bluuebunny/crossref_metadata_2025 huggingface dataset:
Minor Salivary Gland Duct-associated Lymphoid Tissue (DALT) in Monkeys Changes with Age
Authors: Nair P.N.R. , Zimmerli I. , Schroeder H.E.
Published: November 2010

The duct-associated lymphoid tissue (DALT) of minor salivary glands (MSG) is accessible to oral antigens by retrograde passage. DALT responds immunologically to such purely local and duct-derived antigenic stimuli. This study addressed the question as to whether DALT, like other mammalian lymphoid tissues, would change with age. Labial and buccal mucosae of eight Macaca fascicularis animals of known age were processed for light microscopy by Epon embedding. Sections of approximately 1-2 μm thick were prepared, and a total of 144, more or less equidistant, labial and 63 buccal sections were selected and analyzed for various tissue components, by means of morphometric point-counting. The raw data were transformed into stereological parameters. The results showed that DALT and interaeinar plasma cells are totally absent in the newborn monkey. They begin to appear early in life and reach a maximum volume density by one year of age. With further increasing age, the DALT volume showed a sharp decline, followed by a plateauing from year 3 onward, while the plasma cell concentration remained stable. This change was more pronounced in the labial mucosa. These observations on the age-related changes of simian DALT are suggestive of its antigen-induced and antigen-dependent nature. DALT, being part of the gut-associated lymphoid tissue, may play a substantial role in the local immuno-surveillance of the oral cavity.
Parotid Gland Function in Streptozotocin-diabetic Rats
Authors: Anderson L.C.
Published: November 2010

The in vivo response of parotid glands to adrenergic, cholinergic, and peptidergic agonists was studied in control, streptozotocin- (one month's duration), and insulin-treated (three hr) diabetic rats. Neither diabetes nor insulin had an effect on the response to physalaemin. In contrast, physalaemin threshold-dose was lower and maximal response greater in control rats placed on a bulk diet. As previously described, diabetes resulted in nonparallel changes in parotid protein composition, including a reduction in amylase and an increase in peroxidase concentrations (mg/mg protein). In contrast to the results observed with physalaemin, response to methacholine was significantly reduced in diabetic animals, and could be restored to control levels by insulin. Placement of animals on a bulk-diet, however, had no effect on threshold response to methacholine. Finally, response threshold for epinephrine was unaffected by diabetes, insulin, or bulk diet. Thus, insulin appears, directly and specifically, to alter the response of parotid acinar cells to cholinergic stimulation.
Physiological Factors Influencing Salivary Clearance of Sugar and Fluoride
Authors: Lagerlof F. , Oliveby A. , Ekstrand J.
Published: November 2010

The salivary clearance of sugar and fluoride is influenced by several physiological factors not yet fully investigated or understood. There are reasons to believe that these factors influence both the acid production by sugar fermentation in the dental plaque and the cariostatic action of fluoride on the enamel surface and its immediate environment. This paper presents theoretical and experimental considerations of physiological factors which influence the kinetics of sugar and fluoride in the oral cavity.
Nerve Interactions in Salivary Glands
Authors: Emmelin N.
Published: November 2010

In the salivary reflex, not only secretory cells are activated, but also myo-epithelial cells are contracted to support these cells and promote the flow of saliva, and blood vessels dilate to meet the increased demands of the tissues. The various effector cells often receive nerves from both parts of the autonomic system, and interactions may occur when the nerves act on the same type of effector, or on different types of effectors.

While in an experiment electrical stimulation of the sympathetic trunk may decrease a parasympathetic salivary flow by causing marked vasoconstriction, this does not occur in the salivary reflex, since the vasoconstrictors do not take part. On the contrary, the normal sympathetic vasoconstrictor tone of the resting gland is easily overcome by activity in parasympathetic vasodilator nerves when secretion starts. Pronounced synergism can be demonstrated between sympathetic and parasympathetic secretory nerves. In dogs, for instance, in which sympathetic secretion is β-adrenoceptor-mediated, this is marked in the case of fluid secretion. In rats and rabbits, in which β-receptors elicit secretion of amylase, the potentiating interaction among the nerves is striking when amylase secretion is considered. Even the random release of acetylcholine from the post-ganglionic parasympathetic axons, by itself insufficient to evoke secretion, can increase the sympathetic effects. Motor nerves interact with secretory nerves by causing myo-epithelial contraction, mechanically promoting secretion. Interactions between the nerves in their long-term regulatory function on the sensitivity of the acinar secretory and myo-epithelial cells can also be demonstrated.
Regulatory Aspects of N-linked Glycoproteins
Authors: Kousvelari E.E. , Fox P.C. , Baum B.J.
Published: November 2010

Activation of β-adrenoreceptors in rat parotid acinar cells leads to copious exocrine protein secretion. Additionally, β-adrenergic stimulation dramatically increases specific secretory protein synthesis and enhances N-linked glycosylation of secretory glycoproteins. Recently, efforts have been directed toward understanding the mechanisms underlying these biosynthetic events. We have been particularly interested in the receptor-mediated regulation of glycosylation. In this report, we evaluate available mechanistic information from the rat parotid gland and present initial data examining the ability of various regulatory agents to modulate N-linked glycosylation in enzymatically-dispersed cell aggregates from surgical specimens of human parotid glands. We conclude that glycosylation of human parotid N-linked glycoproteins may be regulated by extracellular signaling similar to that operative in the rat parotid gland.
Regulation of Salivary Proteins
Authors: Johnson D.A. , Alvares O.F. , Etzel K.R. , Kalu D.N.
Published: November 2010

