bluuebunny/crossref_metadata_2025 huggingface dataset:
Psychological Disorder, Conditioning Experiences, and the Onset of Dental Anxiety in Early Adulthood
Authors: Locker D. , Thomson W.M. , Poulton R.
Published: January 2009

Most studies examining the origins of dental fear and anxiety have relied on cross-sectional data. These are subject to several problems, such as recall and uncertainty concerning temporal relationships. This paper uses longitudinal data from the Dunedin Multidisciplinary Health and Development Study to assess risk factors for the development of dental anxiety in persons between the ages of 18 and 26 years. It was hypothesized that psychological factors would be as important as conditioning experiences in the genesis of dental anxiety over this period. The eight-year incidence of dental anxiety was 16.5%. Five variables entered models predicting onset: multiple fears, symptoms of substance dependence, previous experience of invasive dental treatment, dental visiting pattern, and the extraction of one or more teeth. Separate analyses for those avoiding and those using dental services resulted in different explanatory models. These results indicated that both psychological and conditioning variables contributed to the development of dental anxiety in this population of young adults.
Concise Review Biomaterials & Bioengineering: Meta-analytical Review of Factors Involved in Dentin Adherence
Authors: Leloup G. , D'Hoore W. , Bouter D. , Degrange M. , Vreven J.
Published: January 2009

Literature data on adherence tests of dentin-bonding systems (DBS) may differ widely, even for the same DBS. The problem of bond testing is that materials are seldom compared with a standard, and experimental conditions often vary. We sought to identify the parameters that influence this variability. Using inclusion and exclusion criteria, we conducted a meta-analytical review of 75 articles, published between 1992 and 1996 in SCI reviews, that give bond strength data for 15 dentin-bonding agents of the so-called third and fourth generations. Seventeen selected parameters were classified into four groups: Group A includes factors related to the dentin substrate (i.e., nature of teeth); group B, composite and bonding area (i.e., composite stiffness); group C, storage conditions of the bonded samples (i.e., thermocycling); and group D, test design (i.e., crosshead speed). For each report, the experimental features, the bond strength means and standard deviations, and the failure mode were extracted and tabulated. Statistical Analysis System software was used to perform Pearson correlation analysis and analysis of variance, with bond strength as the dependent variable and experimental conditions as the independent variables. The meta-analytical review highlighted the significant influence of various parameters in the different groups: origin of dentin, types of teeth, pulpal pressure, tooth storage temperature, maximum storage time of teeth, and dentin depth in group A; type and stiffness of composite and bonding area in group B; storage of bonded samples (medium, temperature, and time) in group C, and testing mode and crosshead speed in group D. A significant positive correlation was observed between the mean bond strength and the rate of cohesive failure. It can be concluded from this study that some of these parameters should be controlled by the use of a standardized protocol. Unfortunately, the substrate-related variables are more difficult to control, even though their influence is consistent.
Tuned Aperture Computed Tomography to Evaluate Osseous Healing
Authors: Nair M.K. , Seyedain A. , Agarwal S. , Webber R.L. , Nair U.P. , Piesco N.P. , Mooney M.P. , Grondahl H.-G.
Published: January 2009

Quantification of osseous healing is a challenging task, requiring expensive advanced imaging modalities. To improve diagnostic osseous imaging, we undertook this prospective study to explore the potential of Tuned Aperture Computed Tomography®. Eighty defects in 20 rabbit mandibles, randomly carrying an osteoblast suspension or a polymer matrix or a combination thereof or no treatment, were imaged at 3, 6, 9, and 12 weeks post-surgery. TACT slices, iteratively restored TACT, and conventional digital radiographs were evaluated. Mean-gray-value distribution within regions of interest was correlated with histomorphometric data. Lesions treated with osteoblast/polymer-matrix delivery systems demonstrated the highest mean gray-value, while the diagnostic efficacy of TACT-IR was significantly better than that of other imaging modalities (p < 0.001). Thus, TACT is an accurate imaging modality for non-destructive quantification of osseous dynamics.
Oral Function and Diet Quality in a Community-based Sample
Authors: Shinkai R.S.A. , Hatch J.P. , Sakai S. , Mobley C.C. , Saunders M.J. , Rugh J.D.
Published: January 2009

Overall diet quality indices, such as the Healthy Eating Index (HEI), are preferred for epidemiological studies, yet studies in dentistry have focused on isolated dietary components. This study investigated the influence of socio-demographic and masticatory variables (masticatory performance, bite force, number of posterior functional tooth units, TMJ disorder, and dentition status) on overall diet quality in a community-based sample (n = 731). Cross-sectional data were derived from clinical examinations, bite force recordings, masticatory performance measurements, and two 24-hour dietary recalls. Females, European-Americans, and older subjects had better HEI scores than males, Mexican-Americans, and younger subjects, respectively. Income, education, and the masticatory variables were not related to diet quality. Analyses according to dentition status (good dentition, compromised dentition, partial denture, and complete dentures) showed no inter-group differences for HEI except for the age groups. The results suggest that the chewing-related factors evaluated in this sample are not predictors of overall diet quality across the socio-demographic groups.
Decrease of Sulfate-reducing Bacteria after Initial Periodontal Treatment
Authors: Langendijk-Genevaux P.S. , Hanssen J.T.J. , Van der Hoeven J.S.
Published: January 2009

