bluuebunny/crossref_metadata_2025 huggingface dataset:
A 30-month Longitudinal Study of the Effects of Some Oral Hygiene Measures on Streptococcus mutans and Approximal Dental Caries
Authors: Axelsson P. , Kristoffersson K. , Karlsson R. , Bratthall D.
Published: November 2010

The effects of some oral hygiene measures on Streptococcus mutans and approximal dental caries were evaluated. One hundred and eighty-seven 13-year-old individuals with high levels of salivary S. mutans (>106/mL) were selected. They were randomly distributed into three groups. Group I initially received professional mechanical toothcleaning, tongue-scraping, chlorhexidine treatment, and oral hygiene instructions concentrated on the approximal surfaces most colonized by S. mutans. The treatment was given four times with intervals of two days, followed by one single treatment every six months throughout the experimental period. The initial treatment period for group II, also consisting of four visits, included the same oral hygiene instructions as for group 1. The instructions were repeated every six months. Group III was maintained in the preventive program provided by the local Dental Health Office, based on mechanical plaque control and topical use of fluorides and chlorhexidine at individualized intervals. Group I showed a significant immediate reduction of S. mutans in saliva as well as on approximal tooth surfaces. After six months, there were no differences among the three groups regarding these variables. Compared with baseline, there was a significant reduction of S. mutans in all groups. There was no significant difference in caries progression among the three groups. However, the selected "high-risk" individuals in group I developed 0.25 new manifest caries lesions approximallylyear, compared with 0.27 for all children of the same age group in the area. Seventeen individuals had approximal surfaces with consistently high or consistently low S. mutans levels. Forty-six percent of the surfaces with high values developed new or progressive caries, compared with 2% of the surfaces with low values.
HSV-1-infected Oral Epithelial Cells are Targets for Natural Killer Cells
Authors: Lindemann R.A. , Golub S.H. , Park N.-H.
Published: November 2010

A mechanism of cell-mediated immunity was investigated to determine whether natural killer (NK) cells were able to lyse antigenically-altered epithelial cell targets. Using standard four-hour chromium-release assays, we tested human peripheral blood lymphocytes against autologous untreated epithelial cells and autologous HSV-1-infected epithelial cells and calculated the percentage of lysis. With adherent cell-depleted peripheral blood, only epithelial cells infected with virus were lysed (p = 0. 009). Evidence that NK cells were responsible for the lysis exists because: (1) peripheral blood lymphocytes were able to lyse allogeneic as well as autologous virus-infected cells; (2) when NK cells were depleted with the lysosomotropic drug L-leucine methyl ester, cytotoxicity against infected targets was abrogated; and (3) depletion of NK cells by the monoclonal antibody Leu-11b, plus complement, also eliminated cytotoxicity against virus-infected targets. Additional evidence suggests that lysis of targets does not involve antibody-dependent cellular cytotoxicity. These findings indicate that NK cells have the potential to perform a similar in vivo immunologic role in the oral cavity and initiate cell-mediated lysis of virus-infected epithelial cells.
Ameloblast Modulation and Changes in the Ca, P, and S Content of Developing Enamel Matrix as Revealed by SEM-EDX
Authors: Sasaki T. , Debari K. , Garant P.R.
Published: November 2010

Freeze-dried rat incisors were examined by high-resolution scanning electron microscopy (SEM) combined with energy-dispersive x-ray microanalysis (EDX) for determination of the correlation between the morphology of the enamel organ and the concentrations in the adjacent developing enamel matrix of calcium (Ca), phosphorus (P), and sulfur (S), as well as the CalP ratio. In SEM examination of the freeze-dried enamel organ, it was possible to identify the stages of enamel secretion, transition, and maturation, and furthermore to identify ruffle-ended and smooth-ended maturation ameloblasts. EDX analysis of the outer layer of forming and maturing enamel was carried out from the apical to the incisal end at interval points of approximately 50 μm. Ca and P concentrations increased gradually and continuously from the secretion zone to the end of the maturation zone, but never showed a steep rise in any of the zones examined. Maturing enamel overlaid by either ruffle-ended or smooth-ended maturation ameloblasts showed similar Ca and P concentrations. Throughout the outer enamel layer, the CalP molar ratio was fairly constant. Sulfur concentration began to decrease in the zone of enamel secretion, and was no longer detected in the middle of the maturation zone.
In vitro Caries-like Lesion Production by Streptococcus mutans and Actinomyces viscosus Using Sucrose and Starch
Authors: Clarkson B.H. , Krell D. , Wefel J.S. , Crall J. , Feagin F.F.
Published: November 2010

We investigated the formation of caries-like lesions on root and enamel sections by S. mutans and A. viscosus when grown in four different carbohydrate substrates. The substrates were: sucrose, starch + α-amylase, and a combination of starch and sucrose with and without a-amylase. Twenty-four sections with exposed windows on both the root and enamel surfaces were exposed to the individual bacterial species in each of the four substrates for three weeks. At three weeks, the sections were removed and lesion depths measured. When grown in sucrose alone, S. mutans produced significantly deeper lesions in both root and enamel surfaces when compared with A. viscosus. However, S. mutans failed to produce lesions when grown in "limited" sucrose with starch added, whereas A. viscosus in this same substrate produced lesions in the enamel and root surfaces. A. viscosus also produced either similar or significantly deeper lesions in both root and enamel surfaces, when compared with S. mutans grown in the two substrates with amylase. Thus, under these in vitro conditions, it was demonstrated that A. viscosus could utilize starch, whereas utilization of starch by S. mutans was α-amylase-dependent.
Characterization of Polydimethacrylates and Their Composites by Dynamic Mechanical Analysis
Authors: Wilson T.W. , Turner D.T.
Published: November 2010

