bluuebunny/crossref_metadata_2025 huggingface dataset:
The Prevalence of Root Caries in a Diabetic Population
Authors: Tavares M. , Depaola P. , Soparkar P. , Joshipura K.
Published: November 2010

The objective of this study was to assess the level of root caries in a population of diabetic adults. Diabetics are of special interest because they are alleged to be periodontally compromised and have atypical patterns of refined carbohydrate ingestion. Diabetic subjects were patients of the Joslin Diabetic Center in Boston and had significantly elevated blood glucose and glycosylated hemoglobin levels over at least a ten-year period. Eligible subjects had to be between the ages of 45 and 65 and have a minimum of ten teeth and three sites with recession. Data were collected on coronal caries, oral hygiene, gingivitis, pocket depth, recession, and root caries and were compared with data from control subjects from a larger nondiabetic study group. There were 88 diabetics and 185 controls with mean ages of 55.7 and 56.3 years, respectively. The groups were found to be similar with respect to the numbers of buccal surface sites with gingival recession and the numbers of carious root lesions. There was a distinct difference, however, with respect to restored root surfaces: 1.76 mean filled surfaces were observed in the controls, as compared with 0.49 in the diabetics. A Katz Root Caries Index (for which lesions are calculated as a percentage of the numbers of exposed root surfaces) was determined to be 15.2 for the controls and 7.1 for the diabetics. A reasonable inference is that these differences are the result of a restricted ingestion of refined carbohydrates by the diabetic group. This was confirmed by a dietary survey of subsamples from the diabetic and nondiabetic groups.
Association of Gingival Crevicular Fluid Aspartate Aminotransferase Levels with Histopathology during Ligature-induced Periodontitis in the Beagle Dog
Authors: Cohen R.L. , Alves M.E.A.F. , Crawford J.M. , McSwiggin T. , Chambers D.A.
Published: November 2010

Previous investigations have shown a clear association between the presence of the enzyme aspartate aminotransferase (AST) in gingival crevicular fluid (GCF) and clinical evidence of periodontal disease in humans, as well as in the beagle dog model. This paper describes a 26-week study that uses the beagle dog model of ligature-induced periodontitis in which GCF-AST (corrected for collection time) was correlated with microscopic evidence of tissue destruction in the periodontium at the sites of fluid collection. GCF and clinical data were collected at baseline, at optimal gingival health, during gingivitis, and after ligation. A cross-mouth design was implemented so that six premolar teeth in each dog were ligated for periods up to five weeks. Formalin-fixed tissues from the sites of GCF collection were prepared for light microscopy and evaluated for the presence of epithelial ulceration, bone resorption, and inflammatory cell infiltration. The relationship between GCF-AST levels and microscopic findings was analyzed by calculation of sensitivity and specificity and by plots of Receiver Operating Characteristics. These data revealed a correlation between elevated enzyme concentration and microscopic evidence of disease activity. Taken together with human studies, these results provide support for the use of AST as a marker of periodontal disease progression.
The Effect of Periodontal Therapy on Salivary Pseudocholinesterase Activity
Authors: Yamalik N. , Özer N. , Çağlayan F. , Çağlayan G. , Akdoğanli T.
Published: November 2010

The effects of different stages of periodontal therapy on salivary pseudocholinesterase (PCE) activity in patients with periodontitis were determined by use of a spectrophotometric method. The mean PCE activity in whole saliva was 17.95 U/L in the pre-treatment phase, 4.67 U/L after scaling and oral hygiene instructions, and 1.93 U/L following surgical procedures. It was observed that the mean salivary PCE activity in patients with periodontitis showed a tendency to decrease in both phases of treatment, and PCE levels at the end of periodontal therapy were similar to those of healthy subjects.
Dental Caries and Fluoride Exposure in Western Australia
Authors: Riordan P.J.
Published: November 2010

Most water supplies in Western Australia (WA) have been fluoridated since about 1968, but one region has persistently resisted. Supplement use has been encouraged there, and fluoride toothpaste is widely used. Caries prevalence and caries experience in children in Perth (F- 0.8 mg/L) have declined steadily since fluoridation, but in the Bunbury region (F- <0.2 mg/L), caries measures remain higher than in Perth. The purpose of this study was to correlate the magnitude and timing of fluoride exposure with caries experience. Altogether, 592 randomly selected children born in 1978 (mean age, 11.8 years) in Perth and the Bunbury region provided residence and fluoride exposure information for the periods from birth to four and from four to 12 years of age. Caries experience was recorded clinically in accordance with DMFT and WHO criteria. Sixty-one percent had been continuous residents of fluoridated areas from birth to four years, and 51% between the ages of four and 12 years. Fluoride supplement use was low. By the age of 1.5 years, 42% had used toothpaste. The prevalence of caries was 0.38 in Perth and 0.61 in the Bunbury region, and mean DMFT scores were 0.89 (SD, 1.39) and 1.57 (SD, 1.60), respectively. Bivariate analysis revealed all fluoride exposure to be associated with reduced caries experience, but there were large correlations between some variables. When unconditional logistic regression analysis was used, the most important (p < 0.05) odds ratios associated with no caries experience were for residence in a fluoridated area from four to 12 years of age and early use of toothpaste. Residence in a fluoridated area from birth to four years of age and use of supplements at any age did not reduce caries risk significantly (p>0.05) at 12 years of age. Increased total fluoride exposure (up to optimal exposure) was associated with decreased mean DMF scores. These data suggest that water fluoridation had an important anti-caries effect; the post-eruptive effect was more important than the pre-eruptive effect.
Synergistic Degradation of Mucin by Streptococcus oralis and Streptococcus sanguis in Mixed Chemostat Cultures
Authors: Van der Hoeven J.S. , Camp P.J.M.
Published: November 2010

