bluuebunny/crossref_metadata_2025 huggingface dataset:
Predominant Obligate Anaerobes in Human Carious Dentin
Authors: Hoshino E.
Published: November 2010

With the adoption of an anaerobic glove box system, we isolated and identified the predominant micro-organisms in lesions of carious dentin from four permanent third molars. The overwhelming majority of the micro-organisms isolated from both shallow and deep layers of carious dentin were obligate anaerobes, suggesting that conditions in the dentin were strictly anaerobic. The predominant obligate anaerobes were Gram-positive rods which were identified as members of the following genera: Propionibacterium, Eubacterium, Arachnia, Lactobacillus, Bifidobacterium, and Actinomyces. Clostridia, Gram-negative rods (Bacteroides and Fusobacterium) and Gram-positive cocci (Peptococcus, Peptostreptococcus, and Streptococcus) were also isolated, although they constituted a minor part of the flora.
pH-Dependent Fluoride Inhibition of Peroxidase Activity
Authors: Thibodeau E.A. , Bowen W.H. , Marquis R.E.
Published: November 2010

Fluoride was found to be a potent inhibitor of bovine lactoperoxidase and of salivary peroxidase at acid pH values. Inhibition was reversible at neutral pH, and appeared to involve HF binding by the enzyme. Fluoride inhibition of lactoperoxidase occurred with all reductants tested, including thiocyanate, iodide, and guaiacol. Fluoride concentrations for 50% inhibition of enzymatic activity with iodide as reductant were: less than 0.05 mM at a pH value of 4.0, 0.3 mM at 5.0, 4.0 mM at pH 6.0, and more than 10.0 mM at pH 7.0. Salivary peroxidases were found to have lower pH optima but to be approximately as sensitive to acid-dependem fluoride inhibition as was purified bovine lactoperoxidase. The findings suggest that the fluoride in dental plaque may be inhibitory to the antimicrobial peroxidase system.
The Reliability of the Iodide Permeability Test Applied to the Natural Dentition
Authors: Tavares M. , DePaola P.F. , Soparkar P.M. , Van Houte J. , Alman J.E.
Published: November 2010

The purpose of this study was to assess the reliability of the iodide permeability test when applied to the human dentition. Twenty-two subjects were seen once a week for three weeks. At each visit, consecutive iodide permeability measurements were obtained: four from the right central incisor and four from the left. Results of these trials were examined for the degree of variability from one replication to another within the same day, as well as for the variability from one week to the next. Within-day and between-week reliability of the test results was assessed by two indices: the Hoyt Index, which estimates the reliability of the average of the four replicate measurements per tooth, and the Intraclass correlation, which estimates the reliability of a single measurement. The results indicate that the iodide permeability test produces sufficiently replicable measurements for use in future clinical studies.
Colonization of the Human Oral Cavity by a Strain of Streptococcus mutans
Authors: Hillman J.D. , Yaphe B.I. , Johnson K.P.
Published: November 2010

Streptococcus mutans strain JH1001 produces a bacteriocin that can kill virtually all other strains of this micro-organism. The ability of JH1001 to colonize the human oral cavity was tested in a study involving five subjects and three different infection regimens, all of which involved multiple exposures to large numbers of organisms. Two and one-half years after infection, JH1001 was found to have persistently colonized three of the subjects. The indigenous S. mutans in one subject were reduced below the level of detection. Levels of (total) S. mutans and S. sanguis were not affected in persistently colonized subjects. Mutants of indigenous S. mutans resistant to the bacteriocin were not observed. The results indicate the importance of host variability and infection regimen for superinfection by this strain of S. mutans. The efficient replacement of indigenous S. mutans by JH1001 in one subject lends support to the eventual application of replacement therapy to the prevention of dental caries.
Fluoride Uptake and Fluoride Resistance in Oral Streptococci
Authors: Kashket S. , Preman R.J.
Published: November 2010

Fluoride uptake was examined in the highly F-sensitive Streptococcus salivarius strain 25975, the F-resistant mutant Flr103, and the relatively insensitive S. sanguis H7PR3. F was taken up by all strains from media at neutral pH, containing 1 or 10 μ g F/ml (0.053-0.526 mmol/L), and uptake was directly proportional to the ΔpH that was maintained by the cells. The final intracellular concentrations of F in the F-resistant strains were higher than those in the F-sensitive strain. Similar differences in F uptake were observed in buffer at pH 5.5, although both ΔpH and F uptake were higher in all strains at the lower pH. These experiments demonstrate that resistance to F does not necessarily involve the exclusion of F from the cells. The lower uptake of F by F-sensitive cells is attributed to the finding that F dissipates the transmembrane pH gradient, and this, in turn, limits the concentration of intracellular F.
A New Microsample Grinding Technique for Quantitative Determination of Calcium and Phosphorus in Dental Enamel
Authors: Apap M. , Goldberg M.
Published: November 2010

A new microsampling method is described for measuring variations in calcium and phosphorus distribution in dental enamel. Ten successive layers, 10 μm thick, from five human enamel posts with previously abraded flat upper surfaces were ground and analyzed. Mean Ca and P values were, respectively, 1116 ± 110 and 527 ± 47 μg/ mm3 , and mean Ca/P w/w and molar ratios, 2.11 ± 0.10 and 1.63 ± 0.08, respectively. Despite its limitations, the present method allows for accurate investigation of the mineral content in sound, experimentally-treated enamel.
The Relationship between Serum IgG Levels to Subgingival Gram-negative Bacteria and Degree of Periodontal Destruction
Authors: Naito Y. , Okuda K. , Takazoe I. , Watanabe H. , Ishikawa I.
Published: November 2010

The relationship between the serum IgG antibody titer against seven species of Gram-negative periodontopathic bacteria and clinical parameters (including plaque index, gingival index, periodontal pocket depth, and alveolar bone loss) was studied in 38 subjects. IgG antibody titer against the sonicated antigens was determined by micro-ELISA. A statistically significant correlation was found between the serum antibody titer against B. gingivalis and the degree of clinical parameters, especially pocket depth.

