bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of β2-Adrenoceptor Agonists on Saliva Proteins and Dental Caries in Asthmatic Children
Authors: Ryberg M. , Möller C. , Ericson T.
Published: November 2010

Twenty-four children, from 10 to 20 years old, with asthma treated with β2-adrenoceptor agonists were matched with healthy controls of the same age, sex, and social background. Stimulated whole and parotid saliva was collected, and decayed and filled tooth surfaces as well as oral hygiene habits were recorded. The dietary and sugar intake was carefully checked by a four-day dietary record. The asthmatic children had a 26% lower (p<0.05) value for secretion rate of whole saliva. Seventy percent of the children with Streptococcus mutans counts >2×105colony-forming units/mL of whole saliva belonged to the asthmatic group (p<0.05). The concentrations of total protein and amylase in parotid saliva were significantly lower for the asthmatic children. The concentrations of potassium, salivary peroxidase, bacteria-aggregating glycoproteins, and secretory IgA were not affected, but the secretion rate of parotid saliva was 36% lower in the asthma group (p<0.05). Oral hygiene and dietary habits did not differ between the groups. The asthmatic children had higher DFS scores, but these were not significantly different from those of the healthy controls (p = 0.07). We suggest that subjects with asthma treated with β2-receptor agonists should receive special prophylactic attention.
Methotrexate-induced Changes in Rat Parotid and Submandibular Gland Function
Authors: McBride R.K. , Harper C. , Siegel I.A.
Published: November 2010

Methotrexate (MTX) was injected intraperitoneally at a dose of 15 mglkg into adult rats daily for three consecutive days. When compared with saline-injected, ad libitum-fed rats or pair-fed saline-injected rats, MTX decreased unstimulated parotid gland weight, RNA content, and amylase content. RNA content was also decreased in submandibular glands. The pqrotid and submandibular gland outputs of sodium and chloride, but not that of potassium, were decreased following MTX injection. Ductal perfusion demonstrated decreased net efflux of sodium and chloride from the excretory duct of the submandibular gland. The effects of MTX on unstimulated parotid gland weight, RNA content, and amylase content are consistent with its ability to inhibit protein synthesis through depletion of folate co-factors. However, the mechanism by which the alterations in ion transport occurred is not clear at this time.
Bacterial Endotoxin Inhibits Migration, Attachment, and Orientation of Human Gingival Fibroblasts in vitro and Delays Collagen Gel Contraction
Authors: Pitaru S. , Soldinger M. , Madgar D. , Metzger Z.
Published: November 2010

The purpose of this study was to assess the effect of endotoxin adsorbed to dental surfaces and to collagen type I on the migration, attachment, and orientation of human gingival fibroblasts (HGF). Transversely cut porcine tooth root slices (RS), 200 μm thick, were prepared. Half of the RS obtained were partially demineralized in EDTA. Half of the demineralized and non-demineralized RS were incubated with 400 μg/mL of endotoxin for 24 hr, whereas the other half were maintained in PBS and served as controls. Experimental and control RS were placed on confluent layers of HFG and cultured for six days.

Cell migration toward and cell attachment to the periphery of the RS and the formation of oriented cell sheets were assessed by means of photographic techniques. Additionally, six-day-old cultures were fixed and processed for SEM observation. In separate experiments, the effect of endotoxin on cell attachment to collagen type I and on contraction of three-dimensional collagen gels was assessed.

It was found that: (i) bacterial endotoxin inhibited migration and attachment of HGF to both demineralized and non-demineralized cementum and interfered with the development of oriented cellular structure ; (ii) the inhibitory effect was significantly more pronounced for non-demineralized than for demineralized cementum; (iii) the morphology of HGF attached to endotoxin-treated dental surfaces was altered compared with that of their controls; and (iv) bacterial endotoxin inhibited cell attachment to collagen type I and delayed the contraction of collagen gel.
Shear Strength of the Composite Bond to Etched Porcelain
Authors: Stangel I. , Nathanson D. , Hsu C.S.
Published: November 2010

The shear bond strength of composite resin to porcelain was investigated to optimize variables for bonding porcelain laminate veneers. Scanning electron microscopy was initially used to examine the surface configuration of porcelain prepared under various conditions. A factorial experiment was undertaken to determine the effects of three different bonding methods on both etched and non-etched porcelain. Composite resin was bonded to the porcelain groups using (a) unfilled resin, (b) silane, and (c) silane with dentin adhesive. The results indicated a significant difference in shear bond strength for the three bonding groups, depending on the porcelain surface condition. For the unetched samples, significant differences in bond strength were obtained for all three bonding conditions. However, for the etched group, there were no differences between the silane and silane-with-dentin-adhesive groups. Porcelain etching significantly increased bond strength across all three bonding methods and was the main contributor to the obtained values.
Relationship Between Dental Plaque Indices and Bacteria in Dental Plaque and Those in Saliva
Authors: Schaeken M.J.M. , Creugers T.J. , Van Der Hoeven J.S.
Published: November 2010

