bluuebunny/crossref_metadata_2025 huggingface dataset:
A Genome Segment on Mouse Chromosome 12 Determines Maxillary Growth
Authors: Oh J. , Wang C.J. , Poole M. , Kim E. , Davis R.C. , Nishimura I. , Pae E.-K.
Published: January 2009

The primary and modifier genes that regulate normal maxillofacial development are unknown. Previous quantitative trait locus (QTL) analyses using the F2 progeny of 2 mouse strains, DBA/2J (short snout/wide face) and C57BL/6J (long snout/narrow face), revealed a significant logarithm-of-odds (LOD) score for snout length on mouse chromosome 12 at 44 centimorgan (cM). We further sought to validate this locus contributing to anterior-posterior dimensions of the upper mid-face at the D12Mit7 marker in a 44-centimorgan portion of chromosome 12. Congenic mice carrying introgressed DNA from DBA/2J on a C57BL/6J background were selected for submental vertex cephalometric imaging. Results confirmed QTLs, determining that short snout length (P < 0.05) and face width relative to snout length (P < 0.01) were present in the 44-cM region of chromosome 12. We conclude that one or more genes contributing to the shape of the maxillary complex are located near 44 cM of mouse chromosome 12.
Osteogenic Gene Expression by Human Periodontal Ligament Cells under Cyclic Tension
Authors: Wescott D.C. , Pinkerton M.N. , Gaffey B.J. , Beggs K.T. , Milne T.J. , Meikle M.C.
Published: January 2009

The forces that orthodontic appliances apply to the teeth are transmitted through the periodontal ligament (PDL) to the supporting alveolar bone, leading to the deposition or resorption of bone, depending upon whether the tissues are exposed to a tensile or compressive mechanical strain. To evaluate the osteogenic potential of PDL cells, we applied a 12% uni-axial cyclic tensile strain to cultured human PDL cells and analyzed the differential expression of 78 genes implicated in osteoblast differentiation and bone metabolism by real-time RT-PCR array technology. Sixteen genes showed statistically significant changes in expression in response to alterations in their mechanical environment, including cell adhesion molecules and collagen fiber types. Genes linked to the osteoblast phenotype that were up-regulated included BMP2, BMP6, ALP, SOX9, MSX1, and VEGFA; those down-regulated included BMP4 and EGF. This study has expanded our knowledge of the transcriptional profile of PDL cells and identified several new mechanoresponsive genes.
Molecular Pathogenesis of Oral Squamous Cell Carcinoma: Implications for Therapy
Authors: Choi S. , Myers J.N.
Published: January 2009

The development of oral squamous cell carcinoma (OSCC) is a multistep process requiring the accumulation of multiple genetic alterations, influenced by a patient’s genetic predisposition as well as by environmental influences, including tobacco, alcohol, chronic inflammation, and viral infection. Tumorigenic genetic alterations consist of two major types: tumor suppressor genes, which promote tumor development when inactivated; and oncogenes, which promote tumor development when activated. Tumor suppressor genes can be inactivated through genetic events such as mutation, loss of heterozygosity, or deletion, or by epigenetic modifications such as DNA methylation or chromatin remodeling. Oncogenes can be activated through overexpression due to gene amplification, increased transcription, or changes in structure due to mutations that lead to increased transforming activity. This review focuses on the molecular mechanisms of oral carcinogenesis and the use of biologic therapy to specifically target molecules altered in OSCC. The rapid progress that has been made in our understanding of the molecular alterations contributing to the development of OSCC is leading to improvements in the early diagnosis of tumors and the refinement of biologic treatments individualized to the specific characteristics of a patient’s tumor.
PDGF Up-regulates CSF-1 Gene Transcription in Ameloblast-like Cells
Authors: Wittrant Y. , Bhandari B. Sriniketan , Abboud H. , Benson N. , Woodruff K. , MacDougall M. , Abboud-Werner S.
Published: January 2009