The serum IgG levels against the seven micro-organisms in 16 periodontal patients before and after clinical treatment were also determined. Responses to B. gingivalis decreased (p<0.001), whereas responses to E. corrodens (p<0.01) increased slightly. No marked differences were noted between pre- and post-treatment sera in titers against B. intermedius, B. loescheii, F. nucleatum, A. actinomycetemcomitans, and C. ochracea.
Basic Biological Sciences Induction of Chondrogenesis in Muscle, Skin, Bone Marrow, and Periodontal Ligament by Demineralized Dentin and Bone Matrix in vivo and in vitro
Authors: Inoue T. , Deporter D.A. , Melcher A.H.
Published: November 2010

Induction of chondrogenesis in vivo by rolls of demineralized dentin implanted in muscle, subcutaneous connective tissue of skin, medullary cavity of femur, and periodontal ligament of rat was investigated. Specimens were examined at various times up to 21 days after implantation, using light microscopy and morphometric analysis. Induction of cartilage occurred most quickly in muscle, followed by subcutaneous connective tissue of skin and medullary cavity of femur, and most slowly in periodontal ligament. Significantly more cartilage was found in muscle than in subcutaneous connective tissue of skin and medullary cavity of femur at the times examined, and least of all in periodontal ligament. Outgrowth of cells from rat muscle, dermis and subcutaneous tissue, bone marrow and periodontal ligament cultured in vitro on demineralized bone matrix for up to 35 days produced similar results.
Effect of Streptozotocin Diabetes on Gingivitis in Plaque-susceptible Rats
Authors: Takai N. , Shinohara M. , Yoshida Y. , Ohura K. , Mori M. , Kakudo Y.
Published: November 2010

The periodontal pocket probing depths of mandibular incisors of plaque-susceptible (Sus) rats, which spontaneously exhibit gingivitis with accumulation of plaque, were increased 20 days after injection of streptozotocin (70 mglkg, i.v. ). The accumulated plaque weights were also increased in Sus rats with streptozotocin diabetes, and a positive correlation was found between the plaque weights and the pocket depths. Histological findings showed that this inflammatory reaction in gingival tissue was higher and more extensive in diabetic Sus rats than in control Sus rats. These findings suggest that the accumulated plaque is the important factor for the severe breakdown of gingival tissue in this experimental model.
Kinin Generation in the Gingival Inflammatory Response to Topically Applied Bacterial Lipopolysaccharides
Authors: Montgomery E.H. , White R.R.
Published: November 2010

A water-soluble lipopolysaccharide from Salmonella enteritidis and a phenol-soluble lipopolysaccharide from Leptotrichia buccalis were applied topically to the healthy marginal gingivae of beagle dogs. Saline was applied to contralateral areas as an internal control. Increases in vascular permeability were monitored by measurement of gingival fluid, and the collected gingival fluid samples were assayed for kininogenase and kinin activities. Both lipopolysaccharides induced an inflammatory response, as indicated by increased gingival fluid flow. Kininogenase-kinin activities paralleled the increases in gingival fluid flow, with the highest values being associated with peak increases in gingival fluid. The results indicate that both lipopolysaccharides, although different in lipid solubility, penetrate healthy sulcular epithelium and initiate an inflammatory response which is mediated in part by the kallikrein-kinin system. Interrelationships between this system and other inflammatory mediators suggest that kinin generation not only plays a role in the early phases of acute gingival inflammation, but may also contribute to the activation of other mediators appearing later in the response and in chronic inflammatory lesions.
Establishment of a Large Collection of Extracted Teeth for Research
Authors: Jablonski N.G. , Quackenbush L.E. , Lee S.L. , Dimmer A. , McKenna J.J.I. , McDonald D.F. , Renson C.E. , Fearnhead R.W.
Published: November 2010

A collection of over 14,000 teeth extracted at the Prince Philip Dental Hospital since 1982 has been organized and catalogued on a computerized database management system. The computer catalogue provides, for each tooth in the collection, information on the age and sex of the patient, and the date of extraction and condition of the tooth. The catalogue can be searched according to any combination of the descriptive variables in the database record. Researchers, including visiting scientists, can borrow teeth from the central "tooth library" on a temporary or permanent basis. Further information on particular teeth (e.g., patient's medical and dental histories, dental radiographs) can be obtained from patients' charts. Establishment of this collection has greatly facilitated the work of researchers in clinical dentistry, dental anatomy, and dental anthropology.
Enamel Demineralization and the Length of Intra-oral Exposure to Different Concentrations of Glucose or Sucrose
Authors: Tehrani A. , Goulet D. , Brudevold F. , Attarzadeh F.
Published: November 2010

