bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between Enzyme Activities Involved in Oxygen Metabolism and Oxygen Tolerance in Black-pigmented Bacteroides
Authors: Amano A. , Tamagawa H. , Takagaki M. , Murakami Y. , Shizukuishi S. , Tsunemitsu A.
Published: November 2010

In this study, the relationship between enzyme activities involved in oxygen metabolism and the degrees of oxygen tolerance in black-pigmented Bacteroides was investigated. All strains of Bacteroides tested possessed the activities of NADH oxidase and superoxide dismutase, whereas the activities of catalase and peroxidases were not detected in the cell-free extracts. There were relatively high correlations between ozygen tolerance and activity of either NADH oxidase or superoxide dismutase. The activity of superoxide dismutase showed a higher correlation with oxygen tolerance than with that of NADH oxidase. Among the species tested, Bacteroides gingivalis showed the highest activities of both the enzymes and was the most tolerant in the presence of oxygen. Furthermore, the activities of these two enzymes increased during aeration of the oxygen-tolerant strain Bacteroides gingivalis 381, but not in the oxygen-sensitive strain Bacteroides denticola ATCC 33185. These results suggest that superoxide dismutase and NADH oxidase might be important for protection of black-pigmented Bacteroides against the toxic effect of oxygen.
Fluoride Redeposition and Retention during Bone Turnover in Lactating Rats
Authors: Nopakun J. , Guo M.K. , Messer H.H. , Ophaug R.H.
Published: November 2010

The ability of the adult skeleton to retain fluoride (F) during times of Ca stress was assessed in lactating rats. Rats incorporated F into their skeletons throughout growth by consumption of water containing 50 ppm F from weaning to 11 weeks of age. The rats were then changed to a low-F intake and mated. At delivery, nine dams were killed as a baseline group, and 20 dams were fed a low-F diet plus distilled water during lactation. Half of the rats were subjected to the additional stress of a low-Ca intake to stimulate bone resorption. F loss was determined during lactation. Bone turnover was measured by the loss of previously incorporated tritiated tetracycline (3H-TC), and changes in bone Ca and F contents were compared with changes in 3H-TC content. The extent of bone resorption ranged from 16.5% in the humerus of the adequate-Ca group to 77.1% in the vertebrae of Ca-deficient dams. Loss of bone F was greatest in animals with greatest loss of 3H-TC. Once F was resorbed from bone, only a relatively small portion was redeposited (0-31.4%). The low extent of F redeposition appears to be related to a low Ca deposition in lactating rats.
In vitro Root Caries Progression Measured by 125I Absorptiometry: Comparison with Chemical Analysis
Authors: Almqvist H. , Wefel J.S. , Lagerlof F. , Ekstrand J. , Henrikson C.O.
Published: November 2010

Radiation from a 125I source and a non-image-forming detector was used for non-destructive measurements of root caries progression. Blocks were cut parallel to the cementum surface of unexposed human roots. These blocks were then individually demineralized in under-saturated calcium phosphate solutions over an 84-hour period. In order for the in vitro root surface demineralization to be followed, the changes in transmission (ΔT) through the blocks were measured, by 125I absorptiometry, eight times during the course of the experiment. Chemical analyses of the calcium output (ΔCa) from the blocks into the demineralizing solutions were also performed, and the rate of demineralization (Vdem ) was calculated from these values. The precision of 125I absorptiometry was calculated from 176 duplicate transmission measurements, and the coefficient of variation was found to be 0.20%. The correlation coefficient between ΔT and total ΔCa for each of 22 cementumldentin blocks ranged between r = 0.934 and r = 0.998. The progression of root hard-tissue lesions observed by these two methods and by the calculated Vdem was found to be proportional to the square and cubic roots of time. The study shows that 125I absorptiometry can be used for continuous non-destructive measurements of root hard-tissue demineralization in vitro.
Evaluation of Submandibular Salivary Flow Rate in Different Age Groups
Authors: Tylenda C.A. , Ship J.A. , Fox P.C. , Baum B.J.
Published: November 2010

The production of unstimulated and citrate-stimulated submandibular saliva was examined in 90 male and female adults, aged 26-93 years. None was taking prescription medications for treatment of systemic disease. There was no diminution in submandibular gland fluid output, at rest or during stimulation, with increasing age. Similar findings, previously reported for the parotid glands, were also confirmed. These results demonstrate that major gland fluid secretion capacity is maintained in healthy older individuals.
Muscle Spindles in the Digastric Muscle of the Rabbit
Authors: Muhl Z.F. , Kotov O.
Published: November 2010

The digastric muscle of the rabbit was studied for the presence of muscle spindles. One of the 19 adult digastric muscles we examined contained in excess of 12 spindles scattered throughout the belly. No spindles were found in the contralateral muscle, or in any of the digastric muscles from other animals. Although jaw depressor muscles of most mammals contain few, if any, muscle spindles, their occasional presence suggests that these muscles have a potential for spindle formation.
The Use of Whole-cell DNA Probes for the Identification of Bacteroides intermedius Isolates in a Dot Blot Assay
Authors: Moncla B.J. , Strockbine L. , Braham P. , Karlinsey J. , Roberts M.C.
Published: November 2010