Macrophage colony-stimulating factor (CSF-1) is a key regulatory cytokine for amelogenesis, and ameloblasts synthesize CSF-1. We hypothesized that PDGF stimulates DNA synthesis and regulates CSF-1 in these cells. We determined the effect of PDGF on CSF-1 expression using MEOE-3M ameloblasts as a model. By RT-PCR, MEOE-3M expressed PDGFRs and PDGF A- and B-chain mRNAs. PDGF-BB increased DNA synthesis and up-regulated CSF-1 mRNA and protein in MEOE-3M. Cells transfected with CSF-1 promoter deletion constructs were analyzed. A PDGF-responsive region between −1.7 and −0.795 kb, containing a consensus Pea3 binding motif, was identified. Electrophoretic mobility shift assay (EMSA) showed that PDGF-BB stimulated protein binding to this motif that was inhibited in the presence of anti-Pea3 antibody. Analysis of these data provides the first evidence that PDGF-BB is a mitogen for MEOE-3M and increases CSF-1 protein levels, predominantly by transcription. Elucidation of the cellular pathways that control CSF-1 expression may provide novel strategies for the regulation of enamel matrix formation.
Butyric Acid Induces Apoptosis in Inflamed Fibroblasts
Authors: Kurita-Ochiai T. , Seto S. , Suzuki N. , Yamamoto M. , Otsuka K. , Abe K. , Ochiai K.
Published: January 2009

Butyric acid, an extracellular metabolite from periodontopathic bacteria, induces apoptosis in murine and human T- and B-cells, whereas intact gingival fibroblasts isolated from healthy humans are resistant to butyric-acid-induced apoptosis. We examined the susceptibility of inflamed gingival fibroblasts isolated from adult persons with periodontitis to butyric-acid-induced apoptosis. Butyric acid significantly suppressed the viability of inflamed gingival fibroblasts and induced apoptosis in a dose-dependent manner. The incubation of inflamed gingival fibroblasts with butyric acid induced DNA fragmentation and apoptotic changes such as chromatin condensation, hypodiploid nuclei, and mitochondrial injury. Furthermore, butyric-acid-induced apoptosis in inflamed gingival fibroblasts was reduced by caspase-3/7, -6, -8, and -9 inhibitors. Thus, inflamed gingival fibroblasts from adult persons with periodontitis appear to be highly susceptible to mitochondria- and caspase-dependent apoptosis induced by butyric acid, compared with healthy gingival fibroblasts.
Anxiety and Ability to Recognize Clinical Information in Dentistry
Authors: Eli I. , Schwartz-Arad D. , Bartal Y.
Published: January 2009

Stress significantly affects a person’s cognitive ability to process information. Therefore, we hypothesized that patients’ ability to recognize information related to the procedure they are about to undergo will be affected by the stressfulness of the situation (less recognition under a high-stress situation as compared with a low-stress situation). Patients (n = 66) were evaluated for their ability to recognize clinical information supplied on two different occasions: immediately before oral surgery (high-stress condition) and before suture removal (low-stress condition). Dental and state of anxiety and expectation of pain were also assessed. On both occasions, the patients’ ability to recognize information correctly was low (less than 50%). Patients recognized significantly less information pre-operatively than before suture removal. State of anxiety, dental anxiety, and expectation to experience pain had a profound effect on their ability to recognize provided information correctly. Apparently, before dental treatment (high or low on stress), patients’ ability to process information may be severely impaired.
Trajectory Patterns of Dental Caries Experience in the Permanent Dentition to the Fourth Decade of Life
Authors: Broadbent J.M. , Thomson W.M. , Poulton R.
Published: January 2009

Dental caries is a chronic, cumulative disease, but no studies have investigated longitudinal patterns of caries experience. The objective of this study was to identify and describe developmental trajectories of caries experience in the permanent dentition to age 32. Longitudinal caries data for 955 participants in a longstanding birth cohort study were analyzed by trajectory analysis. Three caries experience trajectories were identified by the SAS macro PROC TRAJ; these were categorized as "high" (~ 15%), "medium" (~ 43%), and "low" (~ 42%) DMFS (Decayed, Missing, and Filled Surfaces). All were relatively linear, although the higher trajectories were more "S-shaped". This effect disappeared following adjustment for the number of unaffected surfaces remaining at each age, suggesting that, among individuals following a similar caries trajectory, caries rate is relatively constant across time.
No Alteration in Bone Mineral Density in Patients with Periodontitis
Authors: Hattatoğlu-Sönmez E. , Özcakar L. , Gökce-Kutsal Y. , Karaağaoğlu E. , Demiralp B. , Nazliel-Erverdi H.
Published: January 2009

