and sectioned following stain development. Microleakage was scored linearly along the dentin-restoration interface. All restorations exhibited microleakage which was unaffected by load cycling. Both the DBA and the GIC significantly reduced microleakage independently. When GIC was present, the additional presence of the DBA did not provide a statistically significant additional reduction of microleakage.
Streptococcal Adherence on Various Restorative Materials
Authors: Satou J. , Fukunaga A. , Satou N. , Shintani H. , Okuda K.
Published: November 2010

The adherence of Streptococcus sanguis ATCC 10556, S. sanguisATCC 10557, S. mutans Ingbritt, and S. mutans OMZ 176 to the surfaces of composite resins, amalgam alloys, and a Au-Ag-Pd alloy was measured. Adhesion was correlated with values for hydrophobicity and ζ-potential of the bacteria and the restorative materials. The hydrophobicity of the restoratives showed a positive correlation between the numbers of adherent S. sanguis cells, suggesting that hydrophobic interactions are important for the adherence of this bacterial species. In contrast, the numbers of adherent S. mutans cells showed a positive correlation with the ζ-potential of the restoratives, suggesting that electrostatic interactions are important in adherence of this bacterium.
The Effects of Upper Incisor Separation on the Submandibular and Sublingual Glands of Rats
Authors: Kamogashira K. , Yanabu M. , Ichikawa K. , Itoh T. , Matsumoto M. , Ishibashi K. , Abe K.
Published: November 2010

The effects of upper incisor separation on the submandibular and sublingual glands of rats were examined biochemically, immunohistologically, and radio-immunologically during 28 days of treatment.

Lateral separation of the upper incisors by application of force from an orthodontic appliance caused significant enlargement of the sublingual and submandibular glands of rats by three and seven days, respectively, after the beginning of the orthodontic treatment. This enlargement was followed by a significant increase of both RNA and DNA content, with some evidence of hyperplasia and hypertrophy. The enlargement was also associated with a significant increase of substance P at early stages after treatment, suggesting the involvement of the sensory nerves. These changes were largely inhibited by phenoxybenzamine, an α-adrenergic blocker, but not by atropine or morphine. Wet weights and RNA contents of the sublingual glands were markedly reduced by atropine. In comparison with control animals, the enlarged submandibular glands of rats subjected to orthodontic treatment secreted additional proteins identical with those secreted by glands enlarged by chronic administration of isoproterenol. In addition, chemical sympathectomy with 6-hydroxydopamine and phenoxybenzamine stimulated the synthesis of these abnormal proteins, but atropine and morphine did not. In contrast, protease activities in the convoluted granular tubule cells in the submandibular glands were increasingly reduced after treatment, as seen in rats subjected to chronic treatment with isoproterenol. However, the submandibular and sublingual glands completely recovered after removal of the orthodontic appliance.
Dental Fluorosis in the Primary and the Permanent Dentition in Fluoridated Areas with Consumption of either Powdered Milk or Natural Cow's Milk
Authors: Larsen M.J. , Senderovitz F. , Kirkegaard E. , Poulsen S. , Fejerskov O.
Published: November 2010

The aim of the present study was to describe the patterns of dental fluorosis in the primary and the permanent dentition of children born and reared in two different fluoridated areas, one in which powdered milk suspended in tap water was commonly used (Narssaq, Greenland: 1.1 ppm fluoride in the water) and one in which cow's milk was provided (Vordingborg, Denmark: 1.4-1.6 ppm fluoride in the water). Dental fluorosis was recorded by Thylstrup and Fejerskov's classification. In both locations, the prevalence of dental fluorosis increased the later in life the tooth type was formed. The prevalence of dental fluorosis in the earliest formed teeth was higher in the area where powdered milk was suspended in fluoride-containing tap water than where pasteurized cow's milk was used. In the first permanent molars, the maxillary incisors, and the canines, the prevalence was rather similar in the two areas. In the latest formed teeth, the premolars, the level of fluorosis was higher in Vordingborg. The pattern of dental fluorosis suggests that when powdered milk was used frequently, the children were exposed to a higher fluoride intake earlier in life than were those consuming cow's milk during infancy and childhood.
Allelic Variants for Complement Factors C3, C4, and B in Acute Necrotizing Ulcerative Gingivitis
Authors: Melnick S.L. , Go R.C.P. , Cogen R.B. , Roseman J.M.
Published: November 2010