A variety of indices has been developed for the quantitation of dental plaque. The aim of this study was to determine the correlation between the Löe plaque index and the number of bacteria on the same tooth. Furthermore, the effect of plaque accumulation on the salivary counts of some dental plaque organisms was estimated. Twenty volunteers were asked to abstain from all oral hygiene for a one-week period. Clinical indices and bacteriological samples were taken at the start and at the end of the experimental period. After an interval of seven days, the experiment was repeated. The relationship between the Löe plaque index and the total bacterial counts on the same area of the tooth was found to be highly significant. After seven days without oral hygiene, the total counts and the Actinomyces viscosus/naeslundii and Streptococcus sanguis counts in dental plaque had increased by approximately two log units, while the Streptococcus mutans counts had increased by more than one log unit. The large increase in the number of bacteria on the teeth was reflected in the salivary counts of the Actinomyces species, but not in the S. sanguis or S. mutans counts. This was due to differences in ecological habitats of these species in the mouth. Highly significant correlations were found between the S. mutans level in dental plaque and the salivary level, and between the S. mutans counts of the subjects in the first and second trials of the experiment.
Effects of Cheese Extract and its Fractions on Enamel Demineralization in vitro and in vivo in Humans
Authors: Silva M.F. de A. , Burgess R.C. , Sandham H.J.
Published: November 2010

In order to isolate and identify the most active anti-cariogenic components(s) of aqueous cheese extract (CE), we separated it into low (LMW) (MW < 500), medium (MMW) (500 < MW < 10,000), and high (HMW) (MW > 10,000) molecular weight fractions by means of the Amicon ultrafiltration system. These fractions were then tested in vitro with a bacterial system containing S. mutans, adapted from that of Turtola (1977). The LMW fraction reduced the demineralization caused by the fermentation of sucrose by 96% (p <0.001) as compared with the water control; this was not significantly different from a 50% concentration of the CE. The MMW and HMW fractions reduced demineralization by 36 and 42%, respectively. The concentrations of acid-soluble calcium and phosphorus in CE, LMW, MMW, and HMW were 1509 and 462, 991 and 310, 231 and 7, and 162 and 3 μg/mL, respectively. A solution containing the same levels of calcium and phosphorus as CE was somewhat more effective in reducing demineralization in vitro than was CE itself (p <0.01). In vivo , the addition of these same calcium and phosphorus levels to a 10% sucrose solution reduced its cariogenicity by 67% (p <0.001), as judged by the intra-oral cariogenicity test (ICT). Plaque calcium and phosphorus concentrations were significantly higher in the ICT plaque samples subjected to the sucrose-Ca,P solution (p <0.01) than in the sucrose control. The resting pH, minimum pH, and shape of the pH curves produced by the sucrose control and sucrose-Ca,P were similar. These results indicate that most of the anti-cariogenic effect of cheese extract is due to its calcium and phosphorus content, which probably influences the demineralization-remineralization process.
Pharmacological of an Intra-oral Fluoride-releasing Device in Adolescents
Authors: Kula K. , Kula T. , Davidson W. , Parker E.
Published: November 2010

The purpose of this study was to quantify fluoride (F) concentrations in body fluids of adolescents wearing two intra-oral fluoride-releasing devices (IFRDs) designed to release 0.10 mg Fiday. Fluoride concentrations were determined potentiometrically.

No significant increases occurred in urine or serum F concentratiotis during the 26-week device phase. Elevated salivary F concentrations were maintained throughout the device phase when broken or depleted IFRDs were replaced. However, salivary F concentrations returned to pre-device phase values, by 26 weeks when the original IFRDs were maintained. These findings suggest that IFRDs can significantly elevate salivary F concentrations of adolescents without significant elevations in systemic F concentrations.
A Cross-reactivity Study of Whole Genomic DNA Probes for Haemophilus actinomycetemcomitans, Bacteroides intermedius, and Bacteroides gingivalis
Authors: Strzempko M.N. , Simon S.L. , French C.K. , Lippke J.A. , Raia F.F. , Savitt E.D. , Vaccaro K.K.
Published: November 2010

In this study, we evaluated the sensitivity and specificity of whole genomic DNA probes for the periodontal pathogens Haemophilus actinomycetemcomitans, Bacteroides intermedius, and Bacteroides gingivalis. By means of these probes, DNA hybridizations were performed against other organisms found in the oral cavity and organisms previously determined to be genetically similar. All three probes were sensitive to 103 cells for their respective organism. The H. actinomycetemcomitans probe cross-reacted with several haemophilus strains, Wolinella, and Campylobacter, indicating that H. actinomycetemcomitans-specific sequences would have to be identified and cloned for accurate detection of this organism in heterogeneous patient samples. Only very low levels of cross-reactivity were observed between the B. intermedius probe and representative black-pigmented Bacteroides. This low level of cross-reactivity did not interfere with the accurate identification of B. intermedius in sample evaluations. The B. gingivalis probe showed no cross-reactivity. Whole genomic probes will be used for the detection of B. intermedius and B. gingivalis in patient samples.
Lumen Formation During Development of the Rat Submandibular Gland
Authors: Cutler L.S. , Mooradian B.A.
Published: November 2010