Alveolar bone destruction can be magnified in the presence of generalized skeletal disorders. We questioned whether severe generalized periodontitis patients display signs of bone metabolism disturbances. Our objective was to assess skeletal bone mineral density (BMD) and biochemical bone parameters in premenopausal women with periodontitis. Forty-five patients and 40 control individuals were included in the study. We measured BMD by dual-energy x-ray absorptiometry. The results showed no difference in BMD values between the periodontitis and control groups (p > 0.05). A positive relationship between the clinical attachment level and Body Mass Index (BMI) scores was observed (p = 0.03). Increased serum creatinine levels were noted in the periodontitis group (p = 0.04). Analysis of the data suggests that there is no evidence for an association between skeletal BMD and severe periodontitis in premenopausal women. There may be a link between elevated creatinine levels and periodontitis. The persons with high BMI scores seemed to be at risk for periodontitis.
Refractive Index Mismatch and Monomer Reactivity Influence Composite Curing Depth
Authors: Shortall A.C. , Palin W.M. , Burtscher P.
Published: January 2009

Limited cure depth is a drawback of light-activated composites. We hypothesize that curing light transmission and cure depth are influenced by monomer reactivity and filler/resin refractive index mismatch. Light transmission throughout cure was recorded for composites based on strontium (refractive index 1.51) or barium (refractive index 1.53) glass fillers. Fillers were mixed (70 wt%) with 4 bisphenol-A diglycidyl-ether-dimethacrylate (bis-GMA):triethylene glycol dimethacrylate (TEGDMA) formulations with refractive indices ranging from 1.4703 to 1.5370. Following polymerization, cure depth and pre- and post-cure translucency parameters were determined. Transmission changes and cure depths related to monomer reactivity and filler/resin refractive index mismatch with significant interaction. Composites became more opaque or translucent on curing. Optimizing filler/resin refractive index mismatch provides increased curing depth and assists shade-matching.
Unraveling Human Cleft Lip and Palate Research
Authors: Vieira A.R.
Published: January 2009

The focus of this work is to highlight the most recent advances in the understanding of cleft lip and palate occurrence. Information regarding research on long-term outcomes, genes and their interactions with other genes, and gene-environment interactions is compiled to provide the reader with a critical and up-to-date overview on the current knowledge of the etiology of cleft lip and palate. Recent epidemiological evidence strongly suggests that individuals born with clefts have a shorter lifespan and may have a higher incidence of cancer and psychological disorders. IRF6 has been shown to be an important contributor to cleft lip and palate, but the functional variant leading to the defect has not yet been defined. Inactivation of MSX1 and genes in the FGF family has also been shown to lead to cleft lip and palate. In addition, missense mutations in several candidate genes may cause cleft lip and palate, but definitive evidence regarding the biological consequences of these mutations is yet to be unraveled. Maternal cigarette smoking increases the risk of a baby born with clefts, in particular when the mother carries the GSTT1-null variants. The latest approaches in cleft research include the analysis of several additional phenotypical features of the population, with the goal of increasing the statistical power of genetics studies.
Surface Roughness Analysis of Fiber Post Conditioning Processes
Authors: Mazzitelli C. , Ferrari M. , Toledano M. , Osorio E. , Monticelli F. , Osorio R.
Published: January 2009

The chemo-mechanical surface treatment of fiber posts increases their bonding properties. The combined use of atomic force and confocal microscopy allows for the assessment and quantification of the changes on surface roughness that justify this behavior. Quartz fiber posts were conditioned with different chemicals, as well as by sandblasting, and by an industrial silicate/silane coating. We analyzed post surfaces by atomic force microscopy, recording average roughness (Ra) measurements of fibers and resin matrix. A confocal image profiler allowed for the quantitative assessment of the average superficial roughness (Ra). Hydrofluoric acid, potassium permanganate, sodium ethoxide, and sandblasting increased post surface roughness. Modifications of the epoxy resin matrix occurred after the surface pre-treatments. Hydrofluoric acid affected the superficial texture of quartz fibers. Surface-conditioning procedures that selectively react with the epoxy-resin matrix of the fiber post enhance roughness and improve the surface area available for adhesion by creating micro-retentive spaces without affecting the post’s inner structure.
Mandibular Appliance Modulates Condylar Growth through Integrins
Authors: Marques M. Rubia , Hajjar D. , Franchini K. Gomes , Moriscot A. Sigari , Santos M. Fagundes
Published: January 2009

