bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of TGF-β on Hyaluronan Anabolism in Fibroblasts Derived from the Synovial Membrane of the Rabbit Temporomandibular Joint
Authors: Tanimoto K. , Suzuki A. , Ohno S. , Honda K. , Tanaka N. , Doi T. , Yoneno K. , Ohno-Nakahara M. , Nakatani Y. , Ueki M. , Tanne K.
Published: January 2009

Hyaluronan (HA) synthesis in the synovial membrane is affected by various chemical mediators. It is hypothesized that transforming growth factor-beta1 (TGF-β1) would be a mediator to modulate HA synthesis in cultured synovial membrane fibroblasts of the temporomandibular joint (TMJ). Fibroblasts were extracted from the TMJ synovial membrane of four-week-old Japanese white rabbits. The amount of HA and expression levels of HA synthase (HAS) mRNAs induced by TGF-β1 treatment were analyzed by means of high-performance liquid chromatography and real-time polymerase chain-reaction, respectively. Both medium and large amounts of HA were enhanced by the stimulation of TGF-β1. HAS2 mRNA expression was enhanced 13-fold after six-hour stimulation with TGF-β1 (10 ng/mL), whereas HAS3 mRNA expression was not changed significantly. These results suggest that TGF-β1 enhances the expression of HAS2 mRNA in the TMJ synovial membrane fibroblasts and may contribute to the production of high-molecular-weight HA in the joint fluid.
Variation in Daily Masticatory Muscle Activity in the Rabbit
Authors: Langenbach G.E.J. , van Wessel T. , Brugman P. , van Eijden T.M.G.J.
Published: January 2009

The daily use of masticatory muscles remains largely unclear, since continuous recordings were limited in space and time. This study’s purpose was to use radio-telemetry to examine daily muscle use and its inter- and intra-individual variations. A telemetric device was implanted into the rabbit masseter, and the transmitted signals were digitally stored for 7 days. Muscle use was analyzed by calculation of the total time each muscle was activated above 5, 20, and 50% of the day’s peak activity. Rabbits (n = 6) spent only 2% of the time chewing. Muscles were activated up to 20% of the total time at levels exceeding 5% of peak activity, and only about 0.5% of the time in forceful behaviors utilizing 50% of maximum contraction. It can be concluded that daily muscle use remained constant during succeeding days, but differed significantly among muscle regions and individuals.
Identification of in vivo Pellicle Constituents by Analysis of Serum Immune Responses
Authors: Li J. , Helmerhorst E.J. , Troxler R.F. , Oppenheim F.G.
Published: January 2009

Human acquired enamel pellicle is composed of molecules that selectively adsorb from saliva onto tooth surfaces and provides a protective interface between the tooth enamel and the oral environment. To identify the micro-amounts of components present in pellicle, we immunized mice with in vivo-formed human acquired enamel pellicle and analyzed the serum immune responses. Selective reactivities of the serum (OD > 1.0 above background) against albumin, amylase, carbonic anhydrase II, sIgA, IgG, IgM, lactoferrin, lysozyme, proline-rich proteins, statherin, histatin 1, and mucous glycoprotein 1 were observed. We further confirmed the presence of proline-rich proteins, lactoferrin, lysozyme, and carbonic anhydrase II by probing in vivo pellicle with specific polyclonal anti-sera. The polyclonal antibody approach provided a powerful method for the identification of various pellicle proteins, including some which show mineral homeostasis or antimicrobial activity.
Study on the Organoleptic Intensity Scale for Measuring Oral Malodor
Authors: Greenman J. , Duffield J. , Spencer P. , Rosenberg M. , Corry D. , Saad S. , Lenton P. , Majerus G. , Nachnani S. , El-Maaytah M.
Published: January 2009

The 0–5 organoleptic scale is used widely in breath research and in trials to measure the efficacy of anti-odor agents. However, the precise relationship between odor scores and gas concentrations of target odorants is unknown. The purpose of this study was to relate mean organoleptic scores from odor judges (n = 7) for pure odorants (n = 8) representative of those found in oral malodor. Judges used a common 0–5 scale to report the odor intensity of sample sets in random order of concentration. Regression analysis of data showed that odor score was proportional to the log concentration of odorant, and comparison of slopes showed H2S to be the most significant in terms of odor power. Detection thresholds (mol.dm−3) were: Skatole (7.2 × 10−13) < methylmercaptan (1.0 × 10−11) < trimethylamine (1.8 × 10−11) < isovalerate (1.8 × 10−11) < butyrate (2.3 × 10−10) < hydrogen sulphide (6.4 × 10−10) < putrescine (9.1 × 10−10) < dimethyl disulphide (5.9 × 10−8). The study demonstrates the exponential nature of the olfactory response and shows that any single compound’s contribution to malodor depends on odor power and threshold in addition to concentration.
The Molecular Basis of Salivary Gland Involvement in Graft-vs.-Host Disease
Authors: Nagler R.M. , Nagler A.
Published: January 2009

During the past two decades, the involvement of salivary glands in graft vs. host disease (GVHD) had been intensively researched and published. GVHD occurs in 40–70% of patients treated with bone marrow and peripheral blood stem cell transplantation (PBSCT), and improved survival rates have led to a continuously increasing number of GVHD patients suffering from induced salivary insult. Limited studies suggest that a large percentage of GVHD patients is affected and that the induced salivary dysfunction occurs rapidly following the transplantation. It affects both major and minor salivary glands and reflects the severity of the disease. Moreover, profound sialochemical alterations may be diagnostic of GVHD. An additional reason for this vast research is that GVHD, as an autoimmune-like disease, seemed to be an appropriate model for studying a much more prevalent and well-known and well-studied autoimmune disease involving salivary glands: Sjögren’s syndrome. The purpose of the current review—which is, to the best of our knowledge, the first of its kind—is to describe the GVHD-related sialometric and sialochemical data published in the past two decades for both major and minor salivary glands and to discuss the pathogenesis and molecular basis of the disease.
Blue Light Differentially Modulates Cell Survival and Growth
Authors: Wataha J.C. , Lewis J.B. , Lockwood P.E. , Hsu S. , Messer R.L. , Rueggeberg F.A. , Bouillaguet S.
Published: January 2009

