bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Technique for Screening Chemical Toxicity to the Pulp from Dental Restorative Materials and Procedures
Authors: Hume W.R.
Published: November 2010

An in vitro test system is described which allows for quick and relatively inexpensive examination of the potential for chemical toxicity to the pulp of materials and procedures used in the restoration of single teeth. The test system consisted of two sequential steps. First, a restorative procedure was carried out on a freshly-extracted human tooth crown, to the pulpal surface of which had been attached a chamber filled with sterile tissue-culture medium. The preparation was kept at 37°C. The culture medium was removed at day one and replaced with fresh medium, which was removed at day 3. In the second step, we used a standard tissue-culture toxicity assessment technique to examine both culture medium samples for the presence of chemical toxins. In use, this system gave results which correlated well with the known clinical potential for pulpal toxicity of various dental materials and techniques. For example, zinc oxide-eugenol used as temporary filling or base had no apparent potential for toxicity. Sealing a cotton pellet containing phenol into a cavity was of high apparent potential toxicity. Acrylic resin as intracoronal or extracoronal fillings showed potential for toxicity; this potential was decreased by lining with calcium hydroxide cement. Composite resin placed onto etched dentin had apparent toxic potential, but had less such potential when placed onto unetched dentin. The technique had some advantages over previously described in vitro toxicity tests for restorative materials, because it included a step requiring diffusion of potential toxins into and through human dentin, and because it allowed for examination of variations in technique which mimic clinical behavior, and of materials used in sequence or in combination.
Time-dependent Deformation of Composite Resins — Compositional Considerations
Authors: Ferracane J.L. , Matsumoto H. , Okabe T.
Published: November 2010

The compressive yield strength and creep of 21 dental composite resins were evaluated and correlated with filler volume percent and extent of cure in the resin. In general, yield and creep of composites were more dependent upon filler volume fraction than on extent of cure. However, the types of monomers and fillers used in the composite formulation appeared to play a major role in determining the compressive characteristics of the materials.
Development of Sustained-release Antimicrobial Dental Varnishes Effective Against Streptococcus mutans in vitro
Authors: Balanyk T.E. , Sandham H.J.
Published: November 2010

Two antimicrobial varnishes were developed to be applied to the teeth for the eradication of Streptococcus mutans infections. One of them contained chlorhexidine acetate as the antimicrobial agent and the other, erythromycin base. Both varnishes contained Sumatra benzoin. Each of the two antimicrobial agents was shown to be highly effective against S. mutans and to be compatible with the benzoin vehicle. When applied to extracted teeth, both varnishes dried to form a tough, adherent, and colorless transparent layer. Dried samples of the varnishes, when suspended in frequently-changed buffer, released their microbial agents at low but bactericidal levels for at least 12 days. After the first day, drug release from the chlorhexidine varnish showed approximately zero-order kinetics, while the erythromycin varnish showed a combination of zero-order and first-order kinetics.
Sulfur Uptake by Type I Collagen from Methyl Mercaptan/Dimethyl Disulfide Air Mixtures
Authors: Johnson P.W. , Tonzetich J.
Published: November 2010

Type I acid-soluble collagen, suspended in 0.02 M Tris/0.13 M NaCl buffer (pH 7.4), was exposed to air atmosphere admixed with 10.7 × 10-9 moles of [35 S]-labeled dimethyl disulphidelmethyl mercaptan mixture in the ratio of 99.82% (CH 3 S)2 /0.18% CH3SH. Gas chromatographic analyses of head-space following one and four days of incubation indicated that all of the CH3 SH was absorbed from the head-space by the collagen-containing liquid phase, while the (CH3 S)2 concentration of the head-space remained essentially unchanged. Of the total [ 35 S]-activity initially present in the head-space, only 1.0 and 1.86% was absorbed by the collagen-containing liquid phase within one and four days, respectively. Paper chromatographic separation of the reaction mixture showed that only 0.42 and 0.60% of the radioactivity in the head-space was associated with collagen after one and four days of reaction.

In comparable [ 35 SJ-H2 S systems devoid of (CH3 S)2 , all of the H2 S was absorbed within 48 hours of incubation with 18.04% (1 day) and 18.28% (4 days) of the available [35 S]-H2 S complexed with collagen. The results provide evidence that the reaction of collagen with H2 S and CH3 SH/(CH3 S)2 mixture proceeded via the H2 S and CH3SH thiol groups.
Uptake and Retention of Aluminum by Dental Enamel
Authors: Kleber C.J. , Putt M.S.
Published: November 2010

The uptake, depth of penetration, and retention of aluminum (Al) in sound and acid-etched dental enamel were determined following in vitro applications of solutions containing 0.005 M or 0.037 M Al. Compared with controls, significant amounts of Al uptake (approximately 2000 to 6000 ppm) were detected in both sound and etched enamel, with significantly more Al deposited in the latter. Analysis of successive layers of treated enamel demonstrated that Al was located predominately within the first 20 μ m of surface enamel. Only slight reductions in Al retention occurred following one week of water-soaking or one minute of brushing with water or dentifrice, indicating that Al was firmly bound by enamel.
Prevalence of Legionella-specific IgG and IgM Antibody in a Dental Clinic Population
Authors: Fotos P.G. , Westfall H.N. , Snyder I.S. , Miller R.W. , Mutchler B.M.
Published: November 2010