This study utilized electron microscopy and enzyme histochemistry to examine the morphological steps associated with the formation of a lumen in the end-buds of the embryonic rat submandibular gland. Lumen formation involved the development of junctional complexes by the central cells of the end-buds late on the 16th day of gestation. These junctional complexes established the apical domains of the presecretory cells, and cytofilament aggregates were observed beneath the presumptive luminal plasma membranes. This central area of the end-buds showed strong myosin ATPase activity, presumably associated with the cytofilaments. On the 17th day of gestation, small lumina appeared at the sites delineated by the junctional complexes. The myosin ATPase activity appeared to surround the newly opened lumina. By the 18th day of gestation, microvilli were seen projecting into the lumina, and secretory granules were often visible in the apical cytoplasm near the luminal plasma membranes of the early secretory cells. Myosin ATPase activity was greatly reduced once the lumina had formed.
Incorporation into Human Enamel of Fluoride Slowly Released from a Sealant in vivo
Authors: Tanaka M. , Ono H. , Kadoma Y. , Imai Y.
Published: November 2010

Fluoride incorporation into human enamel from an experimental sealant resin in vivo was investigated. The sealant consisted of a newly synthesized methacryloyl fluoride-methyl methacrylate (MF-MMA) copolymer resin, which contains acidic fluoride covalently bonded to carbonyl groups and releases fluoride ions slowly by hydrolysis in an aqueous environment. This experimental sealant was applied to the enamel of permanent pre-molars and the control sealant without MF-MMA copolymer to that of the contralateral teeth. Fluoride concentration was determined by an enamel biopsy procedure with acid-etching four weeks after the sealant application. As much as 3500 ppm fluoride was found to be deposited at 10 μm depth in the enamel under the MF-MMA copolymer sealant. The increase in fluoride concentration was significant even at 60 μm. Of the fluoride incorporated into the enamel, from 70 to 80% was present as a tightly bound form. This resin sealant is expected to protect the enamel from caries attack even after detachment of the sealant.
Temporomandibular Joint Morphology in Two Australian Aboriginal Populations
Authors: Richards L.C.
Published: November 2010

The morphology of the temporomandibular joints in two Australian populations with previously established differences in patterns of tooth wear and craniofacial morphology did not differ significantly from that described in other comparable populations. The relationships between age and linear and angular measures of joint form were generally not significant, but the shape of the mandibular condyle was age-related, with flattening and cavitation of the posterior and medial aspects being more common in older age groups. Comparison of tooth-wear data in groups with different mandibular condylar shapes suggested that rapid anterior tooth wear was associated with flattening or cavitation of the condyle, while relatively rapid posterior tooth wear was more commonly associated with a convex condylar shape.
Immunocytochemical Evidence for the Coexistence of Catecholestrogen and Catechol-O-methyltransferase in the Rat Parotid Gland
Authors: Inoue K. , Yoshizawa I. , Creveling C.R.
Published: November 2010

Catechol-O-methyltransferase (COMT) (EC 2.1.1.6) and catecholestrogen were localized in the parotid gland of the rat by immunocytochemical methods. Specific immunoreactive deposits for COMT and catecholestrogen were found in the cytoplasm of duct cells, but only those for COMT in myo-epithelial cells. The pattern of localization of COMT and catecholestrogen in the parotid gland suggests a functional relationship between COMT and catecholestrogen.
Setting Stress in Composite Resin in Relation to Configuration of the Restoration
Authors: Feilzer A.J. , De Gee A.J. , Davidson C.L.
Published: November 2010

The setting stress in composite resins was studied as a function of restoration shape. The shape is described by the configuration factor, C, the ratio of the restoration's bonded to unbonded (free) surfaces. In an experimental set-up, the shape of the restoration was simulated by cylindrical forms of various dimensions. The shrinkage stress was measured continuously. It was shown that in most of the clinically relevant cavity configurations, the stress-relieving flow is not sufficient to preserve adhesion to dentin by dentin-bonding agents.
Comparison of the Effects of Fluoride and the Ionophore Nigericin on Acid Production by Streptococcus mutans and the Resultant in vitro Enamel Demineralization
Authors: Van Loveren C. , Fielmich A.M. , Ten Brink B.
Published: November 2010

In an in vitro demineralization experiment with a plaque of S. mutans C180-2 over enamel, the effect of 0.5 mmol fluoride/L was compared with that of 10 nmol nigericin/L. Since the effects of both substances on the acid production in a dense cell suspension were of the same magnitude, and since nigericin did not affect the enamel solubility, the present demineralization experiment may differentiate between the effect of fluoride on bacterial metabolism alone and the combined effect of fluoride on both the bacterial metabolism and enamel solubility. In our experiments, the effect on bacterial metabolism accounted for 75% of the caries-inhibiting effect of fluoride.