Functional orthopedic therapy corrects growth discrepancies between the maxilla and mandible, possibly through postural changes in the musculature and modulation of the mandibular condylar cartilage growth. Using Wistar rats, we tested the hypothesis that chondrocytes respond to forces generated by a mandibular propulsor appliance by changes in gene expression, and that integrins are important mediators in this response. Immunohistochemical analyses demonstrated that the use of the appliance for different periods of time modulated the expression of fibronectin, α5 and αv integrin subunits, as well as cell proliferation in the cartilage. In vitro, cyclic distension of condylar cartilage-derived cells increased fibronectin mRNA, as well as Insulin-like Growth Factor-I and II mRNA and cell proliferation. A peptide containing the Arginine-Glycine-Asparagine sequence (RGD), the main cell-binding sequence in fibronectin, blocked almost all these effects, confirming that force itself modulates the growth of the rat condylar cartilage, and that RGD-binding integrins participate in mechanotransduction.
Molecular Mechanisms Controlling Bone Formation during Fracture Healing and Distraction Osteogenesis
Authors: AI-Aql Z.S. , Alagl A.S. , Graves D.T. , Gerstenfeld L.C. , Einhorn T.A.
Published: January 2009

Fracture healing and distraction osteogenesis have important applications in orthopedic, maxillofacial, and periodontal treatment. In this review, the cellular and molecular mechanisms that regulate fracture repair are contrasted with bone regeneration that occurs during distraction osteogenesis. While both processes have many common features, unique differences are observed in the temporal appearance and expression of specific molecular factors that regulate each. The relative importance of inflammatory cytokines in normal and diabetic healing, the transforming growth factor beta superfamily of bone morphogenetic mediators, and the process of angiogenesis are discussed as they relate to bone repair. A complete summary of biological activities and functions of various bioactive factors may be found at COPE (Cytokines & Cells Online Pathfinder Encyclopedia), http://www.copewithcytokines.de/cope.cgi .
Active Management of Incipient Caries and Choice of Materials
Authors: Trairatvorakul C. , Kladkaew S. , Songsiripradabboon S.
Published: January 2009

Evidence of the effects of various sealant and fluoride materials in stabilizing or reversing incipient caries lesions has been reported. However, a knowledge gap still exists as to what material yields the best results. Thus, the objective of this study was to find the most effective material by comparing the effects of a resin-based sealant (sealant), a fluoride-containing sealant (F-sealant), a fluoride varnish (F-varnish), and a glass-ionomer cement (GIC) on deremineralization of incipient artificial caries and adjacent intact enamel on proximal surfaces of posterior teeth. The 4 materials were applied to lesions created on proximal surfaces. Areas of intact enamel 0.5 mm adjacent to the materials were also studied. The specimens were thermo- and pH-cycled. Cross-sections of the two areas were analyzed under polarized light microscope and quantified with Image-Pro plus®. The most effective material in reducing the carious areas was GIC, followed by F-varnish, F-sealant, and sealants. GIC followed by F-varnish was most efficient in inhibiting new caries lesions 0.5 mm adjacent to the materials.
Effects of Fluoride Dentifrices on Enamel Lesion Formation
Authors: Toda S. , Featherstone J.D.
Published: January 2009

An in vitro pH cycling model was used to test the hypothesis that the effects of 3 different fluoride compounds on de/remineralization are a function of the free fluoride ion concentration. Groups of 10 human enamel specimens were treated with one of: (a) amine fluoride (AmF), 1250 ppm F; (b) sodium monofluorophosphate (NaMFP), 1000 ppm F; (c) sodium fluoride (NaF), 1100 ppm F; (d) NaF, 250 ppm F; (e) Placebo (< 1 ppm F) dentifrices; or with aqueous solutions (f) NaF 900 ppm F or (g) NaF 30 ppm F. Lesions were assessed by cross-sectional microhardness. Mean ± SEM ΔZ (vol.% x μm) values of 3 dentifrices were: (a) 344 ± 155, (b) 4259 ± 257, and (c) 591 ± 83. The AmF (1250 ppm F) was not statistically significantly different from the NaF (1100 ppm F) dentifrice in this model. The NaMFP (1000 ppm F) dentifrice, without hydrolysis, had only the same efficacy as the NaF (30 ppm F) aqueous solution.
The Endangered Clinical Teacher Scholar: Will this Eliminate Discovery from the Dental School Environment?
Authors: Oakley M. , Vieira A.R.
Published: January 2009