Impaired immune defense mechanisms and genetic factors appear to play a role in susceptibility to acute necrotizing ulcerative gingivitis (ANUG). Therefore, possible etiological mechanisms might involve genes at the Major Histocompatibility Complex, which include the complement factor loci. We have tested for a possible association between certain complement factor alleles and ANUG using a case-control study design. Specific alleles at complement factors C3 and C4, and properdin factor B (Bf) loci were determined indirectly by high voltage agarose gel electrophoresis in 58 subjects with a history of ANUG and in 58 age-sex-matched healthy controls. The highest relative risk of ANUG, as obtained by conditional logistic regression, for alleles at the C3 locus was 1.9 (90% confidence limits 0.8 to 4.8; p = 0.229) for C3*F-positive individuals. The highest relative risk for alleles at the C4 locus was 2.6 (0.5 to 14.9 ; p = 0.358) for C4A*3-positive individuals. There was no evidence for an association between Bf allotype and risk of ANUG, with a relative risk of 1. 2 for Bf*F- and relative risk of 1.0 for B*S-positive individuals. None of our estimates was statistically significant. We conclude, therefore, that it is unlikely that there is any association between complement factor gene haplotype and susceptibility to ANUG.
The Relationship Between Plaque pH, Plaque Acid Anion Profiles, and Oral Carbohydrate Retention After Ingestion of Several 'Reference Foods' by Human Subjects
Authors: Dodds M.W.J. , Edgar W.M.
Published: November 2010

The primary aim of this study was to rank several reference foods (apple drink, caramel, chocolate, cookie, skimmed milk powder, snack cracker, and wheat flake) according to their plaque pH response as monitored in a panel of 12 volunteers by the plaque-sampling method for comparison with data previously reported with other methods used to assess cariogenicity potential. Secondary experiments (using subsets of the panel of subjects) were undertaken in an attempt to elucidate some of the reasons for the observed plaque pH changes. Oral carbohydrate retention was measured at a single time period after food use as total anthrone-positive carbohydrate material, and as specific acidogenic sugars by gas-liquid chromatography after gel-exclusion chromatography. The concentrations of acid anions in the plaque fluid after food consumption were measured by isotachophoresis eight min after food use. According to the plaque pH response, apple-flavored fruit drink and chocolate were the most acidogenic foods and skimmed milk powder the least acidogenic. There were significant correlations (p < 0.05) between the plaque pH data and lactate-plus-acetate concentrations in plaque fluid, but the correlations between the pH data and any of the carbohydrate retention parameters were not significant.
The Determination of Extracellular Fluid Volume in Whole Dental Plaque Using Potassium- or Chloride-selective Micro-electrodes
Authors: Carey C.M. , Vogel G.L. , Chow L.C.
Published: November 2010

This paper describes a procedure for the determination of the volume of water available for diffusion in whole plaque samples collected from single sites. In this procedure, known micro volumes of H2O were added to single-site plaque samples with calibrated nanoliter pipettes and the potassium or chloride concentration at each dilution measured with ion-selective micro-electrodes. By plotting the inverse of the concentration versus the volume of H2O added, one can determine the original volume of plaque fluid available for diffusion. Volumes determined in simultaneous measurements performed with chloride and potassium micro-electrodes were statistically indistinguishable. From the observed constancy in the initial potassium concentration in rat and human plaque fluid, a simplified macro method is suggested which allows for estimation of the extracellular fluid volume within 20% error in plaque samples.
The Ca, Pi, F, and Proline Content of Developing Bovine Enamel Under GBHA-stained and Unstained Bands
Authors: Bawden J.W. , Keels M.A. , Deaton T.G. , Crenshaw M.A.
Published: November 2010

The surface enamel of fetal bovine teeth was stained with GBHA to indicate the position of bands of smooth-ended and ruffle-ended ameloblasts relative to the developing enamel. The boundaries of the bands were scored, under a dissecting microscope, and the bulk enamel under each band was collected. The enamel samples were assayed for Ca, Pi, F, and proline.