Bacteroides intermedius includes two distinct groups of organisms that are phenotypically indistinguishable by conventional methods. These two groups are represented by the type strain of the species ATCC 25611T (B . intermedius type I) and by ATCC 33563 (B. intermedius type II). Members of each group can be distinguished from each other by analysis of the cellular protein composition by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and by DNA-DNA homology studies, because they share less than 40% homology. The purpose of this study was to prepare specific DNA probes for the two groups of Bacteroides intermedius and to test them against field isolates. Whole-cell DNA probes were prepared from B. intermedius types I and II and tested against 253 field strains of Bacteroides which had been identified by conventional phenotypic tests as B. intermedius. Of these, 170 (67%) hybridized with the B. intermedius type I DNA probe, 28 (11%) with the type II, and 23 (9%) failed to react with the B. intermedius probes but did hybridize with either B. melaninogenicus, B. loescheii, or B. corporis whole-cell DNA probes. The 32 (13%) remaining isolates failed to hybridize with any of the fzve Bacteroides probes or with probes to B. asaccharolyticus, B. buccae, B. buccalis, B. denticola, B. gingivalis, B. oralis, or B. oris. These data demonstrate the usefulness of whole-cell DNA probes for the identification of phenotypically similar or identical field isolates.
Histochemical Demonstration of Carbonic Anhydrase Activity in the Odontogenic Cells of the Rat Incisor
Authors: Sugimoto T. , Ogawa Y. , Kuwahara H. , Shimazaki M. , Yagi T. , Sakai A.
Published: November 2010

Aldehyde-fixed, EDTA-demineralized frozen sections of the rat maxillary incisor were histochemically stained for carbonic anhydrase activity, by use of Hansson's method. Intense staining was observed in the odontoblasts, all types of epithelial cells of enamel organ in the maturation zone, cementoblasts, and the cells of the lingual dental sac. Less intense but consistent staining was observed in all types of epithelial cells of odontogenic origin directly facing the pulp and pulp cells adjacent to the odontoblast cell layer in the apical part of the pulp, and was considered due to the carbonic anhydrase-catalyzed reaction. Staining of these cells was completely inhibited by heat pretreatment (120°C, 30 min), 10-6 mol/L acetazolamide in the incubation medium, incubation by continuous immersion under the liquid surface, and omission of the substrate, NaHCO3. The dentin also exhibited heavy staining which was inhibited by the heat pre-treatment. However, this dentinal staining resisted the inhibition by 10-3 mol/L acetazolamide and was not inhibited by incubation by continuous immersion or incubation without the substrate NaHCO3. The dentinal staining was thus judged to have been due to non-enzymatic cobalt precipitation.
Sn in the Ag-Hg Phase of Dental Amalgam
Authors: Mahler D.B. , Adey J.D.
Published: November 2010

In a recent study, Sarkar and Eyer (1986) studied an amalgam which was formed using a unique procedure. Based on their results, they concluded that the solubility of Sn in the Ag-Hg (γ1) phase of dental amalgam was virtually nil (<0.25 wt%). This finding is contrary to the published results of other investigations. The purpose of the present study was to clarify these disparate findings. A low-copper dental amalgam was examined by electron probe microanalysis. This amalgam was selected because it exhibits unusually large γ1 grains (10 μm). Because the influence of the electron-analyzing beam can be completely contained within these large grains, grain boundaries or peripheral phases would not be excited, and a valid analysis of the γ 1 grains themselves could be made. The analyses showed significant Sn contents of 2.0-3.0 wt%. Analyses of areas which contained grain boundaries showed slight or no differences in Sn content compared with that for the grains alone. Furthermore, secondary electron scans of this dental amalgam failed to reveal the intergranular precipitates of Sn-Hg observed by Sarkar and Eyer (1986) in their amalgam. These different results can be explained by the fact that the unique amalgam investigated by Sarkar and Eyer does not exhibit the same diffusional patterns as does dental amalgam, and that the composition of the γ1 in the two amalgams is not the same. The final conclusion is that the Ag-Hg (γ1) phase in dental amalgam does indeed contain a significant amount of Sn.
Metallurgical Aspects of High-palladium Alloys
Authors: Mezger P.R. , Stols A.L.H. , Vrijhoef M.M.A. , Greener E.H.
Published: November 2010

Nine commercial high-Pd alloys were investigated. Microstructure and phase composition were screened by x-ray diffraction, light microscopy, and an electron microprobe. After being etched, some high-Pd alloys revealed dendritic structures. The others showed a more homogeneous structure with distinct grain boundaries. Etching was necessary to reveal distinct structures, though the overall etching effect turned out to be limited. On unetched specimens, only a slight chemical heterogeneity could be determined. Except for one alloy, the systems turned out to have complex multi-phase structures. The main face-centered-cubic (fcc) phase was Pd-based. As secondary phases, body-centered-cubic (bcc) and/or simple cubic ones were detected. The latter phases were similar to a Cu3Ga and PdGa intermetallic compound, respectively. Face-centered-tetragonal (fct) structures reported by other investigators were not found.
Influence of Desalivation in Rats on Incidence of Caries in Intact Cagemates
Authors: Bowen W.H. , Madison K.M. , Pearson S.K.
Published: November 2010