The objective was to characterize, by dynamic mechanical analysis (DMA), the polymeric materials used to restore teeth and, in particular, to assign a glass transition temperature, T g. Generally, in DMA work, Tg is taken as the temperature at which the internal damping, i.e., tanδ, has a maximum value. However, in the present work it was shown that the classical method of assigning T g corresponds more closely to an assignment based on changes in elastic modulus. On this basis, a bis-GMA copolymer and a proprietary dental composite, both polymerized by exposure to light, were assigned Tg values of -25°C and +10°C, respectively. The composite had an even lower value, Tg =-10°C, after saturation with water. The value of Tg can be increased considerably by treatments which are known to increase the degree of polymerization, i.e., by heating or by γ-irradiation.

The present findings imply that composites made by photopolymerization may undergo marked changes in mechanical state (becoming glassy, leathery, and rubbery) in the oral cavity, due to changes in temperature from about 0°C to 50°C. It is not known which of these states would give best service properties, such as wear resistance, but in any case variation of properties in service would appear to be undesirable.
Fluoride in Dental Products: Safety Considerations
Authors: Whitford G.M.
Published: November 2010

This review summarizes the nature of acute fluoride toxicity, its time-course, and the fluoride doses that are involved. The generally accepted "certainly lethal dose" range for 70 kg adults, i.e., from 5 to 10 g of sodium fluoride or from 32 to 64 mg fluoride/kg, is discussed. Based on recent case reports of fluoride-induced fatalities, it is concluded that this dose range has little utility in cases involving young children. The concept of a "probably toxic dose" (PTD) is advanced. The PTD, 5.0 mg Flkg, is defined as the dose of ingested fluoride that should trigger immediate therapeutic intervention and hospitalization because of the likelihood of serious toxic consequences. The concentrations and quantities of fluoride in selected dental products are discussed in relation to the PTD. It is concluded that, as these products are currently packaged, most of them contain quantities of fluoride sufficient to exceed the PTD for young children. Recommendations are made to reduce the risk of toxicity associated with their use.
Topical Fluoride Therapy: Discussion of Some Aspects of Toxicology, Safety, and Efficacy
Authors: Newbrun E.
Published: November 2010

Although ingestion of an acute toxic dose of fluoride is extremely rare in dental treatments, practitioners should be familiar with the signs and symptoms and with emergency measures of treating accidental overdosage. The amount of fluoride ingested chronically from the use of self-applied topical fluoride can be reduced to safe limits by instructing parents to dispense small amounts of toothpaste for their young children and to ensure that fluoride dentifrices and mouthrinses are fully expectorated. Similarly, when custom-fitted trays are used, only minimal amounts of fluoride gels are necessary. The minimal amount of such gels that can be dispensed appears to be influenced by their viscosity. Clinical efficacy does not support a reduction in the concentration of fluoride in commercial dentifrices.
Invited Review: The Neurobiology of Facial and Dental Pain: Present Knowledge, Future Directions
Authors: Sessle B.J.
Published: November 2010

This review outlines recent research which has identifed critical neural elements and mechanisms concerned with the transmission of sensory information related to oral-facial pain, and which has also revealed some of the pathways and processes by which pain transmission can be modulated. The review highlights recent advances in neurobiological research that have contributed to our understanding of pain, how acute and chronic pain conditions can develop, and how pain can be controlled therapeutically. Each section of the review also identifies gaps in knowledge that still exist as well as research approaches that might be taken to clarify even further the mechanisms underlying acute and chronic oral-facial pain.

The properties of the sense organs responding to a noxious oral-facial stimulus are first considered. This section is followed by a review of the sensory pathways and mechanisms by which the sensory information is relayed in nociceptive neurones in the brainstem and then transmitted to local reflex centers and to higher brain centers involved in the various aspects of the pain experience—namely, the sensory-discriminative, affective (emotional), cognitive, and motivational dimensions of pain. Reflex and behavioral responses to noxious oral-facial stimuli are also considered. The next section provides an extensive review of how these responses and the activity of the nociceptive neurones are modulated by higher brain center influences and by stimulation of, or alterations (e.g., by trauma) to, other sensory inputs to the brain. The neurochemical processes involved in these modulatory mechanisms are also considered, with special emphasis on the role of neuropeptides and other neurochemicals recently shown to be involved in pain transmission and its control. The final section deals with recent findings of peripheral and central neural mechanisms underlying pain from the dental pulp.
Colonization of the Human Oral Cavity by a Streptococcus mutans Mutant Producing Increased Bacteriocin
Authors: Hillman J.D. , Dzuback A.L. , Andrews S.W.
Published: November 2010