Previous studies have shown that several factors — such as alloxan-induced diabetes, adrenalectomy, or removal of the thyroid-parathyroid gland complex — can influence the flow rate, protein concentration, and protein composition of rat parotid saliva. The present study was undertaken to explore further the influence of glucocorticoids and thyroxine on rat parotid saliva in hormonally intact animals. As compared with untreated animals, adult male rats treated with 10 μg dexamethasone per 100 g body weight for eight days demonstrated a 75% reduction in volume of parotid saliva secreted in response to a uniform stimulus. The protein concentration of the saliva was increased three-fold. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed relative decreases in acidic and basic proline-rich proteins and in a protein identified as Fraction V, while amylase was increased. The electron microscopic appearance of the granules was markedly different from that of the control, in that the granules exhibited an electron-dense periphery and core, with the remainder of the granule having an electronlucent appearance. In contrast, rats treated for eight days with 20 μg thyroxine per 100 g body weight exhibited a 50% increase in volume of saliva collected in response to a secretory stimulus. Although the concentration of protein was not different from that of the control, gel electrophoresis showed relative increases in acidic and basic proline-rich proteins and a decrease in Fraction V. Amylase was unchanged. The secretory granules of thyroxine-treated rats were electronlucent and amorphous. The granules appeared to coalesce within the cell. These effects on flow rate, protein concentration, and protein composition which occur in the dexamethasone- or thyroxine-treated groups are opposite those shown to occur following removal of the adrenal or thyroid-parathyroid glands, respectively. In summary, the results indicate that hormones of several endocrine systems are involved in the regulation of salivary flow rate, protein concentration, and protein composition.
A Comparative Study of the Effects of Dentinal Bonding Agents and Application Techniques on Marginal Gaps in Class V Cavities
Authors: Zidan O. , Gomez-Marin O. , Tsuchiya T.
Published: November 2010

The effectiveness of eight dentinal bonding agents (DBA's) and four of their combinations in eliminating marginal gaps in class V cavities was evaluated by the bulk method of composite application and two different incrementation techniques. The cavities were prepared one-half in enamel and one-half in dentin. Basic fuchsin 0.5% in propylene glycol was used for detection of the presence of gaps. For each cavity, the presence of gaps was scored as 0 or 1, at five enamel and five dentin locations. Marginal gaps were present in 6% of all enamel locations and in 75% of all dentin locations investigated. The gap frequency was lowest at the enamel occlusal locations, it increased gradually toward the dentin, and attained the highest value at the gingival locations. In enamel, the occurrence of gaps was dependent on the DBA's but independent of the particular technique used. In dentin, there was significant difference in gap occurrence between DBA's with any of the incrementation techniques. The frequency of gap occurrence was not significantly changed by the incrementation techniques. The most effective single agent in producing gap-free restorations was the Gluma, and the most effective combination was the GlumalClearfil.
A New to the Condensation of Amalgam Under in vivo Conditions
Authors: Lussi A.S. , Buergin W.B.
Published: November 2010

The purpose of this study was to investigate the condensation pressure of amalgam achieved under close to in vivo conditions by 42 general practitioners who were asked to fill a pre-cut standard class 2 cavity in a mannequin head. A measuring device was designed to allow the maximum and average condensation pressures and working and resting periods to be obtained. The results showed a maximum condensation pressure of 9.17 ± 3.04 MPa and 4.09 ± 1.41 MPa with a small (diameter, 1.15 mm) and a large (diameter, 1.8 mm) amalgam plugger, respectively. Only one of the 42 dentists reached the recommended condensation pressure of 15 MPa (Jørgensen, 1977). A significant (p ≤ 0.001) correlation between the duration of the working periods and the maximum condensation pressure was found (r = 0.61). Further investigations are required to determine the influence of these different condensation pressures on the physical properties of various amalgams.
Developmental Changes in the Volumes, Protein, and Some Electrolyte Concentrations of Male and Female Rat Submandibular Saliva Secreted in Response to Methoxamine and Pilocarpine
Authors: Abe K. , Hidaka S. , Ishibashi K. , Yanabu M. , Kamogashira K. , Itoh T. , Matsumoto M.
Published: November 2010

Saliva secreted in response to methoxamine and pilocarpine was collected from the cannulated ducts of the submandibular glands of male and female rats at weekly intervals from two to 10 weeks of age. It was analyzed for volume and for concentrations of protein, potassium, calcium, and inorganic phosphate. Following the collection of saliva, the submandibular glands were removed and weighed.

The wet weights of the glands increased substantially up to seven weeks of age and then reached almost plateau values in both sexes. The salivary volumes secreted in response to both agents in both sexes were positively correlated with the gland weights, except that after five to six weeks of age there was no correlation between gland weight and methoxamine-stimulated salivary volume. The concentrations of protein, potassium, and inorganic phosphate were inversely related to the flow rates only at relatively low rates of flow. The concentration of calcium was positively correlated with the protein concentration and was independent of the nature of the stimulus and of sex differences during postnatal development.
Altered Sympathetic-Salivary Gland Development: Delayed Response to Postnatal Castration
Authors: Melvin J.E. , Hamill R.W.
Published: November 2010

These studies defined the normal and hormonally altered development of activity for tyrosine hydroxylase (T-OH), the rate-limiting enzyme in catecholamine biosynthesis (Levitt et al., 1965), and choline acetyltransferase activity (CAT) in the male rat superior cervical ganglion (SCG). Additionally, salivary gland weight was monitored. Two distinct developmental plateaus for postsynaptic T-OH activity exist. The first plateau represents the prepubertal level, which is significantly lower than the second postpubertal plateau. In contrast, presynaptic CAT activity displayed only a single plateau, commencing at approximately 45 days of age.