Microradiographic data showed subsurface lesions in the control and nigericin group and a slight surface-softening in the fluoride group. In addition, the effects of fluoride and nigericin on the cellular internal pH during glycolysis were studied. Analysis of these data suggested that glycolysis was inhibited when the intracellular pH reached about pH 5.2, which supports the view that acidification of the cell cytoplasm is a mechanism by which fluoride inhibits glycolysis.
Characteristics of Trypsin-like Activity in Subgingival Plaque Samples
Authors: Bretz W.A. , Loesche W.J.
Published: November 2010

Previous studies have demonstrated that the hydrolysis of the trypsin substrate N-benzoyl-DL-arginine-2-naphthylamide (BANA), by subgingival plaque obtained from a single site, correlates best with the numbers and proportions of spirochetes in plaque samples and may serve as an indicator of clinical disease. In this investigation, we determined whether the association between BANA hydrolysis and spirochetes could be obtained in pooled subgingival plaque samples. Concomitantly, the characteristics of this reaction in terms of substrate type and concentration, microbial numbers needed to give a positive reaction as assessed by microscopic counts, rapidity of hydrolysis, and the effect of pH and various additives on the plaque BANA hydrolytic activity have been studied in pooled plaque samples from patients who were periodontally healthy or diseased. In addition, it was determined whether BANA hydrolytic activity found in subgingival plaque reflected contributions from saliva and supragingival plaque. Results indicated that the assay can best be performed with 0.67 mmol/L BANA at pH 7.0. EDTA and CaCl2 gave a slight inhibition and DTT a slight enhancement of the BANA reaction by the pooled plaque suspensions. The majority of the reactions (85%) developed their full color after overnight incubation. BANA hydrolysis was not found in saliva and occurred with much greater frequency in subgingival plaque as opposed to supragingival plaque. Analysis of the data indicated that BANA hydrolysis by pooled subgingival plaque samples is a suitable test for the detection of spirochetes when two or three spirochetes per high microscopic field are present in the sample.
A Cephalometric Study of Young Marmosets (Callithrix jacchus)
Authors: Sampson W.J. , Townsend G.C. , Goss A.N.
Published: November 2010

Linear and angular measurements of young marmosets taken at three-month intervals from a series of cephalograms are presented. They show that linear craniofacial development was largely complete by six months of age, subsequent angular changes being mainly related to dental development. No sexual dimorphism was apparent, and there was substantial homogeneity in results for animals of the same age. Thus, marmosets, with their low cost, ease of handling, and rapid maturation, may provide a useful animal model for craniofacial research.
Lack of Genotoxic Effects of Fluoride in the Mouse Bone-marrow Micronucleus Test
Authors: Li Y. , Dunipace A.J. , Stookey G.K.
Published: November 2010

The purpose of this investigation was to examine the potential genotoxic influence of sodium fluoride (NaF) on mammalian cells by means of a mouse bone-marrow micronucleus test. Mice of genotype B6C3F1were obtained at about eight weeks of age and maintained on a low-fluoride diet (< 0.2 ppm F) and distilled water ad libitum throughout the experiment. At approximately 12 weeks of age, the animals were randomly assigned to seven groups, with multiple sampling schedules. The animals were intubated with various doses of NaF, ranging from 0.1 mg/kg to the Maximum Tolerable Dose (MTD), with sampling at 30, 48, and 72 hours after treatment. Negative (distilled water) and positive (cyclophosphamide) controls were included. Coded slides of femur marrow cells were prepared and examined, without identification as to treatments, for the frequency of micronucleated polychromatic erythrocytes (MN-PCE). The humera were analyzed for fluoride for monitoring of the absorption of fluoride following oral intubation. The results indicated that doses of NaF up to the MTD did not significantly increase the frequencies of MN-PCE when compared with the negative controls, although the bone fluoride content increased as the dose of NaF was increased.
Collagen Phagocytosis by Fibroblasts in the Periodontal Ligament of the Mouse Molar During the Initial Phase of Hypofunction
Authors: Beertsen W.
Published: November 2010

This study was undertaken in order to determine whether hypofunction of teeth is associated with changes in collagen phagocytosis by fibroblasts of the periodontal ligament. In mice, the lower right molars were extracted and the animals killed one, two, three, four, or seven days later. The maxillary first molars with their surrounding periodontium were processed for electron microscopy and their periodontal ligament subjected to morphometric analysis. It was observed that, whereas the volume density of extracellular collagen in the ligament of the hypofunctional molars decreased from 50% to 30% during the course of the experiment the fraction of fibrillar collagen ingested by the cells increased over two-fold. This increase was already manifest very shortly after the onset of the experiment and offers an explanation for the net loss of collagen fibrils from the extracellular space.
Adherence of Treponema denticola to Modified Hydroxyapatite
Authors: Cimasoni G. , McBride B.C.
Published: November 2010

Small samples of hydroxyapatite (HA) beads were coated with 10 μL of either saliva, serum, human crevicular fluid, or a preparation of lysosomal enzymes from human polymorphonuclear leucocytes (PMN), before being added to suspensions of Treponema denticola. The beads were then observed with the scanning electron microscope.

Abundant T. denticola were found to adhere to HA or HA coated with saliva, serum, or crevicular fluid. Coating the beads with lysosomal enzymes consistently prevented the adhesion of T. denticola. Adhesion of treponemes to hard surfaces, modulated by enzymes from PMNs, could represent a new virulence factor for these bacteria.
The Effect of Desalivation on Coronal and Root Surface Caries in Rats
Authors: Bowen W.H. , Pearson S.K. , Young D.A.
Published: November 2010