This study was undertaken to determine the frequency of Legionella infection in a dental clinic setting. Serum samples from 270 dental clinic personnel were evaluated using an enzyme-linked immunosorbent assay to detect Legionella-specific IgM and IgG antibodies. The pooled-species whole-cell-antigen preparation used in these assays was derived from six Legionella pneumophila strains and one strain each from Legionella bozemanii and Legionella micdadei. Significant levels of IgG and IgM antibodies were found in 20% and 16%, respectively, of the samples. This compares with 8% and 10%, respectively, for a randomly selected non-clinical group from the region (P<0.005). Samples from clinic personnel with significant IgG titers (>1 :128) were also evaluated for activity to each of the eight single-species antigens, with the following results: L. pneumophila, 45% (combined six strains); L. micdadei, 37%; and L. bozemanii, 18%. Comparing individuals' "years spent in the clinic environment" with the incidence of significant antibody levels strongly suggests that the risk of Legionella infection increases proportionately with increased clinic exposure time (P<0.05). Analysis of these data implies that Legionella may be present in the dental clinic environment, thus creating an increased risk for clinical personnel or patients.
The Relation Between Caries Prevalence and Strontium Concentrations in Drinking Water, Plaque, and Surface Enamel
Authors: Curzon M.E.J.
Published: November 2010

Samples of plaque and surface enamel were collected from 80 boys aged 14 years living in five communities in Ohio (USA). Mean (± SE) strontium concentrations in plaque were 1.43 ± 0.18 μg/g (wet) and 12.34 ± 1.63 μg/g (dry). For surface enamel, the mean concentration was 421 ± 31 μg Srlg. Concentrations of strontium in both plaque and enamel were significantly related to strontium levels in the drinking water. Caries prevalence as DMFS was inversely related to strontium levels in water, plaque, and enamel.
Materials Science Effect of Filler Content and Size on Properties of Composites
Authors: Li Y. , Swartz M.L. , Phillips R.W. , Moore B.K. , Roberts T.A.
Published: November 2010

Two series of dental composites, along with the unfilled resin matrix, were examined to determine the effects of filler level and size on selected properties. Both series were prepared by incorporating a silanated barium borosilicate filler into a visible-light-activated polyphenylene polymethacrylate resin matrix. One series had a filler particle size of 2 μm, with filler levels of 20, 40, 45, 50, and 53% (vol). The second series contained a 15-μm filler in amounts of 20, 40, 50, 60, and 65% (vol). Tests conducted included: depth of cure as evaluated by hardness, water sorption, compressive strength, stress-strain behavior under slow compression, toothbrush abrasion, and wear by hydroxyapatite. Analysis of the data indicated that increased filler levels resulted in increased hardness, compressive strength and stiffness, and decreased water sorption. Also, there was a slight trend toward improved depth of cure. Incorporation of the 2-μm filler decreased the abrasion resistance of the resins to toothbrushing as compared with the unfilled resin, while addition of the 15-μm filler improved resistance. All filled resins exhibited a significant improvement in resistance to wear by hydroxyapatite as compared with the unfilled resin. There was a trend for increased wear with increased filler level. The particle size of the filler appeared to have a moderate influence on the properties. When compared with 15-μm filled resins of the same filler levels, the 2-μm filled series appeared to have inferior properties in terms of depth of cure, compressive strength, water sorption, and resistance to toothbrush abrasion. Properties which were less affected by particle size were hardness, stiffness, and wear resistance to hydroxyapatite.
Composite Resin Compatibility and Bond Longevity of a Dentin Bonding Agent
Authors: Chan D.C.N. , Reinhardt J.W. , Boyer D.B.
Published: November 2010

The shear strength of a commercial dentin bonding agent was studied using human dentin in vitro. The agent was tested for compatibility with three proprietary composite resins. In addition, some samples were subjected to prolonged water immersion and thermocycling to determine effects on bond strength. There was no statistically significant difference in shear strengths when the three composite resins were used. In addition, there was no difference in shear strengths among those samples thermocycled or immersed for up to one year. The implications of this study are that the dentin bonding agent may be used with several composite resins with no significant difference in bond strengths, and that the bond seems stable when subjected to immersion or simulated intra-oral thermal stresses.
Adsorption of Zirconyl Salts and Their Acids on Hydroxyapatite: Use of the Salts as Coupling Agents to Dental Polymer Composites
Authors: Misra D.N.
Published: November 2010

Zirconyl methacrylate (I) and zirconyl-2-ethylhexanoate (II) were synthesized, and their adsorption isotherms from solutions onto synthetic hydroxyapatite were studied. The isotherms of methacrylic and 2-ethylhexanoic acids were also determined from the same solvents.

The adsorption of I was irreversible from methylene chloride, and that of II was irreversible from cyclohexane. The adsorption in both cases was constant from solutions above a certain concentration, and exhaustive below this threshold concentration. Both compounds rendered the dried apatite powder extremely hydrophobic; however, the adsorbate was slowly washed off by excess water. The configuration of the adsorbate molecules, deduced from the maximum adsorption and other adsorption characteristics of the two compounds, indicated that: (i) in both cases the adsorbate may be held to the surface by concerted hydrogen bonding of the carboxylate and zirconyl oxygen atoms; and (ii) the hydrocarbon moieties in both adsorbates expose themselves toward the solution, thereby making the dried surface hydrophobic. The adsorptive behavior of the respective acids was similar to that of the salts.