The effects of postnatal castration (at 10 or 11 days of age) on the submandibular gland and T-OH activity were delayed until after puberty. No change in T-OH activity was seen at two and four post-operative weeks between control and castrated animals; however, T-OH activity was significantly less in castrated animals at 12 and 16 post-operative weeks. Testosterone replacement reversed the effect of castration on T-OH activity. Conversely, CAT activity in the SCG was unchanged by postnatal castration for at least 16 post-operative weeks, the longest time point studied. The failure of castrated animals to display the normal developmental increase in T-OH activity following puberty was comparable with the effect of castration on the development of submandibular salivary gland weight.

These results suggest that in postpubertal male rats, development of T-OH activity in the superior cervical ganglion is influenced by testosterone. The parallel effects of castration on submandibular gland weight imply that testosterone regulates T-OH activity via an indirect mechanism. In contrast to noradrenergic enzyme activity and target tissue size, the ontogeny of presynaptic CAT activity appears to be insensitive to testosterone levels.
Substrate Specificity of Fucosyltransferase Purified from Human Parotid Saliva
Authors: Tamagawa H. , Iwakura K. , Amano A. , Shizukuishi S. , Tsunemitsu A.
Published: November 2010

The purified fucosyltransferase from human parotid saliva was shown to transfer fucose from GDP-fucose onto the oligosaccharide chains containing the Galβl→3GlcNAc or Gal β 1→4GlcNAc/Glc sequences. Competition studies between asialotransferrin and either lacto-N-fucopentaose 1 or 2'-fucosyllactose provided evidence that both the substrates competed for a common enzyme active site. These results suggest that the fucosyltransferase activities for the three acceptors may be catalyzed by the same enzyme.
Immunocytochemical Localization of Osteocalcin in Developing Rat Teeth
Authors: Gorter de Vries I. , Quartier E. , Boute P. , Wisse E. , Coomans D.
Published: November 2010

Osteocalcin was purified by gel chromatography from a crude extract obtained after decalcification of rat incisors. The apparent molecular weight, as determined by 5-15% SDS-polyacrylamide gel electrophoresis, was 18,000, and amino acid analysis revealed 60 γ-carboxyglutamic acid residues per 1000. Antisera against osteocalcin, raised in rabbits, reacted specifically with osteocalcin when investigated by immuno-electroblotting of dentin crude extract. 4-μm cryosections of formaldehyde-fixed tooth germs showed positive immunocytochemical staining for osteocalcin in dentin and odontoblasts. The staining of the mantle dentin at the coronal sides of the tooth germs was more intense than that of the adjacent circumpulpal dentin, while the odontoblasts involved in the formation of mantle dentin showed stronger immunoreactivity than did odontoblasts involved in circumpulpal dentin formation. This marked difference was not observed on the root sides of the tooth germs. In 1-μm cryosections, osteocalcin immunoreactivity was found evenly distributed throughout the entire cell body, with the exception of the Golgi region, which was less intensely stained, while the nucleus and the cell process were negative. The positive staining reaction with anti-osteocalcin antiserum was found in dentin from the very onset of its formation in the fetus. ln conclusion, our results demonstrate the presence of osteocalcin in odontoblasts and dentin. Its immunocytochemical localization may be compatible with a distinct role in early dentinogenesis.
Effects of Bicarbonate-based Dental Powder, Fluoride, and Saccharin on Dental Caries and on Streptococcus sobrinus Recoveries in Rats
Authors: Tanzer J.M. , Grant L. , Ciarcia J.
Published: November 2010

The effects of NaHCO 3-based dental powder containing NaF and sodium saccharin on dental caries and Streptococcus sobrinus recoveries in rats were studied. Weanling specific-pathogen-free Osborne-Mendel (SPFOM) rats were inoculated with S. sobrinus 6715-13WT. One of six infected groups was topically treated with either demineralized water (DW), a dental powder suspended such that there was 1 part solid per 2 parts DW, 0.073% NaF, 0.5% Na-saccharin (Nas), or a combination of NaF and Nas at the same concentrations. NaF-supplemented DW (at 10 ppm F-) was provided to the 6th group of infected rats as a positive treatment control, but this group was otherwise untreated. A seventh but uninfected group was topically treated with DW. All topical treatments were given once for one min daily per rat, for five days per week. Animals' teeth were swabbed for recovery of 6715-13WT and total recoverable flora. At 37 days after start of treatment, S. sobrinus recoveries were lower only for those rats topically treated with the dental powder (p<0.05) by comparison with recoveries from the infected, topical DW-treated group. Caries scores, however, were 42% lower for the groups receiving the dental powder (p<0.005), 30% lower for those treated with the combined NaF-Nas (p<0.005), and 47% lower for the NaF-supplemented drinking water group (p<0.005). The dental powder effects, like those for the combined NaF-Nas and NaF drinking water, were evident on both smooth and fissure tooth surfaces. Both the 10 ppm F- drinking water and the dental powder significantly (p<0.005) reduced fissure caries scores below the level elicited by the indigenous mutans-free flora in the DW-treated uninfected rats; however, these reductions were not significantly different from one another. Thus, the 10 ppm F- drinking water and the dental powder equally inhibited not only the S. sobrinus-attributable component of caries but probably also the component of caries attributable to the indigenous oral flora.
The Effects of Tenotomy on the Morphology of the Rabbit Digastric Muscle
Authors: Waryjas R.J. , Muhl Z.F.
Published: November 2010