Although the presence of coronal caries is declining in much of the Western Hemisphere, the prevalence of root surface caries is likely to increase as teeth are retained longer than heretofore. At the same time, an increasing number of the population suffer from dry mouth as a result of taking prescription drugs, with an apparent concomitant increased susceptibility to root surface caries. This study attempted to develop an animal model which would aid in the exploration of the effects of desalivation and the development of root surface caries. Animals were desalivated, infected with Actinomyces viscosus and Streptococcus mutans (sobrinus) 6715, and fed a cariogenic diet. Coronal caries developed rapidly in the animals; sufficient disease was present after two weeks to permit evaluation of potential therapeutic agents. Alveolar bone loss and root surface lesions developed in three to four weeks. S. mutans (sobrinus) and A. viscosus established readily in all animals; however, as the investigation progressed, populations of the latter declined, possibly because of the highly acidogenic environment. This model will facilitate investigation of the influence of hyposalivation and help in the exploration of agents to alleviate the adverse effects of salivary gland dysfunction.
A Comparative Study of Human Periodontal Ligament Cells and Gingival Fibroblasts in vitro
Authors: Somerman M.J. , Archer S.Y. , Imm G.R. , Foster R.A.
Published: November 2010

Both periodontal ligament and gingival tissue are thought to harbor cells with the ability to stimulate periodontal regeneration, i.e., formation of new bone, cementum, and connective tissue attachment. To understand further the role of these cells in the regenerative process, we compared human periodontal ligament cells and gingival fibroblasts, both derived from the same patient, same passage, in vitro. Protein and collagen production was significantly greater in periodontal ligament cells when compared with that of gingival fibroblasts. In addition, periodontal ligament cells had higher alkaline phosphatase levels when compared with those of gingival fibroblasts.
A Feedback Method to Determine the Three-dimensional Bite-force Capabilities of the Human Masticatory System
Authors: van Eijden T.M.G.J. , Koolstra J.H. , Brugman P. , Weijs W.A.
Published: November 2010

A feedback procedure is described that enables a subject to exert bite forces in certain specified directions during static contraction of the human jaw muscles. The output of a three-dimensional transducer is fed to a computer. The magnitude and direction of the resultant force are computed and visualized by a cross on the screen of the computer terminal. In a bite experiment, the subject is instructed to match this cross with a point on the screen, representing the desired bite-force direction. The procedure allows for determination of the range of possible bite-force directions and magnitudes for various locations on the dental arch and study of the concomitant recruitement patterns of the jaw muscles. Some examples of measurement are given.
The Relationship Between Oxide Adherence and Porcelain-Metal Bonding
Authors: Mackert J.R. , Ringle R.D. , Parry E.E. , Evans A.L. , Fairhurst C.W.
Published: November 2010

The lack of a reliable bond test has hindered the elucidation of the mechanism for porcelain-metal bonding in dental systems, because a test capable of detecting differences among porcelain-metal bonds of various qualities is required before the reasons for these differences may be ascertained. A method was developed in the present study whereby specimens of alloys with differing physical properties may be deformed to a constant strain to yield a fracture surface suitable for measurement of the area fraction of retained porcelain by an x-ray spectrometric technique described previously. The method proved sufficiently discriminating that significant differences could be found in 48 of the possible 66 comparisons among alloys and treatments. Linear regression analysis revealed a strong correlation (r 2 = 0.947) between the area fractions of retained porcelain measured in the present study and the oxide adherence strength values measured previously. This strong correlation, when considered in light of the literature evidence for the presence of an oxide layer at the porcelain-metal interface, provides compelling support for the oxide layer theory of porcelain-metal bonding in dental alloy systems.
Fraunhofer Diffraction of Light by Human Enamel
Authors: O'Brien W.J.
Published: November 2010

Fraunhofer diffraction patterns of human enamel samples were photographed with a helium-neon laser beam (λ = 633 nm). The first-order diffraction angle was in reasonable agreement with a prediction based upon enamel prisms acting as a two-dimensional grating. These results support the hypothesis that enamel diffracts light because of the periodic structure of enamel prisms with interprismatic spaces, which act as slits.
Intra-oral Retention of Fluoride by Bovine Enamel from Amine Fluoride Toothpaste and 0.4% Amine Fluoride Liquid Application
Authors: Ten Cate J.M. , Exterkate R.A.M. , Rempt H.E.
Published: November 2010

The purpose of this study was to compare in vivo fluoride accumulation in enamel and in enamel lesions from a single topical fluoride application and daily toothbnsshing with a fluoride dentifrice. Amine fluoride preparations were used for both products. Intra-oral appliances with bovine enamel specimens were worn by volunteers during a period of seven weeks. After this period, the specimens were analyzed for fluoride uptake and change in demineralization susceptibility. The results demonstrated that lesions had a high fluoride uptake capacity. Fluoride content values increased by 25-30 μg/cm2 during a single topical application, as compared with 10-15 μg/cm2 during seven weeks of toothbrushing. About half the fluoride acquired as a result of topical treatment was lost during subsequent exposure to the oral fluids when no further fluoride supplementation was given. The uptake of fluoride by sound enamel was comparatively small, regardless of the use of fluoride dentifrice or application. The presence of mature plaque at the time of fluoride application did not affect the amounts of fluoride delivered. Acid susceptibility tests showed that the enamel solubility exhibited a negative correlation with fluoride content of the specimens.
Tooth Mortality in an Adult Rural Population in Kenya
Authors: Manji F. , Baelum V. , Fejerskov O.
Published: November 2010