Oral streptococci can grow in mucin by utilizing the oligosaccharide chains as a source of carbohydrate. The degradation of the oligosaccharides by these species is accomplished by exoglycosidase activities. In this experiment, it was investigated whether strains from different species could cooperate in the release of sugars from the mucin oligosaccharide. To this end, Streptococcus sanguis Ny 584 and Streptococcus oralis strain Ny 586 were grown continuously in a chemically-defined medium, with pig gastric mucin as the growth-limiting source of carbohydrate. In pure cultures, strain Ny 586 attained approximately three-fold-higher cell densities than did strain Ny 584 in the mucin medium. This was in accordance with the observation that S. oralis Ny 586 exhibited fucosidase activity, as indicated by the presence of fucose in the culture fluid. In contrast, strain Ny 584 has no fucosidase activity against mucin, and therefore cannot attack fucose-ending oligosaccharide chains. Stable mixed cultures of the strains were obtained. It appeared that S. sanguis Ny 584 reached significantly higher cell densities in mixed cultures with S. oralis Ny 586 than in pure culture. Stimulation of the growth of strain Ny 584 was probably due to the generation of non-fucose-ending oligosaccharide chains by fucosidase from strain Ny 586. It is concluded that the synergistic degradation of oligosaccharides in glycoproteins is a potential factor influencing the streptococcal populations in the mouth.
Identification by Biotinylated DNA Probes of Capnocytophaga Species Isolated from Supragingival Calculus
Authors: Morita M. , Yamamoto T. , Watanabe T.
Published: November 2010

The distribution, genetic relatedness, and peptidase activity in hydrolyzing N-benzoyl-L-arginine- p-nitroanilide by Capnocytophaga species isolated from calculus- and non-calculus-formers were determined in this study. The proportion and prevalence of Capnocytophaga species were higher in plaque samples from the calculus group than in those from the non-calculus group, and these bacteria showed high peptidase activity. C. gingivalis were found more frequently in the calculus group than in the non-calculus group, and possessed much higher peptidase activity than C. ochracea and C. sputigena. Black-pigmented colonies were also recovered more frequently from the calculus group than from the non-calculus group. Since these organisms had little or no peptidase activity, they were not studied further.
Detection of Two Anaerobic Periodontopathogens in Children by Means of the BANA and ELISA Assays
Authors: Watson M.-R. , Lopatin D.E. , Bretz W.A. , Ertel I.J. , Loesche W.J.
Published: November 2010

The mouths of young children become colonized by a variety of bacteria, but there have been only a few studies that have sought the presence of periodontopathic species in this population. Almost all of these studies used culturing techniques rather than the newer detection methodologies for various periodontopathogens.

Studies in adults have shown that Treponema denticola and Porphyromonas (Bacteroides) gingivalis can be detected in dental plaque by use of the BANA and ELISA diagnostic tests. In the present study, plaque samples from four subgingival sites in each of 157 children (aged from two to 18 years) were tested for BANA hydrolysis with a BANA reagent card, and for T. denticola and P. gingivalis with an ELISA assay. Anaerobic periodontopathogens hydrolyzing the BANA substrate were found to be present in at least one of four plaque samples in 88 children (56%). T. denticola and/or P. gingivalis were detected by ELISA in at least one plaque sample in each of 135 children (86%). This study shows that children are widely colonized by these micro-organisms. A higher proportion of Black children than Caucasian children was colonized by these BANA-positive organisms. Also, children having a parent with a documented history of periodontal disease were more likely to be BANA-positive than were children of parents with unknown periodontal status.
Upper Central Incisor and Canine Tooth Crown Size in 47,XXY Males
Authors: Alvesalo L. , Tammisalo E. , Townsend G.
Published: November 2010

Enamel and dentin thicknesses were measured in permanent tooth crowns of 47,XXY (Klinefelter syndrome) males. In 47,XXY males, enamel thickness in maxillary central incisors was significantly greater than that in control males or females, and dentin thickness in incisors and canines was significantly greater than that in control females, but smaller than that in normal males. These findings confirm the concept that human dental growth is affected by sex chromosomes. Amelogenesis is promoted by both X and Y chromosome genes, and sexual dimorphism in average tooth size is evidently determined by a promoting effect of the Y chromosome on dentin growth, probably through cell proliferation. This effect can also explain sex predilection for males in the numbers of supernumerary and ordinary teeth.
An Eight-year Follow-up of the Occlusal Surfaces of First Permanent Molars
Authors: Vehkalahti M.M. , Solavaara L. , Rytömaa I.
Published: November 2010

The state of the occlusal surfaces of the first permanent molars (FPMs) in a representative group of subjects from seven to 15 years of age was followed retrospectively year by year. Data were taken from oral health records. Standardized charts include information on dental check-ups, oral health status, and the treatment given. The state of each occlusal surface was classified into four categories: (1) sound but unsealed, (2) sealed, (3) filled, or (4) decayed. An overall annual attack rate for all occlusal FPM surfaces was 5.9% per year, and for approximal surfaces, 1.3%. Occlusal caries attacks had been most prevalent between seven and nine years of age, whereas new approximal lesions had been most frequent from ages 11 to 13. The FPMs that had been sealed at the age of seven developed fewer caries than did any other group during the follow-up.
Crevice Corrosion Products of Dental Amalgam
Authors: Sutow E.J. , Jones D.W. , Hall G.C. , Owen C.G.
Published: November 2010