The digastric muscles of 17 New Zealand White rabbits were subjected to tenotomy. A sham operation was performed on six animals. Groups of three or four animals were killed at one hour, one day, 10 days, 30 days, and 60 days after the tenotomy. There was evidence of tendon regeneration by 10 days, and by 30 days the tendon appeared normal macroscopically. The tendon was normal in microscopic appearance in the animals examined at 60 days.

Muscle belly length and fascicle length decreased after the tenotomy, and the angle of pinnation increased. Sarcomere lengths underwent a transient decrease within one hour of the tenotomy, but then were as long as or longer than those in the sham-operated group.

A biomechanical analysis suggests that the net result of the morphological changes produced by the tenotomy leads to a reduction in force capability of only about 12%. The shorter belly and fascicle lengths, however, may diminish the effective range over which effective force can be exerted.
X-ray Photoelectron Spectroscopic Studies of the Adsorption of Salivary Constituents on Enamel
Authors: Kubokit Y. , Teraoka K. , Okada S.
Published: November 2010

Time-dependent change of adsorption of salivary components on the outermost surface layer of enamel was studied by x-ray photoelectron spectroscopy. Adsorption of proteinaceous components, as monitored in terms of the relative mass of nitrogen, was detected within 30 min, increased with time, and reached a plateau at 90 min, Thus, the ratio of nitrogen to calcium in the two-hour sample increased to about 240 times that in the control sample. The ratio of carbon to nitrogen on the surface decreased to about one-half of that in the control sample. The data established the time required for equilibrium between the proteinaceous component in saliva and the amount of material adsorbed onto the tooth surface.
The Efficiency of Half-mouth Examinations in Estimating the Prevalence of Periodontal Disease
Authors: Hunt R.J.
Published: November 2010

Several studies, including the NIDR 1985 national survey of working adults, have used periodontal examinations of only two quadrants of the mouth to estimate the prevalence of periodontal conditions. To investigate the efficiency of half-mouth periodontal examinations, I compared the results from the examination of all teeth in a sample of 477 dentate elderly people with scores that would have been obtained if randomly selected pairs of quadrants had been examined instead. In this elderly dentate population, relatively little information would have been lost if diagonal half-mouth or same-side half-mouth scores instead of whole-mouth scores had been used to estimate the number or proportion of teeth with periodontal conditions. However, the proportion of people with the less prevalent conditions, i.e., deep pocketing and mobility, was underestimated slightly. Slightly less efficiency was also noted for the less prevalent conditions. These findings suggest that half-mouth recording may be useful for prevalence surveys, but cannot be recommended for incidence surveys or clinical trials, where incremental changes may be small.
The Uptake of Horseradish Peroxidase in Monkey Temporomandibular Joint Synovium after Occlusal Alteration
Authors: Kubo Y.
Published: November 2010

We conducted an electron microscopic study on the alterations in the tempomandibular joint (TMJ) synovium of the monkey after at was subjected to unilateral bite-raising, by means of a maxillary occlusal splint. The uptake of intravenously injected horseradish peroxidase (HRP) by type A cells was demonstrated in the disturbed TMJ, The uptake of HRP decreased three to six wk after occlusal alteration, and was the same as in normal type A synovial cells after 16 wk.
Pharmacokinetic Aspects of Topical Fluorides
Authors: Ekstrand J.
Published: November 2010

Pharmacokinetic studies have revealed quantitative information about the bioavailability, rate of absorption, distribution, and clearance of fluoride following the use of fluoride-containing dentifrices, gels, varnishes, and solutions. It is concluded that following the use of topical fluoride products, variable amounts of fluoride are swallowed and absorbed into the systemic circulation-amounts which may be sufficient to produce acute or chronic side-effects. Pharmacokinetic data should, therefore, form part of the basis for the optimal and safe use of fluoride products. In addition, there is a need for future research to determine the kinetics of fluoride in the oral fluids after the application of topical fluoride agents and to determine the associated changes in the composition of the mineral components of the oral fluids.
Hard Tissue Barrier Formation in Pulpotomized Monkey Teeth Capped with Cyanoacrylate or Calcium Hydroxide for 10 and 60 Minutes
Authors: Cvek M. , Granath L. , Cleaton-Jones P. , Austin J.
Published: November 2010

Monkey incisor teeth were pulpotomized in groups of 10. After physiological hemostasis, the pulps of group I were covered with isobutyl cyanoacrylate, and those of groups II and III with calcium hydroxide for 10 and 60 minutes, respectively, whereafter this compound was washed away and the wound surfaces covered with Teflon. In group IV, calcium hydroxide was used as a positive control, and Teflon as a negative control in group V. The animals were killed after 12 weeks and the teeth removed in tissue blocks. The material was processed and evaluated histologically with respect to location and continuity of a hard tissue barrier, type of newly formed hard tissue, state of the pulp, and presence of stainable bacteria in the coronal cavity.