Sulfate-reducing bacteria (SRB) are associated with periodontitis, but it is unknown if elimination of these potential pathogens accompanies clinical improvement. This longitudinal study examined the occurrence of SRB and clinical effects following scaling and root planing. In this study, the presence of periodontal SRB was determined in 38 selected patients before and six months after mechanical therapy. SRB were detected by the enrichment culture technique. Mechanical periodontal treatment resulted in elimination of SRB in 89% of the patients, and 95% of the sites (n = 76). SRB were significantly reduced in patients with progressive, adult, and refractory periodontitis. The elimination of SRB was accompanied by clinical improvement. The mean gain of attachment of these pockets was 3 mm (p < 0.001). The reductions in pocket depth (p < 0.001) and bleeding were significant (p < 0.001). Persistence of SRB correlated with the initial pocket depth (p < 0.02) and attachment level (p < 0.02), and with bleeding of the site after treatment (p < 0.05). In conclusion, mechanical debridement is generally effective for the elimination of SRB.
Transforming Growth Factor-β1 and Basic Fibroblast Growth Factor Modulate Osteocalcin and Osteonectin/SPARC Syntheses in Vitamin-D-activated Pulp Cells
Authors: Shiba H. , Uchida Y. , Kamihagi K. , Sakata M. , Fujita T. , Nakamura S. , Takemoto T. , Kato Y. , Kurihara H.
Published: January 2009

Vitamin D deficiency elicits hypocalcified dentin. However, little is known about the action of vitamin D on the syntheses of dentin matrix proteins. In this study, we examined the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on the expressions of osteocalcin and osteonectin/secreted protein, acidic and rich in cysteine (SPARC), by human pulp cells in the presence or absence of transforming growth factor-β1 (TGF-β1) or basic fibroblast growth factor (bFGF). 1,25(OH)2D3 markedly increased osteocalcin at protein and mRNA levels. The osteocalcin level induced by 1,25(OH)2D3 was decreased and increased by TGF-β 1 and bFGF, respectively. 1,25(OH)2D3 suppressed SPARC synthesis at protein and mRNA levels. TGF-β1, but not bFGF, increased SPARC synthesis in the presence of 1,25(OH)2D 3. SPARC, but not osteocalcin, increased DNA synthesis in pulp cells. These findings suggest that 1,25(OH)2D3 and growth factors interactively regulate the expression of osteocalcin and SPARC in pulp cells, and that SPARC can stimulate DNA synthesis by pulp cells.
Contributions of Three Glucosyltransferases to Sucrose-dependent Adherence of Streptococcus mutans
Authors: Ooshima T. , Matsumura M. , Hoshino T. , Kawabata S. , Sobue S. , Fujiwara T.
Published: January 2009

Streptococcus mutans produces 3 types of glucosyltransferase (GTF), whose cooperative action is considered to be essential for its cellular adherence to the tooth surface. However, the precise mechanisms for synthesizing adhesive glucans and the specific roles of each GTF in cellular adherence to smooth surfaces have not been elucidated. In the present study, seven types of isogenic mutants of S. mutans MT8148 lacking GTFB, GTFC, and/or GTFD activities were constructed by inactivation of the genes encoding GTFB, GTFC, and/or GTFD. Furthermore, recombinant GTFB, GTFC, and GTFD were prepared from Escherichia coli cells harboring recombinant plasmids containing each of the gtf genes. Using these GTF-deficient mutants and rGTFs, we reconstituted sucrose-dependent adherence of S. mutans resting cells and examined the role of each GTF in vitro. The highest level of sucrose-dependent adherence was found at the ratio of 20 rGTFB:l rGTFC:4 rGTFD in both the resting cells of GTF-deficient mutants and insoluble glucan synthesized by rGTFs. Moreover, when rGTFC and rGTFD were both present at concentrations of 1.5 mU and 6 mU, respectively, the insoluble glucan synthesized from sucrose by the rGTFs showed a high level of adhesiveness to smooth surfaces, even without rGTFB. These results suggest that the presence of all three GTFs at the optimum ratio is necessary for sucrose-dependent adherence of S. mutans, and that GTFC and GTFD may play significant roles in the synthesis of adhesive and insoluble glucan from sucrose.
The Capacity of Porphyromonas gingivalis to Multiply Under Iron-limiting Conditions Correlates with its Pathogenicity in an Animal Model
Authors: Grenier D. , Goulet V. , Mayrand D.
Published: January 2009

Isolates of Porphyromonas gingivalis have various abilities to induce infections in an animal model. The hypothesis of this study was that pathogenic strains of P. gingivalis could multiply under iron-limiting conditions, while non-pathogenic strains could not. Three pathogenic strains (W50, W83, and ATCC 49417) grew to a final optical density (660 nm) > 2 in horse serum, while the growth of the 3 non-pathogenic strains (ATCC 33277, LB13D-2, and HW24D-1) was negligible. When an excess of hemin or ferric chloride was added to the serum, significant growth of the non-pathogenic strains occurred. Under iron-limiting conditions, the pathogenic strains of P. gingivalis had a much lower requirement for human iron-loaded transferrin and hemin than the non-pathogenic strains. Proteolytic degradation of transferrin, which may be associated with the release of iron, was not markedly different for pathogenic and nonpathogenic strains. In addition, no relationship could be established between the level of 55Fe uptake from 55Fe-transferrin and the pathogenicity of strains. Our study provided evidence that the ability of P. gingivalis to multiply in vitro under iron-limiting conditions may be correlated with its ability to induce infections in an animal model. Isolates of P. gingivalis possessing a low requirement for iron are likely to have a higher potential for initiating periodontal infections.
Polymorphisms of the Interleukin-1 Gene Family, Oral Microbial Pathogens, and Smoking in Adult Periodontitis
Authors: Laine M.L. , Farre M.A. , Garcia-González M.A. , van Dijk L.J. , Ham A.J. , Winkel E.G. , Crusius J.B.A. , Vandenbroucke J.P. , van Winkelhoff A.J. , Pena A.S.
Published: January 2009