The objective of this study was to determine the in vitro corrosion products that resulted from crevice corrosion of low-and high-copper dental amalgams. Specimens were potentiostatically polarized in a chloride-containing electrolyte while set against a PTFE surface to form a crevice. After 16 h, corrosion products were examined by light microscopy, SEM, EDS, and XRD. Analysis showed the presence of three previously reported products [Sn4(OH)6Cl2, SnO, and Cu2O] and a new product, CuCl, which formed on high-copper, γ2-free amalgams. Thermodynamic considerations show that CuCI is stable for the reported in vivo potentials of amalgam restorations and the high acidity and high chloride ion concentration associated with crevice corrosion.
Importance of Polymerization Initiator Systems and Interfacial Initiation of Polymerization in Adhesive Bonding of Resin to Dentin
Authors: Imai Y. , Kadoma Y. , Kojima K. , Akimoto T. , Ikakura K. , Ohta T.
Published: November 2010

Although various adhesive resins for dentin have been developed and used clinically, most attention has been directed to adhesion-promoting monomers and pre-treatment agents. The role of polymerization initiator systems in bonding has been overlooked. The purpose of this work was to study the role of initiators from the viewpoint of interfacial initiation of polymerization in dentin bonding. The bond strength between dentin and methyl methacrylate resin was significantly improved by a possible interfacial initiation with (1) the combination of ferric chloride, adsorbed onto dentin, and oxidized tri-n-butylborane (TBBO) and (2) the addition of tertiary butyl peroxymaleic acid (containing a carboxylic acid group, which has an affinity with dentin) to chemically- or light-activated initiator systems.
Serum Fluoride Level and Fluoride Content of Enameloid
Authors: Prostak K.S. , Seifert P. , Skobe Z.
Published: November 2010

We investigated diverse groups of fish species to determine whether the fluorine (F) contents of the dental hard tissues were related. to baseline serum F levels. Serum samples, enameloid, dentin, ganoid/enamel, and bone were analyzed for F by either electron microprobe or wet chemistry. Species were categorized into two groups based on the F content of the enameloid. One group contained greater than 2.6 wt% F in enameloid, whereas the other group had less than 0.45 wt% F in enameloid. The dentin and bone from all species (or, in skates, the cartilage), as well as the ganoid/enamel layer of a Holostean fish (alligator gar), showed consistently low F content. In those species whose teeth developed in sequential rows, the F content of enameloid increased with progressive tooth development. The serum F levels of all fish were below 0.05 μg F/mL (2.63 μmol/L) and were not significantly related to the F content of the enameloid. The results substantiate the idea that F incorporation into enameloid is related to fish phylogeny, not food or habitat. It is suggested that specialized outer dental epithelial cell configurations may facilitate the incorporation of F into enameloid.
The Effect of Thromboxane on Contraction of Canine Mesenteric and Lingual Arteries
Authors: Greenberg S.S. , Wang Y. , Xie J. , Smartz L. , Rammazatto L. , Curro F.A.
Published: November 2010

Thromboxane A2 (TXA2), a potent vasoconstrictor agent, is released from platelets and smooth muscle during inflammation and trauma. TXA2 may cause lingual artery (LA) contraction, leading to lingual paresthesia. The effects of U-46619, a TxA2 mimetic, on isolated rings of canine LA and mesenteric artery (MA) were examined. U-46619 (1 nmol/L to 1 μmol/ L) caused a triphasic contraction of LA and MA; a rapid, phasic contraction; a slow, sustained contraction; and, upon washout of U-46619, a maintained contraction. The MA relaxed slowly, but the LA remained contracted for at least three h after washout. Decreasing extracellular calcium ion (Ca2+0) to <0.1 μmol/L with 2 mmol/L EGTA relaxed MA, but not LA. EGTA (4 mmol/L) partially relaxed the maintained contraction of LA. Inhibition of protein kinase C with amphotericin B or staurosporine inhibited the phasic and sustained contractions of LA, but did not affect the maintained contraction in the presence or absence of EGTA. Thus, CA2+0was required for the initial contraction of the LA by U-46619, but did not appear to be required for the maintained contraction following washout of U-46619. The data support the conclusion that following a brief exposure to U-46619, maintained contraction of LA persists by a unique mechanism that may be independent of Ca2+ and protein kinase C. Sustained LA contraction after exposure to endogenous TXA2during inflammation and trauma may contribute to impaired lingual blood flow and orofacial tissue injury.
Effect of a Beta-adrenergic Blocking Agent on Dental Anxiety
Authors: Liu H.H. , Milgrom P. , Fiset L.
Published: November 2010

The effect of propranolol was studied on 23 dental phobics in a double-blind, placebo-controlled clinical trial involving actual dental treatment. The subjects were selected because they showed high physiological reactivity in the dental situation. Twelve subjects received the test drug and 11 subjects received the placebo at individualized doses of either 80 or 120 mg. A significant difference in self-reported anxiety at the injection phase of treatment and less overall pain intensity and aversiveness were observed for the propranolol as compared with the placebo group. No differences were detected for behavior ratings. Beta-adrenergic blocking agents may have utility for reducing anxiety in individuals fearful of dental treatment.
Lack of Correlation Between Food Retention on the Human Dentition and Consumer Perception of Food Stickiness
Authors: Kashket S. , Van Houte J. , Lopez L.R. , Stocks S.
Published: November 2010