Seven of nine teeth in group I showed a hard tissue barrier. The corresponding figure for group II was eight out of 10 teeth. All teeth in groups III and IV had a barrier. The incidence of a continuous barrier increased from group I through group IV, as did the incidence of its location below the level of the original wound surface. The condition of the pulp was related to the presence of bacteria and the continuity of the barrier to the presence of inflammation. There was no bridging in group V.

The results support the theory that a low-grade irritation is responsible for the formation of a hard tissue barrier in exposed pulps.
Prevalence of Total Tooth Loss, Dental Caries, and Periodontal Disease in Mexican-American Adults: Results from the Southwestern HHANES
Authors: Ismail A.I. , Burt B.A. , Brunelle J.A.
Published: November 2010

The Southwestern portion of the Hispanic Health and Nutrition Examination Survey (HHANES) was conducted by the National Center for Health Statistics (NCHS) in 1982 and 1983. The survey population was Mexican-Americans residing in five Southwestern states. This report presents data on the prevalence of total tooth loss, dental caries, and periodontal diseases in 3860 Mexican-American adults aged from 18 to 74. Results show that 4.3% of this group was edentulous. Among the dentate, Mexican-Americans had lower overall DMF scores but higher numbers of untreated decayed teeth than did residents of the same region seen in the NHANES I survey in 1971-1974. Caries of the smooth surfaces in both posterior and anterior teeth was more pronounced in the older than in the younger age groups. Mexican-Americans had more gingivitis but fewer periodontal pockets than did the general population in the Western states during NHANES 1. The caries pattern in the Mexican-Americans suggests that caries among adults may remain a problem in the future, with the possibility of increased involvement with the aging, although modest, of smooth tooth surfaces.
Changes of Serum Alkaline Phosphatase Following Mandibular Osteotomy in the Rat
Authors: Nilsson L.P. , Granström G.
Published: November 2010

Activity of alkaline phosphatase in serum (S-ALP) was characterized and compared with that of non-specific alkaline phosphatase (APase) of hard-tissue origin in the rat. The enzyme was characterized bio-chemically, and optimal incubation procedures were determined. S-ALP levels were determined before and after mandibular osteotomy combined with different degrees of periosteal reflections. Separation of S-ALP isoenzymes by isoelectric focusing revealed four major bands. A marked decrease of S-ALP activity was seen after osteotomy, and all isoenzymes were affected similarly. After treatment with hyperbaric oxygen, a smaller decrease in S-ALP was seen. S-ALP could be used as a marker for hard-tissue turn-over after surgical procedures.
Hyaluronidase Activity of Rabbit Skin Wound Granulation Tissue Fibroblasts
Authors: Ruggiero S.L. , Bertolami C.N. , Bronson R.E. , Damiani P.J.
Published: November 2010

The objective of this work was to identify and compare hyaluronidase activities of normal dermal and dermal wound granulation tissue fibroblasts. Direct evidence of the fibroblast as a source of tissue hyaluronidase was obtained. Fourth passage rabbit dermal fibroblasts were harvested on culture days 4, 8, 14, 18, and 22. Hyaluronidase activity and [35S]-sulfate- or [3H]-glucosamine-labeled glycosaminoglycans (GAGs) were monitored. Hyaluronidase assays were performed on medium and cellular fractions at the designated intervals. Enzyme activity of cellular fractions for both normal dermal and 14-day post-wound granulation tissue fibroblasts increased progressively through culture day 8. Thereafter (days 14-22), an eight-fold drop in cellular activity was coupled with cell death and emergence of hyaluronidase activity in medium fractions. Marked increases in degradation of secreted matrix components were concurrent with lysis-induced release of hyaluronidase. In this culture system, hyaluronidase activity was confined exclusively to cellular fractions and was released into the medium only under non-physiological conditions conducive to cellular death and lysis. Accordingly, this work suggests that previously reported skin wound hyaluronidases may be offibroblastic origin and that susceptible GAGs are not degraded extracellularly, but, rather, must be internalized as a prerequisite to devolymerization.
Abnormal 45Ca Fluxes in Dispersed Submandibular Acini of Rats Treated with Reserpine
Authors: Müller R.M. , Martinez J.R.
Published: November 2010