Six subjects wore intra-oral devices carrying eight bovine enamel blocks which were covered with a layer of S. mutans. They rinsed their mouths for five sec, one min, or multiples of one min with a 5 or 10% glucose (G) solution. Demineralization was measured after 45 min by determining the change in iodide permeability (ΔIp) of the enamel. In addition, saliva samples, taken at intervals during the test, were analyzed for G, and the time of clearance (tc ) was calculated. Demineralization scores (ΔIp) were consistently greater from the 10% than from the 5% G solution. Both solutions produced an increase in ΔIp with an increase in the rinsing time (tr ). The G remaining in saliva after the rinse did not significantly affect ΔIp. The ΔIp scores showed good correlation with the final pH of the S. mutans cell mass, r= -0.77. For each rinse solution, the scores also showed good correlations with tr (r= 0.87 and 0.79) and much weaker correlations with tr + tc (r=0.44 and 0.53). Continuous in vitro exposure to 1, 5, or 10% solutions of sucrose (S) in saliva for 30 min or more caused a linear increase in ΔIp with time with no concentration effects. A linear increase was also observed in vivo when a one-minute mouth-rinse with 10% solution of S was administered every 30 min. The findings indicate that significant demineralization may occur while carbohydrate foods are consumed, and that brushing the teeth or rinsing the mouth after meals may not be as effective against caries as is generally believed.
Measurement of the Permeability of Dental Enamel and its Variation with Depth using an Electrochemical Method
Authors: Hoppenbrouwers P.M.M. , Scholberg H.P.F. , Borggreven J.M.P.M.
Published: November 2010

To investigate the permeability of the dental enamel of erupted and unerupted human pre-molars and its variation with depth, we determined the resistivity of successive 100-μm-thick layers. The electrical resistance of halved tooth crowns at zero Hertz, which according to Scholberg et al. (1982, 1984) is inversely related to the permeability, was measured before and after removal of successive enamel layers from the outer surface toward the dentino-enamel junction (D.E.J.).

The resistivity of the successive enamel layers increased from the D.E.J. toward the outer surface in approximately the same way in erupted as well as in unerupted pre-molars, except within the outermost layer of 100 to 200 μm thickness. The resistivity of this layer in erupted pre-molars was considerably higher than that in unerupted pre-molars, which may be due to post-eruptive mineralization.
Enamel Fluoride Retention after DCPD and APF Application and Prolonged Exposure to Fluoride in vitro
Authors: Crall J.J. , Bjerga J.M.
Published: November 2010

The effect of a topical fluoride regimen consisting of a four-minute pre-treatment with a saturated dicalcium phosphate dihydrate (DCPD) solution followed by a four-minute application of APF was compared with that of a four-minute application of APF alone with respect to the deposition of fluoride in enamel in an apatitic form in vitro. Following the topical applications, specimens were washed in either (1) an inorganic wash solution for 24 hrs or (2) an inorganic wash solution with I ppm F added for 28 days; specimens were then subjected to KOH extraction for 24 hrs. Fluoride-by-depth profiles revealed that the DCPD/APF treatment resulted in a significant increase in the apatitic F concentration of enamel to a depth of 20 μm, while APF application alone did not. All groups exposed to the 1 ppm F wash acquired significant amounts of apatitic F, with the differences between groups remaining relatively constant.
Host Factors in Juvenile Periodontitis
Authors: Cogen R.B. , Roseman J.M. , Al-Joburi W. , Louv W.C. , Acton R.T. , Barger B.O. , Go R.C.P. , Rasmussen R.A.
Published: November 2010

This study was undertaken to determine whether defects in leukocyte function or in genes at the MHC play a role in the etiology of either localized (LJP) or generalized (GJP) juvenile periodontitis. Thirteen LJP and five GJP patients (ranging in age from 13 to 22 years) and their matched controls were compared with respect to selected leukocyte functions and HLA phenotypic frequencies.

The results of these studies indicated that there were significant decreases in the phagocytic and chemotactic abilities of polymorphonuclear leukocytes (PMN) in both LJP and GJP. All JP patients displayed intrinsic cell defects in chemotaxis compared with controls; in addition, some patients displayed multiple defects, including those which were serum-associated. Also, there appeared to be a significant association between JP and HLA-DR2 and HLA-A33 phenotypes. Fifty percent of the JP patients were HLA-DR2-positive, whereas only six percent of the matched controls were positive. Thirty-six percent of JP patients were HLA-A33-positive, whereas none of the controls was positive. The association seen with DR2 may be due to sampling, since there were no significant differences between the JP cases and a larger unmatched control sample which was not evaluated for periodontal disease.