When dental health professionals advise that sticky foods be avoided, it is left to the consumer to choose correctly among different foods. In this study, comparisons were made among consumer ratings of stickiness of 21 commercially available foods and objective measurements of tooth retention of each of the foods. No correlation was found between the two, and neither the rates of clearance of food particles from the teeth nor the rates of clearance of food-derived sugars from the saliva correlated with ratings of food stickiness. Cookies, crackers, and potato chips were most retentive, whereas caramels, jelly beans, raisins, and milk chocolate bars were among those poorly retained. Clearance rates appeared to vary inversely with initial retention. However, chocolate-caramel bars exhibited high initial retention and a very rapid rate of clearance from the teeth. The findings show that consumers cannot accurately assess the retentiveness of foods and, thus, the advice simply to avoid sticky ones is inadequate.
Age-hardening Mechanisms in a Commercial Dental Gold Alloy Containing Platinum and Palladium
Authors: Tani T. , Udoh K. , Yasuda K. , Van Tendello G. , Van Landuyt J.
Published: November 2010

The age-hardening mechanism of a commercial dental gold alloy containing platinum and palladium (in wt.%, 15 Cu, 6 Ag, 5 Pt, 3 Pd, 3 Zn, with the balance as gold) was elucidated by means of electrical resistivity, hardness tests, x-ray and electron diffraction and electron microscopy, as well as high-resolution electron microscopy. The sequence of phase transformations during isothermal aging below the critical temperature, Tc = 825 K, was described as follows: disordered solid solution α 0 (FCC) → metastable AuCu I' ordered phase (FCT) → metastable α 2 disordered phase (FCC) equilibrium AuCu I ordered phase (FCT) + equilibrium α 2 disordered phase (FCC). The hardening was due to the introduction of coherency strain at the interface between the AuCu I' platelet and the matrix. These ordered platelets had mutually perpendicular c-axes to compensate for the strain introduced by their tetragonality. A loss of coherency at the interface brought about softening of the alloy, i.e., over-aging.
Kinetics of Bone-resorbing Activity in Developing Periapical Lesions
Authors: Wang C.-Y. , Stashenko P.
Published: November 2010

The presence and kinetics of bone-resorbing activity in periapical lesions were studied with a rat model system. Lesions were found to expand most rapidly between induction on day 0 and day 15 ("active phase"), with enlargement occurring at a slower rate thereafter (days 20 and 30, "chronic phase"), as assessed by measurement of magnified radiographs and automated image analysis. Pooled extracts of periapical tissues obtained on day 15 contained significant levels of bone-resorbing activity, as determined by 45Ca release from pre-labeled fetal rat long bones. Normal rat dental pulp and periodontal ligament contained no activity. In two kinetic experiments, highest levels of bone-resorbing activity were detected in tissues on days 10 (10.4% and 11.6% specific 45Ca release/mg/mL) and 15 (8.9%). Activity declined thereafter on day 20 (4.4% and 6.1%) to near baseline levels by day 30 (1.4% and 3.3%). Identical levels of resorbing activity were found in the presence or absence of polymyxin-B, an inhibitor of bacterial lipopolysaccharide. These findings demonstrate that bone-resorbing activity is temporaly related to periapical bone destruction and suggest that this model may be useful for studies of mediators that are involved in the pathogenesis of inflammatory bone resorption.
Effect of Examining Half the Teeth in a Partial Periodontal Recording of Older Adults
Authors: Hunt R.J. , Fann S.J.
Published: November 2010

Limited evidence to date has suggested that half-mouth examinations can be used in epidemiological surveys for accurate estimation of the prevalence of periodontal conditions. This study investigated the accuracy and efficiency of half-mouth periodontal examinations of mesial and buccal sites by comparing whole-mouth findings from those sites with findings that would have been obtained by examining only two randomly selected quadrants of teeth in three older dentate adult populations: 263 whites in Iowa, 309 whites in North Carolina, and 384 blacks in North Carolina. Mean half-mouth scores for gingival recession, pocket depth, attachment loss, and Extent and Severity Index were almost identical to those of mean whole-mouth scores, with correlations between means exceeding 0.93. However, the proportions of the population having selected levels of moderate or severe periodontal disease in mesial and buccal sites were underestimated by as much as 13%. This study showed that half-mouth examinations can be accurate and efficient in estimating mean periodontal measures, but may underestimate the prevalence of periodontal conditions.
The Effect of Crown Receipt on Measures of Gingival Status
Authors: Bader J. , Rozier R.G. , McFall W.T.
Published: November 2010

Although the association between crown margins and increased inflammation and probing depth is well-established, studies examining these effects have been largely post hoc. Change in gingival status measures due to receipt of crowns may affect longitudinal evaluations in clinical trials and epidemiological studies. This study examined the effects of receipt of crowns on the periodontal health of the Ramfjord index teeth. Gingival status descriptors included measures of plaque, gingival inflammation, calculus, probing depth, and gingival recession. Changes in periodontal status scores (1987-89) for teeth receiving crowns among 67 patients were compared with change in scores for teeth not receiving crowns. Teeth that were crowned showed small, but significant, differences. These teeth had greater decreases in calculus scores for both surfaces, increases in inflammation compared with decreases for teeth not receiving crowns, and increased facial probing depths. Change in gingival recession was markedly decreased on facial surfaces among teeth receiving crowns. The results suggest that crown status should be recorded routinely in clinical trials involving gingival status, and that teeth receiving crowns during the course of the study should be eliminated from the analyses.
Factors Influencing the Creep of Dental Amalgam
Authors: Mahler D.B. , Adey J.D.
Published: November 2010