Interleukin (IL)-1α, IL-1β, and lL-1ra contribute to regulation of the inflammatory response in periodontal tissues. We aimed to investigate the distribution of polymorphisms in the IL-1 gene family among periodontitis patients and controls, taking into account smoking and microbiology as additional variables. Fifty-three non-smoking and 52 smoking patients with severe adult periodontitis and 53 controls were genotyped for bi-allelic IL-1A-889, IL-1B +3954, and a penta-allelic 86-bp VNTR IL-1RN gene polymorphisms. The presence of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans was established by culture techniques. We found a higher frequency of allele 2 carriage in IL-1A, IL-1B, and IL-1RN in periodontitis patients who were non-smokers and in whom P. gingivalis and A. actinomycetemcomitans could not be detected (42.1 % vs. 11.3% in controls; P = 0.0068; OR 5.7, 95% CI: 1.6-19.8). Our results provide evidence that polymorphisms in genes of the IL-1 family are associated with severe adult periodontitis in the absence of other risk factors tested in this patient population.
Growth-hormone-stimulated Dentinogenesis in Lewis Dwarf Rat Molars
Authors: Young W.G. , Li H. , Xiao Y. , Waters M.J. , Bartold P.M.
Published: January 2009

In dentinogenesis, certain growth factors, matrix proteoglycans, and proteins are directly or indirectly dependent on growth hormone. The hypothesis that growth hormone up-regulates the expression of enzymes, sialoproteins, and other extracellular matrix proteins implicated in the formation and mineralization of tooth and bone matrices was tested by the treatment of Lewis dwarf rats with growth hormone over 5 days. The molar teeth were processed for immunohistochemical demonstration of bone-alkaline phosphatase, bone morphogenetic proteins-2 and -4, osteocalcin, osteopontin, bone sialoprotein, and Ell protein. Odontoblasts responded to growth hormone by more cells expressing bone morphogenetic protein, alkaline phosphatase, osteocalcin, and osteopontin. No changes were found in bone sialoprotein or E11 protein expression. Thus, growth hormone may stimulate odontoblasts to express several growth factors and matrix proteins associated with dentin matrix biosynthesis in mature rat molars.
Extracellular Matrix Molecules Improve Periodontal Ligament Cell Adhesion to Anorganic Bone Matrix
Authors: Lallier T.E. , Yukna R. , Moses R.L.
Published: January 2009

Bone replacement graft (BRG) materials are used in periodontal therapy to encourage new bone formation. Extracellular matrix proteins may improve periodontal ligament fibroblast (PDLF) attachment to these materials. We demonstrate that PDLFs adhere well to the extracellular matrix (ECM) proteins fibronectin, vitronectin, laminin, and collagen types I and IV. PDLFs express numerous ECM-receptor integrin subunit transcripts (α1, a2, a3, a4, a5, α11, (31, β5, and (38) at high levels, while others (a6, a9, aV, β3, (36, and β7) are expressed at reduced levels. Despite the fact that PDLFs adhere well to fibronectin and collagen type IV bound to plastic, and express integrins that recognize these ECM proteins, they do not attach well to anorganic bovine bone matrix (ABM) coated with these same proteins. However, the addition of vitronectin, laminin, or collagen type I to these same ABMs substantially increased PDL cell attachment. Thus, selective use of ECM proteins may be clinically useful in promoting cell attachment to ABM and bone regrowth. Abbreviations: extracellular matrix (ECM), periodontal ligament (PDL), bone replacement graft (BRG), anorganic bovine bone matrix (ABM), reverse transcriptase polymerase chain-reaction (RT-PCR).
Nanomechanical Properties of Hydrated Carious Human Dentin
Authors: Marshall G.W. , Habelitz S. , Gallagher R. , Balooch M. , Balooch G. , Marshall S.J.
Published: January 2009

Most restorative materials are bonded to caries-affected dentin that has altered structure. We tested the hypothesis that hydrated dentin of the transparent zone did not have increased hardness or elastic modulus. Nanoindentation by modified AFM was used to determine site-specific elastic modulus and hardness for components of hydrated dentin from 8 carious and non-carious human teeth. Indentations in intertubular dentin were made at intervals from pulp through the affected layers (subtransparent, transparent, and discolored zones). The values of intertubular dentin increased slightly from near the pulp into the transparent zone, then remained constant or decreased slightly through transparent dentin (E, 18.3 GPa; H, 0.8 GPa; confirming the hypothesis), and decreased markedly through the discolored region. Peritubular dentin values were unaltered in transparent dentin, and intratubular mineral had values between those of normal peritubular and intertubular dentin. Superficial areas contained distorted tubules without peritubular dentin or intratubular mineral.
The Vipeholm Dental Caries Study: Recollections and Reflections 50 Years Later
Authors: Krasse Bo
Published: January 2009

KEY WORDS: dental caries, human, history, Vipeholm.
Mercury Uptake and Kinetics after Ingestion of Dental Amalgam
Authors: af Geijersstam E. , Sandborgh-Englund G. , Jonsson F. , Ekstrand J.
Published: January 2009