This paper reports on the pattern of tooth loss in a random sample of 1131 adults aged from 15 to 65 years in a rural area of Kenya in which access to formal dental care is minimal. We found that the majority of the population retained most of their dentition in a functional state even up to the age of 65 years: In all age groups, more than 50% had at least 26 teeth present, and more than 90% had at least 16 teeth present. The prevalence of edentulousness was less than 0.3%. The principal cause of tooth loss in all age groups was caries, and this was true for all tooth-types except incisors, for which periodontal disease was the main cause of tooth loss. The cultural practice of removing lower central incisors was observed only in those over 40 years of age. More teeth were lost due to caries among women than among men, while the reverse was true for teeth lost due to periodontal diseases. In view of the fact that most people retain most of their teeth throughout life, it is suggested that the most appropriate strategies for dental health care in this population should be those promoting self care, rather than the introduction of a formal treatment-oriented approach provided by dentists.
Preliminary Observations on the Effect of Mantle Field Radiotherapy on Salivary Flow Rates in Patients with Hodgkin's Disease
Authors: Bucher J.A. , Fleming T.J. , Fuller L.M. , Keene H.J.
Published: November 2010

Changes in stimulated and non-stimulated whole saliva flow rates were measured in 11 Hodgkin's disease patients who received therapeutic doses of radiation to a mantle field at the M. D. Anderson Hospital in Houston, Texas. Salivary flow rates were examined before, during, and after radiotherapy. Mean flow rate reductions of 54% for non-stimulated saliva and 55.7% for paraffin-stimulated saliva were observed post-radiotherapy. Flow rates had not returned to pre-irradiation levels in any of the patients who were observed for two to three months after completion of therapy. Results obtained from this preliminary study indicate that most patients who receive therapeutic doses of radiation to a mantle field experience a significant reduction in salivary output which is manifest during the period of treatment and persists for a period of at least two to three months post-radiotherapy.
Effect of a-Receptor Stimulation on Cl Transport by Rat Submandibular Acini
Authors: Martinez J.R. , Reed P.
Published: November 2010

Dispersed salivary acini isolated from the rat submandibular gland by enzymatic digestion were used to study the effects of a-receptor stimulation on transmembrane transport of36Cl. In the absence of secretagogue, the tracer accumulated in the cells in a time-dependent manner until a steady-state content of 6.8 ± 0.1 nmol/mg protein was attained after 3-5 min of incubation. Epinephrine (1 μmol/L) alone did not modify36Cl accumulation but in the presence of the β-receptor blocker propranolol (1 μmol/L) caused a significant (21%) reduction in the isotope content of the cells to 5.2 ± 0.1 nmol/mg protein. In acini pre-loaded with36Cl for 12 min, 1 μmol/L epinephrine caused a rapid but transient net efflux of tracer, but the isotope content subsequently increased to pre-stimulation levels. In the presence of propranolol, however, the efflux of36Cl induced by epinephrine was larger and more sustained and was partially inhibited by the K-channel blocker quinidine (1 mmol/L) and significantly by the absence of Ca2+in the incubation medium. The a-agonist phenylephrine (10 μmol/L) also significantly reduced the steady-state36Cl content of tracer-pre-loaded cells. By contrast, exposure of the acini to epinephrine in the presence of the a-receptor blocker phentolamine, or the β-agonist isoproterenol, increased the tracer content of the cells, whether the drugs were added at time zero or to tracer-pre-loaded cells. The results indicate that stimulation of a-receptors in salivary acinar cells causes a Ca2+-dependent efflux of Cl which seems to be functionally linked to K release. These effects are similar to those observed following stimulation of cholinergic receptors. The lack of effect of β-receptor stimulation on Cl efflux suggests that this response is not regulated by a cAMP-mediated pathway in salivary cells. The extent of stimulation-induced Cl efflux is likely to be relevant in terms of the amount of saliva secreted upon stimulation.
Age Changes in Secretory Function of Male and Female Rat Parotid Glands in Response to Methoxamine and Pilocarpine
Authors: Inanaga A. , Habu T. , Tanaka E. , Taniguch T. , Nishiura T. , Ishibashi K. , Naruse S. , Abe K.
Published: November 2010

Saliva secreted in response to methoxamine and pilocarpine was collected from the cannulated ducts of both parotid glands of male and female rats at weekly age intervals from three to 10 weeks, and at 3.5, 8, and 15 months of age. It was analyzed for the concentrations of protein, potassium, calcium, inorganic phosphate, and for amylase activity. The types of protein were determined electrophoretically, and an amino acid analysis of the total protein was also carried out.