Polymer, filled with synthetic hydroxyapatite covered with irreversibly adsorbed I, had a diametral tensile strength about 50% greater than that of the polymer filled with untreated apatite. The strength of the composite was not affected by treatment of the apatite with II or with the acids.
Dentin-Polymer Bond Promoted by Gluma and Various Resins
Authors: Munksgaard E.C. , Irie M. , Asmussen E.
Published: November 2010

Gluma-treated dentin was covered with various resins before a microfilled composite was applied. The strength of the bond between dentin and composite established by this procedure was measured in shear and tensile tests. The effectiveness of the bonding was further tested by the width of the marginal contraction gap around fillings made in dentin by the above procedure.

Resins containing propanal promoted shear bond strength of about 15 MPa. The tensile bond strength exceeded 22 MPa by one of the resins, but could not be measured because of frequent rupture in the composite. Between 30 and 70% of the fillings were without contraction gaps when propanal or p- toluenesulfinate-containing resins were used.

It is proposed that oxygen inhibition of the polymerization on the dentin surface suppresses the bonding. Resins containing reducing agents may reduce oxygen inhibition and increase bonding by the adhesive.
Pharmacological Studies on the Anti-inflammatory Action of Phenolic Compounds
Authors: Azuma Y. , Ozasa N. , Ueda Y. , Takagi N.
Published: November 2010

The mechanism of the anti-inflammatory action of phenolic compounds was examined using neutrophil chemotaxis. Chemotactic activity of guinea pig peritoneal neutrophils to N-formylmethionyl-leucylphenylalanine (FMLP) was suppressed in a concentration-dependent manner. The order of drug potency in inhibiting the neutrophil chemotaxis was eugenol » thymol > guaiacol » phenol. The concentrations of phenolic compounds used in these experiments did not induce lactate dehydrogenase (LDH) release and did not affect neutrophil viability. There was a consistent positive relation between the ID50 of superoxide anion generation in neutrophils and the inhibitory dose for neutrophil chemotaxis by phenolic compounds. A free phenolic hydroxyl group is essential for scavenging oxygen free-radicals and is also essential for inhibiting leukocyte chemotaxis, as was demonstrated in these experiments. These findings suggest that inhibition of leukocyte chemotaxis may be involved in the anti-inflammatory action of phenolic compounds, and that one of the anti-inflammatory actions of phenolic compounds is the prevention of the production of oxygen free-radicals by leukocytes.
Levels of Glandular Kallikrein in Whole Saliva Obtained from Patients with Solid Tumors Remote from the Oral Cavity
Authors: Jenzano J.W. , Courts N.F. , Timko D.A. , Lundblad R.L.
Published: November 2010

Glandular kallikrein activity in whole saliva was determined in 16 patients with malignant tumors distant from the oral cavity and in an equal number of healthy control subjects of similar age and sex distribution. The level of glandular kallikrein was significantly greater in saliva obtained from the patients with solid tumors as determined with a tripeptide nitro-anilide substrate, D-Val-Leu-ArgpNA. A basis for the higher levels of glandular kallikrein in saliva obtained from the solid tumor patients has not been established, nor is it possible to establish a role for glandular kallikrein in the pathogenesis of malignant disease. The higher level of glandular kallikrein observed in whole saliva obtained from patients with solid tumors suggests the need for further investigation of the role of kallikrein in malignant disease and the usefulness of salivary measurements of this enzyme as a reflection of systemic changes.
Determinants of Requests for Water Fluoride Assay Among North Carolina Dentists
Authors: Levy S.M. , Rozier R.G. , Bawden J.W.
Published: November 2010

Fluoride content of drinking water is an important criterion in prescribing fluoride supplements. The majority of practicing dentists and physicians prescribe fluoride supplements, yet many apparently are unaware of the fluoride levels in their patients' drinking water. Characteristics of North Carolina (NC) dentists, their practices, and their communities were investigated to determine factors associated with whether they requested fluoride assays of their patients' drinking water. Comparisons were made between dentists sampling (assaying) and those not sampling. Licensure renewal files provided characteristics of the 79 pedodontists and 1768 general pracritioners (GP's) active in NC. Eighty-eight GP's (5%) and 26 pedodontists (33%) requested water fluoride analyses between December, 1982, and May, 1983. Significant predictors of fluoride assay request by GP's were the dentist's age, the geographic region of the state, the number of dentists in the practice, and an interaction between geographic region and the number of dentists in the practice. Younger GP's and those with fewer dentists in the practice were more likely to request fluoride assays of patients' water. For pedodontists, dentist's age and geographic region were significant predictors. Additional training concerning the need for water fluoride assay appears necessary, especially among older practitioners.
Actinomyces viscosus Colonization of Mouse Teeth
Authors: Crawford P.C. , Clark W.B.
Published: November 2010

The implantation of Actinomyces viscosus strain T14V-J1 was studied in mice in vivo. The optimum age range for implantation was from 40 to 80 days. The minimum infective dose of strain T14V-J1 required for colonization in all inoculated animals (ID100) was 5 x 108 CFU for 40-day-old mice and 1 x 109 CFU for 100-day-old mice. The high ID100 reguired for implantation of strain T14V-J1 in these mice is consistent with the finding that tooth surfaces of these animals are not colonized by detectable indigenous Actinomyces. The infection could also be transmitted to non-infected mice housed with infected mice. This in vivo model can be used to evaluate the potential for reducing or preventing Actinomyces colonization on teeth by vaccination with fimbrial adhesins.
The Effect of Intermittent Forces on Eruption of the Rabbit Incisor
Authors: Proffit W.R. , Sellers K.T.
Published: November 2010