The aim of the present study was to investigate the G-I uptake of mercury (Hg) after intake of a single dose of amalgam-Hg, followed by pharmacokinetic analysis of the data. Eleven volunteers without amalgam fillings ingested 1.00 g amalgam powder. Hg in plasma vs. time was analyzed with a two-compartment model by means of mixed-effects modeling. A fraction of the absorption rate of Hg to the central compartment was inversely proportional to the plasma ferritin levels. The population mean half-life of the terminal phase of Hg in plasma was 37 days, with a considerable standard deviation in the population. The absorbed fraction of the administered dose was estimated to be about 0.04%. It is concluded that the G-I uptake of Hg is of quantitative importance during dental treatment.
Molecular Structure of Acid-etched Dentin Smear Layers-in situ Study
Authors: Spencer P. , Wang Y. , Walker M.P. , Swafford J.R.
Published: January 2009

It is commonly reported that acid etchants remove the smear layer, but to date, there has been no chemical evidence to support these observations. The purpose of this study was to determine the molecular structure of acid-etched carbide- and diamond-bur-created smear layers. This project tested the null hypothesis that such smear layers are totally removed with current etchants. Smear layer/demineralized/mineralized dentin interfaces were analyzed at 1- m intervals by micro-Raman spectroscopy. Features associated with the organic component were substantially broadened with loss of fine structure, and mineral peaks were clearly evident in the spectra of acid-etched smear layers. The organic features in the spectra of the EDTAtreated smear layer showed relative intensity ratios similar to demineralized dentin without contribution from the mineral phase. The disorganized collagen within the smear layer was not removed but was denatured by the acid treatment; the mineral was trapped in this gelatinous matrix and shielded from complete reaction.
The Trend and Risk Factors of Perceived Toothache among Finnish Adolescents from 1977 to 1997
Authors: Honkala E. , Honkala S. , Rimpela A. , Rimpelä M.
Published: January 2009

Toothache is a subjective oral health indicator that should become uncommon when oral health is improving. The aim of this study was to assess changes in perceived toothache between 1977 and 1997 among Finnish adolescents. In the Adolescent Health and Lifestyle Survey, a self-administered questionnaire was mailed to a representative sample of 12-, 14-, 16-, and 18-year-old Finns every second year. The sample sizes in the surveys varied from 2422 to 11,105, making a total of 35,349 subjects in the entire study. The incidence of toothache during the previous 2 years was requested in 1977, 1985, 1991, 1995, and 1997, and the prevalences were 31%, 25%, 28%, 29%, and 37%, respectively. The increase between 1995 and 1997 was highest among 16- and 18-year-olds. There was no tendency for perceived toothache to decline over the study period, despite the decrease in caries experience. Toothache varied by age, socioeconomic status (SES), place of residence, and toothbrushing frequency. The increase in the incidence of toothache reported after 1995 could be a warning signal that economic recession in Finland has caused changes in the dental care system.
Association of Caries Activity with the Composition of Dental Plaque Fluid
Authors: Gao X.J. , Fan Y. , Kent R.L. , Van Houte J. , Margolis H.C.
Published: January 2009

This study tests the hypothesis that caries activity is associated with lower degrees of saturation with respect to enamel mineral in dental plaque fluid following sucrose exposure. Plaque fluids were obtained from caries-free, caries-positive, and caries-active subjects. Samples were collected before and at 3 and 7 min after a sucrose rinse on consecutive weeks and analyzed for organic acids, inorganic ions, pH, calcium activity, and, in selected samples, total protein. After sucrose, pH values were significantly lower in the caries-active group in comparison with the caries-free and caries-positive groups. Total and free calcium concentrations increased with decreasing pH, with free calcium being about one-third of total calcium. The caries-active group exhibited significantly lower degrees of saturation with respect to enamel mineral, after sucrose, and had significantly higher mutans streptococci levels in plaque than did the caries-free samples. Thus, saturation levels in post-sucrose plaque fluids reflect the cariogenic potential of dental plaque.
Developmental Changes in the Nicotinic Acetylcholine Receptor in Mouse Tongue Striated Muscle
Authors: Yamane A. , Ohnuki Y. , Saeki Y.
Published: January 2009

There are no published studies on synaptogenesis focusing on the elimination of the superfluous nicotinic acetylcholine receptor (nAChR) outside the neuromuscular junction and the nAChR subunit switch from the embryonic-type (α2βγδ subunits) to the adult-type (α2β∈δ subunits) in mouse tongues. To identify the time course of nAChR subunit elimination and switch, we analyzed the expression levels of a, e, and γ subunit mRNAs, and the immunolocalization of the 8 subunit protein in the mouse tongue and corresponding hind limb. The analysis included the period from embryonic day (E) 11 to the newborn stage. The nAChR elimination and subunit switch began at E15 in the tongue and at E17 in the hind limb. They were nearly complete at birth in the tongue, but not in the hind limb. The early completion of synaptogenesis in the tongue at birth may be related to the early functional demands placed on the tongue, such as suckling and swallowing, immediately after birth.
Mapping Energy Metabolism in Jaw and Tongue Muscles during Chewing
Authors: Rikimaru H. , Kikuchi M. , Itoh M. , Tashiro M. , Watanabe M.
Published: January 2009