Streptococcus mutans strain JH1005 is a mutant that produces levels of bacteriocin activity three-fold-elevated than those produced by its parent, JH1001. A single infection regimen with JH1005 was found to result in persistent colonization of the teeth of all three adult subjects tested. This is a significant improvement over JH1001, which required multiple exposures in order to colonize the teeth of humans reliably. The levels of total cultivable bacteria and indigenous S. sanguis were not affected by JHI005 colonization. In two of the three subjects, total (indigenous plus JH1005) S. mutans levels were significantly decreased. The results provide additional support for the role of bacteriocin production as an ecological determinant in colonization by S. mutans. They also indicate that a practical regimen for infection by an effector strain might be achieved for use in the replacement therapy of dental caries.
Membrane-associated and Solubilized ATPases of Streptococcus mutans and Streptococcus sanguis
Authors: Sutton S.V.W. , Marquis R.E.
Published: November 2010

The proton-translocating, membrane ATPases of oral streptococci have been implicated in cytoplasmic pH regulation, acidurance, and cariogenicity. Membranes were isolated from Streptococcus mutans GS-5 and Streptococcus sanguis NCTC 10904 following salt-induced lysis of cells treated with lysozyme and mutanolysin. The ATPase activities of these membranes were 1.8 and 1.1 units per mg membrane protein, respectively. F1 ATPases were washed free from the membranes and purified by fast protein liquid chromatography (FPLC). Hydrolytic activities of the F 1 ATPases were maximal at pH values between 6.0 and 6.6, whereas the membrane-bound enzymes had pH maxima of 7.5 (S. sanguis) and 6.0 (S. mutans). The F1 ATPases of the streptococci were similar to the well-characterized enzyme of Escherichia coli; they consisted of five different polypeptides and had apparent, aggregate molecular weights of from 335 to 350 Kd. The membrane-bound ATPases were characterized biochemically and found to be similar to those of proton-translocating ATPases of E. coli and Streptococcus faecalis. Km values for the membranes with respect to ATP were found to be 0.9 and 1.0 mmol/L for S. mutans and S. sanguis, respectively. Both enzymes had specificities for purine triphosphates and were active with a variety of divalent cations, although optimal activity occurred with ATP and Mg. The membrane-associated enzymes were sensitive to the inhibitors dicyclohexylcarbodiimide (DCCD) and azide, but insensitive to ouabain and vanadate. Overall, it appears that the membrane-associated ATPases of S. mutans and S. sanguis are similar to the extensively studied proton-translocating ATPases of E. coli and S. faecalis, and that differences in pH sensitivities of the enzymes from the oral bacteria are greater for the membrane-bound, proton-translocating forms than for the soluble, F, forms.
Structural Determinants of Activity of Chlorhexidine and Alkyl Bisbiguanides Against the Human Oral Flora
Authors: Baker P.J. , Coburn R.A. , Genco R.J. , Evans R.T.
Published: November 2010

We assayed chlorhexidine and a series of its analogues, in which the chlorophenyl terminal substituents were replaced with alkyl chains, for their in vitro antimicrobial activity against the Gram-negative and Gram-positive oral bacteria. Changes in antimicrobial activity were correlated with changes in agent structure for identification of structural criteria which may be important in the optimization of agent activity.

Chlorhexidine showed substantial antimicrobial activity against the Gram-negative as well as the Gram-positive oral bacteria. The alkyl agents were comparable with chlorhexidine in their activity against Bacteroides gingivalis and Bacteroides intermedius, black-pigmented Gram-negative obligate anaerobes associated with periodontal disease in adults. Alkyl agents alexidine, heptihexidine (1,6-bis-n-heptylbiguanidohexane), hexoctidine (1,8-bis-n-hexylbiguanidooctane), and hexhexidine (1,6-bis-n -hexylbiguanidohexane), as well as chlorhexidine, were active against Actinobacillus actinomycetemcomitans, a Gram-negative organism associated with localized juvenile periodontitis. Hexidecidine (1,10-bis-n-hexylbiguanidodecane) and heptoctidine (1,8-bis-n-heptylbiguanidooctane) were more active, and hexhexidine was as active as chlorhexidine against Fusobacterium nucleatum, also associated with periodontal disease. Seven of the agents were more active than chlorhexidine against Actinomyces species. All test agents were active against Streptococcus mutans, a Gram- positive coccus associated with dental caries. Hexidecidine had activity equal to that of chlorhexidine when evaluated against the entire battery of organisms.

Analysis of structure-activity relationships revealed that alkyl chains could replace chlorophenyl groups with retention or improvement of antimicrobial activity. Agents with lower lipophilicity were generally more active than those with higher lipophilicity. Within an isolipophilic series, activity increased as methylene bridge length increased, with a requirement for a bridge of at least six carbons for activity against most bacteria. Agents with branched terminal groups were more active than agents of the same bridge length but with unbranched terminal groups.