We conclude from these data that increased susceptibility of some patients to a very aggressive and destructive form of periodontal disease (JP) is based on defects in PMN responsiveness. Further investigations are necessary to determine whether these defects are under genetic control.
Complexes of Iron Cations with N-Phenylglycinate or Oxalic Acid
Authors: Bowen R.L. , Misra D.N.
Published: November 2010

N-phenyglycine plays a very important role in obtaining adhesion of restorative composites to dentin and enamel (Bowen et al., 1982a). In a systematic investigation, ferric or ferrous N-phenylglycinate complexes formed when aqueous ferric nitrate or ferrous chloride was combined with solutions of potassium N-phenylglycinate in stoichiometric proportions. The molal ratios of iron ion to N-phenylglycinate ion in each complex were confirmed by osmolality measurements with a freezing-point osmometer. The reaction of aqueous solutions of oxalic acid with ferric nitrate indicated formation of ferric oxalate complexes with a stoichiometry of Fe2 (oxalate)3 in solution, using Job's method of continuous variations (1925;1928).
Tooth Loss and Retention: Analysis on 500 Maxillae of a Multitribal Group of Bantu-speaking South African Blacks
Authors: Tal H. , Tau S.
Published: November 2010

This study analyzes tooth loss and retention in 500 dry maxillae of adult South African Bantu-speaking blacks. The tribe, sex, and stated age at death were available. Specimens were equally distributed over the third to the seventh decades of life. The presence of dental units was recorded and analyzed between and within age groups. A total of 5063 dental units was recorded. Reduction of the frequency of dental units was mild and not significant between the third and fourth decades of life and between the sixth and seventh. Severe and significant tooth loss was recorded between the fourth and the fifth, and between the fifth and the sixth decades of life. Specimens from younger individuals (from 21 to 30 years of age) retained more teeth in the anterior region; after the third decade of life, there was a clear and significant persistence of canines with tendency toward loss of teeth anterior and posterior to them. Based upon the present observations and previous studies in this population, it is suggested that: (a) in most teeth, tooth retention pattern is indirectly related to periodontal bone loss (In the canines, however, the long roots rather than "resistance" to periodontitis may be the cause for the relatively high longevity rate); and (b) caries may have been the main cause for tooth loss until the fourth decade of life - later, periodontal disease may have become the predominant reason.
Influence of Plasticizer on Soft Polymer Gelation
Authors: Jones D.W. , Sutow E.J. , Graham B.S. , Milne E.L. , Johnston D.E.
Published: November 2010

An evaluation has been made of the soft polymer gel systems of the type used as prosthodontic short-term denture-lining materials. The purpose of the study was to determine the effect upon gel strength and gelation time produced by variations in the composition of the plasticizer liquids. Poly(ethylmethacrylate) co-polymers were mixed with combinations of ethyl alcohol and the esters dibutyl phthalate (DBP), butylphthalyl butylglycolate (BPBG), and benzyl salicylate (BS).

The relative rate of gelation of plasticizer polymer compositions was obtained by means of a reciprocating rheometer. The gelation rate was found to increase rapidly with an increase in the ethyl alcohol content. Significantly shorter gelation times were also found with liquids containing the lower-molecular-weight esters. A linear relationship was found between the ethyl alcohol content and the log of the gelation time.

The higher-molecular-weight esters produced the strongest gel. A linear relationship was found between the gelation (log) times and the seven-day puncture strength. The ratio of polymer to plasticizer liquid was found to have a very significant influence upon the puncture strength and gelation time. Molecular weight or molecular volume of the ester plasticizers was found to have a greater influence on gel formation than the cohesive energy parameter. The strong polar bonding of ethyl alcohol was found to have a significant influence on both the rate of gel formation and the subsequent gel strength. The data indicate that controlled variations in the characteristics of plasticity and gel strength of dental soft polymer systems can be made to suit different clinical prosthodontic requirements.
An Analytical Model to Predict the Effects of Heating Rate and Applied Load on Glass Transition Temperatures of Dental Porcelain
Authors: Dehoff P.H. , Anusavice K.J.
Published: November 2010

An analytical model was developed to predict the effects of heating rate and load on the glass transition temperature (Tg) of dental porcelain. An equation similar to the Moynihan equation relating heating rate to Tg was found for midspan load. The validity of the analytical model was demonstrated by using viscosity data from one published study to predict Tg behavior in an independent study. Values of Tg calculated with the analytical model for a dilatometer specimen were found to be higher than Tg values calculated for a bending beam viscometer.
In vivo Effects of a SnF2 Gel on Acid-softened Enamel
Authors: Clark J.W. , Quiros A. , Corpron R.E. , More F.G. , Kowalski C.J.
Published: November 2010

The purpose of this investigation was to study the intra-oral rehardening of acid-softened enamel and fluoride uptake from SnF2 gel. Bovine enamel slabs were softened with 0.1 mol/L lactate buffer at pH 4.0 for 14 hrs and then mounted in a mandibular removable Hawley appliance. Control slabs were worn for 96 hrs by seven adult males whose teeth were brushed daily with a fluoride-free dentifrice. Test slabs were exposed once/day to 0.4% SnF2 gel. The gel was swabbed onto the slabs for one minute before being replaced in the mouth unrinsed. The natural dentition was brushed 4x/day with a fluoride-free dentifrice. Microhardness testing was performed after a intra-oral exposure (IOE) and after acid-resistance-testing (ART) following immersion in 0.01 mol/L lactate buffer for 24 hrs at pH of 4.0. Fluoride uptake was measured on separate controls, test slabs, and test slabs after ART, with 0.5 mol/L HClO4 etches of from 15 to 60 sec. The F content was measured with a F-ion-specific electrode and the phosphate content by spectrophotometry. Following IOE, microhardness recovery was 35.6% for control and 37.9% for test slabs, and control slabs retained 1.4% resistance to acid, as compared with 18.6% for the test slabs. The F content of control slabs was significantly less than that of SnF2-treated slabs from 5 to 60 μm in depth, and the F content of SnF2-treated slabs after ART was significantly less at depths of from 5 to 35 μm than that of SnF2-treated slabs not exposed to ART. Both control and SnF 2 enamel slabs demonstrated rehardening after IOE, but only SnF 2-treated enamel retained a significant fraction of that rehardening after ART.
Thermal Behavior of the Gypsum Binder in Dental Casting Investments
Authors: Mori T.
Published: November 2010

This study examined the thermal behavior of cast gypsum specimens, with and without additives, by means of simultaneous differential thermal analysis-thermogravimetry (DTA-TG) and dilatometry. Specimens were prepared from wet-calcined hemihydrates (Hydrocal and Den-site). The additives studied were boric acid (H3BO 3) and sodium chloride (NaCl), and these were added to the hemihydrate powders in concentrations of 2 wt% (in the case of H3BO3) and 0.5 wt% (in the case of NaCl).