Investigators have used positron emission tomography with 18F-fluoro-D-deoxyglucose to obtain information not only for the diagnosis of cancers, but also for researching physiology in skeletal muscles. The aim of this study was to evaluate the activities of the jaw and tongue muscles during gum-chewing. Five volunteers aged 32-61 years were studied by positron emission tomography. They were requested to chew two pieces of chewing gum for 30 min after intravenous injection of 18F-fluoro-D-deoxyglucose. 18F-fluoro-D-deoxyglucose uptake in the intrinsic tongue muscle was significantly (p < 0.05) higher than that in the masseter, temporal, and medial pterygoid muscles. Heterogeneous uptake of 18F-fluoro-D-deoxyglucose was observed in the masticatory muscles. In addition, the tongue exhibited higher activity than the masticatory muscles. In conclusion, positron emission tomography with 18F-fluoro-D-deoxyglucose appeared to be a useful technique for investigating the physiologic activities of the skeletal muscles, which have been difficult to examine by conventional methods.
Smokeless Tobacco Extracts Modulate Keratinocyte and Fibroblast Growth in Organotypic Culture
Authors: Wang Y. , Rotem E. , Andriani F. , Garlick J.A.
Published: January 2009

Smokeless tobacco is associated with pathologic alterations of the oral mucosa, yet its direct effects on human keratinocytes and fibroblasts in stratified squamous epithelium are not well-understood. We hypothesized that smokeless tobacco could modulate the growth of keratinocytes and fibroblasts in an in vivo-like, organotypic tissue model. To test this, we exposed organotypic cultures for 3 days to smokeless tobacco aqueous extracts and determined the changes in morphology and proliferation of human keratinocytes and fibroblasts. All smokeless tobaccos stimulated keratinocyte proliferation at low doses (0.25% w/v) and suppressed growth at higher doses (> 0.5% w/v). In contrast, smokeless tobacco extracts promoted fibroblast growth at all concentrations without inducing fibroblast turnover. Fibroblasts and keratinocytes, therefore, were differentially affected by smokeless tobacco extracts in an organotypic tissue model, suggesting incipient changes that may occur in vivo.
Tumor Necrosis Factor Modulates Fibroblast Apoptosis, PMN Recruitment, and Osteoclast Formation in Response to P. gingivalis Infection
Authors: Graves D.T. , Oskoui M. , Voleinikova S. , Naguib G. , Cai S. , Desta T. , Kakouras A. , Jiang Y.
Published: January 2009

P. gingivalis is an important oral pathogen, which has been closely linked to periodontal disease as well as lesions of endodontic origin. Both infections are associated with a decrease in fibroblast numbers, formation of an inflammatory infiltrate, and bone resorption. The goal of this study was to investigate the role that the host response plays in the capacity of P. gingivalis to stimulate fibroblast apoptosis, PMN recruitment, and osteoclastogenesis. This was accomplished by the use of an in vivo calvarial model in mice with targeted deletion of TNF receptors p55 and p75 and matched wild-type mice. The results indicate that P. gingivalis induces fibroblast apoptosis in vivo and establish for the first time that this involves the stimulation of a host response. Moreover, bacteria-stimulated PMN recruitment and osteoclastogenesis were also dependent upon the host response. The results suggest that much of the damage caused by P. gingivalis infection, including fibroblast apoptosis, at least under some circumstances, results from stimulation of the host response rather than the direct effect of bacterial products. Furthermore, this may represent a more general mechanism by which bacterial challenge induces apoptosis of matrix-producing cells through the induction of TNF.
Effects of Vascular Endothelial Growth Factor on Osteoclast Induction during Tooth Movement in Mice
Authors: Kaku M. , Kohno S. , Kawata T. , Fujita T. , Tokimasa C. , Tsutsui K. , Tanne K.
Published: January 2009

For orthodontic tooth movement, remodeling of the alveolar bone is maintained by a repeated process of bone resorption and new bone formation, controlled, respectively, by osteoclasts and osteoblasts. Recently, we have found that recombinant human vascular endothelial growth factor (rhVEGF) acts as a macrophage colony-stimulating factor in osteoclast induction in osteopetrotic (op/op) mice. The purpose of this study was to investigate whether rhVEGF stimulates osteoclast differentiation during experimental tooth movement. Purified rhVEGF was injected once into the buccal gingival groove around the incisors. An experimental appliance with a helical loop was bonded onto the upper incisors, and an initial force of 1.0 g was applied for three days. The number of osteoclasts appearing in the periodontal ligament space on the pressure side of the alveolar bone was increased markedly. These results suggest that local administration of rhVEGF enhances the number of osteoclasts, and may increase the rate of orthodontic tooth movement.

Abbreviations: recombinant human vascular endothelial growth factor (rhVEGF), macrophage colony-stimulating factor (M-CSF), osteopetrotic mice (op/op mice), fms-like tyrosine kinase (Flt-1), periodontal ligament (PDL), phosphate-buffered saline (PBS), tartrate-resistant acid phosphatase (TRAP), and analysis of variance (ANOVA).
Expression and Regulation of MMP-20 in Human Tongue Carcinoma Cells
Authors: Väänänen A. , Srinivas R. , Parikka M. , Palosaari H. , Bartlett J.D. , Iwata K. , Grenman R. , Stenman U.-H. , Sorsa T. , Salo T.
Published: January 2009

Human matrix metalloproteinase-20 (MMP-20, enamelysin) fragments the enamel-specific protein amelogenin and has been shown to be synthesized exclusively by odontoblasts and ameloblasts and in certain odontogenic tumors. Here we demonstrate, for the first time, the expression of MMP-20 mRNA and protein in two carcinoma cell lines originating from the tongue. Treatment of the SCC-25 and HSC-3 cells with phorbol 12-myristate 13-acetate (10 nmol/L) up-regulated MMP-20 mRNA and protein expression by up to 1.6-fold, but transforming growth factor beta (10 ng/mL) had no effect. The latent proform of recombinant (r) human MMP-20 was converted by tumor-related trypsin-2. Activated rMMP-20 did not degrade type I or type II collagen, but efficiently hydrolyzed fibronectin, type IV collagen, laminin-1 and -5, tenascin-C, and (3-casein. This implies that MMP-20 not only participates in dental matrix remodeling but is also present in tongue carcinoma cells.
The Localization of Periodontal-disease-associated Bacteria in Human Periodontal Pockets
Authors: Noiri Y. , Li L. , Ebisu S.
Published: January 2009

