bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Mechanism of Mucin Secretion: I. The Role of Intragranular Charge Shielding
Authors: Verdugo P. , Deyrup-Olsen I. , Aitken M. , Villalon M. , Johnson D. 
Published: November 2010

Mucus is an ubiquitous polymer hydrogel that functions as a protective coat on the surface of integument and mucosa of species ranging from simple animals (such as coelenterates) to mammals. The polymer matrix of mucus is made out of long-chain glycoproteins called mucins that are tangled together, forming a randomly woven, highly polyionic network (Lee et al., 1977; Verdugo et al., 1983). Mucin-containing granules, produced by mammalian goblet cells in vitro, undergo massive post-exocytotic swelling. Their swelling kinetics is similar to the swelling of condensed artificial polymer gels (Verdugo, 1984; Tanaka and Fillmore, 1979). We had proposed that mucins must be condensed in the secretory granule and expand by hydration during or after exocytosis (Verdugo, 1984; Tam and Verdugo, 1981). However, the polyionic charges of mucins prevents condensation unless they (the mucins) are appropriately shielded. The present experiments were designed to assert the presence of an intragranular shielding cation and its role in secretion. Giant mucin granules of the slug (Ariolimax columbianus) are released intact from mucus-secreting cells of the slug's skin. They burst spontaneously outside the cell, forming, upon hydration, the typical slug mucus (Deyrup-Olsen et al., 1983). We report here that these granules contain from 2.5 to 3.6 moles calcium/kg dry material, and that calcium is released from the granules immediately before the burst that discharges their secretory product. Therefore, we propose that calcium functions as a shielding cation of poly ionic mucins, and that the bursting discharge of mucins from secretory granules must result from the release of calcium from the intragranular compartment. Calcium release would unshield the polyionic charges of mucins, driving the mutual repulsion of polymer chains and triggering a quick expansion of the mucin network (resembling a Jack-in-the-box mechanism). The existence of a poly ion associated with a shielding cation seems to be a common feature in a large variety of secretory granules. Thus, the proposed spring-loaded release system based on the unshielding of a condensed polyion may serve as a general model for explaining the molecular mechanism of product release in secretion.
The Effect of Taste Adaptation on Salivary Flow Rate and Salivary Sugar Clearance
Authors: Dawes C. , Watanabe S. 
Published: November 2010

To provide an objective measure of the rate of taste adaptation, we measured changes in the flow rate of parotid saliva from 12 subjects while a tastant was infused continuously into their mouths. The tastants employed were sucrose, sodium chloride, and citric acid, each at two different concentrations. With all stimuli, the higher concentration elicited significantly higher initial flow rates, which declined exponentially with time. The half-time for adaptation of flow rate was independent of the nature or concentration of the stimulus and averaged 11.3 sec, which suggests that adaptation follows a single exponential curve. The model of salivary sugar clearance developed by Dawes (1983) predicted that the rate of clearance would be independent of the initial sucrose concentration. However, this model did not take into account the effect of tast adaptation on salivary flow. This process was thus incorporated into the model, which then predicted that the time for clearance would be dependent on the initial sucrose concentration, as found experimentally by Goulet and Brudevold (1984). Hence the process of taste adaptation progressively reduces the stimulated salivary flow rate, which retards the rate of salivary clearance of sugar from the oral cavity.
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.
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.
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.
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.
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.
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.
Experimental Masticatory Muscle Pain
Authors: Bowley J.F. , Gale E.N. 
Published: November 2010

Ten female subjects with no history of temporomandibular disorders performed five exercises designed to induce masticatory muscle pain. Three of the exercises were replications of Christensen's tooth-clenching (1970) and tooth-grinding (1971) studies and Scott and Lundeen's mandibular protrusion (1980) study. The other two exercises were designed to induce specific unilateral masticatory muscle pain. The amount of muscle pain as well as the time of onset and the duration were assessed by a clinical palpation exam and a pain questionnaire. These five pain-inducing methods did not consistently produce masticatory muscle pain in non-pain subjects. However, certain individuals appeared to be very susceptible to developing pain during or after most of the exercises. These susceptible individuals demonstrated a bilateral muscle pain pattern after the unilaterally stressful exercises. None of the five exercises produced a statistically significant amount of site-specific masticatory muscle pain as determined by either the palpation examination or the pain questionnaire, even when the exercise was intended to produce such specificity. The fact that some subjects did develop masticatory muscle pain is indicative that muscle exercise and fatigue may lead to TMD-like symptoms.
Reliability of Visual Analog and Verbal Descriptor Scales for "Objective" Measurement of Temporomandibular Disorder Pain
Authors: Le Resche L. , Burgess J. , Dworkin S.F. 
Published: November 2010

Eight dentists viewed standardized videotapes showing palpations of the temporomandibular joint and muscles of mastication and recorded their judgments concerning the amount of pain the patient was experiencing. Judgments were recorded using a four-point verbal descriptor scale (VDS) ("none", "mild", "moderate", "severe "pain) or a 100-mm visual analog scale (VAS) anchored with the terms "no pain" and "worst pain possible". Test/re-test reliability over a one-week period and interjudge reliabilities were calculated for each scale; reliabilities of the two scales were directly compared based on the statistical equivalence of weighted kappa and the Intraclass Correlation Coefficient. Neither scale showed satisfactory reliability. Median test/re-test reliabilities were k = 0.590 for the VDS and r = 0.822 for the VAS. Interjudge reliabilities averaged k = 0.394 for the VDS and r = 0. 735 for the VAS. Direct comparison of reliabilities for the two scales showed no clear advantage for either scale. The marginal reliabilities of these scales, when used by dentists to quantify the patient's pain, suggest that neither scale should be regarded as an "objective" pain measure.
An in vivo Study of Microhardness and Fluoride Uptake in Partially Demineralized Human Enamel Covered by Plaque
Authors: Reintsema H. , Arends J. 
Published: November 2010