Previous studies have reported that blue light (400–500 nm) inhibits cell mitochondrial activity. We investigated the hypothesis that cells with high energy consumption are most susceptible to blue-light-induced mitochondrial inhibition. We estimated cell energy consumption by population doubling time, and cell survival and growth by succinate dehydrogenase (SDH) activity. Six cell types were exposed to 5 or 60 J/cm2 of blue light from quartz-tungsten-halogen (QTH), plasma-arc (PAC), or argon laser sources in monolayer culture. Post-light SDH activity correlated positively with population doubling time (R2 = 0.91 for PAC, 0.76 for QTH, 0.68 for laser); SDH activity increased for cell types with the longest doubling times and was suppressed for cell types with shorter doubling times. Thus, light-induced exposure differentially affects SDH activity, cell survival, and growth, depending on cell energy consumption. Blue light may be useful as a therapeutic modulator of cell growth and survival.
Antibacterial Titanium Plate Anodized by being Discharged in NaCl Solution Exhibits Cell Compatibility
Authors: Shibata Y. , Kawai H. , Yamamoto H. , Igarashi T. , Miyazaki T.
Published: January 2009

Implant surfaces should be modified to achieve excellent cell compatibility as well as antibacterial activity. Our previous study demonstrated that titanium plates anodized by being discharged in NaCl (Ti-Cl) exhibited high antibacterial activity. Since Ti-Cl was prepared with a NaCl solution, we hypothesized that Ti-Cl would exhibit low toxicity toward cells. The aims of this study were to characterize the surface of Ti-Cl and investigate the cell compatibility (MC3T3-E1 and L929 cells) of Ti-Cl. The results demonstrated that, since the TiCl3 formed on the Ti-Cl surface was hydrolyzed into HCl, HClO, and TiOH after immersion in pure distilled water, TiCl3 contributed to the antibacterial activity of Ti-Cl. On the other hand, TiO formed on the Ti-Cl surface enhanced cell extension and cell growth through a larger adsorption of fibronectin compared with the pure titanium control. These findings suggest that antibacterial titanium is a promising material for use in dental implant systems.
Effectiveness of Single-surface ART Restorations in the Permanent Dentition: A Meta-analysis
Authors: Frencken J.E. , van ’t Hof M.A. , van Amerongen W.E. , Holmgren C.J.
Published: January 2009

Over the past few years, there has been an increase in the number of studies reporting on various aspects of the Atraumatic Restorative Treatment (ART) approach. Five randomized clinical trials in which ART restorations with glass ionomers were compared with amalgam restorations in permanent teeth for a maximum period of 3 yrs constituted the database. This meta-analysis divided the publications into ‘early’ (1987–1992) and ‘late’ (1995-) studies on the basis of improvements in the approach. The analysis showed that, in the ‘early’ studies, single-surface amalgam restorations survived statistically significantly longer than comparable ART restorations after 1, 2, and 3 yrs. This trend did not continue into the late group of studies; no statistically significant difference between the 2 types of restorations was found. Based on the available data, it appears that there is no difference in survival results between single-surface ART restorations and amalgam restorations in permanent teeth over the first 3 yrs.
Biting Suppresses Stress-induced Expression of Corticotropin-releasing Factor (CRF) in the Rat Hypothalamus
Authors: Hori N. , Yuyama N. , Tamura K.
Published: January 2009

Corticotropin-releasing factor (CRF) expressed in the hypothalamus plays an important role in mediating behavioral responses to stressors. Restraining the body of an animal has been shown to activate and induce an enhanced expression of CRF in paraventricular neurons of the rat hypothalamus. Since aggressive biting behavior is known to suppress stress-induced noradrenaline secretion in the central nervous system and the formation of gastric ulcers, we investigated the effect of biting on restraint-induced CRF expression in the rat hypothalamus. The number of CRF-expressing neurons in the paraventricular nucleus increased significantly after short time restraint (30 or 60 min) followed by a 180-minute post-restraint period. Biting of a wooden stick during the restraint stress significantly suppressed the restraint-induced enhancement of CRF expression in the paraventricular nucleus. These observations suggest a possible anti-stress effect of biting and an important role of para-functional masticatory activity in coping with stressful events.
In vitro Effects of Enamel Matrix Proteins on Rat Bone Marrow Cells and Gingival Fibroblasts
Authors: Keila S. , Nemcovsky C.E. , Moses O. , Artzi Z. , Weinreb M.
Published: January 2009

Emdogain® (EMD), a formulation of Enamel Matrix Proteins (EMP), is used clinically for periodontal regeneration, where it stimulates cementum formation and promotes gingival healing. In this study, we investigated the in vitro effects of EMD on rat bone marrow stromal cells (BMSC) and gingival fibroblasts (GF). EMD (at 25 μg/mL) increased the osteogenic capacity of bone marrow, as evidenced by ~ three-fold increase in BMSC cell number and ~ two-fold increase in alkaline phosphatase (ALP) activity and mineralized nodule formation. The presence of EMD in the initial stages (first 48 hrs) of the culture was crucial for this effect. In contrast, EMD did not induce osteoblastic differentiation of GF (evidenced by lack of mineralization or ALP activity) but increased up to two-fold both their number and the amount of matrix produced. These in vitro data on BMSC and GF could explain the promotive effect of EMD on bone formation and connective tissue regeneration, respectively.
Association of ALDH2 Genotypes and Alcohol Consumption with Periodontitis
Authors: Nishida N. , Tanaka M. , Hayashi N. , Nagata H. , Takeshita T. , Nakayama K. , Morimoto K. , Shizukuishi S.
Published: January 2009