The alkyl bisbiguanides, agents which do not contain chlorophenyl moieties, have activity against the oral flora comparable with that of chlorhexidine. Of the alkyl agents evaluated in this study, hexidecidine, hexhexidine, and alexidine offer the most promise for use in control of oral diseases.
The Prevention of Sub-surface Demineralization of Bovine Enamel and Change in Plaque Composition by Casein in an Intra-oral Model
Authors: Reynolds E.C.
Published: November 2010

The ability of bovine milk phosphoprotein (casein) to be incorporated into plaque, prevent enamel sub-surface demineralization, and affect bacterial composition was determined using a modified intra-oral caries model. The intra-oral model consisted of a removable appliance containing a left and right pair of bovine enamel slabs placed to simulate an approximal area. Supragingival plaque was collected and impacted into the left and right inter-enamel spaces. The left side of the appliance was exposed to various sugar and salt solutions, while the right side was exposed to sugar and casein solutions. Sodium caseinate, the major fraction αs1-casein, and a tryptic digest of αs1-casein (TD-casein) were studied. Sodium caseinate at a level of 2% w/v in a 3% sucrose-3% glucose-salt solution (pH 7.0) prevented sub-surface enamel demineralization over a ten-day period as shown by microradiography and microhardness. Two exposures of a 2% wlv sodium caseinate, αs1-casein, or TD-casein solution (pH 7.0) per day prevented sub-surface enamel demineralization caused by six exposures of a 3% sucrose-3% glucose-salt solution per day over a ten-day period. Intact αs1-casein and tryptic peptides were shown immunochemically to be incorporated into the inter-enamel plaque. The incorporation of casein and its breakdown in plaque did not produce a significant change in the amount or composition of plaque bacteria. The ability of casein and tryptic peptides to prevent enamel demineralization was related to their incorporation into plaque, thereby increasing plaque calcium phosphate and acid-buffering capacity by the phosphoseryl, histidyl, glutamyl, and aspartyl residues and indirectly through catabolism by plaque bacteria.
Wear and Microhardness of Glass-Ionomer Cements
Authors: McKinney J.E. , Antonucci J.M. , Rupp N.W.
Published: November 2010

Pin-and-disc wear and Knoop Hardness measurements were made on three commercial glass-ionomer cements having slightly different compositions. The specific objective was to determine whether these cements have potential for use in posterior teeth, and, if not, what modifications in composition and structure would be appropriate to enhance their performance. The specimens were pre-conditioned in air, water, or lactic acid at 37°C for one week prior to being wear-tested. Although differences among the samples were noted, some common trends were observed. From changes in hardness, before and after storage, two opposing trends were observed. One trend involved continued cross-linking and possible dehydration, resulting in a substantial increase in hardness. The other trend involved softening from penetrant liquid absorption and a concomitant decrease in hardness. The wear resistances compared favorably with those for resin-based composites except for the lactic-acid-stored specimens, for which changes in microstructure were revealed by SEM. All specimens were very brittle, and catastrophic failure during wear was frequent. Although our conclusion is that glass-ionomer cements with composition similar to those evaluated here are not acceptable for posterior occlusal application, some compositional changes may enhance their performance in stress-bearing applications.
Effect of Time at 37°C on the Creep and Metallurgical Characteristics of Amalgam
Authors: Mahler D.B. , Adey J.D. , Marshall S.J.
Published: November 2010

When aged at 37°C for six months, dental amalgam exhibits a marked decrease in the property of creep. The objective of this study was to investigate the relationship between this decrease in creep and selected metallurgical characteristics. The formation of β1 (Ag-Hg), the grain size of γ 1 (Ag-Hg), and the composition of γ1 were chosen for investigation. Creep was determined according to ADA Specification test No. 1, β1 was measured by x-ray diffraction, and γ 1 grain size and γ1 composition were determined by electron-probe microanalysis. The results showed that the decrease in creep was related to β1 formation and not to changes in either γ1 grain size or γ1 composition.
Enhanced Caries Inhibition by Certain NaF-Surfactant Combinations in Animal Models
Authors: Caslavska V. , Gron P. , Kent R.
Published: November 2010

The purpose of this animal investigation was to determine whether the cariostatic effect of sodium fluoride can be enhanced by combining it with certain surfactants. The surfactants, Zonyl FSC and Lodyne S-110, were selected because they had been found to accelerate the rate of deposition of firmly-bound fluoride in vitro in enamel during enamel-fluoride interaction. Sixty male hamsters and 60 female rats, 21 days old, were placed on the high-sucrose diet 2000 and inoculated with Streptococcus mutans (strain #6715). Each set of animals was divided into six groups of 10 each. The groups received either distilled water, NaF, NaF with Lodyne S-110, NaF with Zonyl FSC, Lodyne S-110, or Zonyl FSC. The animals were scored for caries at the termination of the study. The caries findings in the hamster and the rat series closely paralleled each other. Animals receiving NaF with Zonyl FSC experienced the least decay (about 90% inhibition compared with about 65% for the NaF-alone group). A statistical evaluation showed significant interaction between Zonyl FSC and NaF. No effect on caries experience was seen from administration of Lodyne S-110.
L-serine Enhances the Anaerobic Lactate Metabolism of Veillonella dispar ATCC 177451
Authors: Hoshino E.
Published: November 2010

Under anaerobic conditions, the rate of metabolism of lactate by starved resting cells of Veillonella dispar ATCC 17745 was very low. Because pyruvate was metabolized well by the starved cells, oxidation of lactate to pyruvate, which is the first step of the lactate metabolism, must have been limited in the cells. In the starved cells, the levels of the metabolic intermediates, oxalacetate or fumarate, of which reductions to malate or to succinate could be coupled with lactate oxidation to pyruvate and initiate lactate metabolism, were quite low, suggesting that these had been reduced during the starvation steps under strictly anaerobic conditions. Thus, the starved cells were unable to start the anaerobic lactate metabolism because of shortage of such reducible substrates. L-serine greatly enhanced anaerobic lactate metabolism of the starved cells. This enhancement may have been due to metabolism of L-serine itself and conversion to oxalacetate and fumarate, which made it possible to begin lactate oxidation.
Ratings of Fears Associated with Twelve Dental Situations
Authors: Stouthard M.E.A. , Hoogstraten J.
Published: November 2010