Rabbits were prepared so that a variable capacitance displacement transducer (VCDT) could be used to monitor the eruptive movements of a previously-amputated lower incisor, and a strain gauge transducer mounted on a relay-controlled plate was used to place precisely controlled intermittent forces opposing the erupting tooth. Forces of one or three g were applied under time conditions of one second on, nine seconds off (1:9); one second on, three seconds off (1:3); and one second on, one second off (1:1). The data indicate that with force present for 10% of the time (1 :9), there was little or no effect on eruption rate. In contrast, 50% time (1:1) produced essentially the same intrusive effect as continuous force, and 25% time (1:3) gave an intermediate response. The data are consistent with the hypothesis that force duration is more important than force magnitude for the vertical equilibrium, as is the case for facio-lingual equilibrium.
Response of Lingual Ascorbic Acid Test and Salivary Ascorbate Levels to Changes in Ascorbic Acid Intake
Authors: Leggott P.J. , Robertson P.B. , Rothman D.L. , Murray P.A. , Jacob R.A.
Published: November 2010

This study sought to determine whether the lingual ascorbic acid test (LAAT) and measurement of salivary ascorbate refXect plasma and leukocyte ascorbate levels during controlled periods of ascorbic acid depletion and supplementation.

Eleven healthy non-smoking men, aged 19-28 years, ate a diet that was repeated every seven days and was adequate in all nutrients except ascorbic acid (AA). This basal diet, which provided less than 5 mg of AA per day, was supplemented with 60 mg of AA per day for two weeks, 0 mg (placebo) per day for four weeks, 600 mg per day for three weeks, and 0 mg per day for four weeks. Oral examinations, the lingual ascorbic acid test, and measurement of salivary, plasma, and leukocyte ascorbate concentrations were conducted throughout the study.

Ascorbic acid concentrations in plasma and leukocytes responded rapidly to changes in vitamin C intake. LAAT-derived ascorbate values were unrelated to ascorbic acid intake and plasma and leukocyte ascorbate concentrations. Salivary ascorbate levels approached the lower limits of detection of the assay and remained constant throughout the investigation. Oral hygiene was consistently excellent, and no severe mucosal or periodontal changes were observed. It was concluded that lingual ascorbic acid test values and salivary ascorbate levels are not related to changes in ascorbic acid intake and are not consistent with plasma or leukocyte ascorbate concentrations.
Glass-ionomer Cements of Improved Flexural Strength
Authors: Prosser H.J. , Powis D.R. , Wilson A.D.
Published: November 2010

The effect of glass and polyacid composition on cement strength has been investigated with a view to improving the glass-ionomer cements. The flexural strength of glass-ionomer cements was found to be greatly dependent on the glass and polyelectrolyte used to prepare them. Opaque and opal glasses containing crystallites tended to yield cements with high flexural strength. Flexural strength was also found to be increased by increasing the molecular weight of the polyacid. In water-setting systems, cement strength was shown to be critically dependent on the glasslpolyacid ratio.
Growth of Micro-organisms from Supragingival Dental Plaque on Saliva Agar
Authors: De Jong M.H. , Van Der Hoeven J.S. , Van Os J.H.
Published: November 2010

The role of saliva in supporting the growth of dental plaque has scarcely been investigated. We have studied the growth and recovery of micro-organisms from dental plaque samples on saliva-agar plates, prepared from filter-sterilized wax-stimulated whole saliva. Under optimal conditions, the mean recovery of plaque samples on saliva agar was about 50% (range, 22-77) of the recovery on blood agar. Addition of 2.5 mmol/L dithiothreitol (DTT) strongly facilitated filter-sterilization of saliva, but DTT concentrations higher than 1 mmol/L reduced the recovery of plaque micro-organisms on saliva agar.

Catalase (100 U/ml) offered protection against the inhibitory effect of DTT. Addition of glucose (1-5 mmol/L) increased only slightly the recovery of plaque micro-organisms on saliva agar. When supragingival plaque was plated on saliva- and blood-agar plates, the composition of the microflora isolated from saliva agar strongly resembled that isolated from blood agar. The predominant species — i.e., Streptococcus and Actinomyces — all grew on saliva agar though usually in numbers somewhat lower than those on blood agar. In addition, most species normally found only in low proportions in supragingival dental plaque were also found to grow on saliva agar. Collectively, the results lead to the conclusion that the supragingival microflora can utilize saliva as a complete source of nutrients.
Production and Characterization of Monoclonal Antibodies to Bacteroides gingivalis
Authors: Simonson L.G. , Merrell B.R. , Rouse R.F. , Shklair I.L.
Published: November 2010

The rapid detection of Bacteroides gingivalis by immunological methods using monoclonal antibodies could greatly improve the diagnosis and prognosis of severe periodontal disease in adults. In this study, three distinct hybridomas were produced which secrete monoclonal antibodies to soluble and whole-cell antigen preparations of B. gingivalis. The BGII, V F9/2D hybridoma produced a murine antibody that can detect all of the B. gingivalis isolates studied while never cross-reacting with the other oral microbial antigens tested.Received September 11, 1985 Accepted October 31, 1985
Identification of a Streptococcus sanguis Receptor for Salivary Agglutinins
Authors: Robinovitch M.R. , Malamud D. , Rosan B. , Golub E.E. , Lancy P.
Published: November 2010