There is little information regarding the association between alcohol consumption and periodontitis risk. We assessed whether alcohol consumption and ALDH2 genotypes were associated with periodontitis. Subjects’ lifestyle was examined by a self-administered questionnaire, and the percentage of pocket depths ≥ 3.5 mm was used as a periodontal parameter. ALDH2 genotypes were determined with the use of a PCR/RFLP method. Multiple logistic analyses showed that alcohol consumption was significantly associated with periodontitis, and its odds ratio was 1.98. There was no significant relationship between periodontal status and ALDH2 genotypes. However, ALDH2*1/*2 subjects who consumed ≥ 33 g/day of alcohol had a significantly greater percentage of pocket depths ≥ 3.5 mm than those whose daily consumption was lower, while there was no significant difference in periodontal status associated with alcohol consumption in ALDH2*1/*1 subjects. Our results suggest that alcohol consumption may be a risk indicator for periodontitis in ALDH2*1/*2 subjects who consume larger amounts of alcohol.
Differential Expression of RANKL and Osteoprotegerin in Gingival Crevicular Fluid of Patients with Periodontitis
Authors: Mogi M. , Otogoto J. , Ota N. , Togari A.
Published: January 2009

The receptor activator for NF-κB ligand (RANKL) plays an important role in osteoclast formation. A recent study with animal models suggests the involvement of RANKL in the pathogenesis of this periodontal disease. However, no one has examined the level of RANKL in the body fluid of human subjects. This communication reports on the in vivo concentrations of RANKL and the RANKL decoy receptor osteoprotegerin (OPG) in the gingival crevicular fluid (GCF) of periodontal subjects with severe, moderate, and mild forms of the disease. An increased concentration of RANKL and a decreased concentration of OPG were detected in GCF from patients with periodontitis (*p < 0.05 vs. control subjects). The ratio of the concentration of RANKL to that of OPG in the GCF was significantly higher for periodontal disease patients than for healthy subjects (*p < 0.01). Taken together, these data suggest that RANKL and OPG contribute to osteoclastic bone destruction in periodontal disease. Abbreviations: GCF, gingival crevicular fluid; IL, interleukin; OPG, osteoprotegerin; RANKL, receptor activator for NF-κB ligand.
Effect of Acculturation on Objective Measures of Oral Health in Haitian Immigrants in New York City
Authors: Cruz G.D. , Shore R. , Le Geros R.Z. , Tavares M.
Published: January 2009

Acculturation is a complex phenomenon that can serve as a proxy for cultural norms and behaviors affecting care-seeking, prevention behaviors, and, ultimately, health outcomes. The purpose of this study was to assess the effect of acculturation on the oral health of Haitian immigrants in New York City. We hypothesized that acculturation would be a predictor of the oral health status of the participating individuals. An acculturation scale was specifically developed and validated for this study. A sample of 425 adult Haitian immigrants living in NYC was obtained through outreach activities. Oral health examinations were conducted, and a questionnaire was administered to the participants. After adjustment for age, sex, education, income, and marital status, acculturation was negatively associated with measures of decayed teeth, periodontal attachment loss of ≥ 4 mm, and the number of missing teeth. Results suggest a positive impact of acculturation on the oral health status of these individuals.
Collagen Degradation by Host-derived Enzymes during Aging
Authors: Pashley D.H. , Tay F.R. , Yiu C. , Hashimoto M. , Breschi L. , Carvalho R.M. , Ito S.
Published: January 2009

Incompletely infiltrated collagen fibrils in acid-etched dentin are susceptible to degradation. We hypothesize that degradation can occur in the absence of bacteria. Partially demineralized collagen matrices (DCMs) prepared from human dentin were stored in artificial saliva. Control specimens were stored in artificial saliva containing proteolytic enzyme inhibitors, or pure mineral oil. We retrieved them at 24 hrs, 90 and 250 days to examine the extent of degradation of DCM. In the 24-hour experimental and 90- and 250-day control specimens, we observed 5- to 6-μm-thick layers of DCM containing banded collagen fibrils. DCMs were almost completely destroyed in the 250-day experimental specimens, but not when incubated with enzyme inhibitors or mineral oil. Functional enzyme analysis of dentin powder revealed low levels of collagenolytic activity that was inhibited by protease inhibitors or 0.2% chlorhexidine. We hypothesize that collagen degradation occurred over time, via host-derived matrix metalloproteinases that are released slowly over time.
In vitro Estrogenicity of Resin Composites
Authors: Wada H. , Tarumi H. , Imazato S. , Narimatsu M. , Ebisu S.
Published: January 2009