The evidence that dental caries is an infectious and transmitted disease in rodents is unequivocal. However, the factors controlling the transmission of micro-organisms from one animal to another have not been extensively explored. Results from previous studies in our laboratory showed that desalivated animals became infected by Streptococcus sobrinus in a shorter period of time than did intact animals. Furthermore, an additional study in our laboratory showed that animals with intact salivary function caged with desalivated animals harbored more S. sobrinus immediately following establishment of infection than did intact animals housed with other intact animals. Therefore, it seemed appropriate to determine the influence on caries development of caging a desalivated animal with an intact animal. In this study, intact Sprague-Dawley rats were caged with desalivated animals; additional groups of intact animals were housed with chlorhexidine-treated animals that were either intact or desalivated. Although chlorhexidine suppressed both caries development and the level of infection by S. sobrinus, nevertheless, intact animals caged with desalivated animals invariably developed more caries than did intact animals housed with other intact animals. Treating intact animals with chlorhexidine did not affect caries scores in untreated intact cagemates. Overall, the results suggest that a highly acidogenic flora with enhanced virulence (including S. sobrinus) is selected in the desalivated animals; this flora is apparently readily transmitted to intact cagemates, leading to enhanced levels of smooth-surface caries.
The Prevalence of Dental Attrition and its Association with Factors of Age, Gender, Occlusion, and TMJ Symptomatology
Authors: Seligman D.A. , Pullinger A.G. , Solberg W.K.
Published: November 2010

Dental attrition severity in 222 young adults was assessed from dental casts as the sum of the most severe facet in each arch segment. The attrition scores were compared by age, gender, bruxism awareness, prior bite adjustment, orthodontic class, maxillomandibular relationship, and temporomandibular dysfunction symptoms. Awareness of bruxism was not associated with the wear scores and should not be used to define bruxist groups. Attrition scores did not differ significantly between age groups, indicating that notable attrition, when present, often occurs early. Men had higher attrition scores than women (p<0.01), despite fewer signs and symptoms. Dental attrition was not associated with the presence or absence of TMJ clicking, TMJ tenderness, or masticatory muscle tenderness. Class II division 2 males had laterotrusive attrition scores lower than those of Class III (p<0.05). Class III females had lower incisor attrition scores than did other Angle Classes (p<0.05). Discernible dental attrition in a non-patient population was not associated with signs and symptoms of temporomandibular disorders, nor with the occlusal factors studied. These results are compatible with the findings in other studies that point to bruxism as a centrally induced phenomenon common to all people and unrelated to local factors.
Electrical Stimulation of Salivary Flow in Patients with Sjögren's Syndrome
Authors: Steller M. , Chou L. , Daniels T.E.
Published: November 2010

Patients with the salivary component of Sjögren's syndrome (SS) develop chronic xerostomia, which causes oral symptoms and functional impairment in approximate proportion to its severity. The purpose of this double-blind study was to determine whether an electrical stimulus applied to the tongue and hard palate by a battery-operated device (SAL II, Biosonics, Inc.) could stimulate salivary flow in subjects with generally severe SS. Twenty-nine patients with the salivary component of SS (diagnosed as the presence of focal chronic sialadenitis in a labial salivary gland biopsy specimen with a focus score of > 1 focus/4 mm2) were randomly assigned active or placebo devices, which they used for three minutes, three times a day for four weeks. Whole saliva flow rates were measured at weeks 0, 2, and 4 by collection of whole saliva both before and after stimulation with the device. Twenty-four subjects completed the study. The change in mean post-stimulation flow rate from week 0 to week 4 was greater for the 13 subjects using an active device (0.08 ± S.D. 0.08 gl2 min, to 0.24 ± 0.33 gl2 min) than for the 11 subjects using a placebo device (0.11 ± 0.15 gl2 min, to 0.08 ± 0.18 gl2 min) (p = 0.04). However, the magnitude of the mean difference was small, because three subjects using active devices responded and others did not. Only five subjects, all using active devices, reported a subjective increase in the amount of their saliva. The results of this study indicate that some SS patients with residual salivary flow show a significant response to electrical stimulation, but others with low or absent whole saliva flow rates do not respond.
The Effects of Different Levels of Dietary Sucrose on Root Caries subsequent to Gingivectomy in Conventional Rats Infected with Actinomyces viscosus M-100
Authors: Firestone A.R. , Graves C.N. , Feagin F.F.
Published: November 2010

Three groups of weanling, Sprague-Dawley-derived rats were inoculated with Actinomyces viscosus M-100 and fed powdered diet containing either 67%, 5%, or 0% confectioner's sugar. Two further groups were fed diet containing 5% confectioner's sugar and inoculated with Streptococcus sobrinus 6715 or S. sobrinus 6715 plus A. viscosus M-100. The most coronal 1 mm of gingiva was removed from maxillary and mandibular right molar quadrants (gingivectomy), and the animals re-inoculated following gingivectomy. The animals were killed 64 days following gingivectomy, and the lingual surface of mandibular first molar roots was measured for exposed root-surface area and root caries. In the groups of rats infected with A. viscosus M-100, root caries area was significantly greater in the group fed diet containing 67% confectioner's sugar. Sucrose level did not significantly affect the amount of exposed lingual first molar root area regardless of whether the tooth had been subjected to a gingivectomy. In the groups of rats receiving diet containing 5% confectioner's sugar, there were no significant differences in root caries area or exposed root-surface area, regardless of the infection status of the animals. In the rat model presented here, a high level of dietary sucrose was a necessary condition for the initiation of root caries in the absence of other readily fermentable carbohydrates.
The Effect of Casting Ring Liners on the Potential Expansion of a Gypsum-bonded Investment
Authors: Earnshaw R.
Published: November 2010

Cellulose paper (used wet) and ceramic paper (used dry) are replacing asbestos paper as cushioning ring liners in dental casting. A study was made of the effects of all three of these materials on the setting and subsequent thermal expansion of a gypsum-bonded cristobalite casting investment (W/P = 0.40). Thermal expansion measurements were made on the same specimens that were produced during the setting expansion tests.