The objective of this study was to characterize a fraction from oral streptococci containing receptor activity for salivary agglutinin molecules. Several species and strains of streptococci were disrupted in a Ribi press. The supernatant was nuclease-treated and subjected to differential centrifugation. Receptor activity in the fractions was measured by the inhibition of saliva-mediated bacterial aggregation. In addition, bacterial strains were tested for their ability to aggregate and to deplete saliva of agglutinin activity. Three patterns of activity were observed: Streptococcus sanguis M5 depleted saliva of agglutinin activity and aggregated well; Streptococcus sanguis CC5A depleted saliva of agglutinin but did not aggregate well; and Streptococcus faecalis S-161 neither depleted saliva of agglutinin nor did it aggregate. The 105,000 g supernatant fractions derived from Ribi-disrupted Streptococcus sanguis M5 and CC5A, but not from Streptococcus faecalis, showed dose-dependent inhibition of saliva-mediated aggregation. This inhibitory activity was non-dialyzable, had the same heat and trypsin sensitivity as that seen with intact bacteria, and was not due to enzymatic digestion of the salivary agglutinin. Iso-electric focusing revealed a single active region with a pI of 5.5 which was clearly separated from the bulk of the bacterial proteins.
Chlorpromazine Inhibition of Muscarinic-Cholinergic Responses in the Rat Parotid Gland
Authors: Van Der Ven P.F. , Takuma T. , Baum B.J.
Published: November 2010

The ability of chlorpromazine (CPZ) to inhibit muscarinic-cholinergic secretory events was studied in vitro in rat parotid acinar cells. CPZ inhibited carbachol-induced amylase release in a dose-dependent fashion but had no effect on that elicited by isoproterenol. The inhibition of parotid protein synthesis induced by carbachol, but not that induced by A23187, was blocked by CPZ. CPZ exhibited a dose-dependent inhibition of [3H]quinuclidinyl benzilate (QNB) binding to muscarinic receptors, and altered the KDof the receptor for the ligand. These results are consistent with an ability of CPZ to inhibit muscarinic-cholinergic-induced salivary secretion by complex interference with receptor binding. In addition, CPZ may block parotid-muscarinic responses by impeding a post-receptor signaling step which is proximal to Ca2+mobilization.
Oral Mucosal Langerhans Cells Express DR and DQ Antigens
Authors: Walsh L.J. , Seymour G.J. , Savage N.W.
Published: November 2010

The expression of the Class II antigens HLA-DR and HLA-DQ in human oral mucosa was examined in health and in the presence of inflammation. DQ antigens were detected on dendritic intra-epithelial cells which expressed the Langerhans cells (LC) phenotype T6+, DR+. In healthy gingiva, DR and DQ were co-expressed on Langerhans cells, whereas in an experimental gingivitis (day 8), more LC expressed DR than DQ. Absolute LC numbers were increased in inflammation. Traumatic ulceration of the buccal mucosa resulted in a decrease in the density of T6-, DR-, and DQ-positive cells. Re-population of migrating and regenerated epithelium was complete 10 days after ulcer induction. Disparity between DR and DQ expression was seen in both normal buccal mucosa and throughout the ulcer healing period. These results are in agreement with the reported sequence of Class II antigen expression on lymphoid cells.
Phosphorylation of Salivary Proteins by Salivary Gland Protein Kinase
Authors: Madapallimattam G. , Bennick A.
Published: November 2010

Human saliva contains a number of phosphorylated acidic proline-rich proteins (APRP). Monkey parotid saliva contains a similar protein with the same phosphorylated sequences as the human proteins. A crude protein kinase was prepared from Macaca fascicularis parotid glands which phosphorylated human APRP. The enzyme was activated by Mg2+, it had a pH optimum between pH 7.0 and 7.5, the Kmfor ATP was 78 μmol/L, and for APRP it was 85 μmol/L. Phosphorylation of APRP was independent of cAMP and calmodulin. Phosphate was incorporated as phosphoserine, and the kinase phosphorylated the same residues in dephosphorylated APRP which are phosphorylated in the secreted protein. In addition, the enzyme preparation also phosphorylated dephosphorylated and native APRP in a region which is not phosphorylated in the secreted protein. There was no difference in the rate of phosphorylation of APRPs and their tryptic peptides. The kinase also phosphorylated other dephosphorylated salivary phosphoproteins. An enzyme was demonstrated in the human salivary gland which gave the same pattern of phosphorylation of APRP as did the simian kinase. More than one kinase may be necessary for the observed phosphorylation.
Dental Caries and Staining after Twenty-eight Months of Rinsing with Stannous Fluoride or Sodium Fluoride
Authors: Leverett D.H. , McHugh W.D. , Jensen O. E.
Published: November 2010

The aim of this study was to compare the effects of daily mouthrinsing with aqueous solutions of 0.05% NaF or 0.1% SnF2 on dental caries and tooth staining. The study population consisted of 437 children, aged from 12 to 15 years at baseline, residing in a non-fluoridated community. By stratified random sampling, the subjects were divided into two groups, one group rinsing daily under supervision for 28 months with the NaF solution and the other with the SnF2 solution. The SnF2 group exhibited four to five times as much extrinsic stain as did the NaF group, although the stains were quite mild and not explicitly distinguishable between groups. There were no statistically significant differences between the two groups in terms of total DMFS. However, the increment of pit and fissure caries was 0.9 surfaces fewer for the SnF2 group (p = 0.04), while the increment of smooth surface caries was 0.6 surfaces fewer for the NaF group (p = 0.04). These data suggest that there may be a difference in mechanism of action between SnF2 and NaF rinses.
An Image Analysis System for the Determination of Tooth Dimensions from Study Casts: Comparison with Manual Measurements of Mesio-distal Diameter
Authors: Brook A.H. , Pitts N.B. , Yau F. , Sandar P.K.
Published: November 2010

