bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nerve Regeneration Through Collagen Tubes
Authors: Colin W. , Donoff R.B. 
Published: November 2010

Severe nerve injuries may require microsurgical grafting to span a defect. Introduction of graft material into a highly vascular recipient bed is documented to aid in early regeneration of neuronal blood supply. A silicone rod (SR)-induced fibrovascular sheath was employed to evaluate the regeneration of rat tibial nerve through 2-mmdiameter collagen tubes (CT) or contralateral nerve autografts (AUTO). At first operation, 5 mm of right tibial nerve was resected from 30 retired male breeder Sprague-Dawley rats. Resected nerve was replaced with either a 5 x 2 mm SR or the nerve ends were sutured to the intermuscular fascia. Four weeks later, animals were repaired by replacing the SR with either a CT or a contralateral AUTO from the left tibial nerve. Three months later, EMG testing was performed, and histologic sections were prepared. The EMG latency and the size of the compound action potential for sheathed or non-sheathed CT or AUTO were statistically superior to controls at the 95% confidence level. All other intergroup comparisons of latency and action potential size were statistically insignificant. The proportion of nerve fibers traversing the surgical sites was not influenced by the method of repair or by the presence or absence of sheathing. Tubulized repairs most closely resembled unoperated nerves, and autografted repairs had a large diameter, but much fibrosis, whereas controls displayed immaturity and disorganization. Our observations suggest that there was no difference between repairs performed with or without a vascular pseudosheath. However, CT supported regeneration better than did AUTO repair.
Basic Biological Sciences Effect of Substance P on Exocrine Secretion by Rat Submandibular Gland Cells
Authors: Fleming N. , Bilan P.T. , Graham K.W. 
Published: November 2010

The effects of the undecapeptide, substance P(SP), on the secretion of mucin and proteolytic enzymes from dispersed cells of the rat submandibular gland were studied. The peptide, at a concentration of 1 x 10-7 M, stimulated the release of 31.9 ± 3.0% (mean ± SEM) of intracellular mucin over 40 min, compared with 12.5 ± 1.5% in untreated controls (p<0.01). This effect was duplicated by the homologous peptides, physalaemin, and eledoisin-related peptide. Substance P action was not affected by pre-incubation of cells with phentolamine or propranolol and was therefore independent of adrenergic stimulation. Furthermore, SP did not enhance the intracellular concentrations of cyclic AMP or cyclic GMP, confirming that cyclic nucleotides were not involved in its stimulus-secretion coupling mechanism. The isoproterenol-stimulated secretion of mucin from dispersed cells was reduced to 75.7% of the normal response (p<0.01) after a brief exposure to SP. This inhibitory effect was probably mediated by intracellular events rather than by direct effects on cell surface receptors. However, mucin release after treatment with SP followed by norepinephrine (NE) was 161% of that caused by NE alone (p<0.01) and may reflect an additive response to the independent stimulation of SP and NE receptors. Substance P and related peptides had no effect on arginine esterase secretion in the experimental model, although a response was elicited by α- and β-adrenergic agonists. It is, therefore, proposed that serous cells of the granular convoluted tubule in the rat submandibular gland lack substance P receptors.
Anti-bacterial Determinants of Stannous Fluoride
Authors: Camosci D.A. , Tinanoff N. 
Published: November 2010

The growth of bacteria on stainless steel wires was used as a model to investigate which properties of SnF2 produced anti-bacterial effects against S. mutans. Wire-adherent bacteria were exposed for one min, twice a day, to various fluoride or control compounds having similar ions, pH, valence, or atomic weights. After two days, the thickness of adherent bacteria was scored visually, and the decrease in pH of the growth medium was determined. Bacteria from each wire were then dried, weighed, and analyzed for metal content. Electron microscopy and electron microprobe were used to identify the location of heavy metal deposits in the bacteria. Only SnF2 dramatically altered S. mutans growth and metabolism, and this anti-bacterial effect was associated with a large uptake of tin into the bacterial cells. The fluoride salts of sodium, lead, zinc, and copper had little influence on S. mutans growth in this test system. The pH of the various fluoride salts or controls generally had no effect on the activity of the test compounds, except for the noted inactivation of SnF2 at elevated pH's. Since SnF4 did not alter the growth or metabolism of S. mutans, a unique property of SnF2 - possibly the reactivity in an aqueous environment - may be responsible for its anti-bacterial properties.
Sustained Release Device Containing Metronidazole for Periodontal Use
Authors: Golomb G. , Friedman M. , Soskolne A. , Stabholz A. , Sela M.N. 
Published: November 2010