A large shrinkage was observed in the range of 300 to 500°C, and this was greatly reduced when either H3BO3 or NaCl was present. The dehydration of gypsum (calcium sulfate dihydrate) was not completed until the initial stage of this large shrinkage was reached, but the phase transition of calcium sulfate anhydrite (III-CaSO4 to II-CaSO4) was the major cause for the large shrinkage. This phase transition occurred over a much wider temperature range than that suggested by the DTA-TG results. Dehydration conditions similar to those employed in wet calcination of gypsum appeared to be produced under atmospheric pressure when NaCl was present.
Light Scattering and Gloss of an Experimental Quartz-filled Composite
Authors: Campbell P.M. , Johnston W.M. , O'Brien W.J.
Published: November 2010

For samples of polymethylmethacrylate with and without quartz filler, the inverse of the contrast-gloss ratio is shown to be related to surface roughness and to the optical scattering coefficient. This finding adds to the importance of optical scattering, which has been widely studied because of its relation to color and translucency of materials. Furthermore, optical scattering by composite fillers is shown to be linearly related to the concentration of the filler material within the range of concentrations studied. Quartz fillers were incorporated at concentrations from 5 to 20 weight percent and were short fibers or granular powder, with the granular particles ranging in median equivalent spherical diameter from 15 to 3.3 μm. The efficiency of optical scattering for the granular quartz filler increased as the size of the filler decreased.
A Functional Comparison of the Deep and Superficial Parts of the Human Anterior Temporal Muscle
Authors: Wood W.W.
Published: November 2010

The electromyographic activity of the deep and superficial portions of the anterior temporal muscle were recorded simultaneously during varied isometric clenching tasks designed to determine whether the two parts of the muscle were capable of differential contraction. The results indicated that for six of the seven subjects tested, significantly different (0 < 0.01) activity of the two portions of the muscle occurred during performance of one or more tasks.
Fatigue of Dental Ceramics in a Simulated Oral Environment
Authors: Morena R. , Beaudreau G.M. , Lockwood P.E. , Evans A.L. , Fairhurst C.W.
Published: November 2010

Fatigue in ceramics refers to the subcritical growth of cracks, aided by the combined influence of water and stress. The dynamic fatigue (constant stressing rate) method was used to obtain subcritical crack growth parameters for three dental ceramics: a feldspathic porcelain, an aluminous porcelain, and a fine-grain, polycrystalline core material. The constant stressing rate experiments were carried out at 37°C for all three ceramics in distilled water, and, for the feldspathic porcelain, in artificial saliva as well. Considerable differences were found in the value of the crack growth exponent (n) among the three ceramics. The feldspathic porcelain was lowest in n-value, while the fine-grain ceramic had the highest n-value. No differences were found for the feldspathic porcelain with respect to n measured in water and in the artificial saliva. Lifetime prediction curves in 37°C water, constructed from the n-values and inert strengths, showed that fatigue failure within five years is a good possibility for feldspathic porcelain specimens at stress levels which can reasonably be anticipated to occur in the oral environment. Little likelihood of failure was perceived for the fine-grain ceramic. The aluminous porcelain was intermediate between these two materials with respect to failure probability.
A Clinical and Radiographic Assessment of a Porous-surfaced, Titanium Alloy Dental Implant System in Dogs
Authors: Deporter D.A. , Friedland B. , Watson P.A. , Pilliar R.M. , Howley T.P. , Abdulla D. , Melcher A.H. , Smith D.C.
Published: November 2010

A new endosseous dental implant system incorporating a porous-surface geometry with a tapered, truncated-cone shape was placed bilaterally in edentulous areas of dog mandibles in a two-stage procedure. All implants had been stabilized by bone ingrowth by the time of the second procedure (insertion of a transgingival collar and implant-supported bridge). The transgingival collar had a porous-surface geometry on its apical one-third, and was meant to encourage gingival connective tissue ingrowth and attachment, but in fact provided an excellent milieu for bacterial contamination. As a consequence, many of the implants showed clinical and radiographic signs of impending failure by eight months. Only those implants for which the porous coat, including that of the transgingival collar, was completely submerged in bone were observed to be successful. This study reports on the radiographic and clinical assessment of this implant system in dogs during the period of function.
Humoral Responses and Cross-reactivity to Viridans Streptococci in Recurrent Aphthous Ulceration
Authors: Hoover C.I. , Olson J.A. , Greenspan J.S.
Published: November 2010