The amount of Ca and P i in the enamel increased in successive bands and seemed unrelated to the overlying ameloblast cell type. The loss of proline seemed unrelated to cell type. The fluoride content of enamel increased by approximately 50% in the first stained band immediately adjacent to the secretory zone. The F level returned to secretory values in the succeeding unstained band. Thus, only changes in the F level of developing enamel appeared to be related to GBHA staining patterns.
Serological Examinations for Antibodies against Legionella Species in Dental Personnel
Authors: Reinthaler F.F. , Mascher F. , Stunzner D.
Published: November 2010

Serum samples from 107 dentists, dental assistants, and dental technicians were examined with an indirect immunofluorescence test for antibodies to Legionella pneumophila SG1-SG6, L. micdadei, L. bozemanii, L. dumoffii, L. gormanii, L. jordanis, and L. longbeachae SG1 +2. Thirty-six (34%) employees from dental personnel from 13 practices showed a positive reaction for antibodies to Legionella pneumophila. Only five samples (5%) from a control group (non-medical workers) were positive. Of the 36 positive serum samples, 13 (36%) reacted with Serogroup 6, 12 with SG 1 (33%), 12 with SG 5 (33%), and three with SG 4 (8%), and eight samples were positive for antibodies to other Legionella species. Dentists had the highest prevalence (50%) of L. pneumophila antibodies, followed by assistants (38%) and technicians (20%). These results indicate that dental personnel are at an increased risk of legionella infection.
Relationships between Periodontal Health, Salivary Steroids, and Bacteroides intermedius in Males, Pregnant and Non-pregnant Women
Authors: Jonsson R. , Howland B.E. , Bowden G.H.W.
Published: November 2010

Relationships between four steroids, determined by radio-immunoassay of whole saliva, and clinical and bacteriological parameters were studied in 90 subjects: males, menstruating females, and pregnant females. Pocket depths and both plaque and gingival bleeding scores were recorded. Total counts and percentages of Gram-negative organisms Bacteroides and B. intermedius were determined from anaerobic cultures of subgingival plaque from 9-14 subjects in each group. None of the clinical parameters for the pregnant females differed significantly from those of non-pregnant females, nor did these parameters show any significant correlation with progression of pregnancy. No correlations were detected between bacterial and clinical parameters in the pregnant group. There were no statistically significant differences between the total bacterial counts from the three groups, yet males had significantly higher proportions of Gram-negative bacteria, Bacteroides, and B. intermedius, than did pregnant and non-pregnant females. Proportions of B. intermedius did not differ significantly between the two female groups, nor was there any correlation with progression of pregnancy. While some steroids appeared to affect some clinical or bacteriological parameters in some groups, no obvious patterns consistent with different steroid levels were detected. The results do not indicate that increased hormone levels cause more severe periodontal disease in pregnant women, nor that high salivary steroid levels result in increased recovery of B. intermedius from subgingival plaque.
Attachment of Bacteroides gingivalis to Collagenous Substrata
Authors: Naito Y. , Gibbons R.J.
Published: November 2010