Some Gram-negative anaerobes are associated with the incidence and progression of periodontal disease. In periodontal pockets, however, the localization of those bacteria is unknown. We investigated the localization of 5 bacterial species in human periodontal pockets. Fifteen teeth with a part of periodontal pockets from 10 adult periodontitis patients were obtained, and the localization of bacteria was examined immunohistochemically. Positive reactions with anti- Prevotella nigrescens antibody were located at the epithelium-associated plaque area in the middle pocket zones. In the middle and deep pocket zones, Fusobacterium nucleatum and Treponema denticola were especially localized in the unattached plaque area, but Eikenella corrodens was observed in the tooth-attached plaque area. Actinobacillus actinomycetemcomitans, detected in 2 of 15 samples examined, was found in the unattached plaque area, in the middle pocket zone. The present findings indicated that the 5 bacterial species examined localized at distinct regions in human periodontal pockets.
Pressure-Pain Thresholds and MRI Effusions in TMJ Arthralgia
Authors: Shaefer J.R. , Jackson D.L. , Schiffman E.L. , Anderson Q.N.
Published: January 2009

It has been suggested that MRI-depicted effusions identify patients with TMJ arthralgia. The Research Diagnostic Criteria (RDC) propose a pressure-pain threshold (PPT) of 1 pound for the identification of TMJ arthralgia. The hypotheses in this study were that: (1) there is no association between MRI-depicted effusions and TMJ arthralgia, and (2) a PPT of 1 pound does not discriminate between subjects with and those without arthralgia. Thirty females with TMJ disc displacement with reduction were divided into two groups based on the presence or absence of the self-report of TMJ pain. Bilateral TMJ PPTs and MRIs were obtained. Increasing palpation pressure from 1 to 3 pounds increased the sensitivity for identifying arthralgia from 22% to 100%, with a corresponding decrease in the specificity from 100% to 81%. The sensitivity and specificity of effusions for identifying arthralgia were 85% and 28%, respectively. These results suggest that the use of palpation pressures greater than 1 pound is a valid test for TMJ arthralgia. However, TMJ effusions lack adequate specificity for identifying TMJ arthralgia and were not associated with pain.
Regulation of Tooth Development by the Novel Type I TGFβ Family Member Receptor Alk8
Authors: Payne T.L. , Skobe Z. , Yelick P.C.
Published: January 2009

We have recently identified, in zebrafish, a novel type I receptor of the TGFβ family, alk8, that participates in Bmp signaling pathways to mediate early dorsoventral patterning of neurectodermal and mesendodermal tissues. Since Bmps play significant roles in tooth specification, initiation, and differentiation, we hypothesized that alk8 may play a role in directing the Bmp-mediated epithelial mesenchymal cell interactions regulating tooth development. Immunohistochemical analysis demonstrates that Alk8 is expressed in developing zebrafish and mouse teeth. Examination of tooth development in zebrafish with disrupted alk8 signaling revealed specific defects in tooth development. Ectopic expression of constitutively active Alk8 results in the formation of elongated tooth structures, while expression of dominant-negative Alk8 results in arrested tooth development at the bud stage. These results are consistent with the established requirements for Bmp signaling in tooth development and demonstrate that Alk8 is a key regulator of tooth development.
Topographic Changes of Focal Adhesion Components and Modulation of p125FAK Activation in Stretched Human Periodontal Ligament Fibroblasts
Authors: Molina T. , Kabsch K. , Alonso A. , Kohl A. , Komposch G. , Tomakidi P.
Published: January 2009

Mechanical stress has been shown in vitro to modulate integrin-β1-mediated activation of p125FAK/FAK. To test the hypothesis whether this also applies to periodontal ligament fibroblasts (PDLs), we subjected human PDLs to mechanical stretch and analyzed stress-induced changes of p125FAK activation by quantitative immunoprecipitation of p125FAK and changes in the topography of molecules localizing in focal adhesions by indirect immunofluorescence. Generally, all components of focal contacts under study-including detection of phosphotyrosine, i.e., integrin-β1, p125FAK, and paxillin-revealed a relative co-localization during stretch application. Under stretch, we observed a re-distribution of all components from the cell periphery to the cytoplasm following the main axes. Tyrosine phosphorylation of p125 FAK was monitored up to 72 hours under stretch. While the amount of p125FAK remained essentially constant, the activation of p125 FAK was clearly modulated. Tyrosine phosphorylation of p125FAK increased from 15 minutes up to 1 hour and declined after stretching periods of 24, 48, and 72 hours. The analysis of our data indicated a stretch-induced re-distribution of focal adhesion components and a modulation of p125 FAK activation, suggesting alterations in focal adhesions and their associated signal cascade.
Dantrolene Counteracts the Masseter Muscle Damage Induced by Artificial Occlusal Wear: Studies in a Rat Model
Authors: Bani D. , Bergamini M.
Published: January 2009