Control specimens setting against a smooth dry surface showed a total expansion of 1.7%. Specimens setting against dry ceramic liners had similar total expansions, in the range 1. 6 to 1.7%. Specimens setting against either of the wet lining materials showed an increased total expansion (in the range 2.2 to 2.3%), by virtue mainly of a large increase in setting expansion.

In order for reproducible setting expansion results to be obtained with wet liners, it was necessary to control the amount of absorbed water carefully. Dry asbestos and dry cellulose liners gave higher expansions than pre-wetted ones, since they abstracted water from the mix, reducing its effective WlP ratio (giving a thicker mix), and then functioned as wet liners.

These results suggest that, at least as far as potential investment expansion is concerned, wet cellulose liners have an effect similar to that of the traditional wet asbestos liners. Dry ceramic liners give a much lower investment expansion, and when these liners are used, an investment with an increased measured expansion could be an advantage.
Influence of Incisal Length of Ceramic and Loading Orientation on Stress Distribution in Ceramic Crowns
Authors: Anusavice K.J. , Hojjatie B.
Published: November 2010

For ceramic crowns, the recommended depth of tooth reduction from the incisal edge of anterior teeth is 1.5 mm to 2. 0 mm. Although some prosthodontists have suggested that incisal heights of ceramic which exceed 2 mm are associated with dangerously high intra-oral stresses, this theory has not been verified. The objective of this study was to test the hypothesis that the stress distribution in ceramic crowns designed for a prepared maxillary central incisor which are subjected to applied loading is relatively insensitive to the incisal length of ceramic. Finite element stress analyses were performed on three crown designs loaded with a horizontal or vertical force of 200 N along the lingual surface near the incisal edge. Ceramic crowns for maxillary central incisors were modeled with incisal lengths of 1.0 mm (Case I), 1.9 mm (Case II), and 4.0 mm (Case III). Zinc phosphate cement with a film thickness of 30 μm was included for each case. Plane-stress finite element analyses indicated that tensile and compressive stresses which were induced in cement and ceramic due to a vertically applied load of 200 N were comparable in magnitude for all three cases within the gingival third of the crowns. For Cases I, II, and III, tensile stresses at the facial region were 6.7, 5.4, and 6.5 MPa, respectively, in cement and 46.2, 48.6, and 49.2 MPa, respectively, in the ceramic. The results of this study tend to support the hypothesis that the amount of tooth reduction (1 to 4 mm) in an incisogingival direction does not significantly influence the stress distribution in the crown or cement layer. In fact, the orientation of the applied load is a more significant factor than the geometry of the crown or prepared tooth.
The Effects of Partial Demineralization and Fibronectin on Migration and Growth of Gingival Epithelial Cells on Cementum in vitro
Authors: Pitaru S. , Hekmati M. , Geiger S. , Savion N.
Published: November 2010

The capacity of mineralized cementum to support epithelial cell migration and growth and the effect that fibronectin and partial demineralization of cementum have on these processes were assessed in vitro. Dog gingival explants, 1 x 2 mm, were cultured on the cementum surfaces of pig root pieces in a defined medium consisting of DMEM and F12 (1V/1V, transferrin, insulin, epidermal growth factor, cortisone, selenium, and high-density lipoprotein. Sixty root pieces were divided into four equal groups according to the treatment: (1) untreated mineralized cementum; (2) treated with 5 μg of fibronectin; (3) partially demineralized in 18% EDTA for 30 min; and (4) both partially demineralized and fibronectin-treated as above. Epithelial cell migration and growth on each of the four differently treated cementum surfaces were assessed histomorphometrically by means of scanning electron microscopy. The defined culture medium supported the selective migration and growth of epithelial cells from the gingival explants onto the mineralized cementum. This was confirmed by the positive immunostaining of these cells with antikeratin antibodies. Partial demineralization of cementum inhibited epithelial migration and growth by 83% and 91%, respectively. Fibronectin treatment did not affect epithelial cell migration and growth on mineralized cementum, but it decreased the degree of epithelial cell migration and growth inhibition on partially demineralized cementum to 57% and 43%, respectively. The results indicate that: (i) mineralized cementum may consist of components that are recognized by gingival epithelial cells and support their migration and growth in vitro; (ii) these components can be removed by demineralization; and (iii) fibronectin partially restores epithelial cell migration and growth on partial demineralized cementum in vitro.
Analysis of Site-specific Data in Dental Studies
Authors: Donner A. , Banting D.
Published: November 2010

Much attention has been given recently to issues in the statistical analysis of site data arising from clinical trials in periodontics. As pointed out by Imrey (1986) and Fleiss et al. (1987), it is unreasonable to expect sites within the same patient to respond independently, and thus conventional statistical methods are not directly applicable. In this paper we develop a procedure for comparing the percentage of sites showing a given characteristic across two or more groups of patients that accounts for this lack of independence. The procedure is a straightforward extension of the standard Pearson chi-square test. Two examples are given.
Bone Mineral Content of the Maxilla Estimated by Dual-photon Absorptiometry after Augmentation with Bone or Hydroxyapatite
Authors: Von Wowern N. , Worsaae N.
Published: November 2010