Previously, we have reported that sealants incorporating bisphenol A dimethacrylate showed estrogenicity by a reporter gene assay. This study tested the hypothesis that commercial composites, which contain various monomers and additives, exhibit estrogenic activity in vitro. The estrogenic activities of eluates obtained from 24 composites and 18 chemicals identified from the composites tested were examined with the use of the reporter gene assay. Among the 24 composites, 6 products were estrogenic, and among the 18 constituents, 1 photostabilizer, 2-hydroxy-4-methoxy-benzophenone (HMBP), 1 photoinitiator, 2,2-dimethoxy-2-phenyl-acetophenone (DMPA), and 1 inhibitor, 2,6-di- tert-butyl- p-cresol (BHT) had significant estrogenic activity. The concentration of HMBP in 4 estrogenic eluates was greater than the minimum concentration required for estrogenicity, and DMPA was found at a higher level than the minimum estrogenic concentration in the remaining 2 estrogenic specimens. These results suggest that the observed estrogenic activity of 6 composites is associated with the elution of either HMBP or DMPA.
Mental Stress-induced Physiological Changes in the Human Masseter Muscle
Authors: Hidaka O. , Yanagi M. , Takada K.
Published: January 2009

The effect of a long mental stress on the hemodynamics of masticatory muscles has not been investigated to date. We hypothesized some hemodynamic and electromyographic changes in jaw-closure muscles related to sympathetic nervous system activity. While healthy adult female volunteers performed a two-hour mental stress task, electromyographic activity of the temporal and masseteric muscles was recorded, and hemodynamic changes of the masseter muscle were measured non-invasively. Autonomic function was assessed by heart rate spectral analysis. Integrated electromyographic activity of the temporalis muscle, but not the masseter muscle, showed an increase that coincided with the increase in sympathetic nervous activity. In the masseter muscle, despite little change in integrated electromyographic activity, notable changes were found in hemodynamic parameters. These results suggest that hemodynamics of jaw muscles is susceptible to mental stress, implying a potential role in the etiology of jaw muscle dysfunction associated with mental stress.
Persistent Colonization with Tannerella forsythensis and Loss of Attachment in Adolescents
Authors: Hamlet S. , Ellwood R. , Cullinan M. , Worthington H. , Palmer J. , Bird P. , Narayanan D. , Davies R. , Seymour G.
Published: January 2009

Colonization with Tannerella forsythensis may characterize the conversion of periodontally healthy sites into diseased sites. This three-year study describes the prevalence of T. forsythensis and its relationship to clinical loss of attachment (LOA) in a group of adolescents considered at risk of developing early chronic periodontitis. Adolescents with (LOA+) and without (LOA-) loss of attachment were examined at baseline and 1.5 and 3 yrs subsequently. On each occasion, attachment loss was measured on selected teeth, and the presence of T. forsythensis in their subgingival plaque samples was determined by PCR. T. forsythensis prevalence in LOA+ subjects at baseline (64%) increased to 82% and 86% on subsequent examinations. In contrast, prevalence of T. forsythensis in LOA- subjects was always significantly lower (25%, 36%, and 32%, respectively). The odds of loss of attachment were 8.16 times greater in subjects infected with T. forsythensis at each examination. These results suggest that T. forsythensis is strongly associated with loss of attachment in this adolescent population.
Speech with Maxillary Implant Prostheses: Ratings of Articulation
Authors: Heydecke G. , McFarland D.H. , Feine J.S. , Lund J.P.
Published: January 2009

Speech is often perturbed after placement of maxillary implant-retained prostheses. We tested the hypothesis that the rate of speech errors varies with prosthetic design. Thirty edentulous subjects with mandibular implant prostheses entered two within-subject crossover trials. Subjects wore maxillary fixed prostheses and removable long-bar overdentures (Trial 1), or overdentures with and without palates (Trial 2). Test words from a French language speech battery were recorded after each prosthesis had been worn for two months. The percentages of stops, fricatives, and vowels correctly perceived by lay judges were calculated. Subjects produced a significantly higher percentage of sounds correctly with overdentures than with fixed prostheses. Between-treatment differences were significant for stops and fricatives (p < 0.01), but not for vowels. There were no significant differences in error rates between the two overdentures. In conclusion, maxillary implant overdentures with and without palates enable patients to produce more intelligible speech than fixed prostheses.
Changed Morphology and Mechanical Properties of Cancellous Bone in the Mandibular Condyles of Edentate People
Authors: Giesen E.B.W. , Ding M. , Dalstra M. , van Eijden T.M.G.J.
Published: January 2009

Since edentate subjects have a reduced masticatory function, it can be expected that the morphology of the cancellous bone of their mandibular condyles has changed according to the altered mechanical environment. In the present study, the morphology of cylindrical cancellous bone specimens of the mandibular condyles of edentate subjects (n = 25) was compared with that of dentate subjects (n = 24) by means of micro-computed tomography and by the application of Archimedes’ principle. Stiffness and strength were determined by destructive mechanical testing. Compared with dentate subjects, it appeared that, in edentate subjects, the bone was less dense and the trabecular structure was less plate-like. The regression models of stiffness and strength built from bone volume fraction and the trabecular orientation relative to the axis of the specimen were similar for both dentate and edentate subjects. This indicates that, under reduced mechanical load, the fundamental relationship between bone morphology and mechanical properties does not change.
Prostaglandin E2 Regulates Interleukin-1β-induced Matrix Metalloproteinase-3 Production in Human Gingival Fibroblasts
Authors: Ruwanpura S.M.P.M. , Noguchi K. , Ishikawa I.
Published: January 2009