The purpose of this study was to develop a sustained release device containing metronidazole for insertion within periodontal pockets and to examine the release kinetics in vitro and in vivo. Cast films of ethyl cellulose with or without polyethylene glycol, containing metronidazole, were prepared and exhibited sustained release. Release rate of metronidazole from the film was measured by means of a UV spectrophotometer, and kinetics of release in vitro was found to conform to Higuchi's diffusional model. The microbiological results proved that embedding metronidazole in ethyl cellulose film does not inhibit the biological activity. The release kinetics in vivo correlated with in vitro results, exhibiting a sustained release of metronidazole over a period of three days from 30% metronidazole with polyethylene glycol or 40% metronidazole in ethyl cellulose chloroform cast. This study demonstrates that, by embedding metronidazole in ethyl cellulose, it is possible to obtain sustained release of the drug within the periodontal pocket for three days.
Effect of Chlorhexidine-Fluoride Applications Without and With Sr and Zn on Caries, Plaque, and Gingiva in Rats
Authors: Luoma H. , Seppa L. , Koskinen M. , Syrjanen S. 
Published: November 2010

Molar teeth of four groups of Osborne-Mendel rats, kept on a cariogenic dict, were treated once per day for 48 days with either distilled water (solution C), a solution containing 0.05% chlorhexidine gluconate and 0.04% NaF, pH 5.8 (solution CXF), CXF plus 1000 ppm Sr (solution CXFS), or CXFS plus 1000 ppm Zn (solution CXFSZ). Caries of the hemi-sectioned lower molars was scored according to grades of severity, and the extent of the buccal plaque was estimated. Inflammatory cell infiltration, vascularity, and thickness of the oral mucosa were estimated from stained sections of the buccal oral mucosa to detect possible adverse effects of the treatments. Fissure caries lesions with involvement of the dentin were reduced by 57% (p < 0.01) with the CXF treatment and by 68% (p < 0.001) with the CXFS treatment. The CXFSZ treatment reduced the fissure caries least (44%, p < 0.05), but it appreciably reduced the extent of plaque. The mucosal changes were greatest in the group receiving the CXFSZ treatment, but they were generally small and at a non-pathological level. Supplementation of the CXF solution with Sr thus appeared beneficial for caries reduction.
Selection of Streptococcus mutans and Lactobacilli in an Intra-oral Human Caries Model
Authors: Arneberg P. , Ogaard B. , Aa. Scheie A. , Rölla G. 
Published: November 2010

Microbiologic changes during caries development underneath a plaque-retaining band were investigated by the use of selective media for streptococci, Streptococcus mutans, and lactobacilli. The final four-week plaque samples on 16 experimental teeth in six young subjects were assessed. Seven experimental teeth in three other subjects were sampled at baseline and after one, two, and four weeks. All 23 experimental teeth developed a white spot lesion. In the final four-week plaque samples on the lesions, S. mutans accounted for 8% and lactobacilli 0.1% of the total CFU, both being significantly higher than in plaque from unbanded control surfaces. All experimental teeth sampled during lesion formation showed consistently elevated plaque levels of S. mutans and lactobacilli in comparison with baseline and control values at weeks one, two, and four. The results demonstrated a cariogenic environment in the human mouth associated with rapid selection of aciduric bacterial species such as S. mutans and lactobacilli.
Fluoride-treated Roots and Viability and Attachment of Human Gingival Fibroblasts
Authors: Al-Joburi W.A. , Denys F.R. , Cogen R.B. 
Published: November 2010