The purpose of this study was to investigate the influence of relevant microstructural and compositional factors on the creep of 12 representative dental amalgams by means of stepwise multiple linear regression. The independent variables accepted by the regression were volume percent of the η'(Cu6Sn5) phase, grain size of the γ1 (Ag2Hg3) phase, volume percent of the y (Ag3Sn) plus E (Cu3Sn) phases, number of very small η' crystals (< 1.5μm) per mm, and weight percent of Hg. The results of this regression showed an adjusted R2 of 0.949, significant at p = 0.002.
Chromosomal Deletions in Melibiose-negative Isolates of Streptococcus mutans
Authors: Ushiro I. , Lumb S.M. , Aduse-Opoku J. , Ferretti J.J. , Russell R.R.B.
Published: November 2010

Isolates from a collection of phenotypically melibiose-negative (Mel-) Streptococcus mutans from widely-scattered geographical locations were examined and found to lack the activities of the enzymes α-galactosidase and a-glucosidase, in addition to being unable to transport melibiose. Cloned fragments of S. mutans DNA from the region of the chromosome carrying the genes for a-galactosidase ( aga), sucrose phosphorylase ( gtfA), and dextranglucosidase ( dexB), as well as the genes encoding components of the binding-protein-dependent uptake system for raffinose and melibiose, were used in hybridization studies for investigation of the genetic basis of the Mel- phenotype. A region of at least 12 kilobases, containing all the above genes, was found to be deleted from the chromosome of the Mel- strains. It appears that this region of the chromosome is not essential for survival of S. mutans in the oral cavity. The reason for the frequent occurrence of deletions, as opposed to other forms of mutational events, is unknown.
A Twin Study of Genetic Variation in Proportional Radiographic Alveolar Bone Height
Authors: Michalowicz B.S. , Aepplp D.P. , Kuba R.K. , Bereuter J.E. , Conry J.P. , Segal N.L. , Bouchard T.J. , Pihlstrom B.L.
Published: November 2010

The purpose of this study was to estimate the genetic variance for alveolar bone height by means of the classic twin method and the study of monozygous twins reared apart. Panoramic radiographs were obtained from 120 pairs of adult twins (mean age = 40.4 years, S.D. = 10.4 years), for comparison of 62 pairs of monozygous twins reared together (MZT), 25 pairs of like-sexed dizygous twins reared together (DZT), and 33 pairs of monozygous twins reared apart (MZA). Mesial and distal bone heights were determined as a proportion of tooth length. A full-mouth bone score was computed for each twin by averaging these proportions from all measurable teeth. Between-pair (B) and within-pair (W) variances were computed for each twin group. The population variances (B + W) of the MZT and DZT twin groups were similar, which validated a basic assumption of the twin model. Intraclass correlations and heritability estimates were also computed for the reared-together and reared-apart twin groups. Boot-strap sampling was used to provide estimates and confidence limits for these values. The intraclass correlations for the twin groups were: MZT = 0.70, DZT = 0.52, and MZA = 0.55. The results of this study suggest that there is significant genetic variance in the population for proportional alveolar bone height.
Presence of Vesicles Containing Lactate Dehydrogenase in the Dentin of Bovine Tooth Germs
Authors: Kitamura C. , Terashita M. , Noguchi T.
Published: November 2010

The dentin was removed from bovine tooth germs, followed by the separation of the extracellular matrix vesicle fraction after collagenase treatment. Lactate dehydrogenase (LDH)-containing vesicles with a density different from that of matrix vesicles were detected in the matrix vesicle fraction. LDH in these vesicles did not result from cell lysis and vesicle capture during the preparation of the matrix vesicle fraction. The isoenzyme pattern of LDH in LDHcontaining vesicles was similar to that of cytosolic LDH of odontoblasts. Other cytosolic enzymes were not detected in LDH-containing vesicles, suggesting the presence of a mechanism for specific uptake of cytosolic LDH during the in vivo formation of the vesicles.
A Scanning Electron Microscopic Study of the Contraction of Vascular Wall Cells in Dog Dental Pulp
Authors: Jima T. , Zhang J.Q. , Goto T. , Kondo T. , Tanaka T.
Published: November 2010

Ultrastructural changes in vascular wall cells in dog dental pulp after removal of connective tissue components were studied by scanning electron microscopy following administration of norepinephrine (0.2 mg/kg). Contracted smooth-muscle cells were frequently seen in arterioles of all sizes. The surfaces of these cells were highly irregular with numerous evaginations and invaginations, varying considerably in configuration and size. Many evaginations ran longitudinally or obliquely to the long axis of the vessel. Some meandering evaginations were also observed as, rarely, were small spherical or bulbous projections. Spidery smooth-muscle cells frequently seen in the tunica media of terminal arterioles and thought to be primitive smooth-muscle cells exhibited fewer irregularities than the typical spindle-shaped smooth-muscle cells beneath them. Pericytes in the larger post-capillary venules (20 μm or larger in diameter) often showed evaginations and invaginations, mainly running parallel to the vessel axis. On the other hand, no surface irregularities could be seen in pericytes of either the smaller post-capillary venules (less than 20 μm in diameter) or the capillaries, although occasional evaginations running parallel to the vessel axis were noted on the outer surface of the endothelium.
Age-related Development of the Long-junctional Epithelium in the Senescence-accelerated Mouse
Authors: Sashima M. , Satoh M. , Suzuki A.
Published: November 2010