Prostaglandin E2 (PGE2) exerts its biological actions via EP receptors (EP1, EP2, EP3, and EP4). In the present study, we investigated whether PGE2 regulated interleukin (IL)-1β-induced matrix metalloproteinase (MMP)-3 production in human gingival fibroblasts (HGF) derived from periodontally healthy subjects and diseased patients. In HGF from healthy gingiva, PGE2 down-regulated IL-1β-induced MMP-3 production, whereas in HGF from periodontitis patients, PGE2 enhanced it. Butaprost (an EP2 agonist) and ONO-AE1-329 (an EP4 agonist) suppressed IL-1β-induced MMP-3 production, and 17-phenyl-ω-trinor PGE2 (an EP1 agonist) mimicked the PGE2 effect in HGF from healthy and periodontally diseased tissues, respectively. Analysis of these data suggests that, in HGF from healthy tissue, IL-1β-induced MMP-3 production is down-regulated by PGE2 via EP2 and EP4 receptors, whereas in cells from periodontally diseased tissue, IL-1β-induced MMP-3 production is up-regulated via EP1 receptors. Different regulation of IL-1β-induced MMP-3 production by PGE2 between healthy and periodontally diseased tissues may be involved in the pathogenesis of periodontal disease.
Construction and Immunogenic Characterization of a Fusion Anti-caries DNA Vaccine against PAc and Glucosyltransferase I of Streptococcus mutans
Authors: Guo J.H. , Jia R. , Fan M.W. , Bian Z. , Chen Z. , Peng B.
Published: January 2009

Glucosyltransferases (GTFs) and A cell-surface protein (PAc) are two important virulence factors of the cariogenic organism Streptococcus mutans. They may mediate sucrose-independent or sucrose-dependent attachment of Streptococcus mutans to tooth surfaces, respectively. Thus, inhibiting both virulence factors is predicted to provide better protection against caries than inhibiting a single factor. To develop a highly efficient vaccine against caries, we constructed a fusion DNA vaccine, pGLUA-P, by cloning the GLU region of GTF into a DNA vaccine, pCIA-P, which encodes two highly conservative regions of PAc. In this report, we provide evidence that fewer caries lesions were observed in rats following subcutaneous injection of pGLUA-P, compared with pCIA-P, near the submandibular gland. Our findings suggest that a multigenic DNA vaccine may be more caries-preventive than a single-gene DNA vaccine.
Preparation and Characterization of Electrodeposited Calcium Phosphate/Chitosan Coating on Ti6Al4V Plates
Authors: Wang J. , de Boer J. , de Groot K.
Published: January 2009

Electrolytically deposited carbonate apatite coating demonstrates higher strength but weaker support for bone marrow stromal cell attachment than do biomimetically deposited coatings. It is hypothesized that the incorporation of chitosan will increase the biocompatibility of electrolytic coating while maintaining its original strength. To verify this hypothesis, we formed a hybrid calcium phosphate/chitosan coating through electrodeposition. We found that the incorporation of chitosan influenced calcium phosphate formation and crystallization. Moreover, coating thickness and surface roughness decreased with increasing chitosan concentration. Hybrid coating exhibited an increased dissolution rate in both acidic and neutral simulated physiologic solution, whereas no significant difference on adhesive strength was found between the hybrid and original coatings (P > 0.05). Most importantly, the calcium phosphate/chitosan coating proved to be a more favorable surface for goat bone marrow stromal cell attachment than an unincorporated coating (P < 0.01). Considering its economic and simple production, a hybrid calcium phosphate/chitosan coating is thought to be an attractive candidate for future applications.
Influence of Resin Monomers on Growth of Oral Streptococci
Authors: Takahashi Y. , Imazato S. , Russell R.R.B. , Noiri Y. , Ebisu S.
Published: January 2009

Ethyleneglycol dimethacrylate monomers have been previously reported to stimulate the growth of certain caries-associated bacteria on the basis of turbidity measurements. To elucidate the detail of this effect, we examined the influence of resin monomers on the growth of Streptococcus sobrinus and Streptococcus sanguis by determination of bacterial numbers (colony-forming units), morphological observation, and chemical analysis. Although the absorbance values in the stationary phase of bacterial suspension were increased in the presence of ethyleneglycol monomers, no significant differences were observed for bacterial numbers throughout the incubation period. Scanning electron microscopy observation revealed the formation of sparse vesicular material surrounding bacterial cells when incubated with ethyleneglycol monomers, and these products were proved to be resin polymers. The results demonstrate that the apparent biomass increase during incubation with ethyleneglycol monomers is due not to promotion of bacterial multiplication, but to the polymerization of resin monomers to form vesicular structures attached to cells.
Activation of WNT Family Expression and Signaling in Squamous Cell Carcinomas of the Oral Cavity
Authors: Uraguchi M. , Morikawa M. , Shirakawa M. , Sanada K. , Imai K.
Published: January 2009

The WNT family activates an oncogenic signaling mediated through β-catenin and is up-regulated in a variety of malignant neoplasms. The signaling translocates β-catenin into the nucleus and stimulates carcinoma cells in the epithelial-mesenchymal transition (EMT). However, WNT expression and signaling in oral carcinomas have not been examined. The present study focused on unveiling the involvement of WNTs in oral carcinomas, and showed that carcinoma cells express 11 of 19 WNT family members by reverse-transcription/PCR. WNT-expressing carcinoma cells exhibited increased β-catenin levels in the cytoplasmic pool and translocation to the nucleus. The activation state of signaling correlated with the expression of membrane-type 1 matrix metalloproteinase, which degrades territorial matrices in carcinoma invasion. Immunohistochemistry disclosed that WNT3 expression and nuclear localization of β-catenin were predominant in carcinoma cells at the invasive front. These results suggest that enhanced WNT expression and signaling accelerate the progression of carcinomas via activating EMTs and local invasiveness.
Effect of Nitric Oxide on the Recovery of the Hypofunctional Periodontal Ligament
Authors: Watarai H. , Warita H. , Soma K.
Published: January 2009