Ratings of fear aroused by 12 dental situations were obtained by the method of paired comparisons. The dental situations concerned one of four categories: (a) preparations for the dental visit, (b) preparations for dental treatment, (c) comments by the dentist on oral state, and (d) actual dental treatment. The situations originated from Gale's ranking questionnaire. It was hypothesized that the amount of fear elicited would increase in the order a, b, c, and d.

Results indicated that subjects were capable of ranking dental situations according to the amount of anxiety they aroused. Overall ratings show reasonably good agreement with the results of Gale's study.

The hypothesis concerning the rank order of the situations was partly confirmed. Two situations deviated strongly from the expected order. The categories (c) and (d) were rated highest in the hierarchy of fear arousal, but their rank order couldn't be established. This finding suggests that dental fear contains a component of physical danger as well as a component of threat to a person's self-esteem.
Correlation between Amalgam Restorations and Mercury Concentrations in Urine
Authors: Olstad M.L. , Holland R.I. , Wandel N. , Hensten Pettersen A.
Published: November 2010

The creatinine-adjusted urinary concentration of mercury in 73 schoolchildren with a mean age of 12 years was determined. In addition, the number of amalgam restorations and their size, prevalence of allergy, and days absent from school due to illness were recorded for each individual. A significant positive correlation (r = 0.55) was found between urine Hg and extent of amalgam restorations, but no correlation existed between urine Hg and allergy or between urine Hg and absence from school due to illness. Neither could any correlation be found between extent of amalgam restorations and either allergy or absence from school.
The Spectral Properties of Temporomandibular Joint Sounds
Authors: Gay T. , Bertolami C.N.
Published: November 2010

Spectral analyses were performed on sounds recorded from TMJ's that had previously been classified into different intracapsular categories, in an attempt to determine whether the inherent properties of these sounds were unique for each different disorder. A total of 55 joints was studied: 32 were diagnosed as displaced disc with reduction [DDR], 10 were diagnosed as displaced disc without reduction [DDN], and 13 were diagnosed as degenerative joint disease [DJD]. The spectral analysis for each recorded joint sound was performed using a Fast Fourier transform routine, the results of which were plotted as a frequency vs. amplitude envelope. These analyses showed that different intracapsular TMJ disorders were characterized by sounds whose energy distribution patterns, while showing certain across-group differences, usually shared significant common spectral properties. The joint-propagated noises associated with DDR, DDN, and DJD were each characterized by a spectral envelope whose primary band of energy was centered around a peak at approximately 1 kHz, and which dropped off from that point to background levels. These patterns presumably reflect the resonance characteristics of the disordered joint as defined by the mass and stiffness of its articulating surfaces. Based on the findings of this study, it would appear that comparisons of the spectral envelopes of joint-propagated sounds would have only limited application in the differential diagnosis of intracapsular TMJ disorders.
Morphological Changes of Intercellular Junctions in the Rat Submandibular Gland Treated by Long-term Repeated Administration of Isoproterenol
Authors: Inoue T. , Yamane H. , Yamamura T. , Shimono M.
Published: November 2010

Long-term repeated administration of isoproterenol (lPR) 2 mg/100 g bw, once daily for ten days, resulted in morphological changes in the intercellular junctions of rat submandibular glands, which were investigated by means of the freeze fracture technique. A significantly increased number of tight-junctional strands was present. These junctional strands extended much deeper toward the basal membrane than those in normal acinar cells. The basal frontier strands that branched from the networks of tight junctions were elongated and had either free-endings or terminal loops, which were more frequently observed in the IPR-treated acinar cells than in untreated acinar cells. Some of the strands of tight junctions were connected to small gap junctions. The diameters of gap junctions were not significantly different from those of control acinar cells. However, smooth areas devoid of particles were found intermingling with the usual packed particles in irregularly shaped small gap junctions. There was no significant difference between the desmosomes of IPR-treated and untreated acinar cells, in terms of either morphology or distribution. These changes in junctional morphology in the IPR-treated acinar cells resemble those seen in salivary glands during development, and in some experimental conditions including tumorous changes.
A Non-antibacterial Chemically-modified Tetracycline Inhibits Mammalian Collagenase Activity
Authors: Golub L.M. , McNamara T.F. , D'Angelo G. , Greenwald R.A. , Ramamurthy N.S.
Published: November 2010