A first comparison of an image analysis method with classical hand measurement was made using the mesio-distal diameter data derived by the simplest image analysis method, the jawview mode. Fifty casts of male Hong Kong Chinese dental students, mean age 20.4 years, were examined by both methods. The two techniques gave comparable overall results, the correlation coefficients generally being greater than 0.9. A combination of the buccal and occlusal image analysis views gave the best correlation with hand measurement with a comparable variability for different tooth types. For certain teeth, particularly posteriors, reproducibility was better using hand measurement. Optimal weighting of the data from these two different image analysis views can give an "estimated hand measurement" value. Further development of the method to deal with differing orientations of teeth is possible.
Micro-Raman Line Broadening in Synthetic Carbonated Hydroxyapatite
Authors: De Mul F.F.M. , Hottenhuis M.H.J. , Bouter P. , Greve J. , Arends J. , Ten Bosch J.J.
Published: November 2010

Using a Raman microspectrometer, we have recorded Raman spectra of synthetically produced hydroxyapatite samples with varying carbonate contents. The apatites were produced from aqueous solutions at about 40°C. From line-broadening values of the symmetric phosphate stretch, it was concluded that the carbonate substitution in these lattices has a maximum of 4.5 wt %. Both phosphate and hydroxyl ions seem to be involved in the carbonate substitution process.
The Impact of Composite Structure on Its Elastic Response
Authors: Braem M. , Lambrechts P. , Van Doren V. , Vanherle G.
Published: November 2010

The non-destructive determination of Young's modulus of dental composites by means of the fundamental period was found to be reliable and accurate. Post-polymerization effects could clearly be detected. Exponential regression analysis showed a correlation coefficient of 0.92, after logarithmic transformation, with volumetric filler content.

The high accuracy and reliability of the measurements themselves are reflected in low standard deviations. The results are in excellent agreement with those of other investigations. Furthermore, the ease and speed of operation make this new procedure a powerful laboratory tool for material-testing and practical large-scale investigations.
Dental Fluorosis in an Area of Kenya with 2 ppm Fluoride in the Drinking Water
Authors: Manji F. , Baelum V. , Fejerskov O.
Published: November 2010

We examined 102 children born and reared in an area of rural Kenya with 2 ppm fluoride in the drinking water for dental fluorosis, using the index developed by Thylstrup and Fejerskov (1978). The prevalence of dental fluorosis was 100%, 92% of all teeth exhibited a TFI score of 4 or higher, and 50% of the children had pitting or more severe enamel damage in at least half the teeth present. The fluorotic changes showed a high degree of bilateral symmetry. The intra-oral distribution of the changes corresponded to the pattern of fluoride-induced enamel changes reported by other investigators in high-fluoride areas. The high prevalence and severity of dental fluorosis in a 2-ppm-fluoride area is in accordance with recent observations on dental fluorosis being very prevalent in Kenya, even in low-fluoride areas (<1 ppm F). We are presently investigating the possible variables which may explain this unexpected susceptibility of large populations in Eastern Africa to fluorosis from exposure to low levels of fluoride.
The Influence of 5-Hydroxytryptamine (Serotonin) on Blood Flow in the Dog Pulp
Authors: Kim S. , Trowbridge H.O. , Dorscher-Kim J.E.
Published: November 2010

The effect of intra-arterial injection of 5-hydroxytryptamine (5-HT) on pulpal blood flow of the dog was determined using the 15-μm radioisotope-labeled microsphere injection method. Pulpal blood flow was significantly reduced following the 5-HT injection. This decrease in blood flow appeared to be due to vasoconstriction as determined by an increase in pulpal vascular hindrance. However, our findings do not preclude the possibility that blood flow was reduced as a result of passive compression of venules produced by vasodilation in a low-compliance environment.
Effects of Fluorides on in vitro Acid Production by Dental Plaque
Authors: Bibby B.G. , Fu J.
Published: November 2010

A method that holds human dental plaque on a glass micro-electrode has been used to measure the pH depressions in plaque samples exposed to different concentrations of fluoride from sodium fluoride or sodium monofluorophosphate. Fluoride from both sources gave some inhibition of sucrose-induced acid formation at levels as low as 10 ppm and parallel results at other test concentrations of up to 200 ppm F. Repeated exposures of plaque to fluoride solutions did not interfere with its subsequent ability to ferment sucrose.
An Electrochemical and Multispectroscopic Study of Corrosion of Ag-Pd-Cu-Au Alloys
Authors: Niemi L. , Minni E. , Ivaska A.
Published: November 2010

Corrosion of a multi-phase Ag-Pd-Cu-Au-based commercial dental casting alloy and a Cu-Pd-rich and Ag-rich single-phase alloy was studied by open-circuit potential measurements, atomic absorption spectrometry, and electron spectroscopy. The alloys were immersed in an artificial saliva solution for 24 hr while the open-circuit potentials of the alloys were measured. The potentials were found to stabilize at certain levels after a steep rise during the first hours of the experiment. Cu was found to dissolve considerably from the Cu-Pd-rich alloy, with simultaneous enrichment of Pd in the surface layer of the alloy. Ag dissolved slightly from the Ag-rich alloy, but both Cu and Ag were found to dissolve from the multi-phase alloy. Neither Pd nor Au dissolved from any of the alloys studied.
The Effects of Sorbate on Oral Streptococci Grown in Continuous Culture
Authors: Rogers A.H.
Published: November 2010