It has been proposed that recurrent aphthous ulceration (RAU) is caused by hypersensitivity to oral streptococci. This hypothesis is based on reports that RAU patients have increased levels of circulating IgG antibodies against oral streptococci, and that rabbit antisera prepared against oral streptococci are cross-reactive with oral mucosa. Using indirect immunofluorescence, we have investigated both of these reported phenomena. End-point titers of serum antibodies against three different strains of oral streptococci were assayed from nine RAU subjects with active ulcers and compared with those of nine control subjects. Titers ranged from 1:2 to 1:64 in both groups and do not appear to have any clinical or immunopathogenic significance. Cross-reactivity was studied using hyperimmune rabbit antisera raised against five different strains of oral streptococci. Homologous bacterial titers ranged from 1:1024 to 1 :8192, but none of these anti-streptococcal sera produced heterologous titers greater than 1:32 with oral mucosa. This apparent low level of cross-reactivity with oral mucosal antigens appears to be non-specific and clinically insignificant. In previous reports, we have used both leucocyte migration and lymphocyte blast transformation to study cell-mediated immunity to viridans streptococci in RAU (Gadol et al., 1985; Greenspan et al., 1985). None of our results supports an immunopathogenic role for oral streptococci in RAU.
Comparative Effects of Local Anesthetic Preparations on Gingival Fibroblasts of the Rat
Authors: Johnson R.B. , Dowse C.M.
Published: November 2010

Cultures of rat gingival fibroblasts were exposed to various dilutions of lidocaine hydrochloride (Xylocaine®), mepivacaine hydrochloride (Carbocaine®), and prilocaine hydrochloride (Citanest®). All three anesthetics produced cell-rounding and detachment from the substrate, which varied depending on the anesthetic, its concentration in the medium, and the duration of exposure (p<0.001). Effects were not pH-dependent in the range of 7.0-7.4 and were not modified by epinephrine in the concentration normally present in commercially prepared anesthetic solutions. Prilocaine produced morphological changes at a greater rate and at a lower concentration than did lidocaine or mepivacaine (p<0.001). The effects elicited by prilocaine were irreversible, since prolonged exposures to it resulted in various toxic effects: (1) detachment of the cells from the substrate, and (2) development of pyknotic nuclei and circumferential halos in cells that remained attached. The study strongly suggested that prilocaine has the potential to be more toxic to fibroblasts than either mepivacaine or lidocaine, a situation of potential clinical importance.
Adaptations in the Temporalis Muscles of Rabbits after Masseter Muscle Removal
Authors: Guelinckx P. , Dechow P.C. , Vanrusselt R. , Carlson D.S.
Published: November 2010

Masseter muscles were surgically removed in six young female rabbits so that we could study adaptations of the superficial temporalis muscles (ST) to increased functional requirements. Eight weeks following surgery, we used morphological measurements, histochemistry, contractile properties in situ, and occlusal force in vivo to compare the muscles in the experimental animals and six control rabbits. Analysis of the results demonstrated a decrease in fatigability of ST after masseter myectomy. Incisal occlusal force decreased by 65% during the first two weeks, and no recovery was observed during the following six weeks. At eight weeks post-surgery, the mass, twitch tensions, and tetanic tensions of ST were not significantly different from those of the controls. An increase in the percent of the cross-sectional area composed of fast fatigue-resistant fibers, a slower time-to-peak twitch tension, and a decrease in fatigability suggest an increase in oxidative metabolism. Analysis of these results suggests that muscles used for highly repetitious activities with submaximal loadings adapt to increased functional requirements by increasing fatigue-resistant properties.
A Cinephotographic Study of the Role of the Canine in Limiting Lateral Jaw Movement in Macaca fascicularis
Authors: Kay C.N. , Scaring R.P. , Kay E.D.
Published: November 2010

Three specimens of Macaca fascicularis were examined to test the hypothesis that the canines do not restrict lateral masticatory movements in these animals. The animals were filmed while chewing freely before, shortly after, and seven weeks after canine removal. Facial markers, viewed from the lateral plane, allowed for computer tracings of all mandibular movements. The maximal lateral movement of the mandible was assessed for each chewing cycle, and means were calculated for each test condition and animal. These means were compared intra-animal for statistically significant differences in lateral jaw movement before and after canine removal. No significant long-term increase in lateral movement was found in any animal after the removal of its canine teeth. We conclude that, in accordance with our hypothesis, the lateral movement during mastication did not increase significantly after removal of the canine teeth in three specimens of Macaca fascicularis. Therefore, the use of the macaque as a human model for masticatory studies requires further assessment. This study reveals that the canine teeth are not as important as previously assumed in affecting the form of the masticatory cycle in the macaque.
Effect of Cavity Depth and Application Technique on Marginal Adaptation of Resins in Dentin Cavities
Authors: Hansen E.K.
Published: November 2010

The wall-to-wall polymerization contraction of two restorative resins was investigated in butt-joint dentin cavities prepared in extracted human teeth. The cavity diameter was 4 mm, and the cavity depth ranged between 0.5 and 3.0 mm. The width of the maximum marginal contraction gap was measured, using a light microscope, approximately 0.1 mm below the original free surfaces of the fillings. It was found that increasing the cavity depth from 0.5 to 3.0 mm did not influence the marginal contraction gap close to the free surfaces of the fillings. It was also found that a two-phase application technique, where the surface of the first layer was placed parallel to the free surface of the cavity, did not reduce the marginal contraction gap, while a two-phase technique with oblique layers resulted in approximately a 25% reduction.
Evidence Suggesting Multiple Binding Sites in Experimental Pellicles for Streptococcus mutans JBP
Authors: Peros W.J. , Gibbons R.J.
Published: November 2010