The uptake and efflux of the isotopic tracer45Ca were compared in dispersed submandibular acini of both control rats and rats treated with seven daily doses of reserpine (0.5 mglkg, i.p.). Tracer uptake occurred in a time-dependent manner in both types of acini and reached 8.4 ± 0.2 and 8.0 ± 0.2 pmol/mg protein, respectively, in acini from control and treated animals after 60 min of incubation. Uptake of tracer was 2.35 nmol/mg DNA in control cells and 4 nmol/mg DNA in cells from treated rats at 60 min.45Ca uptake (per mg protein) was enhanced in control acini 48% by 20 μmol/L epinephrine: 38% by 50 μmol/L carbachol; and 23% by 10 μmol/L isoproterenol. A similar order of potency was observed when uptake was expressed per mg DNA. In acini from reserpine-treated rats,45Ca uptake (per mg protein) was increased 53% by epinephrine, 39% by isoproterenol, and only 8% by carbachol. The same enhanced effect of isoproterenol and lack of effect of carbachol were observed when uptake was calculated per mg DNA. In the absence of secretagogue, efflux of45Ca from tracer-pre-loaded acini was larger in acini from reserpine-treated rats (53%) than in control acini (36%). Whether expressed in terms of mg protein or mg DNA, this efflux was increased in control acini 35% by epinephrine, from 25 to 28% by isoproterenol, and 17% by carbachol. In acini of reserpine-treated rats, epinephrine increased45Ca efflux 20%, isoproterenol from 25 to 28%, and carbachol from 14 to 15%. The time course of epinephrine- and isoproterenol-induced efflux was also different from that in control cells. Thus, chronic treatment with reserpine altered uptake and efflux of45Ca in rat submandibular acini. This suggests alterations in secretagogue-sensitive Ca++pools or gating mechanisms and is likely to underlie disturbances in the Ca++-mediated events of the stimulus-response coupling mechanism, such as fluid, electrolyte, and protein secretion.
Bacteriocin-like Inhibitory Activity Associated with Beta-hemolytic Strains of Streptococcus salivarius
Authors: Tompkins G.R. , Tagg J.R.
Published: November 2010

Seven beta-hemolytic Streptococcus salivarius isolates produced bacteriocin-like inhibitory activity in deferred antagonism tests using a set of nine indicator bacteria (I1-I 9). Five of these S. salivarius strains (KWF, TOVE-R, K17, K21, and K26) were inhibitory to indicators I2, I5, I6, and I7. Mutated non-hemolytic derivatives showed concomitant loss of inhibitory activity against I2, I5, and 16, but retained activity against I7. Inhibitory activity against I2, I5, and I6 was restored in beta-hemolytic revertants of such mutants. Strain 3638 was inhibitory to all of the indicator organisms except I3, and this pattern of inhibitory activity was retained by non-hemolytic derivatives. It appeared that strain 3638 produced an additional broadly-active inhibitory agent, since a mutant (strain 3638A), which was apparently defective in the production of this inhibitor, retained both the beta-hemolytic and I2-, I5-, 16-, and I7-inhibitory activities. Non-hemolytic derivatives of strain 3638A were inhibitory only to I7. Strain 3638, therefore, appeared to produce at least three inhibitory agents: one active only on I7; another acting on I 2, 15, and 16 (and associated with beta-hemolytic activity); and a third apparently active on all of the indicators other than I3. S. salivarius strain JH inhibited all nine indicator strains and possessed a beta-hemolytic character which differed from that of the other strains in being readily eliminated on treatment with the plasmid-curing agent novobiocin. Non-hemolytic derivatives of JH retained inhibitory activity against the complete set of indicators. The results of this study suggest that hemolysin production by some S. salivarius strains may be intimately associated with a distinctive type of bacteriocin-like activity.
Verification of Theoretical Modeling of Heat Transmission in Teeth by in vivo Experiments
Authors: Spierings Th. A. M. , Peters M.C.R.B. , Bosman F. , Plasschaert A.J.M.
Published: November 2010

A theoretical axisymmetric tooth model, simulating the conditions involved in the drinking of a liquid of a certain temperature, was compared with results of a similar in vivo experiment.

The temperature changes as a result of one draught of a hot/cold liquid were recorded within the model as well as in the surrounding environment. The experimental data obtained were compared with the calculated results for the theoretical model as determined by the Finite Element Analysis.

The temperatures recorded experimentally agreed reasonably with the calculated results. It can be concluded that the assumptions which have been made concerning the described thermal loading conditions lead to a good approximation of the physical reality.
Evaluation of Biangular Reflection Photometry for Quantitative Study of Etched Alloy Surface Roughness
Authors: Kelly J.R. , Brantle W.A.
Published: November 2010

Biangular reflection photometry was correlated with quantitative stereology and direct pit-depth measurements for an electrolytically etched nickel-chromium-beryllium alloy. Effects of viewing angle, viewing aperture, and plane polarization of incident and viewing light were also studied. The results showed that architectural changes in the etched metal surface could be quantitatively described with the use of reflection photometry. An off-specular peak, located at an angle of reflection considerably different from the angle of incidence, was observed to have an intensity comparable with that of the specular reflection peak. Viewing aperture was found to affect one's ability to distinguish among degrees of surface roughness.
Possible Physico-Chemical Processes in Human Dentin Caries
Authors: Daculsi G. , LeGeros R.Z. , Jean A. , Kerebel B.
Published: November 2010

This study correlated ultrastructural observations on the presence of beta-tricalcium phosphate (β-TCP) in arrested dentin caries with physico-chemical observations on the in vitro formation of Mg-substituted β-TCP. The ultrastructural studies were made using high-resolution transmission electron microscopy (TEM) with the capability of microdiffraction and microanalysis on sites less than 10 nm in diameter. Mg-substituted β-TCP was obtained, by a precipitation method, from solutions with Mg/Ca molar ratios of 5/95 and higher. Such correlation led to the postulation of a possible chronological sequence of physico-chemical events occurring at the crystal level during the progress and arrest of caries in human dentin. It is suggested that the initial mechanism for the observed occurrence of large crystals of Mg-substituted β-TCP and of apatite in the tubule lumen is due to the dissolution of the dentin mineral (a CO 3- and Mg-rich calcium OH-apatite) and reprecipitation of Mg-substituted β-TCP, followed by that of CO3- and Mg-poor apatite.
The Demineralization of Human Dental Roots in the Presence of Fluoride
Authors: Hoppenbrouwers P.M.M. , Driessens F.C.M. , Borggreven J.M.P.M.
Published: November 2010