The antimicrobial effect of potassium sorbate on Streptococcus mutans and S. milleri grown in continuous culture was determined at pH values of 7.0, 5.5, and 5.0. Organisms were grown glucose-limited at a dilution rate of D = 0.1 h-1, corresponding to a doubling time of ca. seven hours, in a chemically defined medium under an atmosphere of 5% CO2 in N2. After equilibration at the appropriate pH level, the culture vessel was pulsed with potassium sorbate to a final concentration of 20 mmol L-1 or with sorbate followed almost immediately by a pulse of glucose (to 40 mmol L-1); that is, the cultures were exposed to transient excesses of sorbate with and without glucose - such as might occur during meals.

At pH 7.0, sorbate had virtually no effect on glucose uptake and on the, albeit transient, increase in growth rate and acid production by both organisms. At pH 5.5 and 5.0, both cell viability and acid production in S. milleri were depressed following a pulse of sorbate, the effect being even more marked after a sorbate/glucose pulse. At low pH, the uptake of glucose in the presence of sorbate was drastically reduced. The effect on S. mutans was less marked, but growth and acid production were greatly depressed at pH 5.0 following consecutive pulses of sorbate.

The antimicrobial effect of the widely used preservative potassium sorbate, at low pH, is confirmed for oral streptococci, and it is suggested that continuous culture offers a relevant system for testing potential antimicrobial agents.
Effects of Ammonia and Volatile Fatty Acids Produced by Oral Bacteria on Tissue Culture Cells
Authors: van Steenbergern T.J.M. , van der Mispel L.M.S. , de Graaff J.
Published: November 2010

Culture filtrates of several bacterial species isolated from the oral cavity were tested for their effects on two types of tissue culture cells: Vero cells, the continuous cell line of African green monkey kidney cells; and chondrocytes, isolated from 15-day-old chick embryo tibiae. Only a limited number of bacterial species — i.e., the asaccharolytic black-pigmented Bacteroides species and Fusobacterium species - affected the two cell types. The effect on Vero cells, detected by the rounding of the cells, correlated with the butyric acid concentration in the bacterial supernatant, which confirms previous findings. A small enhancement of this effect was found with propionic acid and ammonium ions. The same strains which affected Vero cells also affected chondrocytes, detected by a vacuolization of the cells. However, volatile fatty acids on their own had no visible effect on these cells. Instead, ammonium ion in the culture filtrate, when present in concentrations of 20 to 60 mmollL, proved to be responsible for vacuolization of the chondrocytes. The volatile fatty acids (butyric and propionic) had a limited additive effect. No effects were visible with cell extracts of the bacteria.
The Intra-oral Effect on Enamel Demineralization of Extracellular Matrix Material Synthesized from Sucrose by Streptococcus mutans
Authors: Zero D.T. , van Houte J. , Russo J.
Published: November 2010

The role of extracellular matrix material (EMM) synthesized from sucrose (S) by Streptococcus mutans IB-1600 in altering the demineralizing potential of artificial plaque was evaluated with an intra-oral enamel demineralization test (IEDT). The artificial plaque samples were prepared from cells cultivated in Todd-Hewitt broth (THB) supplemented with various S concentrations and by mixing THB-grown cells with increasing proportions of EMM (heat-killed THB + 2% S-cultivated cells). The samples were also evaluated for cell density (DNA content) and acidogenicity in vitro (pH-stat), as well as for in situ pH changes during a 45-minute intra-oral test following a 10% glucose rinse. An increase in the proportion of EMM relative to cell density was associated with an increase in enamel demineralization. This trend reversed when the ratio of cells to EMM was less than 1 :19. Experiments involving strains of S. mitis, S. sanguis, and S. salivarius suggested a similar effect of EMM. The intra-oral pH data suggest that the presence of EMM may enhance demineralization by altering diffusion properties of plaque.
Hamster Cheek Pouch Carcinoma: Effect of Incision and Cortisone on Growth, Invasion, and Metastasis
Authors: Tsiklakis K. , Wood N.K. , Toto P.D. , Doemling D.B.
Published: November 2010

After cheek pouch carcinomas were induced in hamsters by the application of dimethylbenzanthracene (DMBA) to the right pouch for 13 weeks, the animals were divided into four groups and observed for seven more weeks. The control group received no further treatment, two experimental groups had incisional biopsies performed on tumors in their pouches, one of these groups also received injections of cortisone throughout the 20-week experimental period, and a fourth group received cortisone only. The wet weights of the cancerous cheek pouches were determined, and the submandibular and parotid salivary glands with associated cervical lymph nodes, the lungs, and the liver were examined with light microscopy. The cancerous pouches of the animals that received cortisone weighed significantly less than those of animals that received no cortisone but had incisional biopsies of the tumors. There was no significant difference in the degree of histodifferentiation of the tumors among the four groups. The animals in the two groups that received cortisone had significantly more tumors that were invasive than did the animals that did not receive cortisone. Cervical lymph node metastasis occurred in 21% to 38% of the animals but was not significantly different in the four groups. Distant metastases to the lungs or the liver were not found. Incisional biopsy of the tumors stimulated local growth of the cheek pouch tumors, and systemic cortisone administration produced more invasive cheek pouch tumors.
Surface Enamel Fluoride Concentrations of Different Types of Human Teeth in a High- and Near-optimal-fluoride Area
Authors: Grobler S.R. , Louw A.J. , Rossouw R.J.
Published: November 2010