The wet weights of the glands increased substantially up to eight weeks of age, then reached almost plateau values, and finally tended to decrease at 15 months of age in both sexes. The salivary volumes secreted in response to methoxamine and pilocarpine were positively correlated with the parotid gland weights in both sexes. The concentrations of protein, potassium, and inorganic phosphate were inversely related to the salivary flow rates only at relatively low rates of flow. The amylase activity was positively correlated with the concentration of protein, independent of the nature of the stimulus, age, and sex. With methoxamine as a stimulus, the amylase activity was positively correlated with the concentration of calcium, independent of age and sex. The types of protein and amino acid concentrations were independent of the nature of the stimulus, age, and sex up to 15 months of age. However, in parotid saliva of several rats at 8 and 15 months of age, unusual proteins were observed electrophoretically, independent of the nature of the stimulus and sex.
Dental Caries, Fluorosis, and Fluoride Exposure in Michigan Schoolchildren
Authors: Szpunar S.M. , Burt B.A.
Published: November 2010

This study relates the prevalence of caries and fluorosis among Michigan children, residing in four different areas, to the various concentrations of F in the communities' water supplies. Demographic information, details of F history, and dental attendance data were collected by a questionnaire form filled out by parents. Children ages six to 12 were screened for caries by means of the NIDR criteria and for fluorosis by means of the TSIF index. Results pertain only to continuous residents and the permanent dentition. The prevalence of both caries and fluorosis was significantly associated with the F concentration in the community water supply. Approximately 65% of all children were caries-free, ranging from 55.1 % in fluoride-deficient Cadillac to 73.7% in Redford (1. 0 ppm F). About 36% of all children had dental fluorosis, ranging from 12.2 in Cadillac to 51.2 in Richmond (1.2 ppm). All of the fluorosis was very mild. From logistic regression, the prevalence of caries was significantly associated with age, dental attendance, and the use of a water supply fluoridated at 1.0 ppm. The odds of experiencing fluorosis increased at every F level above the baseline (Cadillac), with the use of topical F rinses, and with age. Results suggest that children in the four communities may be ingesting a similar level of F from sources such as dentifrices, dietary supplements, and professional applications, but the factor that differentiates them with respect to the prevalence of caries and fluorosis is the F concentration in the community water supply.
Use of Percoll Density Gradients for Studying the Attachment of Bacteria to Oral Epithelial Cells
Authors: Childs W.C. , Gibbons R.J.
Published: November 2010

An assay for studying the attachment of bacteria to oral epithelial cells has been developed which utilizes Percoll density gradient centrifugation to separate bacteria and epithelial cells. 3H-thymidinelabeled bacteria were incubated with suspensions of buccal epithelial cells in microtitration plates for 2.5 hr at 35°C. The mixtures were then subjected to density gradient centrifugation in 50% Percoll. Epithelial cells with attached bacteria formed a band near the top of the tube, while unattached bacteria formed a band near the bottom. The epithelial cells were collected on membrane filters, and the number of attached bacteria was determined by scintillation counting. Binding of S. mitis C5 was found to increase with time, and equilibrium was attained within two hr. Saturation of available binding sites occurred when 107 S. mitis cells were incubated with 1.5 × 104 buccal epithelial cells. The numbers of streptococci which attached as determined with this assay were in good agreement with values obtained by direct microscopic counts. Adsorption of S. mitis C5 cells was adequately described by a Langmuir isotherm (correlation coefficient 0. 998). This permitted calculation of estimates of the number of binding sites and the affinity of the organism. The assay proved reliable even when as few as 1000 epithelial cells were used. Treating the epithelial cells with neuraminidase or trypsin significantly decreased the number of S. mitis C5 cells which attached. In contrast, binding of A. naeslundii 12104 to neuraminidase-treated cells was increased, and attachment of B. gingivalis 381 was also enhanced, especially to epithelial cells which had been treated with trypsin.
Physical and Biochemical Studies of Streptococcus mutans Sediments Suggest New Factors Linking the Cariogenicity of Plaque with its Extracellular Polysaccharide Content
Authors: Dibdin G.H. , Shellis R.P.
Published: November 2010

Cultures of Streptococcus mutans MFe28 (serotype h) were grown with differing extracellular polysaccharide (EPS) content. Biochemical and physicochemical characteristics considered relevant to caries were measured. Acid production parameters measured in a pH-stat were: Vm = 0.76 ± 0.14 μmol/g/sec (wet weight); apparent Km (acid production) = 100 μmol/L; molar yield = 1.97 ± 0.25 mol acid/mol glucose. Acid anion inhibition of acid production was also noted. Buffering by the pure washed bacterial residue required approx. 112 μmol of baselg (wet weight) of residue to change the pH from 4 to 6.5, and this dropped almost to zero as the EPS content increased to 100%. Diffusion coefficients (D) in the residues were independent of EPS content over a wide range. When the effusion method was used, De (glucose) and De (acetate) were (3.26 ± 0.6) and (5.05 ± 0.8) x 10-6 cm2lsec, respectively. The extracellular fluid fraction, measured by inulin exclusion, increased from 0.33 for the pure bacteria to 0.78 for the pure EPS. It is shown how, by these factors alone, and without any need for diffusion restriction, plaque EPS may lead to a lower pH at the tooth surface, thus increasing the cariogenic challenge.
Occurrence of Root Caries in Relation to Dental Health Behavior
Authors: Vehkalahti M.M. , Paunio I.K.
Published: November 2010

We studied the relationship between the occurrence of untreated root caries and a subject's dental health habits, such as the frequency of tooth-brushing, the avoidance of sugar, and regularity of dental visits. A representative sample of 5028 adults was examined. Information on dental health habits was collected by professional interviewers one to six weeks before the clinical examination. A high frequency of tooth-brushing was strongly related to a low occurrence of root caries. The use of sugar in coffee or tea was strongly associated with root caries occurrence among men. The use of sweets was related to root caries occurrence moderately in men but not at all in women. Regular dental check-up behavior was strongly related to an infrequent occurrence of root caries. It was concluded that dental health behavior influences root caries occurrence and that caries on root surfaces is associated with poor dental health habits. Age and gender differences in root caries occurrence, reported earlier, may relate to different dental health behavior of women and men.
In vitro Studies on the Potential for Pulpal Cytotoxicity of Glass-Ionomer Cements
Authors: Hume W.R. , Mount G.J.
Published: November 2010