Topical fluoride treatment is used to help prevent root caries. It may also be useful in periodontal therapy because of its antimicrobial property. In addition, for therapeutic new attachment to occur, the fibroblasts approximating the treated root surface should remain viable, and should also be able to attach and grow onto the treated root surface. These conditions, at least, are required for fluoride not to interfere with new attachment. This study was designed to determine whether treatment of roots with fluoride adversely affects human gingival fibroblasts in culture; and what effect fluoride treatment has on attachment and growth of cells to the root surface. Cells originally obtained from human gingiva were allowed to grow to confluency in multi-well tissue culture petri dishes, and were then incubated for 24 hr in the presence of root sections as follows: (1) no treatment; (2) root-planed only; (3) 2% NaF only; (4) root-planed + 2% NaF; (5) root-planed + citric acid, pH 1 + 2% NaF. In addition, cells were plated onto roots similarly treated and were subsequently allowed to incubate for 72 hr. Viability of cells was determined by exclusion of vital dye and 51Cr retention. Attachment and growth of cells were determined by histology and scanning electron microscopy. Results indicated that, after 24 hours' exposure, there was little or no difference in cell viability between different treatment groups and control cultures. Also, all roots which had been planed accommodated cell attachment, regardless of additional treatment rendered. We conclude that treatment of roots with NaF or citric acid, or both, did not adversely affect the viability of cells, and also that attachment of cells to the roots could occur as long as they were previously planed.
Hydrolytic Degradation of Dental Composites
Authors: Söderholm K.-J. , Zigan M. , Ragan M. , Fischlschweiger W. , Bergman M. 
Published: November 2010

The leakage of filler elements from four composites after storage in water was investigated by use of atomic absorption spectrophotometry. The results confirmed previous findings that leaching of silicon from different composites is strongly dependent on filler composition. Consideration of the total filler surface of each composite material indicated that quartz as well as pyrolytic silica-containing composites leached less silicon than did composites containing fillers of strontium and/or barium glasses. A correlation between leakage and crack formation in the matrix appeared to exist for all composites except for the microfilled resin. These cracks were explained as a result of osmotic pressure built up at the matrix-filler interface due to hydrolytic degradation of the filler. Of the investigated materials, the microfilled resin was found to be the most stable material in a wet environment with respect to crack formation. This finding was explained by filler composition, filler form, and the specific structure of the microfilled resin.
Salivary Clearance of Sugar and its Effects on pH Changes by Streptococcus mitior in an Artificial Mouth
Authors: Lagerlöf F. , Dawes R. , Dawes C. 
Published: November 2010

We recently developed a computer model of oral sugar clearance (Dawes, 1983), and an artificial mouth has now been constructed which will allow variation in the salivary parameters identified in the model and the study of their effects on bacterial acid production. Using a thin layer of S. mitior, strain 572, over a miniature Sb electrode to measure bacterial pH changes during sugar clearance from the "mouth", we found that three consecutive sets of "Stephan curves" could be obtained with the same bacteria during one day. In each of several experimental series, one salivary parameter was varied, while other parameters were held constant. The maximum pH decrease and the surface area of the registered Stephan curve (Δ pH.min) were used as measures of acid production. The results indicate that the volume of "saliva" in the mouth before and after swallowing, the unstimulated salivary flow rate, and the buffer capacity had significant influences on the extent of the pH changes. Other factors, such as the maximum flow rate, the delay between start of stimulation and maximum flow, the volume of saliva in the mouth at time zero, and the taste threshold for sugar, were of lesser importance, confirming some predictions from the computer model.
Crown Area as an Indicator of Changing Crown Size in Human Pre-natal Teeth
Authors: Prasad N. , Burdi A.R. 
Published: November 2010

This study deals with correlations of tooth size in human primary teeth. Traditionally, mesiodistal or buccolingual measurements have been used to express crown size. However, in this study, crown area was used as a reference parameter. Graphic reconstructions of 38 histologically prepared human fetuses with Crown-Rump Length (CRL) between 54 and 280 mm were used to obtain linear and area measurements. Based on clinical records and physical examinations, these fetuses were considered typical-for-age, or "normal". Correlation matrices indicated high levels of concordance among all developing deciduous tooth crowns and arch measurements. It was concluded that crown area is a statistically better trait to use in comparison of teeth rather than the traditional mesiodistal measurement.
The Competition between the Composite-Dentin Bond Strength and the Polymerization Contraction Stress
Authors: Davidson C.L. , De Gee A.J. , Feilzer A. 
Published: November 2010