The mesial gingiva of the maxillary first molar of SAM-R/1/Iw (senescence-accelerated mouse, resistant/1/Iwate) and the P/2/Iw (prone/2/Iwate) were studied morphologically by quantitative and qualitative methods as a function of age (one-, two-, six-, 12-, and 16-month-old). In this region, neither plaque nor periodontitis has been found (Sashima et al., 1990a). Statistical analyses of the gingival tissues in this region in both strains showed that, with age, the length of the junctional epithelium (JED) increased, the depth of the gingival sulcus (GSD) did not change, and the height of the gingival crest (GCD) decreased. Therefore, long-junctional epithelium developed, and gingival recession occurred, since a periodontal pocket did not develop with age in either strain. In particular, there was a strong correlation between the JED and age in both strains (r = 0.84, p < 0.05 for the R/l/Iw, and r = 0.92, p < 0.05 for the P/2/ Iw). The JED, GSD, and GCD of the P/2/Iw were higher than each of those in the R/l/Iw after six months of age; however, there were no significant differences between the R/l/Iw and the P/2/Iw for any age group (one-, two-, six-, 12-, and 16-month-old).
In vitro Demineralization of Enamel by F-sensitive and F-resistant Mutans Streptococci in the Presence of 0, 0.05, or 0.5 mmol/L NaF
Authors: Van Loveren C. , Spitz L.M. , Buijs J.F. , Ten Cate J.M. , Eisenberg A.D.
Published: November 2010

Lactate production and accompanying enamel demineralization by fluoride-sensitive and fluoride-resistant mutans streptococci were studied in an in vitro demineralization model in the presence of 0, 0.05, or 0.5 mmol/L NaF. The fluoride-resistant strains were derived from laboratory strains or were recently isolated strains from xerostomic patients on high-dose fluoride therapy. The demineralization model was composed of a cell suspension in a glucose-agarose gel overlying a bovine enamel block. Lactate and calcium content of the agarose were determined after 22-hour incubations at 37°C.

Fluoride-resistant variants of Streptococcus sobrinus 6715-15 produced less lactate and caused less demineralization than did the parent strain even in the presence of fluoride. On the other hand, fluoride-resistant variants of Streptococcus mutans C180-2 and of S. mutans GS-5 produced more acid and caused greater demineralization than did their respective parent strains, both in the absence and presence of fluoride. Two recently isolated fluoride-resistant S. mutans strains produced more lactate and demineralized enamel more than did two recently isolated S. mutans strains from normal human subjects, both in the presence of 0 and 0.05 mmol/L NaF.

It is concluded that adaptation to fluoride resistance does not invariably reduce the cariogenicity of mutans streptococci nor the effectiveness of fluoride in preventing demineralization.
In vitro Acidogenic Potential and Mutans Streptococci of Human Smooth-surface Plaque Associated with Initial Caries Lesions and Sound Enamel
Authors: Van Houte J. , Sansone C. , Joshipura K. , Kent R.
Published: November 2010

Samples of human dental plaque were pooled from several "white spot" smooth tooth surface areas as well as from several clinically-sound tooth surface areas in each of 12 caries-positive college students. Each of the two samples from each subject was used for the determination of: (1) pH-lowering potential in vitro involving dispersed plaque suspensions, excess glucose supply, and a 60-minute test, and (2) the proportions of mutans streptococci and lactobacilli. When all subjects were considered, plaques from "white spot" areas, as compared with samples from sound surface areas, were characterized by significantly higher proportions of mutans streptococci, a lower starting ("resting") pH, a faster rate of pH drop between pH 6.0 and 5.0, and a lower minimum pH of the suspension; the lactobacillus proportions were generally very low in both types of plaques. For individual subjects, however, the proportions of mutans streptococci in plaque associated with "white spot" areas showed a wide range (0.001-10.0%), and samples with high as well as low levels of these micro-organisms could exhibit a high rate of pH drop and a low pH minimum. This suggests that, besides mutans streptococci and lactobacilli, other bacteria capable of acidogenesis at a low pH may contribute to the high pH-lowering potential exhibited by many plaques.
Mutans Streptococci and Non-mutans Streptococci Acidogenic at Low pH, and in vitro Acidogenic Potential of Dental Plaque in Two Different Areas of the Human Dentition
Authors: Van Houte J. , Sansone C. , Joshipura K. , Kent R.
Published: November 2010

Samples of human dental plaque were obtained from sound tooth surfaces in the lower anterior and upper posterior areas of each of 11 subjects with various degrees of caries experience. Both types of plaque were compared for: (1) their pH-loweringpotential [pH at 10 and 60 min after sugar addition and the pH drop between 0 and 10 min (delta pH)] with an in vitro method involving dispersed plaque suspensions and excess glucose supply; (2) the proportions ofmutans streptococci; and (3) the distribution of the predominant non-mutans streptococci according to their final pH in glucose broth. Compared with plaque from the lower anterior area, plaque from the upper posterior area exhibited a significantly higher pH-lowering potential, i.e., a lower pH at 10 and 60 min and a greater delta pH and significantly higher levels of mutans streptococci. The final pH values for the non-mutans streptococci exhibited a wide range from about 4.4 to over 5.0. The proportions of such organisms designated as capable of acidogenesis at low pH (final pH < 4.6), whether expressed as a percentage of the total non-mutans streptococci or of the total plaque flora, were significantly increased in plaque from the upper posterior area. The proportions of non-mutans streptococci capable of acidogenesis at low pH in plaque from the upper posterior area were also significantly increased, with decreasing pH values at 10 and 60 min. The findings strengthen the link between the capacity of the plaque flora for acidogenesis at a low pH and its pH-loweringpotential as well as the role of bacterial acidogenesis at a low pH as an oral ecological determinant.
Studies on the Subcellular Localization of Protease and Arylaminopeptidase Activities in Streptococcus sanguis ATCC 10556
Authors: Cowman R.A. , Baron S.S.
Published: November 2010