This study presents evidence suggesting that multiple binding sites exist for S. mutans JBP (serotype c) in experimental salivary pellicles formed on hydroxyapatite surfaces. Adsorption isotherms were performed using S. mutans JBP cells at concentrations ranging from I-1000 ( x 107 ) streptococci per mL to pellicles prepared from whole clarified saliva and from saliva which had been previously absorbed with JBP cells. The isotherms were analyzed using a one- and a two-site model. Adsorption of S. mutans JBP cells to pellicles formed from untreated saliva was statistically significantly better described by the two-site model, and the two classes of binding sites present had widely different affinities. Also, there were approximately one-third fewer high-affinity sites than low-affinity sites. In contrast, adsorption of S. mutans JBP cells to pellicles formed from JBP-absorbed saliva was better described by the one-site model, and the sites present were of low affinity. Thus, the absorption process appeared to remove or alter specific salivary molecules which comprise the high-affinity binding sites for S. mutans JBP cells.
The Dental Caries Status and Dental Treatment Patterns of 12-year-old Children in Hong Kong
Authors: King N.M. , Ling J.Y.K. , Ng B.V. , Wei S.H.Y.
Published: November 2010

A randomly selected sample of 662 12-year-old Hong Kong children, 529 of whom were Southern Chinese and 133 non-Chinese, was clinically examined for dental caries. The DMFT values were 2.76 and 1.66 for the Chinese and non-Chinese children, respectively. The D component for the Chinese children was 2.12, while for the non-Chinese children it was only 0.45. Approximately 24.0% of the Chinese children had attended the dentist because they were in pain. Only 3.8% of the Chinese children had sought orthodontic or preventive treatment, compared with 24.0% of the non-Chinese children. Although these findings indicate the caries experience to be well below the FDI/WHO global goal for the year 2000, there is a great need to increase the level of dental awareness among Chinese children.
In vivo and in vitro Study of the Effects of Vitamin A Deficiency on Rat Third Molar Development
Authors: Harris S.S. , Navia J.M.
Published: November 2010

We have examined the effect of in vivo vitamin A status on subsequent rat third molar formation and mineralization in an in vitro organ culture system. Vitamin A deficiency imposed during an eight-day in vitro period caused effects very similar to those of vitamin A deficiency imposed on rats in vivo. Analysis of the data also demonstrates that retinoic acid is capable of reversing the interference in mineralization of third molars induced by vitamin A deficiency in the organ culture system.
Mandibular Growth Retardation in Growing Rats Chronically Exposed to Hypobaria
Authors: Bozzini C.E. , Alippi R.M. , Barcelo A.C.
Published: November 2010

Weanling male Wistar rats aged 21 days were divided into three groups: initial control, normobaric, and hypobaric (C, N, and H, respectively). C rats were killed three days after being weaned. H rats were placed into an altitude chamber and maintained at 456 mb (6100 m) for 14 days. N rats were maintained at sea-level conditions. Body weight, body and tail lengths, and food intake were recorded every day. Animals were killed at the end of the experimental period, and four linear dimensions of the dried mandible were measured. The amount of food eaten by the H rats during the entire exposure period was 54.6% of that consumed by N ones. Body weight gain in H rats was 32.7% of that seen in N rats. Body length was 49.0% and tail length was 56.6% of normal. All mandibular dimensions were significantly reduced in H rats when compared with N rats and were, in general, in close relation with the reduction observed in skeletal growth. Only one dimension was reduced out of proportion, which indicates some deformation of the mandible. The average daily caloric intake related to metabolic body weight (body weight0.75) of H rats was 60% of the N value. Efficiency of protein utilization for growth was not significantly different between both groups of rats. These results indicate that chronic exposure to hypobaria induces overall skeletal and mandibular growth retardation, which appears to be the result of a diminution in food intake because of decreased appetite.
Salivary Gland Changes in Disease
Authors: Tandler B.
Published: November 2010

Ultrastructural alterations occurring in human salivary glands as a result of a variety of diseases are described. Major changes in these organs in cases of cystic fibrosis are probably the result of duct blockage, as indicated by study of chronically inflamed salivary glands. A new disease of salivary glands is reported in which parotid serous granules are distorted by bundles of fine filaments, which may be due to the untoward polymerization of a secretory protein, perhaps proline-rich protein. Finally, a clear-cell adenocarcinoma of palatine gland origin is described in which the nuclei display complex pseudoinclusions and the cytoplasm contains numerous herpes-type viruses.
Structural Aspects of Salivary Glycoproteins
Authors: Levine M.J. , Reddy M.S. , Tabak L.A. , Loomis R.E. , Bergey E.J. , Jones P.C. , Cohen R.E. , Stinson M.W. , Al-Hashimi I.
Published: November 2010