The relationship between occlusal stimuli and a hypofunctional periodontal ligament (PDL) structure has been reported, though changes in occlusal recovery conditions were still unclear. Nitric oxide (NO) produced by NO synthase (NOS) is considered a factor for vascular and immune system control, and it increases according to mechanical stimuli. The objective of this study was to examine the relationship between NOS and occlusal stimuli in PDL by comparing hypofunction with occlusal recovery. The study focused on the expression of endothelial NOS (eNOS) and inducible NOS (iNOS). Their expression significantly decreased in occlusal hypofunction compared with the control group and increased close to normal in an occlusal recovery group. The change in the immunopositive area was more dramatic than the immunopositive cell number. Moreover, the rate of iNOS increase was higher than that of eNOS. This study suggests that NO plays an important role in the recovery of the hypofunctional PDL.
Effect of Aminoguanidine in Ligature-induced Periodontitis in Rats
Authors: Di Paola R. , Marzocco S. , Mazzon E. , Dattola F. , Rotondo F. , Britti D. , De Majo M. , Genovese T. , Cuzzocrea S.
Published: January 2009

The role of nitric oxide and reactive oxygen species is well-demonstrated in inflammation. In this study, we evaluated the effect of aminoguanidine, a nitric oxide synthase inhibitor, in a rat model of periodontitis. We induced periodontitis in rats by placing a piece of 2/0 braided silk around the lower left 1st molar. At day 8, the gingivomucosal tissue encircling the mandibular 1st molar was removed for biochemical and histological analysis. Ligation significantly increased inducible nitric oxide synthase activity and expression, and damaged tissue revealed increased neutrophil infiltration, lipid peroxidation, and positive staining for nitrotyrosine formation and poly (ADP-ribose) polymerase activation. Ligation significantly increased Evans blue extravasation in gingivomucosal tissue and alveolar bone destruction. Aminoguanidine (100 mg/kg i.p., daily for 8 days) treatment significantly reduced all these inflammatory parameters, indicating that it protects against the tissue damage associated with periodontitis by reducing nitric oxide production and oxidative stress.
Identification of RANKL in Osteolytic Lesions of the Facial Skeleton
Authors: Tay J.Y.Y. , Bay B.H. , Yeo J.F , Harris M. , Meghji S. , Dheen S.T.
Published: January 2009

RANKL (receptor activator of nuclear factor κB ligand) promotes osteoclast differentiation, stimulates osteoclast activity, and prolongs osteoclast survival and adherence to bone. Abnormalities of the RANKL/RANK/osteoprotegerin system have been implicated in a range of diseases, including osteoporosis. To date, no work has been done in osteolytic lesions of the facial skeleton. In this study, specimens of ameloblastomas, dentigerous cysts, odontogenic keratocysts, and radicular cysts were subjected to immunohistochemical analysis for RANKL and tartrate-resistant acid phosphatase (TRAP). Immunofluorescence staining for TRAP was visualized under confocal microscopy. All specimens demonstrated distinct positive immunoreactivity to RANKL and TRAP. The TRAP-positive cells also stained with in situ hybridization for human calcitonin receptor, a definitive marker for osteoclasts. Mononuclear pre-osteoclasts were observed to migrate from blood to the connective tissue stroma and multinucleate toward the bone surface. It can be concluded that RANKL plays a role in bone resorption in osteolytic lesions of the facial skeleton.
Therapeutic Vaccine against Streptococcus sobrinus-induced Caries
Authors: Dinis M. , Tavares D. , Fonseca A.J.M.M. , Faria R. , Ribeiro A. , Silvério Cabrita A.M. , Ferreira P.
Published: January 2009

Streptococcus sobrinus produces a virulence-associated immunomodulatory protein (VIP) which suppresses the host-specific immune response and induces the early production of IL-10. In this study, we evaluated the effects of therapeutic immunization with this VIP on the incidence of caries in S. sobrinus-infected rats. Groups of Wistar rats were orally infected with S. sobrinus and fed with sucrose-sweetened drinking water ad libitum. Five days later, rats were immunized intranasally with active or heat-inactivated VIP plus alum as adjuvant or PBS plus adjuvant (sham-immunized). After 3 wks, all rats were re-immunized as above. Evaluation of dental caries showed that VIP-immunized animals had significantly fewer enamel sulcal and proximal caries lesions than did the sham-immunized animals (p < 0.001). The protective effects following therapeutic VIP immunization were attributed to the induced salivary immunoglobulin A specific to the VIP. These results offer a promising and safe strategy for the development of a vaccine against dental caries.
Amelogenin p.M1T and p.W4S Mutations Underlying Hypoplastic X-linked Amelogenesis Imperfecta
Authors: Kim J.-W. , Simmer J.P. , Hu Y.Y. , Lin B.P.-L. , Boyd C. , Wright J.T. , Yamada C.J.M. , Rayes S.K. , Feigal R.J. , Hu J.C.-C.
Published: January 2009

Mutations in the human amelogenin gene (AMELX, Xp22.3) cause a phenotypically diverse set of inherited enamel malformations. We hypothesize that the effects of specific mutations on amelogenin protein structure and expression will correlate with the enamel phenotype, clarify amelogenin structure/function relationships, and improve the clinical diagnosis of X-linked amelogenesis imperfecta (AI). We have identified two kindreds with X-linked AI and characterized the AMELX mutations underlying their AI phenotypes. The two missense mutations are both in exon 2 and affect the translation initiation codon and/or the secretion of amelogenin (p.M1T and p.W4S), resulting in hypoplastic enamel. Primary anterior teeth from affected females with the p.M1T mutation were characterized by light and scanning electron microscopy. The thin enamel had defective prism organization, and the surface was rough and pitted. Dentin was normal. The severity of the enamel phenotype correlated with the predicted effects of the mutations on amelogenin expression and secretion.
Quantitative Polygraphic Controlled Study on Efficacy and Safety of Oral Splint Devices in Tooth-grinding Subjects
Authors: Dubé C. , Rompré P.H. , Manzini C. , Guitard F. , de Grandmont P. , Lavigne G.J.
Published: January 2009