The influence of contraction stresses, developed during the polymerization of composites, on adhesion to dentin treated with a dentin adhesive was studied for a chemically- and a light-activated microfilled composite, in both linear and 3-D models. The linear model consisted of an arrangement set up in a tensilometer in which the composites could be applied to a flat dentin surface fixed to the stationary cross-head at one end, and mechanically clamped to the cross-head connected to the load cell at the other end. The increase of the bond strength was measured at different time intervals from the start of mixing and was compared with the developing contraction stress. Throughout the complete polymerization process, the adhesion survived the contraction stress, which is explained by flow relaxation, which can occur sufficiently in this configuration. In the three-dimensional model, the composites are attached to more than two dentin walls. In this situation, flow is severely limited, and contraction stress values can exceed the bond strength, leading to separation. This was demonstrated in Class V cavities. The shape of the cavity is considered to be of great importance in conservation of the composite-dentin bond.
Evaluation of 2-Phosphono-butane 1,2,4 Tricarboxylate as a Crystal Growth Inhibitor in vitro and in vivo
Authors: Gaffar A. , Moreno E.C. 
Published: November 2010

The inhibitory activity of 2-phosphono-butane 1,2,4 tricarboxylic acid (PBTA) in the formation of hydroxyapatite (HA) was studied in vitro and in vivo. PBTA, at 4 ppm, inhibited the spontaneous formation of HA in vitro from a supersaturated solution. PBTA, at 2 ppm, completely inhibited the crystal growth of HA; at lower concentrations, a direct relationship was found between the reduction of the initial precipitation rates and PBTA concentrations in the solution. The effects of PBTA on human dental enamel in vitro were also evaluated at pH 5.0 and 7.5. Equimolar levels of EDTA served as the controls. In comparison with EDTA, the dissolution of enamel induced by PBTA was negligible. One percent solution of PBTA was evaluated in a rat calculus assay. In comparison with a placebo solution, it significantly (p = 0.05) reduced calculus formation when applied topically. It was also tested against calculus formation in beagle dogs. A topical application once a day of a 1% solution at pH 7.0 reduced calculus formation by 84% for 16 weeks. Analysis of these data suggests that the agent effectively reduces calculus formation in vivo.
Structural Changes in the Oxidation Zones of Gold Alloys for Porcelain Bonding Containing Small Amounts of Fe and Sn
Authors: Ohno H. , Kanzawa Y. 
Published: November 2010

The oxidized surfaces of cross-sections of gold alloys containing a total of 1.5 mass % Fe and Sn, oxidized at 1000 °C for one hr, have been studied by various techniques, including secondary electron micro-analysis, X-ray micro-analysis, X-ray diffraction, and thermogravimetry. Over the composition range (0.30 - 1.50 mass % Fe), an external oxidation zone containing only Fe oxides was formed. The quantity of Fe203 was greater than that of Sn02 for 0.45 - 1.50 mass % Fe. With an Fe content below 0.45 mass %, the amount of Sn02 was greater than that of Fe2O3 . Traces of Fe304 were formed in high Sn content alloys. Internal oxidation particles composed of Fe203 and Sn02 precipitated deep in the alloy matrix (0.90 - 1.50 mass % Fe), and these changed to an internal oxidation band composed mainly of Sn02 for 0.3 mass % Fe.
Dentin-Polymer Bond in Resin Fillings Tested in vitro by Thermo- and Load-cycling
Authors: Munksgaard E.C. , Itoh K. , Jorgensen K.D. 
Published: November 2010