Intact roots of human molars, which had not been exposed to the oral environment, were exposed to buffer solutions of pH 5.5, which contained, besides calcium and phosphate, various concentrations offluoride. Densitometric measurements on contact-microradiograms of transverse sections of these roots produced data which were used to calculate the rate of demineralization ( Vdem). Vdem appeared to be reduced with increasing fluoride concentration and with decreasing pIOHA (i.e., the negative logarithm of the ionic product of hydroxyapatite) of the buffer solution. In addition, it was observed that, after some days of exposure, remineralization started to occur within the surface layer at some μm from the outer surface and that the region within which remineralization took place was extended inward with increasing time of exposure. These data suggest that fluoride is effective in the prevention of root surface caries. The mechanism of the interaction of fluoride with the root mineral is discussed.
Mitogenic Activity of Cementum Components to Gingival Fibroblasts
Authors: Miki Y. , Narayanan A.S. , Page R.C.
Published: November 2010

Cementum forms the interface between root dentin and periodontal ligament through which periodontal connective tissue is attached to root surfaces. We have examined how cementum components influence the biological activities of gingival fibroblasts. Cementum was harvested from freshly extracted human teeth and extracted sequentially with 0.5 mol/L acetic acid, 4 mol/L guanidine-0.5 mol/L EDTA, and bacterial collagenase. The extracts were concentrated and analyzed for mitogenic activity to human gingival fibroblasts. DNA synthesis was assayed by measurement of [3 H]thymidine incorporation by quiescent fibroblasts activated to divide, and cell growth was determined by the counting of cells over a 10-day period. Results showed that extracts of cementum stimulated quiescent gingival fibroblasts to synthesize DNA and grow. The stimulation was dose-dependent, and most of the stimulatory activity was extracted by acid. Addition of small quantities of serum potentiated the mitogenic activity to levels greater than those of control cultures containing 10% fetal calf serum. The mitogenic activity was heat-stable, but it was destroyed by trypsin. Neither platelet-derived growth factor (PDGF) nor epidermal growth factor (EGF) was detectable in the cementum extract, and extracts of human dentin and skin contained very little mitogenic activity. We conclude that cementum contains substances capable of regulating the growth of gingival fibroblasts, and that these substances may play an important role in gingival connective tissue formation and regeneration.
Effect of Acid Type on Kinetics and Mechanism of Dental Enamel Demineralization
Authors: Patel M.V. , Fox J.L. , Higuchi W.I.
Published: November 2010

The influence of acid type (pKa effects) of weak organic acid buffers on dissolution kinetics of dental enamel was critically examined for rigorous testing of the behavioral validity of the physical model of Patel et al. (1987). Quantitative evaluation of this model indicated that monitoring initial dissolution rates was a viable approach to critical testing of the model. Initial dissolution rates were determined in 0.1 mol/L acetate (pKa = 4.77), benzoate (pKa = 4.20), and salicylate (pKa = 2.98) buffers (pH = 4.50, μ = 0.50), with ground bovine enamel blocks of known surface area mounted in a rotating disk apparatus. The Levich theory was used to study dependence of dissolution rates on stirring rates in these buffers. The experimental data were analyzed by the physical model which includes pKa effects, complexation of the buffer anion with the other ions, surface kinetics, simultaneous diffusion and equilibrium of all species in enamel pores, diffusion layer thickness, and bulk solution composition. The KIAp [ a10Ca2 + a6 PO34-a2OH-] governing the dissolution reaction and the surface

resistance factor were deduced from the model. Dissolution kinetics was also followed in these buffers in the presence of calcium or phosphate common ions. In effect, by conducting both the stirring rate studies and common ion experiments, we derived the driving force function independently by these two techniques. The results obtained in this study were consistent with the model, indicating that pKa effects on the dissolution of dental enamel can be accountedfor quantitatively by the model, and it was found that weak acids do not influence either the apparent solubility or the surface reaction process of bovine dental enamel.
Oxygen Consumption Mediated by M2 Muscarinic Receptors in Rat Salivary Glands
Authors: Stojić D. , Terzić M.
Published: November 2010

Carbachol and oxotremorine stimulated the consumption of oxygen in rat parotid, submandibular, and sublingual gland slices in a dose-dependent manner. Their actions were abolished by atropine and nifedipine but not by trihexyphenidyl. The findings suggest that carbachol and oxotremorine enhanced oxygen consumption in the major salivary gland slices by the activation of the calcium-dependent muscarinic M2receptors.
Corrosion of Ferromagnetic Alloys used for Magnetic Retention of Overdentures
Authors: Vrijhoef M.M.A. , Mezger P.R. , Van der Zel J.M. , Greener E.H.
Published: November 2010

Three ferromagnetic casting alloys intendedfor use with magnetically retained overdentures (compositions in wt%: #1, Pd 50, Co 47, Ga 2, Pt 1 ; #2, Pd 60, Co 37, Ga 2, Pt 2; #3, Pd 49, Co 46, Ga 2, Pt 2) were investigated. A 0.9% saline solution and an artificial saliva (Meyer) were used for evaluation of the electrochemical corrosion behavior of these alloys, utilizing standard potentiodynamic techniques.