The efficacy of occlusal splints in diminishing muscle activity and tooth-grinding damage remains controversial. The objective of this study was to compare the efficacy and safety of an occlusal splint (OS) vs. a palatal control device (PCD). Nine subjects with sleep bruxism (SB) participated in this randomized study. Sleep laboratory recordings were made on the second night to establish baseline data. Patients then wore each of the splints in the sleep laboratory for recording nights three and four, two weeks apart, according to a crossover design. A statistically significant reduction in the number of SB episodes per hour (decrease of 41%, p = 0.05) and SB bursts per hour (decrease of 40%, p < 0.05) was observed with the two devices. Both oral devices also showed 50% fewer episodes with grinding noise (p = 0.06). No difference was observed between the devices. Moreover, no changes in respiratory variables were observed. Both devices reduced muscle activity associated with SB.
The Frictional Coefficient of the Temporomandibular Joint and Its Dependency on the Magnitude and Duration of Joint Loading
Authors: Tanaka E. , Kawai N. , Tanaka M. , Todoh M. , van Eijden T. , Hanaoka K. , Dalla-Bona D.A. , Takata T. , Tanne K.
Published: January 2009

In synovial joints, friction between articular surfaces leads to shear stress within the cartilaginous tissue, which might result in tissue rupture and failure. Joint friction depends on synovial lubrication of the articular surfaces, which can be altered due to compressive loading. Therefore, we hypothesized that the frictional coefficient of the temporomandibular joint (TMJ) is affected by the magnitude and duration of loading. We tested this by measuring the frictional coefficient in 20 intact porcine TMJs using a pendulum-type friction tester. The mean frictional coefficient was 0.0145 (SD 0.0027) after a constant loading of 50 N during 5 sec. The frictional coefficient increased with the length of the preceding loading duration and exceeded 0.0220 (SD 0.0014) after 1 hr. Application of larger loading (80 N) resulted in significantly larger frictional coefficients. In conclusion, the frictional coefficient in the TMJ was proportional to the magnitude and duration of joint loading.
Induction of Tolerance by Porphyromonas gingivalis on APCs: a Mechanism Implicated in Periodontal Infection
Authors: Cohen N. , Morisset J. , Emilie D.
Published: January 2009

The periodontal pathogen Porphyromonas gingivalis (Pg) is a potent inducer of the production of pro-inflammatory cytokines by neutrophils, monocytes, and macrophages, and can desensitize immune cells in vitro and in vivo. We analyzed the ability of Pg lipopolysaccharide (LPS) to induce endotoxin tolerance. Treatment of dendritic cells (DC), the human macrophage cell line THP-1, and monocytes (antigen-presenting cells, APC) with Pg.LPS inhibited APC maturation assessed by CD80 and CD86 expression, and inhibited chemokine (CCL3 and CCL5) production. Pre-treatment with glucocorticoids (GC) and interleukin-10 (IL-10) abolished the effect of Pg.LPS on CD80, CD83, and CD86, and on CCL3 and CCL5 production. We also showed that Pg.LPS enhanced the tolerogenic properties of APCs and up-regulated ILT-3 and B7-H1 expression.
Comparative Study on Adhesive Performance of Functional Monomers
Authors: Yoshida Y. , Nagakane K. , Fukuda R. , Nakayama Y. , Okazaki M. , Shintani H. , Inoue S. , Tagawa Y. , Suzuki K. , De Munck J. , Van Meerbeek B.
Published: January 2009

Mild self-etch adhesives demineralize dentin only partially, leaving hydroxyapatite around collagen within a submicron hybrid layer. We hypothesized that this residual hydroxyapatite may serve as a receptor for chemical interaction with the functional monomer and, subsequently, contribute to adhesive performance in addition to micro-mechanical hybridization. We therefore chemically characterized the adhesive interaction of 3 functional monomers with synthetic hydroxyapatite, using x-ray photoelectron spectroscopy and atomic absorption spectrophotometry. We further characterized their interaction with dentin ultra-morphologically, using transmission electron microscopy. The monomer 10-methacryloxydecyl dihydrogen phosphate (10-MDP) readily adhered to hydroxyapatite. This bond appeared very stable, as confirmed by the low dissolution rate of its calcium salt in water. The bonding potential of 4-methacryloxyethyl trimellitic acid (4-MET) was substantially lower. The monomer 2-methacryloxyethyl phenyl hydrogen phosphate (phenyl-P) and its bond to hydroxyapatite did not appear to be hydrolytically stable. Besides self-etching dentin, specific functional monomers have additional chemical bonding efficacy that is expected to contribute to their adhesive potential to tooth tissue.
Dynamic Intra-articular Space Variation in Clicking TMJs
Authors: Gössi D.B. , Gallo L.M. , Bahr E. , Palla S.
Published: January 2009

During mandibular movement, the geometric relationships of the articular surfaces in the temporomandibular joint (TMJ) change, so that the disc undergoes different stress concentrations with respect to time and position. In this study, we compared the intra-articular space variations of 13 clicking and 15 asymptomatic TMJs for jaw opening/closing. Magnetic resonance imaging and jaw tracking were combined to display the motion of the whole condyle within the fossa. In clicking TMJs, the mediolateral spread s of the stress-field trajectories was 2.4 ± 1.0 mm ( s max = 4.9 ± 2.1 mm) with an aspect ratio a/h of 2.5 ± 1.6, both significantly greater than in controls (p < 0.05). The stress-field trajectories of the controls coincided during opening/closing ( s = 0.9 ± 0.2 mm, s max = 1.8 ± 0.8 mm, a/h = 1.6 ± 0.3). Clicking TMJs showed much less coincident stress-field paths and much “flatter” stress-fields than controls during jaw opening/closing.
Dentonin, a Fragment of MEPE, Enhanced Dental Pulp Stem Cell Proliferation
Authors: Liu H. , Li W. , Gao C. , Kumagai Y. , Blacher R.W. , DenBesten P.K.
Published: January 2009