Tetracyclines (including the semi-synthetic analogues, minocycline and doxycycline) are considered useful adjuncts in periodontal therapy because they suppress Gram-negative periodontopathogens. Recently, these antibiotics were found to inhibit mammalian collagenase activity, a property which may also be of therapeutic value. It has been suggested that the anti-collagenase properties of the tetracyclines are independent of their antibiotic efficacy. To advance this hypothesis further, we chemically converted tetracycline hydrochloride to its non-antimicrobial analogue, de-dimethylaminotetracycline. This chemically-modified tetracycline (CMT), although no longer an effective antibiotic, was found to inhibit the in vitro activity of collagenase from partially purified extracts of human rheumatoid synovial tissue and rachitic rat epiphysis. In a preliminary in vivo study, pathologically-excessive collagenase in skin and gingiva was induced by rendering adult male rats diabetic, and the oral administration of CMT to these rats significantly reduced the excessive collagenase activity in both tissues. Moreover, CMT administration did not affect the severe hyperglycemia in these rats but did prevent, at least in part, the diabetes-induced loss of body weight, skin weight, and skin collagen mass; these effects suggest a lack of toxicity in this animal model. A proposed clinical advantage of CMT over conventional tetracyclines, in the treatment of diseases characterized by excessive collagenolytic activity, is the lack of development of antibiotic-resistant micro-organisms during prolonged use. However, the consideration of clinical trials to support this hypothesis must await further laboratory and extensive toxicity tests.
Diffusion of Fluoride Through the Rat Enamel Organ in vitro
Authors: Bawden J.W. , Deaton T.G. , Crenshaw M.A.
Published: November 2010

This study investigated the diffusion of fluoride through the enamel organ in vitro. The rat molar explants used were entirely in the secretory stage or predominantly in the maturation stage of enamel formation. The removal of the enamel organ or metabolic inhibition with iodoacetate caused significant increases in enamel fluoride uptake at both stages of enamel formation. Inhibition with dinitrophenol caused a significant increase only in the maturation phase. Uptake of fluoride in enamel was related to the fluoride concentration in the medium, except in the maturation stage explants, where increasing the medium fluoride concentration from 0.05 ppm to 0.08 ppm did not significantly increase fluoride uptake at any of the three observation times. The findings indicate that the enamel organ exists as a diffusion-limiting membrane to the movement of fluoride from the extracellular fluid compartment to the developing enamel.
Adhesion of Resins to Ag-Pd Alloys by Means of the Silicoating Technique
Authors: Herø H. , Ruyter I.E. , Waarli M.L. , Hultquist G.
Published: November 2010

The purpose of the investigation was to study the effect of water storage on the bond strengths between silanized, silicoated Ag-Pd alloys and veneered composites, in comparison with the bond strengths of systems with conventional retention beads. Furthermore, the mechanism of the bonding was examined. The bond strength of silanized, silicoated dry specimens and similar specimens stored in water was measured by four-point bending. Water storage for 90 days at 37°C reduced the bond strength by approximately 30% to about 15-20 MPa. Mechanical retention beads caused bond strengths of approximately 16-18 MPa which were unaffected by water storage. SEM and microprobe investigations showed that sandblasting with Al2O3 prior to silanization caused substantial numbers of cracks and porosities in the surface layer of the alloy, partly filled with Al2O3. Some particles of silicon oxide in these surface defects were produced by the flame-spraying of the so-called silicoating technique. Further painting of the surface with a silane adhesion primer provided chemical bonding to the composite at the densely spaced Si-O-H-containing silica particles. Many cracks were observed in the interfaces between these particles; thus, water is likely to penetrate the interface with time. The bond strength is most likely reduced by reaction between water and the compositelSi-O structure. The silicon oxide particles are probably attached to the alloy substrate by mechanical retention. Without sandblasting, no bonding was obtained by means of the silicoating technique.
Effect of Acidic Pretreatment on Adhesion to Dentin Mediated by Gluma
Authors: Asmussen E. , Bowen R.L.
Published: November 2010

Tensile bond strengths between dentin and a typical restorative resin were measured after the dentin was treated with Gluma. Solutions of phosphoric, pyruvic, nitric, or oxalic acid, also containing various amino acids, were used as pretreatments. Without amino acids in the solutions, the pretreatments conferred bonds of low strength. Use of acidic solutions containing glycine or N-phenylglycine was found to give bonds of high strength to both dentin and enamel.
The Impact of Dental and Facial Pain
Authors: Locker D. , Grushka M.
Published: November 2010

This paper presents data from a mail survey on dental and facial pain. The survey was conducted in the City of Toronto in 1986. The aim of the study was to obtain estimates of the prevalence of such pain and its impact on daily life. A random sample of 1014 names was drawn from the voters' list, and, as a result of four mailings, information was obtained on 71.6% of the eligible sample. Of those returning questionnaires, 39.7% reported dental or facial pain in the previous four weeks. A psychological impact in the form of worry or concern was reported by 70.3% of those experiencing pain, while 58.0% reported one or more behavioral impacts. The most common behavioral impacts were consulting a dentist or doctor, avoiding certain foods, taking medication, and disturbance of sleep. Severe behavioral impacts such as work disability, need for bed rest, and reduced social contacts were also reported by some of those having pain. The results suggest that dental and facial pain imposes a significant burden on the community. Further research is indicated, with more sensitive impact measures being used.
Calbindin-D 28K Localization in Rat Molars During Odontogenesis
Authors: Elms T.N. , Taylor A.N.
Published: November 2010