All alloys investigated possessed a good corrosion resistance in the potential range of the oral environment (from - -100 to 300 mV versus SCE). In addition, alloys #1 and 3 appeared to be susceptible to pitting above +300 mV (SCE), while #2 was resistant to pitting and was found to passivate in 0.9% saline solution.
Surface Characterization of Amalgams Using X-ray Photoelectron Spectroscopy
Authors: Hanawa T. , Takahashi H. , Ota M. , Pinizzotto R.F. , Ferracane J.L. , Okabe T.
Published: November 2010

This study is the first to report on the use of x-ray photoelectron spectroscopy (XPS or ESCA) for studying the surface films (less than 10 nm thick) of aged amalgams. The concentrations and electron binding energies of the elements on the surfaces of four different amalgams aged for 20 min, one day, seven days, and 30 days were determined quantitatively. For comparison, the bulk compositions of the amalgams aged for seven days were also determined after removal of approximately 5 nm of material from the surface by argon-ion-sputtering.

The XPS data revealed that the surface films of aged zinc-containing amalgams were not a simple oxide but were primarily composed of a (hydrated) tin and zinc oxy-hydroxide, whereas, in the zinc-free amalgams, the surface films were primarily a tin oxide. The concentration of mercury in this thin surface film after aging was depleted. This suggests that tin and/or zinc preferentially diffused to the surface and combined with oxygen, forming a surface film and diluting the mercury concentration in the surface. Another probable explanation for the depleted mercury is that a minimal amount of mercury in the surface film evaporated during the aging.
Impeded Eruption Rate of the Rat Maxillary Incisor During Exposure to Different Simulated Altitudes
Authors: Giglio M.J. , Sanz A.M. , Constanzo A. , Bozzini C.E.
Published: November 2010

Female rats weighing about 200 g each were separated into normoxic and hypoxic groups. The former were maintained at sea-level conditions. The hypoxic groups were placed in an altitude chamber and maintained at the equivalent of 1850 m, 4100 m, or 7100 m over a period of two weeks. Hematocrit, body weight, body length, and impeded eruption rate were recorded once a week. Food intake was recorded every day. Exposure to 1850 m did not significantly alter hematocrit, body weight and body length gains, food intake, and impeded eruption rate. Nevertheless, exposure to 4100 m and 7100 m decreased body weight and body length gains, food intake, and impeded eruption rate, and increased hematocrit value. These parameters varied as a function of altitude. In spite of the lack of conclusive evidence, this work affords further insight into the particular significance of polycythemia on the eruption rate.
Recolonization of Human Tooth Surfaces by Streptococcus mutans after Suppression by Chlorhexidine Treatment
Authors: Emilson C.G. , Lindquist B. , Wennerholm K.
Published: November 2010

In eight subjects who were initially highly colonized with Streptococcus mutans and who used a 1% chlorhexidine gel, the numbers of this organism were suppressed in both plaque and saliva. Bacterial plaque samples were obtained from all tooth surfaces, and the recolonization pattern of S. mutans was studied over a 26-week period. At baseline, 83% of all surfaces harbored S. mutans with buccal surfaces colonized in higher frequency than the others. After chlorhexidine treatment, the proportion of tooth surfaces colonized by S. mutans was reduced to a low level. Re-appearance was slow. S. mutans was first recovered from the most posterior teeth in the mouth, the molar surfaces were recolonized earlier than were those of pre-molars and anterior teeth, and the buccal surfaces were recolonized more readily than were the other tooth surfaces. The data show that there is a specific recolonization pattern of S. mutans after chlorhexidine treatment, and that the re-emergence of S. mutans is most probably due to regrowth of bacteria which have not been eradicated.
A Longitudinal Study of Anteroposterior Growth Changes in the Palatine Rugae
Authors: Simmons J.D. , Moore R.N. , Erickson L.C.
Published: November 2010

Palatine rugae have been used as internal dental cast reference points for quantification of tooth migration. Some, but not all, investigators have reported the medial rugal region to be stable or to show predictable change. The purpose of this study was to use the longitudinal data base of the Child Research Council of Denver to examine the anteroposterior stability of the medial rugal region.

Dental casts of 20 females and 21 males with untreated normal Angle Class I occlusions were selected. Time intervals measured were: T1 — primary teeth erupted, T2 — earliest cast with permanent first molars erupted, T3 - earliest cast with canines and pre-molars erupted, and T4 — ages 16 to 22. Distinctive left and right anterior and posterior rugae which appeared on all four casts were identified, the medial ends marked, and the anteroposterior distances measured. The data were evaluated with the paired t test, repeated-measures AN-OVA, and Tukey's multiple comparison procedure.

From T1 - T4, the medial rugal region increased 1.4±0.6 mm in females and 2.3±0.8 mm in males. Only two cases showed a trend toward stability. There were no significant differences by side. Significant increases in size occurred between T2 and T3 for females and males and between T3 and T4 for males.

Analysis of these data indicates that the medial rugal region increases significantly in anteroposterior length, but not uniformly between the sexes across observation times. Such changes are characteristic of general craniofacial growth and suggest that the rugal region is responding to the differential growth of the underlying bone. Therefore, medial rugal landmarks appear not to be stable reference points for tooth migration research.