A new, precise, non-invasive method for measuring the bone mineral content (BMC) of the mandible in vivo by dual-photon absorptiometry has recently been introduced. The purpose of the present analysis was to examine the precision in vitro and in vivo and the accuracy in vivo for assessment of BMC in the maxilla. The precision was determined by repeated measurements in vitro on a cranium and in vivo on two test persons with and without a bone specimen fixed to a palatal plate. The accuracy in vivo was determined from the BMC measurements of the two test persons and of nine edentulous persons, scanned before and after augmentation of the maxillary alveolar ridge with hydroxyapatite. The analyses indicated that the precision for maxillary BMC assessments was high (0.9% in vitro and 2.0% in vivo) and the accuracy in vivo was 6.6%, corresponding to the accuracy in vitro for skeletal BMC measurements by dual-photon absorptiometry. The present method therefore seems to be well-suited for follow-up analyses of the BMC changes in the jaws after augmentation of the alveolar ridges with bone or hydroxyapatite.
1H and 13C NMR Studies of the Interaction of Eugenol, Phenol, and Triethyleneglycol Dimethacrylate with Phospholipid Liposomes as a Model System for Odontoblast Membranes
Authors: Fujisawa S. , Kadoma Y. , Komoda Y.
Published: November 2010

To clarify the mechanism of the interaction of eugenol with odontoblast membranes compared with that of phenol and triethyleneglycol dimethacrylate (TEGDMA), we employed dipalmitoylphosphatidylcholine (DPPC) liposomes as a model system for odontoblast membranes. 1H and 13C nuclear magnetic resonance spectroscopy (NMR) was used as the spectroscopic approach in the study of this interaction. No signals of 1H and 13C due to eugenol in the DPPC/eugenol liposomes were observed, indicating that the mobility of eugenol was strongly disturbed by DPPC and that eugenol did not diffuse from the liposomes once it was incorporated. The change in chemical shifts due to phenol between the free state and the DPPC/phenol liposomes was not found, indicating that phenol resides in the aqueous phase or near the surfaces of liposomes, its interaction being markedly weaker than that of eugenol. The signals due to TEGDMA in the DPPC/ TEGDMA liposomes were split into two peaks: a lower-field peak (free TEGDMA) and a higher-field one (membrane-bound TEGDMA). TEGDMA with ethyleneglycol groups seemed to be activated on the liposomes as a surfactant-like agent.
The Effect of Lactic and Acetic Acid on the Formation of Artificial Caries Lesions
Authors: Hoppenbrouwers P.M.M. , Driessens F.C.M.
Published: November 2010

Fluoride specifically adsorbed to hydroxyapatite reduces the rate of dissolution of hydroxyapatite. Since specific adsorption is a property which anions of all weak acids have in common, it is expected that the anions of lactic and acetic acid will be specifically adsorbed to hydroxyapatite too and in this way will cause a reduction in the rate of dissolution of hydroxyapatite. In order to investigate this, we used the experimental results from Featherstone and Rodgers (1981). Calculations of the rate of increase of the lesion depth in dental enamel per mmol. L -1 of the un-ionized acid revealed that lesion progress was pH-dependent and was lowest at that pH which corresponds with the pK-value of the relevant acid. It is concluded that the anions of lactic and acetic acid are specifically adsorbed to the enamel mineral and in this way reduce the rate of dissolution of the mineral. This suggests that a description of the development of an artificial caries lesion in mathematical terms should include the effect on the rate of dissolution of the mineral of specific adsorption of the relevant acid anions to the mineral.
Composition of Pooled Resting Plaque Fluid from Caries-free and Caries-susceptible Individuals
Authors: Margolis H.C. , Duckworth J.H. , Moreno E.C.
Published: November 2010

The composition of pooled resting plaque fluid from 10 population samples, grouped according to age (8-11, 14-17, 18-25 years) and caries status (caries-free, CF, DMFS = 0; caries-susceptible, CS, DMFS > 10), was determined by means of ion chromatography. Subjects received a dental prophylaxis one week prior to plaque collection, abstained from oral hygiene for 48 hours, and did not eat or drink for at least one hour prior to plaque collection. Plaque samples from each group were pooled under mineral oil and centrifuged (15,000 g) for 45 minutes at ambient temperature. Supernatants were analyzed for organic acids, inorganic anions, mono- and divalent cations, and pH value. The ions Na+, NH4+, K +, Ca2+, Mg2+, Cl-, and phosphate were present in all samples. Acetic and propionic acids were predominant, comprising over 75% of the acid (anions) present under resting conditions. Succinic, lactic, formic, and butyric acids were present in lower concentrations. Within each age group, the mean values for pH and NH4+ concentration were higher in the caries-free group; the differences between mean values (CF: pH, 6.35 ; NH4+, 52 mmollL; CS: pH, 5.85 ; NH 4+, 37 mmol/L) were found to be statistically significant (p < 0.05) when all data for the CF and CS groups were combined. Significantly higher concentrations of Mg2+ and butyric acid were also found for the combined CF data. Concentrations of all other constituents were similar. Calculations indicate that plaque fluid is supersaturated with respect to enamel mineral and dicalcium phosphate dihydrate, with a significantly higher degree of saturation with respect to enamel mineral in the CF group. These results suggest that resting plaque fluid from CF individuals has a greater remineralization potential than that from CS individuals. It is suggested that the noted difference in saturation status is related to differences in plaque pH, resulting from differences in NH3 production, which may reflect the presence of different bacterial species and residual energy sources.
The Influence of High- and Low-molecular-weight Inhibitors on Dissolution Kinetics of Hydroxyapatite and Human Enamel in Lactate Buffers: A Constant Composition Study
Authors: Budz J.A. , Lo Re M. , Nancollas G.H.
Published: November 2010