Intact cells of Streptococcus sanguis ATCC 10556 possessed arylaminopeptidases exhibiting activity toward the nitroanilide (NA) derivatives of leucine, alanine, methionine, arginine, or lysine. Weak hydrolytic activity was observed in assays with the NA derivatives of valine, proline, glycine, or glutamic acid. Subcellular localization studies revealed that arylaminopeptidase activities were located in both the cell membrane and cytoplasm. Arylaminopeptidases exhibiting activity toward the leucine, alanine, or methionine NA substrates appeared to be more predominantly associated with the membrane, whereas enzymes exhibiting activity toward arginyl-NA or lysyl-NA were more prevalently located in the cytoplasm. Several results from this study suggest that the membrane-associated arginyl and lysyl arylaminopeptidases were located in such a way that their expression was restricted in the intact cell. The addition of 0.5 mol/L NaCl to protoplast preparations derived from mutanolysin-treated cells resulted in an almost complete solubilization of membrane-associated arylaminopeptidase activities. These observations support the conclusion that the association of arylaminopeptidases with the cell membrane may involve hydrophobic or electrostatic interactions, or both. S. sanguis ATCC 10556 also possessed at least one caseinolytic endopeptidase activity. This activity is most likely located near the membrane surface, as no association with the cell wall was evident. The location of membrane-associated endopeptidase and arylaminopeptidase activities, together with intracellular peptidases, is suggested to provide an efficient mechanism for the hydrolysis and subsequent utilization of polypeptide and oligopeptide substrates as sources of amino acids for growth by this microorganism.
Calcium Uptake in Rat Parotid Gland Secretory Granules
Authors: Porter J.E. , Cheung P. , Dowd F.J.
Published: November 2010

45Ca2+ uptake in isolated rat parotid secretory granules was examined in the presence of oxalate. Uptake of calcium was dependent on time, with the maximum occurring at 15 min. The uptake of calcium was dependent on adenosine-5'-triphosphate (ATP), and substitution of ATP with B,g-methylene-ATP did not stimulate calcium uptake. Enzyme marker analysis indicated that mitochondria accounted for no greater than 3.0 ±0.2% of the observed ATP-dependent calcium uptake. Calcium uptake was blocked by the ATPase inhibitors tributyltin, IC 50 = 12.2 ±0.6 nmol/L and 4-acetamido-4'-isothiocyano-2,2'-stilbene disulphonic acid (SITS), IC50 = 3.0 ±0.3 (μmol/L. These results indicate that in the parotid secretory granule there is a calcium uptake mechanism that is dependent on the hydrolysis of ATP and is suppressed by two inhibitors of granule ATPase.
Dentin Bond Strength of Light-cured Glass-ionomer Cements
Authors: Hinoura K. , Miyazaki M. , Onose H.
Published: November 2010

The purpose of this study was to investigate the influence of surface treatments and irradiation conditions on the bond strength of light-cured glass-ionomer cements to dentin. The light-cured glass-ionomer cements used in this study were Vitrabond, XR Ionomer, and Fuji Lining LC. Three experiments were designed to study the influence of the following factors on bond strength to dentin: (1) effect of the surface treatment of the dentin, (2) effect of the irradiation time, (3) effect of an increase in the interval between mixing of the cement and irradiation. Samples were stored in water for 24 hours, after which shear bond testing was performed at a cross-head speed of 1 mm/min. For Vitrabond, the Scotchprep and Gluma 2 treatments gave the greatest shear bond strengths. For XR Ionomer and Fuji Lining LC, the Scotchprep treatment gave the greatest shear bond strengths. The bond strengths for all cements increased with prolonged irradiation time. Bond strengths decreased with a longer elapsed time between mixing and light-curing. This means that light-curing should be done soon after the cement is placed. The failure mode was found to be cohesive in the ionomer.
Radiopacity and Physical Properties of Titanium-polymethacrylate Composite
Authors: Matsumura H. , Sueyoshi M. , Atsuta M.
Published: November 2010

Titanium-polymethacrylate composite was prepared as an x-ray-opaque filler for composite core materials. The base monomers of the composite were 2,2-bis [4-(3-methacryloyloxy-2-hydroxy propoxy) phenyl]propane (Bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA). Pure titanium powder was used as a radiopaque element. Two functional methacrylates-isopropyl dimethacryloyl isostearoyl titanate (KR-7) and 4-methacryloyloxyethyl trimellitate anhydride (4-META)—were adopted as couplers of titanium powder. The radiopacity of composites was determined in terms of their equivalent thickness of aluminum per unit thickness of material. Compressive and transverse strengths of the composites were measured by use of coupled and untreated titanium fillers. The composites that contained 70% and 80% titanium by weight showed more radiopacity than enamel and less than amalgam. Radiopacity was controlled by the content of titanium filler in the composite. The decrease in compressive and transverse strengths of the composites was 0.7 to 15.9% and 43.7 to 52.9%, respectively, after one year's immersion in water. The decrease in transverse strength was remarkable; however, this deterioration was diminished by use of both KR-7 and 4-META as couplers for titanium. Thus, prepared titanium-polymethacrylate composite may be used as a radiopaque composite filler for self-curing composite core materials.
The Effect of Carbamide-Peroxide Gel on the Shear Bond Strength of a Microfil Resin to Bovine Enamel
Authors: Titley K.C. , Torneck C.D. , Ruse N.D.
Published: November 2010