In previous studies, we showed that the introduction of occlusal alterations to rats results in masseter muscle abnormalities. Here, we investigate whether administration of the muscle relaxant dantrolene to rats with occlusal alteration could counteract the occurrence of such abnormalities. Rats underwent unilateral amputation of molar cusps to cause malocclusion. Some rats received dantrolene (10 mg/kg/day subcutaneously). The masseter muscles ipsilateral to the amputated molars were excised 26 days later. Sham-operated rats were used as controls. The tissue samples were studied by light and electron microscopy and morphometry. Moreover, tissue Ca2+ content, an index of muscle injury, was determined. In the absence of dantrolene, occlusal alteration leads to microvessel constriction, morphologic damage of masseter muscle fibers and blood capillaries, and elevation of tissue Ca2+ content. These changes were nearly abrogated by dantrolene, thus supporting it as a possible new therapeutic tool for the treatment of malocclusion-induced muscle diseases.
Movement of Teeth Adjacent to Posterior Bounded Edentulous Spaces
Authors: Gragg K.L. , Shugars D.A. , Bader J.D. , Elter J.R. , White B.A.
Published: January 2009

Bounded edentulous spaces (BES)-a missing posterior tooth with intact adjacent teeth-are thought to lead to arch collapse resulting from the movement of adjacent teeth. To determine the rate of change in distance between teeth adjacent to a BES, we examined three successive measurable radiographs of 116 untreated posterior BES cases. The distance between the teeth (DBT) adjacent to the space was measured, and change in DBT (A DBT) between pre-extraction and follow-up radiographs was calculated. We used linear spline regression to construct models for tooth movement and to identify factors associated with A DBT. The mean A DBT was < 1 mm during the first year post-extraction, and the DBT continued to decrease at a successively slower rate each following year. Overall and for each tooth type, the greatest rates of decrease in DBT were seen in the zero to two-year period. In a multivariable model, time since extraction and tooth type were significantly associated with A DBT. These findings suggest that movement of teeth adjacent to a posterior BES after the first two years is usually gradual and minor within the time frame of this study.
Association between Genetic Polymorphism of Tumor Necrosis Factor-a and Risk of Oral Submucous Fibrosis, a Pre-cancerous Condition of Oral Cancer
Authors: Chiu C.-J. , Chiang C.-P. , Chang M.-L. , Chen H.-M. , Hahn L.-J. , Hsieh L.-L. , Kuo Y.-S. , Chen C.-J.
Published: January 2009

Many cytokines have been thought to play important roles in the pathogenesis of oral submucous fibrosis (OSF), an areca nut chewing-specific pre-cancerous condition characterized by the deposition of collagen in oral submucosa. Tumor necrosis factor-a (TNF-a), situated in the class III region of human leukocyte antigen (HLA), is a mediator with multiple functions, including the regulation of inflammatory reaction and transcriptions of collagen and collagenase. In total, 809 male subjects were recruited for assessment of the association of OSF with a bi-allelic promoter-region (-308) polymorphism on the TNFA gene. The high production allele, TNF2, was significantly lower among OSF subjects (n = 166) than in areca-chewing controls (n = 284). This association was independent of oral cancer status. The multivariate-adjusted odds ratio for the TNFA 11 genotype was 2.6 (95% confidence interval = 1.4-4.9 ; p = 0.004). The finding may imply a multifunctional etiological factor of TNF-α in OSF pathogenesis.
Remineralization of Enamel Subsurface Lesions by Sugar-free Chewing Gum Containing Casein Phosphopeptide-Amorphous Calcium Phosphate
Authors: Shen P. , Cai F. , Nowicki A. , Vincent J. , Reynolds E.C.
Published: January 2009

Casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP) exhibit anticariogenic potential in laboratory, animal, and human in situ experiments. The aim of this study was to determine the ability of CPP-ACP in sugar-free chewing gum to remineralize enamel subsurface lesions in a human in situ model. Thirty subjects in randomized, cross-over, double-blind studies wore removable palatal appliances with six human-enamel half-slabs inset containing subsurface demineralized lesions. The appliances were inserted immediately before gum-chewing for 20 min and then retained for another 20 min. This was performed four times per day for 14 days. At the completion of each treatment, the enamel half-slabs were paired with their respective demineralized control half-slabs, embedded, sectioned, and subjected to microradiography and densitometric image analysis, for measurement of the level of remineralization. The addition of CPP-ACP to either sorbitol- or xylitol-based gum resulted in a dose-related increase in enamel remineralization, with 0.19, 10.0, 18.8, and 56.4 mg of CPP-ACP producing an increase in enamel remineralization of 9, 63, 102, and 152%, respectively, relative to the control gum, independent of gum weight or type.
The Effect of Mechanical Force on mRNA Levels of Collagenase, Collagen Type I, and Tissue Inhibitors of Metalloproteinases in Gingivae of Dogs
Authors: Redlich M. , Reichenberg E. , Harari D. , Zaks B. , Shoshan S. , Palmon A.
Published: January 2009

Orthodontic force causes an injury to and subsequent degradation of the attachment apparatus, thus leading to the transposition of the tooth. The gingiva, however, is compressed and sometimes becomes hypertrophic with tooth movement and often shrinks after treatment. To study the effect of force on the gingiva, we applied orthodontic force in dogs and analyzed gingival tissues 1, 2, 3, 7, 14, and 28 days later as well as after removing the force. The effect of force on mRNA levels of collagen type I (col-I), matrix metalloproteinase-1 (MMP-1), and tissue inhibitors 1 and 2 (TIMPs) genes was analyzed by RT-PCR, and MMP-1 activity was determined by zymography. The results showed that force significantly increased both the mRNA levels of MMP-1 and its interstitial activity. After the removal of force, MMP-1 gene expression was significantly decreased. The results could partly explain the clinically observed shrinkage and adaptation of the gingiva during tooth movement. KEY WORDS: orthodontic force, MMP-1, gene expression.
Collagen Fiber Orientation Affects Osteoclastic Resorption
Authors: Kingsmill V.J. , Boyde A.
Published: January 2009