The kinetics of dissolution of hydroxyapatite (HAP) and human enamel (HE) powders in lactate buffers was investigated by means of a Constant Composition technique. The rates were interpreted in terms of a surface-controlled dissolution mechanism. It was shown that the overall dissolution of both HAP and HE crystallites in lactate buffers resulted from an interplay of the calcium chelating action of lactate ion, its interaction with surface calcium sites, and the retardation effects of both ionized (L-) and un-ionized (HL) lactic acid due to adsorption at phosphate surface sites. The presence of lactate in demineralizing solutions also influenced the "acquired crystallite resistance" for dissolution, and the rates decreased as the reaction proceeded. The influence of surface protective agents [methanehydroxydiphosphonate (MHDP) and polyacrylic acid (PAA)] on HAP and HE dissolution rates was also extensively studied in partially saturated lactate buffer (0.05 mol L-1). Although the overall kinetic effects of both additives appeared to be similar, there were considerable mechanistic differences. MHDP might interact with lactate by competition for surface calcium sites. In contrast, PAA appeared to act independently of lactate under the experimental condition used. This would tend to support the recommendation of White (1987), that PAA was more suitable as a surface protective agent for artificial caries lesion preparation.
Correlation of the Hydrolysis of Benzoyl-Arginine Naphthylamide (BANA) by Plaque with Clinical Parameters and Subgingival Levels of Spirochetes in Periodontal Patients
Authors: Schmidt E.F. , Bretz W.A. , Hutchinson R.A. , Loesche W.J.
Published: November 2010

Recent studies have shown that the extent of hydrolysis by plaque of the trypsin substrate, N-benzoyl-DL-arginine-2-naphthylamide (BANA), correlates with the numbers and proportions of spirochetes in subgingival plaque samples, and appears to be an indicator of clinical disease. In this study, BANA hydrolysis by subgingival plaque was evaluated in a blind manner for its ability to reflect both clinical parameters and subgingival levels of bacteria and spirochetes. Subgingival plaque samples were collected from periodontally healthy and diseased sites in 23 untreated periodontal patients and in 13 treated and maintained periodontal patients. In untreated patients, BANA hydrolysis was statistically associated with the total number of spirochetes and bacteria in the plaque sample, but in the treated patients BANA hydrolysis was statistically associated only with the spirochetes. Most BANA-positive reactions in both patient groups were from the sites which were clinically diseased and high in spirochetes. The majority of the negative reactions for BANA hydrolysis in both patient groups was among the sites which were periodontally healthy and low in spirochetes. Specificity and sensitivity of the test were above 80% for disease status in untreated patients. The predictive value of a positive and negative test was above 83%. Slightly lower sensitivity, specificity, and predictive values were found in the treated group. The BANA reaction appears to be an accurate and simple indicator of both clinical disease status and plaque levels of spirochetes in individual tooth sites in untreated and treated periodontal patients.
Adhesion of Composite Resin to Bleached and Unbleached Bovine Enamel
Authors: Titley K.C. , Torneck C.D. , Smith D.C. , Adibfar A.
Published: November 2010

Cylinders of microfil and small-particle light-cured composite resin were bonded to the flattened labial enamel surface of young bovine incisor teeth which had previously been subjected to four different treatments: (1) teeth immersed in 35% hydrogen peroxide (HP) for 60 min and etched (E) with 37% phosphoric acid gel for 60 sec; (2) teeth immersed in saline (S) for 60 min and E for 60 sec; (3) teeth E for 60 sec and immersed in HP for 60 min; and (4) teeth E for 60 sec, immersed in S for 60 min. Specimens were stored in water at 37°C for one and seven days prior to tension- and shear-testing. A total of 256 teeth was tested— eight teeth in each group for each day, for each resin, and for each test. Statistical analysis of the results indicated that there was a highly significant reduction in adhesive bond strength of the resins when the enamel was exposed to HP as compared with S. SEM examination of randomly selected fractured test specimens indicated that this reduction in adhesive bond strength occurred primarily at the bonding resin-enamel interface. Less significant differences in bond strength were noted in the control specimens, with regard to resin type, time of storage, and the etching order.
Difference in Amounts between Titratable Acid and Total Carboxylic Acids Produced by Oral Streptococci during Sugar Metabolism
Authors: Iwami Y. , Hata S. , Takahashi N. , Yamada T.
Published: November 2010

The acid produced by the resting cells of Streptococcus mutans NCTC 10449 and HS 6 and S. sanguis ATCC 10556 during sugar metabolism was estimated with a pH-stat and a carboxylic acid analyzer. Lactic, formic, acetic, pyruvic, and carbonic acids were detected in the reaction mixtures, but propionic, citric, succinic, iso-butyric, butyric, iso-valeric, and valeric acids were not detected. The amount of titratable acid estimated by alkaline titration with the pH-stat was larger than the amount of total carboxylic acids estimated with the carboxylic acid analyzer. The difference in quantity between the titratable and the total carboxylic acids increased significantly with an increase in the period of incubation with sugar. Moreover, the value of the alkaline titration of standard lactic, formic, acetic, and pyruvic acids was equal to the amount analyzed with the carboxylic acid analyzer. The results indicated that these two streptococci produced not only these carboxylic acids but also other acid(s), possibly non-carboxylic acid(s), during their sugar metabolism.
Adsorption of 4-Methacryloxyethyl Trimellitate Anhydride (4-META) on Hydroxyapatite and its Role in Composite Bonding
Authors: Misra D.N.
Published: November 2010

The adsorption of 4-methacryloxyethyl trimellitate anhydride (4-META) was studied from ethanol and dichloromethane onto synthetic hydroxyapatite (containing about 1.5 monolayers of physisorbed water) in order to study its role in restorative composite bonding to teeth.