Specific antiserum raised against Calbindin-D28K, a vitamin D-dependent calcium-binding protein (CaBP) isolated from chick intestine, was used for localization of the protein in developing rat molars. Previously, CaBP had been localized in specific cells associated with the continuously erupting rat incisor: late pre-secretory ameloblasts, secretory and maturation zone ameloblasts, stratum intermedium cells adjacent to ameloblasts in the late zone of enamel secretion, and papillary cells underlying maturation zone ameloblasts. In this study, the peroxidase anti-peroxidase technique was used for localization of CaBP in histological sections of rat mandibles from 18-day-old rat embryos through 20-day-old neonates. CaBP was not detected in any cells of the enamel organ, dental papilla, or dental sac during early odontogenesis from the dental lamina stage through the advanced bell stage. The protein first appeared in secretory ameloblasts which were situated opposite odontoblasts with newly secreted dentin. CaBP was present in the cytoplasm of more mature ameloblasts, but not in less mature ameloblasts. Some stratum intermedium cells subjacent to well-developed secretory and maturation zone ameloblasts also contained CaBP. The protein was not detected in odontoblasts, pulp cells, or other cells associated with the developing molars. It was also absent from the demineralized enamel and dentin matrix. In developing rat molars, the time-course of appearance of CaBP, a protein dependent for its synthesis on the vitamin D endocrine system in other organ systems, suggests a potential direct role of this hormonal system in enamel mineralization.
Etiological Factors Influencing the Prevalence of Developmental Defects of Dental Enamel in Nine-year-old New Zealand Children Participating in a Health and Development Study
Authors: Suckling G.W. , Herbison G.P. , Brown R.H.
Published: November 2010

Over 1000 children, participating in a longitudinal study of health and development, possess documented medical histories based on birth records and regular assessments starting at age 3. A dental examination at age 5 of 923 participants recorded their exposure to fluoride and evidence of trauma to the deciduous teeth. The prevalence of developmental defects of dental enamel in 696 of the children when aged 9 was reported as 56% (Suckling et al., 1985). For the present study, a number of illnesses, accidents, and other experiences were selected from the recorded information as possible etiological factors for any defect, demarcated and diffuse opacities, and hypoplasia. Despite extensive statistical testing, positive and strong associations were few. The prevalence of hypoplasia, seen in 15% of the sample, was higher in those children who had chicken pox before age 3 and, as reported previously, in those children with a history of trauma to their deciduous incisors. This study illustrates the difficulty of establishing the etiology of enamel defects, even when medical and dental histories are available.
Etching Patterns of Co-Cr Alloys for Bonded Cast Restorations
Authors: Ekstrand K. , Ruyter I.E.
Published: November 2010

Resin-bonded bridges may replace missing teeth and act as splints in periodontal treatment. The objective of this study was to investigate the etch pattern after electrolytic etching of selected Co-Cr alloys in hydrochloric acid and to assess the changes in alloy composition after different etching times.

The alloys investigated were Vitallium, Wironit, Wironium, Nobilium Hard, and Niranium NN. Alloy specimens were electrolytically etched in a hydrochloric acid solution for 1, 2, 5, and 10 min. The etched specimens were examined in a light microscope and a scanning electron microscope (SEM). Different etching patterns were revealed in the various alloys.

Microprobe analyses after the etching of Vitallium showed generally that Co was released and that Cr content increased at the surface.
Development of an Intra-oral Single-section Remineralization Model
Authors: Wefel J.S. , Maharry G.J. , Jensen M.E. , Harless J.D.
Published: November 2010

An intra-oral model system has been developed which uses a single-section technique for before-and-after measurements on the same tissue. This model allows for placement of sections of enamel at both buccal and approximal sites. These sections may be sound or possess white-spot lesions. This allows for the evaluation of lesion initiation, lesion progression, and/or lesion remineralization. The sections are appropriate for measurement by polarized light microscopy, and, although not included in this study, they are also suitable for microradiographic evalution.

With ten human volunteers, the model system was evaluated by means of three rinse regimens in a cross-over design. The distilled water rinse showed the whole range of possible changes (e.g., demineralization, no change, and remineralization). More consistent remineralization was observed when a fluoride rinse or a remineralizing fluid was used. This model system should prove to be quite useful in evaluation of demineralization and remineralization phenomena in the oral environment.
Effects of Fluoride on the Mouse Sperm Morphology Test
Authors: Li Y. , Dunipace A.J. , Stookey G.K.
Published: November 2010

There has been little information and much confusion regarding the genotoxic effects of fluoride. The purpose of this study was to examine the spermatogenic influence of sodium fluoride (NaF) on the germ cells by means of the mouse sperm morphology test. Male mice of genotype B6C3F1 were 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 13 weeks of age, the animals were randomly assigned to eight groups. Group I was intubated with the Maximum Tolerable Dosage (MTD) of NaF (70 mg/kg). Groups II through VI received NaF by stomach intubation at doses of 35, 20, 10, 1, and 0.1 mg/kg, respectively. Group VII served as a negative control and was intubated with distilled water. The positive control, Group VIII, was exposed to a known mutagen, cyclophosphamide (20 mglkg, i.p). The animals were treated daily for five days, and killed by cervical dislocation 35 days after the first exposure to chemicals. Slides of sperm from the cauda epididymides were prepared and blindly scored for morphological abnormalities. Weight of the testes was recorded, and the femurs were saved for fluoride (F) analysis. Analysis of bone F demonstrated the effective absorption of fluoride following intubation. The counts of abnormal sperm and the weights of the testes for mice exposed to NaF doses up to the MTD were not significantly different from those of the negative control. The results of this study showed that NaF did not have adverse effects on mouse sperm morphology.
Enhanced Enamel F Uptake by Monocalcium Phosphate Monohydrate Gels
Authors: Takagi S. , Chow L.C. , Yamada E.M. , Brown W.E.
Published: November 2010