Elution samples of glass-ionomer cement were prepared in sterile tissue culture medium either by direct contact between the fluid and standard cement samples or through a layer of human dentin, and then tested for toxicity to cultured mouse fibroblasts (L929). The directly-prepared eluates of the cements were highly cytotoxic, but those prepared through dentin were of either limited or no cytotaxicity. The degree of toxicity of some directly-prepared eluates was reduced by adjustment of the pH to neutrality. It was apparent that dentin reduced the potential for cytotoxicity of glass-ionomer cements to a large degree. Proposed mechanisms for the reduction were limited availability of water at the dentin-cement interface and thus limited dissolution of components, buffering of acid components of the cements by dentin, or other chemical interactions with dentin.
Bicarbonate-based Dental Powder, Fluoride, and Saccharin Inhibition of Dental Caries Associated with Streptococcus mutans Infection of Rats
Authors: Tanzer J.M. , Grant L. , McMahon T.
Published: November 2010

The effects of NaHCO 3-based dental powder containing NaF and sodium saccharin on dental caries and Streptococcus mutans recoveries in rats were studied. Weanling specific-pathogen-free Osborne-Mendel (SPFOM) rats were inoculated with S. mutans NCTC-10449S. Four infected groups were topically treated with either demineralized water (DW), a dental powder suspended such that there was 1 part solid per 2 parts DW, 0.073% NaF, or a combination of 0.073% NaF and 0.5% Na-saccharin (Nas). NaF-supplemented DW (at 10 ppm F-) was provided to a 5th group of infected rats as a positive treatment control, but this group was otherwise untreated. A sixth but uninfected group was topically treated with DW. All topical treatments were given once for 1 min daily per rat, for 5 days per week. Animals' teeth were swabbed for recovery of 10449S and total recoverable flora. Recoveries of 10449S were lower from powder-treated rats than from DW-treated rats. This difference approached but did not reach statistical significance. Total caries scores were 51% lower for the dental powder, 36% lower for the topical NaF, 34% lower for the combined NaF-Nas, and 54% lower for the NaF-supplemented drinking water group, all p < 0. 001. While all of the treatments inhibited smooth-surface caries, the dental powder effects, like those for the combined NaF-Nas, and NaF drinking water, were evident in fissure tooth surfaces as well. Both the 10 ppm F- drinking water and the dental powder significantly reduced fissure caries scores below the level elicited by the indigenous mutans-free flora in the DW-treated uninfected rats; however, these reductions were not significantly different from one another. Thus, the 10 ppm F- drinking water and the dental powder equally inhibited not only the S. mutans-attributable component of caries but probably also the component of caries attributable to the indigenous oral flora.
Abnormal Amino Acid Analyses Obtained from Osteogenesis Imperfecta Dentin
Authors: Gage J.P. , Francis M.J.O. , Smith R.
Published: November 2010

Amino acid analyses were carried out on dentin proteins obtained from 33 normal teeth and 59 teeth from osteogenesis imperfecta patients. The analyses revealed that in the control teeth approximately 95% of the insoluble dentin fraction was collagen. The majority of the analyses for teeth obtained from the O.I. patients were biochemically abnormal (55 out of 59). Specifically, there was a significant increase in the acidic amino acids, with a corresponding decrease in the basic amino acids. A small group of patients showed double peaks in the histidine, hydroxylysine, and lysine areas of the chromatograms. These results emphasize that despite the fact that the teeth of O.I. patients may appear to be clinically normal, all but four of the teeth examined had abnormal dentin collagen.
Isolation of Noncollagenous Proteins from Gingival Connective Tissue
Authors: Schlagenhauf U. , Narayanan A.S. , Page R.C.
Published: November 2010

Noncollagenous proteins form an integral part of gingiva and other connective tissues. We have performed studies aimed at purification and partial characterization of the gingival noncollagenous proteins. Healthy gingival tissues from mongrel dogs were extracted in neutral buffers, acetic acid, and 6 mol/L urea. Immunoblots using anti-keratin antibodies and CNBr peptide patterns revealed that the majority of the proteins present in these extracts were keratins. To exclude keratins, gingival connective tissue was separated from the epithelium and then extracted. Acid extracts of the connective tissue contained very little protein, whereas urea extracts contained collagen and other noncollagenous proteins. The noncollagenous proteins present in the urea extract were partially purified by DEAE-cellulose chromatography and separated by affinity chromatography through a Sepharose 4B-type I collagen column. At least eight proteins, which ranged in molecular size from 15 to 75 kilodaltons, were obtained by this procedure. We conclude that keratins are major components of whole gingiva extracts and that epithelium must first be removed in order for connective tissue proteins to be obtained. The gingival connective tissue appears to contain several collagen-binding proteins, and these proteins may play an important role in the structure and function of the gingival matrix.