The effect of stress applied by thermo- and load-cycling to the bond between composite- and bonding-agent-treated dentin was tested. Cylindrical cavities in extracted human teeth, approximately one-half of the margins in dentin, were etched and treated with two bonding agents - Gluma and Clearfil Bond - before being filled with Silux composite. Forty specimens, some provided with cavity floor lining, were cycled several hundred times between 15° and 50°C, either immediately after light-curing or upon 24 hr of water storage. In all cases, microscopic inspection revealed unchanged adaptation at the dentin margins. Teeth with Class 3 and Class 5 cavities, ten of each and with the gingival margins entirely in dentin, were pre-treated and filled as above. The teeth were covered with a dye during loading and unloading in a manner simulating biting and chewing. Inspection of the cavity margins revealed absence of percolation at the dentin margins. It is concluded that effective bonding agents are necessary to prevent contraction gaps in resin-filled cavities where the margins are partly or entirely located in dentin.
Intercuspal Distances of Maxillary Pre-molar Teeth in Australian Aboriginals
Authors: Townsend G.C. 
Published: November 2010

Intercuspal distances and mesiodistal and buccolingual crown diameters of maxillary pre-molars were recorded from dental casts of 262 Australian Aboriginals. Although mesiodistal and buccolingual dimensions showed sexual dimorphism, no significant differences were noted between the sexes for intercuspal distances. Intercuspal dimensions showed greater variability and fluctuating asymmetry than did either of the traditional measures. No significant differences in heritability were noted among the three dimensions. Correlations between mesiodistal and buccolingual dimensions were higher than those between buccolingual and intercuspal measures. It appears that the sex differences, which are observed in overall crown dimensions, are established after the cusp tips are localized. Intercuspal distances appear to have a strong genetic component of variability, although they show high phenotypic variability and fluctuating asymmetry. Total tooth size may be subject to more intense selective pressures than the sites of initial calcification.
Clinical Science
Authors: Torstenson B. , Brannstrom M. , Mattsson B. 
Published: November 2010

Composite resin restorations are often applied in cavities where cervical margins are left unetched, resulting in poorer adaptation in this area. Recent experiments have indicated the possibility of impregnating with resin the gap caused by polymerization contraction. Cavities were prepared in vitro and in vivo. A thin liner was applied inside and outside the cavity. Except for the cervical wall, enamel margins were bevelled and acid-etched, and the cavities restored with Concise Enamel Bond and Composite. In another series, cavities with unetched enamel were restored-Since the liner was placed outside the cavity margins, excess material could be removed without blockage of the air-filled gap. Enamel Bond with a fluorescent additive was applied to various margins. Ground sections were prepared, and the penetration of this resin into the gap was examined with a microscope. In most teeth, the resin penetrated from 0.5 to 2 mm from the cervical margins. Similar penetration was seen from unetched margins, except for the occlusal one. No penetration was seen at acid-etched margins. By impregnating gaps with low-viscous resin after the filling has cured, one can obtain an improved seal at unetched margins.
Enamel Fluoride in Nursing Rats with Mothers Drinking Water with High Fluoride Concentrations
Authors: Drinkard C.R. , Deaton T.G. , Bawden J.W. 
Published: November 2010

The purpose of this study was to determine the F levels in plasma and molar enamel from rat pups whose mothers had received various levels of F during pregnancy and/or lactation. Rats were started on water containing 0 (Group I), 50 (Group II), or 100 (Group III) ppm F at the beginning of pregnancy or on the day of delivery. The mothers and pups were killed 13 days after delivery, and plasma F levels, milk Flevels, and pup molar enamel F levels were determined.The mean maternal plasma F concentrations were 0.02 ± 0.005 ppm in Group I, 0.10 ± 0.031 ppm in Group II, and 0.21 ± 0.057 ppm in Group III. The milk F values were about twice as high as the respective plasma concentrations. The plasma F concentration in control pups was 0.003 ± 0.0002 ppm, and there was a rise to 0.006 ± 0.0002 ppm in Group III. Enamel F concentrations were 0.62 ± 0.13 ppm, 4.72 ± 0.79 ppm, and 8.80 ± 1.74 ppm, respectively. The plasma and enamel F values obtained from pups were not significantly different between the pre-natal/post-natal, and the post-natal-only groups. It was concluded that: (1) fluoride levels in the plasma and enamel of control rat pups were much lower than those found in adult rats, (2) such values could be increased only slightly when high doses of F were given to the mother, and (3) unlike values reported for other species, rat milk fluoride concentrations were higher than the respective plasma values.