In this investigation, microhardness changes in partially demineralized human enamel were studied after in vivo use of fluoridated toothpaste systems. Flattened enamel specimens were demineralized in vitro and subsequently positioned in approximal positions in the prostheses of 27 participants for three weeks; the samples were plaque-covered in vivo. After brushing for one week with a non-fluoridated paste to achieve an in vivo equilibrium, participants brushed with an assigned product for a two-week period. This test was a six-way cross-over design which used randomization of subjects. Five fluoridated and one non-fluoridated paste were tested. Knoop hardness measurements were carried out on sound and on in vitro demineralized enamel, and after in vivo exposure of the enamel to the dentifrice treatments. The results showed that during the two weeks of in vivo exposure to the fluoride products, net rehardening of the demineralized enamel did not occur, and no correlation was observed between fluoride uptake into the demineralized enamel and changes in microhardness. That we failed to observe rehardening may be due to the fact that the duration of this study was too short for any net remineralization to have occurred, especially because the samples were constantly covered with plaque. Other possibilities, such as the type and/or severity of the lesions used in this study, may account for the lack of rehardening.
Microleakage in Class II Composite Restorations Bonded to Dentin Using Thermal and Load Cycling
Authors: Darbyshire P.A. , Messer L.B. , Douglas W.H. 
Published: November 2010

The effectiveness of a dentin-bonding agent (DBA) and a glass-ionomer cement liner (GIC) in reducing the marginal microleakage at the cervical margin of Class II posterior composite restorations was examined. The effect of load cycling on microleakage of this type of restoration was evaluated. The Class II cavities were prepared in extracted human pre-molar teeth, with the cervical margins finished approximately 1 mm below the CFJ. Combinations of DBA, GIC, and control (no liner) were used as mediators between resin and dentin. All restorations were placed incrementally with a 40-second cure per increment and finished with high-speed diamond burs. Half the samples of each treatment group received cyclical axial loading and half did not. All samples were thermocycled at 5° and 55°C for 500 cycles of one min each, stained (four hr) in 50% AgNO 3, and sectioned following stain development. Microleakage was scored linearly along the dentin-restoration interface. All restorations exhibited microleakage which was unaffected by load cycling. Both the DBA and the GIC significantly reduced microleakage independently. When GIC was present, the additional presence of the DBA did not provide a statistically significant additional reduction of microleakage.
The Effects of Upper Incisor Separation on the Submandibular and Sublingual Glands of Rats
Authors: Kamogashira K. , Yanabu M. , Ichikawa K. , Itoh T. , Matsumoto M. , Ishibashi K. , Abe K. 
Published: November 2010

The effects of upper incisor separation on the submandibular and sublingual glands of rats were examined biochemically, immunohistologically, and radio-immunologically during 28 days of treatment. Lateral separation of the upper incisors by application of force from an orthodontic appliance caused significant enlargement of the sublingual and submandibular glands of rats by three and seven days, respectively, after the beginning of the orthodontic treatment. This enlargement was followed by a significant increase of both RNA and DNA content, with some evidence of hyperplasia and hypertrophy. The enlargement was also associated with a significant increase of substance P at early stages after treatment, suggesting the involvement of the sensory nerves. These changes were largely inhibited by phenoxybenzamine, an α-adrenergic blocker, but not by atropine or morphine. Wet weights and RNA contents of the sublingual glands were markedly reduced by atropine. In comparison with control animals, the enlarged submandibular glands of rats subjected to orthodontic treatment secreted additional proteins identical with those secreted by glands enlarged by chronic administration of isoproterenol. In addition, chemical sympathectomy with 6-hydroxydopamine and phenoxybenzamine stimulated the synthesis of these abnormal proteins, but atropine and morphine did not. In contrast, protease activities in the convoluted granular tubule cells in the submandibular glands were increasingly reduced after treatment, as seen in rats subjected to chronic treatment with isoproterenol. However, the submandibular and sublingual glands completely recovered after removal of the orthodontic appliance.
The Ca, Pi, F, and Proline Content of Developing Bovine Enamel Under GBHA-stained and Unstained Bands
Authors: Bawden J.W. , Keels M.A. , Deaton T.G. , Crenshaw M.A. 
Published: November 2010

The surface enamel of fetal bovine teeth was stained with GBHA to indicate the position of bands of smooth-ended and ruffle-ended ameloblasts relative to the developing enamel. The boundaries of the bands were scored, under a dissecting microscope, and the bulk enamel under each band was collected. The enamel samples were assayed for Ca, Pi, F, and proline. The amount of Ca and P i in the enamel increased in successive bands and seemed unrelated to the overlying ameloblast cell type. The loss of proline seemed unrelated to cell type. The fluoride content of enamel increased by approximately 50% in the first stained band immediately adjacent to the secretory zone. The F level returned to secretory values in the succeeding unstained band. Thus, only changes in the F level of developing enamel appeared to be related to GBHA staining patterns.