The protective functions of saliva are attributed, in part, to its serous and mucous glycoproteins. We have studied, as representative molecules, the proline-rich glycoprotein (PRG) from human parotid saliva and the high (MGI ) and low (MG2) molecular weight mucins from submandibular-sublingual saliva. PRG (38.9 kDa) contains 40% carbohydrate consisting of 6 triantennary N-linked units and a single peptide chain of 231 amino acids, 75% of which = PRO+GLY+GLN. PRG's secondary structure is comprised of 70% random coil (naked regions) and 30% β-turns (glycosylated domains). MGI (>103 kDa) contains 15% protein (several disulfide linked subunits), 78% carbohydrate (290 units of 4-16 residues), 7% sulfate, and small amounts of covalently linked fatty acids. MG2 (200-250 kDa) contains 30% protein (single peptide chain), 68% carbohydrate (170 units of 2-7 residues), and 2% sulfate. The major carbohydrate units of MG2 are: NeuAcα2, 3Galβ1, 3GalNAc, Galβ1, 3GalNAc, and Fucα1, 2Galβ1, 3GalNAc. MG1 contains hydrophobic domains, as evidenced by its ability to bind fluorescent hydrophobic probes; MG2 does not. Collectively, the biochemical and biophysical comparisons between MGI and MG2 indicate that these two mucins are structurally different. Several functional properties of MG1, MG2, and PRG have been examined, including their presence in two-hour in vivo enamel pellicle, binding to synthetic hydroxyapatite, lubricating properties, and interactions with oral streptococci. The data presented suggest that these glycoproteins may have multiple functions which are predicated, in part, on their carbohydrate units. The potential significance of the structure-function relationships of these glycoproteins to the oral ecology is discussed.
Antimicrobial Factors in Saliva: Ontogeny and Relation to Oral Health
Authors: Tenovuo J. , Grahn E. , Lehtonen O.-P. , Hyyppa T. , Karhuvaara L. , Vilja P.
Published: November 2010

Antimicrobial agents (antibody and non-antibody) present in human saliva protect oral tissues by a variety of mechanisms, such as prevention of bacterial adhesion, agglutination of micro-organisms, and inhibition of multiplication and metabolism. However, studies in which the concentrations of various salivary antimicrobial agents have been correlated to the presence and severity of oral diseases-of dental caries, in particular-have produced controversial data, and it seems evident, also on the basis of the present study, that no single salivary antimicrobial factor (except flow rate) affects oral health to a significant degree. In the present study, we report the levels of some selected salivary antimicrobial agents in predentate and dentate human infants, with a comparison to the levels found in young adults' saliva. Salivary lysozyme, peroxidase, and hypothiocyanite concentrations were already at the adult level at the time when the primary teeth erupt, whereas immunoglobulin (IgA, IgG, and IgM), lactoferrin, myeloperoxidase, and thiocyanate concentrations were significantly lower in children than in adults. Dentate children had more IgG, thiocyanate, and protein in whole saliva than did predentate children.
Periodontal Mechanoreceptors and Parotid Secretion in Animals and Man
Authors: Anderson D.J. , Hector M.P.
Published: November 2010

Parotid flow was determined in rabbits during feeding. The animals produced more saliva when chewing hard laboratory pellets than with carrots, confirming the findings of Gjörstrup (1980a). We showed that one gland always produced more secretion than the other, and that the dominant gland alternated from side to side with changes in the chewing side. Strain-gauge recordings revealed a remarkable similarity in pattern between mandibular strain and ipsilateral parotid flow. Together, these data suggest that chewing movements and chewing force are involved in the control of parotid secretion.

In man, flow rates of parotid saliva collected with a Lashley cup and cannula were recorded. During intermittent clenching on a bite block, we found: (1) a positive correlation between rectified integrated masseter EMG and parotid flow; and (2) that anesthesia of various intra-oral nerves could reduce the flow almost to zero. Crushing a particle of breakfast cereal between two teeth resulted in a reproducible parotid flow which was reduced by infiltration anesthesia around one of these teeth. These data point to the involvement of periodontal mechanoreceptors in the control of parotid secretion in rabbits and man.
Regulation of Amino Acid Influx and Efflux at the Basolateral Plasma Membrane of the Salivary Gland Epithelium: Effects of Parasympathetic Nerve Stimulation
Authors: Mann G.E. , Yudilevich D.L.
Published: November 2010

Basolateral amino acid transport systems in the salivary epithelium of resting and secreting cat submandibular glands were characterized by means of a rapid paired-tracer dilution technique. Amino acid uptake was measured by comparison of venous tracer concentration profiles for a labeled amino acid and D-mannitol (an extracellular tracer of similar size) following an intra-arterial bolus injection of both radioactive molecules. Unidirectional uptake of 21 amino acids, dopamine, noradrenaline, and serotonin was quantified in non-secreting glands. During 8 Hz parasympathetic nerve stimulation, significant epithelial uptakes were measured for L-[3H] alanine and L-[3H] phenylalanine, but less than 0.2% of the injected amino acid was recovered in the collected saliva. In non-secreting glands, cross-inhibition studies of L-[3H] alanine, L-[3H] phenylalanine, and L-[3H] lysine uptake by unlabeled amino acid competitors and detailed kinetic influx experiments indicated that epithelial uptake was mediated by three distinct parallel transport systems: ASC (short-chain neutral), L (branched-chain and aromatic neutral), and y+ (cationic). Rapid metabolism of alanine was inhibited by aminooxyacetate, and the metabolic uncoupler dinitrophenol selectively accelerated the efflux of transported large neutral amino acids and L-lysine. Concurrent autoradiographic experiments suggest that transport sites for small and large neutral amino acids are localized in the basolateral plasma membrane of acinar, demilunar, and striated ductal cells.