The adsorption lsotherm of 4-META was S-shaped and reversible from ethanol, and followed the Langmuir plot at lower concentrations. The isotherm was irreversible from dichloromethane, and a constant amount of adsorbate was removed from the solutions above a certain concentration. The irreversibly adsorbed compound was completely removed by washing with ethanol. Therefore, the bonding between teeth and the restorative resin containing 4-META as a coupling agent is micromechanical and not chemical in nature. An analysis of isotherms showed that the benzene rings of the adsorbate molecules lie flat on the surface for both solvents. The molecules adsorbed from ethanol rotate about the solvent-modified (esterified) or unmodified carboxylic anhydride moieties with methacrylate hydrocarbon groups which are folded upward. However, the molecules adsorbed from dichloromethane remain fixed to the surface without rotation, and their methacryloxyethyl groups are folded over the rings.

The diametral tensile strength of a BIS-GMA polymer with adsorbate-covered apatite was approximately equal to that of the composite filled with untreated apatite.
Increased Wall-to-Wall Curing Contraction in Thin Bonded Resin Layers
Authors: Feilzer A.J. , De Gee A.J. , Davidson C.L.
Published: November 2010

Wall-to-wall (WTW) polymerization contraction of filled and unfilled chemically and photo-initiated resins was studied in relation to the WTW distance. In an experimental set-up, the resins were bonded to two opposing disks, and the axial (WTW) displacement resulting from the polymerization shrinkage was measured continuously. It was found that the WTW contraction increased with decreasing WTW distance and ultimately reached a value of almost three times the linear polymerization shrinkage.
Fibroblastic Subpopulations in Uninjured and Wounded Rabbit Oral Mucosa
Authors: Bronson R.E. , Treat J.A. , Bertolamp C.N.
Published: November 2010

Fibroblast cultures derived from uninjured and reparative rabbit buccal mucosa were compared in terms of extracellular glycosaminoglycan (GAG) content and cellular response to interleukin-1 (IL-1). Under identical growth conditions, proliferation of both cell lines was the same. Both lines incorporated [3H]-glucosamine into GAG in cellular, pericellular, and medium fractions, with the majority of incorporated label residing in the medium. Dermatan sulfate (DS) was the predominant GAG in the medium fraction of both normal and wound fibroblast cultures; however, the two cell lines differed in the identity of the medium fraction's secondary GAG: chondroitin sulfate (CS) for normal fibroblasts and hyaluronic acid (HA) for wound-derived cells. The GAG content of the pericellular matrix for all cultures was the same regardless of the tissue of origin: heparan sulfate (HS) accompanied by a very small amount of CS. Exposure to IL-1 produced limited but highly specific effects: It was not mitogenic for either cell line but did cause a quantitative change (increase) in overall incorporation into GAG for medium and pericellular fractions for both cell lines. Further, IL-1 induced a qualitative change in GAG composition for normal mucosal fibroblastic medium fractions by causing the synthesis/release of heparan sulfate (HS) and a variant form of DS. These data support the hypothesis that different fibroblastic substrains can populate a given oral site as a function of variables such as injury andlor healing status.
National Survey of Caries Prevalence in 6-15-year-old Children in France
Authors: Cahen P.M. , Turlot J.C. , Frank R.M. , Obry-Musset A.M.
Published: November 2010

The prevalence of dental caries in France is not known on a nationwide basis, despite the fact that a number of epidemiological studies have been conducted in various parts of the country. The aim of the present study was to provide a national baseline examination of the dental health of children in 1987 since, beginning in November, 1986, the sale of fluoridated salt began in France. A multi-stage probability sample of 19,366 children was selected as representative of the 6-to-15-year-old population. The sample covered all the 95 departments of France. Teams of well-calibrated examiners were constituted in each of the sixteen Faculties of Dental Surgery of France. The prevalence of caries for each age group was determined by means of DMFT, DMFS, dft, and dfs indices. Periodontal conditions were assessed by means of the Plaque Index (Silness and Löe, 1964), the Calculus Index (Marthaler, 1966), and the Gingival Index (Löe and Silness, 1963).