Matrix extracellular phosphoglycoprotein (MEPE) is a SIBLING protein, found in bone and dental tissues. The purpose of this study was to determine whether a 23-amino-acid peptide derived from MEPE (Dentonin or AC-100) could stimulate dental pulp stem cell (DPSC) proliferation and/or differentiation. DPSCs were isolated from erupted human molars, and the mitogenic potential of Dentonin in DPSCs was measured by BrdU immunoassay and cell-cycle gene SuperArray. Differentiation of DPSCs with Dentonin was characterized by Western blot and by osteogenesis gene SuperArray. Dentonin enhanced DPSC proliferation by down-regulating P16, accompanied by up-regulation of ubiquitin protein ligase E3A and human ubiquitin-related protein SUMO-1. Enhanced cell proliferation required intact RGD and SGDG motifs in the peptide. This study shows that Dentonin can promote DPSC proliferation, with a potential role in pulp repair. Further studies are required to determine the usefulness of this material in vivo.
Stem-cell-based Tissue Engineering of Murine Teeth
Authors: Ohazama A. , Modino S.A.C. , Miletich I. , Sharpe P.T.
Published: January 2009

Teeth develop from reciprocal interactions between mesenchyme cells and epithelium, where the epithelium provides the instructive information for initiation. Based on these initial tissue interactions, we have replaced the mesenchyme cells with mesenchyme created by aggregation of cultured non-dental stem cells in mice. Recombinations between non-dental cell-derived mesenchyme and embryonic oral epithelium stimulate an odontogenic response in the stem cells. Embryonic stem cells, neural stem cells, and adult bone-marrow-derived cells all responded by expressing odontogenic genes. Transfer of recombinations into adult renal capsules resulted in the development of tooth structures and associated bone. Moreover, transfer of embryonic tooth primordia into the adult jaw resulted in development of tooth structures, showing that an embryonic primordium can develop in its adult environment. These results thus provide a significant advance toward the creation of artificial embryonic tooth primordia from cultured cells that can be used to replace missing teeth following transplantation into the adult mouth.
Do Circumstances in Early Life Contribute to Tooth Retention in Middle Age?
Authors: Pearce M.S. , Steele J.G. , Mason J. , Walls A.W.G. , Parker L.
Published: January 2009

The relative contributions of factors operating in fetal life, childhood, and adulthood to risk of disease in middle age have become an important research issue, though oral health has rarely been considered. This study investigated the relative impacts of risk factors operating at different stages throughout life on the number of teeth retained at ages 49–51 yrs based on data from the Newcastle Thousand Families cohort. Very little variation in tooth retention in middle age was explained by factors operating at earlier stages in life. The previously noted relationship between childhood socio-economic status and oral health in adulthood appears, with respect to tooth retention, to diminish with increasing age as adult socio-economic position and lifestyle factors have an increasing effect. Promotion of a healthier adult lifestyle and continued improvements in oral hygiene would appear to be the public health interventions most likely to increase tooth retention in middle age.
Particle Size Distribution of Food Boluses after Mastication of Six Natural Foods
Authors: Peyron M.-A. , Mishellany A. , Woda A.
Published: January 2009

There is a large variability between and among individuals in the physiology of mastication, but it is not known whether this produces a similar variability in the particle sizes of food boluses at the end of the chewing process. Food boluses obtained just before swallowing were analyzed in ten subjects (aged 36.7 ± 9.5 yrs) with normal dentition. Food samples of 3 nuts (peanut, almond, pistachio) and 3 vegetables (cauliflower, radish, and carrot) were chewed and expectorated after self-estimated complete mastication. Measurements with sieving and laser diffraction methods indicated that particles were much larger in vegetables than in nuts. Particle size distributions were similar among nuts and among vegetables. Surprisingly, no inter-individual variability was observed in the particle distributions for the 6 foods, although several sequence variables differed markedly. A need for a bolus to be prepared with a precisely determined texture before it can be swallowed may explain the inter-subject variability of the masticatory function.
Water-dependent Interfacial Transition Zone in Resin-modified Glass-ionomer Cement/Dentin Interfaces
Authors: Tay F.R. , Sidhu S.K. , Watson T.F. , Pashley D.H.
Published: January 2009

The function of the interfacial transition zone (absorption layer) in resin-modified glass-ionomer cements bonded to deep dentin remains obscure. This study tested the hypotheses that the absorption layer is formed only in the presence of water derived from hydrated dentin and allows for better bonding of resin-modified glass-ionomer cements to dentin. Ten percent polyacrylic acid-conditioned, hydrated, and dehydrated deep dentin specimens were bonded with 2 resin-modified glass-ionomer cements and sealed with resins to prevent environmental water gain or loss. A non-particulate absorption layer was identified over hydrated dentin only, and was clearly discernible from the hybrid layer when bonded interfaces were examined with transmission electron microscopy. This layer was relatively more resistant to dehydration stresses, and remained intact over the dentin surface after tensile testing. The absorption layer mediates better bonding of resin-modified glass-ionomer cements to deep dentin, and functions as a stress-relieving layer to reduce stresses induced by desiccation and shrinkage.