The surface enamel (~ 4 μm) fluoride concentrations of different tooth types (11, 21, 22, 23, 24) were determined in 12-13-year-old children who were life-long residents in a naturally high (3.70 ppm) and in a near optimal (0.62 ppm) fluoride area. Enamel biopsies were taken by means of an acid-etch procedure, and the fluoride levels were measured with an adapted fluoride-ion-selective electrode. The enamel fluoride concentrations were related to the fluoride levels of the drinking water, and it appeared that the enamel fluoride concentrations of the different tooth types (except for the pre-molars) were associated with the length of the pre-eruptive period. In general, for both areas, the mean enamel fluoride concentrations increased from the central incisor to the lateral incisor and were found to be the highest in the canine, while the mean fluoride content of the first pre-molar nearly equaled that of the central incisor. No statistically significant differences (p>0.05) were found between the enamel fluoride concentrations of the different tooth types or the etching depths, from different sexes.
Dexamethasone Inhibits Formation of Osteoclast-like Cells in Bone-marrow Cultures
Authors: Pharoah M.J. , Heersche J.N.M.
Published: November 2010

Our observations confirm the previously reported observation that multinucleated cells develop within a two-week period in cat bone-marrow cultures. Calcitonin induces cytoplasmic contraction in these multinucleated cells, which indicates that they resemble osteoclasts. After seven days of culture, cat bone-marrow cultures contain both non-attached mononuclear cells and attached mononuclear and polynuclear cells. We have cultured the attached and non-attached cell populations separately from day 7 onward and have observed the appearance of multinucleated cells in both culture systems. In both types of cultures, dexamethasone (10 -9-10-7 mol/L) reduced the number of multinucleated cells. This effect of dexamethasone was more rapid in the cultures derived from non-attached cells (seven days) than in cultures derived from attached cells (14 days), suggesting that two different mechanisms are involved. Dexamethasone had no effect on the survival of multinucleated cells already formed.
The Influence of Chemically-induced Modifications of Root Surfaces on Cell Migration, Attachment, and Orientation
Authors: Lowenberg B. , Thibault J. , Lawrence C. , Sodek J.
Published: November 2010

Surface demineralization of tooth root surfaces has been shown to improve re-attachment of cells and to promote tissue reconstruction following periodontal surgery. Exposure of collagen fibers has been thought to facilitate migration, attachment, and orientation of fibroblasts on the root surface. However, using an in vitro assay, we have found that both attachment and orientation of human gingival fibroblasts on demineralized dentin surfaces are further improved following digestion of the exposed collagen with bacterial collagenase. In contrast, pronase and trypsin digestion of the surface collagen had no significant effect, whereas heat denaturation had an inhibitory effect. Dissociative extraction of the demineralized dentin slices with 4 mol/L guanidine hydrochloride (GuHCl) also improved attachment and orientation, and when undemineralized dentin was subjected to dissociative extraction, cell attachment was comparable and orientation, superior to that on demineralized surfaces. These studies indicate that demineralization is not a prerequisite for facilitating attachment, and that enhanced attachment and orientation of cells are not dependent upon a collagenous substratum.
In vivo Measurements of Sulcal Plaque pH After Topical Applications of Sorbitol and Sucrose in Rats Fed Sorbitol or Sucrose
Authors: Firestone A.R. , Navia J.M.
Published: November 2010

To test whether adaptation to sorbitol could be observed in rat plaque, we made pH measurements of rat sulcal plaque in vivo, following topical application of 10% sorbitol solution. Rat pups were inoculated orally with S. mutans 6715 and fed diet MIT 305 (5% sucrose) for 16 days. Baseline sulcal plaque pH response of these rats to topical application of 10% sorbitol solution was measured. One group of 16 rats was then fed 20% sucrose in the diet, and a second group 20% sorbitol. After 13 days' feeding of the experimental diets (four days were used for accommodation to dose, and nine days at the 20% level for sorbitol), there was a significantly greater (p<0.01) drop in pH following topical application of 10% sorbitol in this group than in the sucrose-fed group. There was no difference in the pH response of the two groups to topical application of a 10% sucrose solution when tested six days later. The sulcal enamel caries score was significantly higher (p<0.001) in the sucrose group, but buccal enamel scores were similar in both groups.

Adaptation in rat plaque took place, and could be measured in vivo as an increased drop in sulcal plaque pH following topical application of sorbitol. It is not clear whether this adaptation was primarily due to selection of sorbitol-fermenting micro-organisms, or, more likely, by induction of sorbitol-specific enzymes. Relative to the sucrose-containing diet, the sorbitol diet was hypocariogenic, even under experimental conditions.
Remineralization by a Monofluorophosphate Dentifrice in vitro of Root Dentin Softened by Artificial Caries
Authors: Mellberg J.R. , Sanchez M.
Published: November 2010

Artificial caries-softened dentin lesions in root surfaces were treated with 50% slurries of a monofluorophosphate (MFP®) dentifrice or a placebo dentifrice twice daily for ten days. Between dentifrice treatments, the lesions were kept in a remineralizing solution. Both treatments resulted in statistically significant remineralization, with the MFP dentifrice being significantly better than the placebo. Deposition of new mineral from the MFP dentifrice occurred about equally at or within the surface zone and at the deepest part of the lesion. Mineral deposition from the placebo appeared to be more uniformly distributed within the lesion.