The bone surrounding the teeth is constantly re-modeled throughout life, particularly during tooth movement and following tooth loss. Alveolar bone proper contains many highly oriented extrinsic fibers, but whether their orientation affects resorption is unknown. To determine if it does, we selected sperm whale cementum to provide large anisotropic substrates resembling extrinsic fiber bone. Slices cut either perpendicular or parallel to the extrinsic fiber axis were cultured for 24 hours with pre-hatched chick osteoclasts. Resorption pit areas and volumes were measured by video-rate reflection confocal microscopic mapping. Pits in the perpendicular group were smaller in area and were deeper than those in the parallel group (median values, 402 μm2 and 572 μm 2, n > 950, p < 0.0001; volume/area 5.37 μm and 4.58 μm); volume differences only just reached significance (2137 μm3 and 2554 μm3, p < 0.05). These results show that the fiber orientation within a substrate can profoundly influence the shape of resorption lacunae. This pattern of resorption may help in the maintenance of an optimally functioning attachment of periodontal ligament fibers to alveolar bone.
The Junctional Epithelium around Murine Teeth differs from Gingival Epithelium in its Basement Membrane Composition
Authors: Oksanen J. , Sorokin L.M. , Virtanen I. , Hormia M.
Published: January 2009

It is not known whether epithelial differentiation patterns are reflected in the composition of gingival basement membranes (BMs). We have investigated the expression of laminin isoforms and associated BM components in the murine dento-epithelial junction by using immunofluorescence microscopy. Our results show that chains of laminins 5/6/7/10/11 are expressed in the BM of outer gingival epithelium. The external BM between junctional epithelium (JE) and connective tissue differs from gingival BM by lacking laminin-7 and -11 chains. The internal basal lamina (IBL) between JE and tooth contains only laminin-5. Collagen chains α1,2(IV) and nidogen-1 are present in other BMs except the IBL. The dento-epithelial junction thus has a unique BM composition, suggesting that epithelial cells are able to secrete two extracellular matrices in a polarized manner. The exclusive expression of the non-self-polymerizing laminin-5 indicates that the IBL is not a BM by definition, but rather a simple extracellular matrix lacking network structure.
The Effects of Smoking on Dental Care Utilization and Its Costs in Japan
Authors: Ide R. , Hoshuyama T. , Wilson D. , Takahashi K. , Higashi T.
Published: January 2009

Smoking has been established as an important risk factor for periodontal disease and tooth loss. The purpose of this study was a prospective evaluation of the effects of smoking on dental care utilization and its costs, based on data from 5712 males aged 20–59 yrs. Age, dental health behavior, and history of diabetes were adjusted in a multivariate analysis. Current smokers accrued 14% higher dental care costs than never-smokers over a five-year period. This difference in annual dental care costs was mainly attributable to the increased percentage of participants in the ‘higher dental care cost’ category among current smokers. There was no clear trend identified for the dose-dependent effects of smoking on dental care utilization and its costs. Past smokers incurred lower dental care costs compared with current smokers. Smoking may have played a key role in the increment of dental care utilization and its costs via deterioration in oral conditions.
Detection of Disease Outbreaks by the Use of Oral Manifestations
Authors: Torres-Urquidy M.H. , Wallstrom G. , Schleyer T.K.L.
Published: January 2009

Oral manifestations of diseases caused by bioterrorist agents could be a potential data source for biosurveillance. This study had the objectives of determining the oral manifestations of diseases caused by bioterrorist agents, measuring the prevalence of these manifestations in emergency department reports, and constructing and evaluating a detection algorithm based on them. We developed a software application to detect oral manifestations in free text and identified positive reports over three years of data. The normal frequency in reports for oral manifestations related to anthrax (including buccal ulcers-sore throat) was 7.46%. The frequency for tularemia was 6.91%. For botulism and smallpox, the frequencies were 0.55% and 0.23%. We simulated outbreaks for these bioterrorism diseases and evaluated the performance of our system. The detection algorithm performed better for smallpox and botulism than for anthrax and tularemia. We found that oral manifestations can be a valuable tool for biosurveillance.
Dentin Caries Zones: Mineral, Structure, and Properties
Authors: Pugach M.K. , Strother J. , Darling C.L. , Fried D. , Gansky S.A. , Marshall S.J. , Marshall G.W.
Published: January 2009

Caries Detector staining reveals 4 zones in dentin containing caries lesions, but characteristics of each zone are not well-defined. We therefore investigated the physical and microstructural properties of carious dentin in the 4 different zones to determine important differences revealed by Caries Detector staining. Six arrested dentin caries lesions and 2 normal controls were Caries-Detector-stained, each zone (pink, light pink, transparent, apparently normal) being analyzed by atomic force microscopy (AFM) imaging for microstructure, by AFM nano-indentation for mechanical properties, and by transverse digital microradiography (TMR) for mineral content. Microstructure changes, and nanomechanical properties and mineral content significantly decreased across zones. Hydrated elastic modulus and mineral content from normal dentin to pink Caries-Detector-stained dentin ranged from 19.5 [10.6–25.3] GPa to 1.6 [0.0–5.0] GPa and from 42.9 [39.8–44.6] vol% to 12.4 [9.1–14.2] vol%, respectively. Even the most demineralized pink zone contained considerable residual mineral.