Calculation of the mean DMFT index showed, respectively, 0.5 and 1.0 new carious teeth per year under and over the age of 11. The mean values of the DMFT index at ages 6, 12, and 15 were, respectively, 0.5, 4.2, and 6.9. Under the age of 11, the mean DMFS index increased by one between each successive age group and by nearly two over the age of 11. The mean values of the DMFS index at ages 6, 12, and 15 were, respectively, 0.8, 7.6, and 13.0. The percentage of caries-free children decreased from 32.2% at age 6 to 7.9% at age 15.
Biophysical Analyses of Sequential Bands of Enamel Related to Ruffle-ended and Smooth-ended Maturation Ameloblasts
Authors: McKee M.D. , Martin J.R. , Landis W.J.
Published: November 2010

During amelogenesis in the rat incisor, modulating ruffle-ended (RA) and smooth-ended (SA) ameloblasts are distributed as bands in the enamel organ of the maturation zone. This distribution of the two cell types has been shown to be precisely correlated with a banding of the underlying enamel, as shown by staining and other cyclical indicators (Takano et aL, 1982a,b). Several biophysical approaches have been taken here to characterize the enamel bands sequentially and to determine whether the appearance of such bands is attributable to differences in inorganic composition possibly related to RA and SA. Sprague-Dawley rats were decapitated under ether anesthesia, lower incisors were dissected from surrounding alveolar bone, and enamel organs were wiped from the teeth with moistened gauze. Analyses were performed on either the surface of intact enamel or on individual strips of enamel dissected from the tooth surface, by use of the translucent bands that appear during drying as reference marks for the positions of the overlying cell type. X-ray diffraction (XRD), infrared spectroscopy (IR), x-ray photoelectron spectroscopy (XPS), and wavelength-dispersive electron probe x-ray micro-analysis (WDS) all failed to detect significant differences between analysis areas; data were characteristic of enamel apatite having typical XRD maxima (hkl = 002, 211, 112, 300), IR absorption bands (PO43- and CO32-), XPS Ca and P binding energies (Ca2p = 350.5, 346.9 eV; P2p = 133.7, 132.7 eV), and WDS Ca/P molar ratios (1.33 - 1. 49). It is concluded that discernible differences in Ca and P chemistry in enamel related to RA and SA are extremely small, and that enamel banding may not be solely an intrinsic property of changes in the inorganic component of this tissue but may also be a function of organic matrix effects determined by cumulative cellular modulations during enamel maturation.
A Survey of Reference Accuracy in Five National Dental Journals
Authors: Doms C.A.
Published: November 2010

Previous studies have examined the bibliographic accuracy of citations in medical journals. The purpose of this study was to assess reference accuracy in five national dental journals.

One hundred references were randomly selected from the March, 1987, issue of each of five dental journals (a total of 500 references). Each reference was verified either from the original source or from other indexing tools if the original was unavailable. References were divided into two categories: incorrect and correct. The number of incorrect references was counted and subdivided into major and minor errors. The errors were grouped by types of error: author, article title, citation (which included errors in journal title, volume, issue, and page numbers), and "unable to verify". This survey found 211 (42%) inaccuracies out of 500 references reviewed, with a total of 248 errors within the incorrect group. Out of the latter, 173 (70%) were minor errors, and 75 (30%) were major errors. Types of minor errors ranked as follows: minor article title errors, 86 (35%); minor author errors, 61 (25%); and minor citation errors, 26 (10%). Types of major errors were ranked as follows: incorrect journal citation, 32 (13%); "unable to verify", 25 (10%); incorrect author, 10 (4%); and incorrect article title, 8 (3%). The results of this survey showed that nearly half of the references reviewed were inaccurate.
A New Method for the Estimation of Mutans Streptococci in Human Saliva
Authors: Jensen B. , Bratthall D.
Published: November 2010

A new method for quantitating the numbers of mutans streptococci in saliva-the "Strip mutans" test-was developed. It includes the following steps: A prepared plastic spatula is contaminated with saliva, transferred to a selective broth, incubated for two days, and dried. A predetermined area is counted or evaluated for CFUs of mutans streptococci. The medium contains sucrose to promote adhesion of mutans streptococci to the strip. Bacitracin, added just before use, is the basis for the selectivity. Results with the new medium were compared with those from the "spatula technique" and with those from conventional saliva sampling with dilution. The studies involved 302 and 60 schoolchildren, respectively. There was a highly significant correlation between the results from the new method and those from conventional methods. The strip mutans test is easy to use and has long shelf-life, and the spatulas with adherent colonies can be saved for future comparisons.
Establishment of Latent Ganglionic Infection with Herpes Simplex Virus via Maxillary Gingiva and Viral Re-activation in vivo after Trauma
Authors: Shimizu F. , Monma Y. , Sekizawa T. , Kamiyama K.
Published: November 2010

Herpes simplex virus can remain latent for months or years in sensory and autonomic ganglia of animals and man, and can be re-activated in vivo by several procedures such as neurectomy, irritation of epithelial surfaces, and administration of immunosuppressive agents. The objective of this study was to determine whether dental stimuli can cause re-activation of the latent herpes simplex virus. Homogenization and explantation of ganglia from mice showed that herpes simplex virus (type 1) traveled from maxillary gingiva to trigeminal ganglia, and remained latent. It was also shown that mice passively immunized with rabbit antibody to herpes simplex virus, following the inoculation of herpes simplex virus by the maxillary gingiva route, developed a latent infection in the trigeminal ganglia. Neutralizing antibody was cleared from the circulation and could not be detected in most of these animals after five weeks. A neutralizing test showed that antibody-negative mice with latent infection were able to produce antibody to re-infection with herpes simplex virus, suggesting that re-activation can be identified by measurement of serum antibody. By use of this mouse model system, it was shown that when maxillary gingiva was traumatized with dry ice, viral re-activation occurred in 58% of these animals, as demonstrated by the appearance of neutralizing antibody. Irradiation by a Stomalaser beam had no effect on the re-activation of latent herpes simplex virus. Our mouse model system may serve as a useful model for obtaining new information on re-activating or inhibitory factors in dentistry.