Cylinders of a visible-light-cured microfil resin were formed on, and bonded to, the flattened labial enamel surfaces of young bovine incisor teeth which had previously been subjected to four different treatments: (1) immersion in 10% carbamide-peroxide gel, pH 4.7, for three h; (2) immersion in 10% carbamide-peroxide gel, pH 4.7, for six h; (3) immersion in 10% carbamide-peroxide gel, pH 7.2, for three h; and (4) immersion in 10% carbamide-peroxide gel, pH 7.2, for six h. For each experimental group, a control group of resin-bonded to saline-immersed teeth was prepared. In addition, two groups, prepared according to treatment 4, were leached in distilled water for one and seven d, respectively, prior to resin application. Specimens were stored in distilled water at 37°C for seven d prior to shear-bond-strength testing. A total of 90 teeth was tested. Statistical analysis of the results indicated that there was a highly significant reduction in the shear bond strength to carbamide-peroxide-treated enamel as compared with that to saline-treated enamel. The effects of duration of peroxide treatment and pH, as well as the interaction term, were not statistically significant. Leaching of the peroxide-treated enamel in water for either one or seven d prior to resin application restored the adhesiveness of the enamel. Scanning electron microscopic examination of randomly selected, fractured test specimens indicated that the peroxide-induced reduction in enamel adhesiveness was related to alterations in both attachment-surface area at the resin-enamel interface and resin quality.
The Effect of Chlorhexidine Varnish Treatment on Salivary Mutans Streptococcal Levels in Child Orthodontic Patients
Authors: Sandham H.J. , Nadeau L. , Phillips H.I.
Published: November 2010

A chlorhexidine dental varnish was applied to the teeth of 26 children, ten to 17 years of age, in an attempt to limit the increase in colonization by mutans streptococci that normally accompanies the placement of fixed orthodontic appliances and to assess the acceptance of the application procedure. Despite the insertion of the appliances in the month following the varnish application, the numbers of detectable salivary mutans streptococci in the children were found to remain significantly lower than baseline values for seven months (p < 0.01). Among the 26 children, 16 exhibited high counts (> 2.5 x 105 cfu/mL saliva) at baseline, but none exhibited such counts until three months post-treatment, when one child did. By seven months, eight children had high counts. No significant difference in effectiveness was observed between varnish formulations containing 10% or 20% chlorhexidine acetate, or between children of different ages or past caries experience. The lack of drop-outs and the results of a questionnaire indicated that acceptance of the treatment by the children was excellent. The study indicates that chlorhexidine varnish therapy was acceptable to the children and was effective in suppressing oral mutans streptococcal levels for long periods, even when used prior to the placement of fixed orthodontic appliances.
Expression of Type I Collagen Pro-α2 Chain mRNA in Adult Human Permanent Teeth as Revealed by in situ Hybridization
Authors: Lukinmaa P.-L. , Vaahtokari A. , Vainio S. , Thesleff I.
Published: November 2010

The expression of the gene COL1A2, coding for the pro-α2 chain of type I pro-collagen, was analyzed in fully developed human permanent teeth. The teeth were fixed with formalin, demineralized with EDTA for about ten weeks, and embedded in paraffin. Pro-a2(I) mRNA was localized in the sections by in situ hybridization, with use of [35S]-labeled single-stranded RNA probes.

The amount of mRNA for pro-α 2(I) collagen chain, as indicated by the relative densities of silver grains and the grain counts per cell in autoradiography, was high in odontoblasts, whereas in pulpal fibroblasts it was low. High levels of pro-α2(I) mRNA expression were also present in those odontoblasts which had elaborated new dentin matrix in response to dental caries. Expression in the periodontal ligament, including the cementoblast layer, was slightly stronger than that in odontoblasts.

The intense expression of pro-a2(I) mRNA in odontoblasts of adult teeth suggests that even after the completion of primary dentin formation, they continue to synthesize heterotrimeric type I collagen molecules. Cell type-specific differences in the expression of pro-α2(I) mRNA imply that type I collagen probably plays a major role in the regulation of the structure and function of dental tissues. Finally, in situ hybridization enabled pro-a2(I) collagen mRNA to be detected in tissue sections even after prolonged demineralization, and thus it proved to be a valuable technique for analysis of gene expression in adult dental tissues, as shown here for COL1A2.
Fatty Acids of Healthy and Periodontally Diseased Root Substance in Human Teeth
Authors: Lygre H. , Solheim E. , Gjerdet N.R. , Skaug N.
Published: November 2010

In this comparative study, samples of root substance from healthy and periodontally diseased human teeth were analyzed for fatty acids by means of a gas-chromatographic technique. The sample preparation procedure allowed specimens from individual teeth to be analyzed. The content of the fatty acids C16:0, C16:1, C18:0, and C 18:1 in the superficial layer ofthe periodontally diseased teeth was significantly higher than that of healthy teeth. In the inner layer, there was no such difference. Four different 3-hydroxy fatty acids (3-OH C14:0, 3-OH C15:0, 3-OH C16:0, and 3-OH C17:0) were identified by combined gas-chromatography/mass-spectrometry in the tooth substance of periodontally diseased teeth. This indicates the presence of lipid A, which is the toxic component of bacterial lipopolysaccharides.