The ability of Bacteroides gingivalis 381 to attach to hydroxyapatite (HA) beads, treated with either human type I or type IV collagen, or to particles of bovine bone collagen was studied. All preparations were blocked with human albumin prior to being incubated with 3H-thymidine-labeled B. gingivalis 381 cells. The presence of collagen on HA surfaces (C-HA) significantly promoted attachment of the organism. HA treated with Type IV collagen bound B. gingivalis cells more effectively than did HA treated with type I collagen. Attachment of two additional strains of B. gingivalis to HA was also promoted by collagen. Binding to type I or type IV C-HA occurred rapidly, and equilibrium was attained within 45 min. B. gingivalis 381 cells also bound to particles of bovine bone collagen, and this appeared to be biphasic. Heating the bacteria abolished their ability to bind to C-HA. Attachment of B. gingivalis 381 cells to HA treated with type I collagen was strongly inhibited by the presence of soluble type I or type IV collagen, or gelatin, but not by the presence of human albumin, salivary proline-rich protein 1, or saliva. Human serum, fibronectin, fibrinogen, certain protease inhibitors, and some peptides were also inhibitory. 3H-fibronectin bound to bovine bone collagen particles and blocked the attachment of 14C-B. gingivalis cells. Mild trypsin treatment of the fibronectin-collagen complex restored its ability to promote 14C-B. gingivalis attachment concomitant with the loss of 3H-fibronectin. We suggest that elevated levels of proteases in the gingival sulcus, such as are associated with poor oral hygiene and gingivitis, might remove fibronectin and expose collagen molecules in the basement membrane, thereby promoting the attachment of B. gingivalis cells and facilitating their invasion into gingival tissues.
In vivo and in vitro Effects of Zinc Oxide-Eugenol (ZOE) on Biosynthesis of Cyclo-oxygenase Products in Rat Dental Pulp
Authors: Hashimoto S. , Uchiyama K. , Maeda M. , Ishitsuka K. , Furumoto K. , Nakamura Y.
Published: November 2010

To determine the in vivo effects of a zinc oxide-eugenol mixture (ZOE) on the cyclo-oxygenase system in dental pulp, we used radioimmunoassay to measure the levels of prostaglandin E2 (PGE2), 13,14-dihydro-15-keto-PG (DHK-PG), thromboxane B2 (TXB2), and 6-keto-PGF1α in the dental pulp of rats. When the dental pulp was irritated by a hole made in the dentin of the mandibular incisors without use of any coolants, the levels of these cyclo-oxygenase products in the pulp were increased to, respectively, 2.8, 1.7, 10.0, and 2.6 times those in the normal pulp at six hr after treatment. In contrast, these increases in cyclo-oxygenase products disappeared immediately when the artificial cavity in the dentin was filled with ZOE (P/L; 1 g/0.25 mL), but were not altered when the cavity was filled with zinc oxide-water (ZOW, 1 g/1.5 mL). Most of the eugenol portion of ZOE was released into the pulp within two hr after the cavity was filled with ZOE. The maximal eugenol content was 35 pmol per mg of pulp. Furthermore, when the cavity was filled either with ZOE or by the addition of 10 μmol/L eugenol to the pulp homogenate, biosynthesis of 14C-6-keto-PGF1α, PGF2α, and PGE 2 from 14C-arachidonic acid in the homogenate was inhibited. These results suggest that eugenol released from ZOE in the cavity prepared in the dentin inhibited the biosynthesis of cyclo-oxygenase products during pulp irritation.
Oxidation and Ceramic Coatings on 80Ni20Cr Alloys
Authors: Pask J.A. , Tomsia A.P.
Published: November 2010

Additives and/or impurities in NiCr alloys would be expected to affect the oxidation and adherence of dental glasses. Oxidation characteristics and bonding of several glasses to a commercial impure 80Ni20Cr alloy and laboratory-prepared purer alloys were thus studied at 1000°C. The commercial alloy formed a porous and buckled single-layer oxide scale with lenticular voids at the interface. The scale was penetrated by glass which formed a chemical bond at the alloylglass interface, resulting in excellent adherence with fracture in the glassy phase. The purer alloy formed a complex multilayer oxide scale to which the glass bonded but did not penetrate; the assembly was not satisfactory, since fracture occurred in the oxide scale.