Application of DCPD-forming solutions has been shown to increase substantially the enamel reactivity toward F. The effectiveness of a variation of this treatment procedure, in which the DCPD-forming solution was replaced by a viscous carboxymethylcellulose gel containing monocalcium phosphate monohydrate (MCPM), was evaluated by use of 12 extracted human molars. The MCPM gel was highly effective in enhancing the F uptake by enamel. The mean F uptakes by teeth treated with MCPM gel, followed by exposure to a F solution, were 3972 ( ± 565), 2383 ( ± 312), and 1751 ( ± 313) ppm, respectively, in the outer 5-, 10-, and 15-μm depths in enamel. These uptakes were 2374, 1273, and 852 ppm more than those of the control teeth. Because the F solution was undersaturated with respect to CaF2, the F incorporated into the enamel was believed to be in apatitic form and not as CaF2. The MCPM gel has advantages over the DCPD-forming solution because (1) much longer gel-tooth contact times can be achieved, and (2) the treatment agent can readily be delivered to specific sites where the tooth needs the protection most.
The Effect of Sectioning the Trigeminal Sensory Root on the Periodontally-induced Jaw-opening Reflex
Authors: Collier T.G. , Lund J.P.
Published: November 2010

The experiment was designed to determine the pathway taken to the brain stem by periodontal afferents responsible for the digastric jaw-opening reflex induced by tooth-tapping. Cutting the trigeminal sensory roots of anesthetized decerebrate cats eliminated the ipsilateral periodontally-induced reflex, although the stretch reflexes of the jaw-closing muscles were undiminished. These results suggest that periodontal afferents causing the jaw-opening reflex reach the brainstem through the Vth sensory root, and confirm that muscle spindle afferents travel through the Vth motor root.
The Short-term Uptake and Retention of Fluoride in Developing Enamel and Bone
Authors: Bawden J.W. , Deaton T.G. , Crenshaw M.A.
Published: November 2010

Eight- and 12-day-old rat pups were injected intraperitoneally with fluoride. Plasma, molar enamel, and bone samples were collected at observation times up to six hr after injection. In a second series, adult rats maintained for six weeks on water containing 5 ppm F were injected with fluoride. Plasma, incisor enamel, and bone samples were collected at the same observation times as those used in the first series. Fluoride assays were conducted by means of the microdiffusion, ion-selective-electrode method. In the suckling rats, plasma [F] levels peaked at 15 min and returned nearly to baseline in one hr. Significant increases in the [F] of developing enamel and bone were observed. No significant decline from the peak [F] seen in the hard tissues was observed over the six-hour period. Similar results were seen in the developing enamel of the adult rats. The data gave no evidence of a short-term reversible component of fluoride uptake in developing enamel. Apparent increases in F uptake in enamel and bone beyond peak plasma values suggest the presence of a diffusion-limiting membrane for fluoride from the extracellular fluids into the mineralizing matrix.
Evaluation of Biochemical Validation Measures in Determination of Smoking Status
Authors: Stookey G.K. , Katz B.P. , Olson B.L. , Drook C.A. , Cohen S.J.
Published: November 2010

This study was designed to evaluate the use of salivary cotinine, salivary thiocyanate, and expired-air carbon monoxide as biochemical validation measures for assessing the smoking status of adults. The participants were 20 known non-smokers plus 216 admitted smokers and 102 proclaimed quitters participating in a clinical trial of approaches to facilitate smoking cessation. Conventional analytical procedures were utilized. By use of data from known non-smokers and admitted smokers, the sensitivity and specificity of the validation measures were as follows: salivary cotinine, 99% and 100%; expired-air carbon monoxide, 96% and 100%; and salivary thiocyanate, 67% and 95%, respectively. The salivary cotinine and expired-air carbon monoxide tests confirmed smoking cessation for 55% and 74%, respectively, of the proclaimed quitters. The length of time since quitting was significantly related to the results observed with the latter measures. Consideration of these observations along with various practical factors suggests that expired-air carbon monoxide assays may be the validation measure of choice for most clinical trials.
Relationship Between Root Caries and Coronal Decay
Authors: Vehkalahti M.M.
Published: November 2010

The relationship between caries on root surfaces and untreated coronal lesions was analyzed. A representative sample of 5028 persons was examined, their mean ages being 47.3 years for men and 47.7 for women.

Poor dental health on root surfaces was associated with poor dental health in the coronal areas of the teeth. Subjects with root caries had fewer teeth and fewer fillings, more retained roots and more teeth with untreated coronal decay than did people with no root caries. Compared with the subjects without untreated coronal decay, those with from one to three decayed coronal surfaces showed an odds ratio of 4.5 of having caries on root surfaces. This ratio was 10.1 for the subjects who had more than three decayed coronal surfaces.

It was concluded that factors related to the occurrence of decay are of a similar type whether caries is situated on root surfaces or in the coronal areas of the teeth, and therefore the prevention of caries in both sites may be accomplished by similar means.