Each year, dental schools struggle to do more with less—a reality that is confounded by dental faculty shortages and retention issues reported over the past 15 years. In today’s academic environment, faculty shortages suggest that the resulting smaller faculty population will be tasked with more responsibilities than those who had the benefit of working with a full complement of colleagues. Fewer clinical faculty will likely participate in scholarly activity—in some instances, negatively affecting their chances for promotion and tenure, and ultimately lessening their own job security and feeling of accomplishment and self-worth in the academic environment. New faculty are in need of a formal program endorsed by their administration—one which places them with colleagues experienced in scholarly activity. This program, to include a definitive reward structure for mentors, would likely foster the retention and promotion of faculty and encourage the development of future leaders of dental education. Without a definitive plan, the clinical scholar will become an endangered species, and the research innovations and discovery of our profession will fall short in addressing the needs of the public’s oral and systemic health.
Epithelial Fibroblast Growth Factor Receptor 1 Regulates Enamel Formation
Authors: Takamori K. , Hosokawa R. , Xu X. , Deng X. , Bringas P. , Chai Y.
Published: January 2009

The interaction between epithelial and mesenchymal tissues plays a critical role in the development of organs such as teeth, lungs, and hair. During tooth development, fibroblast growth factor (FGF) signaling is critical for regulating reciprocal epithelial and mesenchymal interactions. FGF signaling requires FGF ligands and their receptors (FGFRs). In this study, we investigated the role of epithelial FGF signaling in tooth development, using the Cre-loxp system to create tissue-specific inactivation of Fgfr1 in mice. In K14-Cre;Fgfr1 fl/fl mice, the apical sides of enamel-secreting ameloblasts failed to adhere properly to each other, although ameloblast differentiation was unaffected at early stages. Prior to eruption, enamel structure was compromised in the K14-Cre;Fgfr1 fl/fl mice and displayed severe enamel defects that mimic amelogenesis imperfecta (AI), with a rough, irregular enamel surface. These results suggest that there is a cell-autonomous requirement for FGF signaling in the dental epithelium during enamel formation. Loss of Fgfr1 affects ameloblast organization at the enamel-secretory stage and, hence, the formation of enamel.
Tumor Necrosis Factor-α-converting Enzyme (TACE) Levels in Periodontal Diseases
Authors: Bostanci N. , Emingil G. , Afacan B. , Han B. , Ilgenli T. , Atilla G. , Hughes F.J. , Belibasakis G.N.
Published: January 2009

Tumor necrosis factor-α-converting enzyme (TACE) is a metalloprotease which can shed several cytokines from the cell membrane, including receptor activator of NF-κB ligand (RANKL). This study aimed to investigate the hypothesis that TACE would be elevated in the gingival crevicular fluid (GCF) of persons with periodontitis. Total TACE amounts in GCF were higher in persons with chronic and aggressive periodontitis than in those with gingivitis or in healthy persons. TACE concentrations in GCF were higher in persons with chronic and aggressive periodontitis than in those with gingivitis, although not significantly higher than in healthy persons. Persons with chronic periodontitis receiving immunosuppressive treatment exhibited over 10-fold lower TACE levels than the other periodontitis groups. TACE was positively correlated with probing pocket depth, clinical attachment levels, and RANKL concentrations in GCF. In conclusion, the increased GCF TACE levels in persons with periodontitis and their positive correlation with RANKL may indicate an association of this enzyme with alveolar bone loss, and may warrant special attention in future therapeutic approaches.
Age and Third Molar Extraction as Risk Factors for Temporomandibular Disorder
Authors: Huang G.J. , Drangsholt M.T. , Rue T.C. , Cruikshank D.C. , Hobson K.A.
Published: January 2009

This study investigated third molar removal as a risk factor for temporomandibular disorder (TMD) in all age groups. We compared 2217 Kaiser Permanente Northwest health plan enrollees with a history of third molar extraction with 2217 age-and gender-matched enrollees with radiographic confirmation of no lifetime third molar removal. Common Dental Terminology codes were used to identify information on third molar removal, and International Classification of Disease codes were used to identify TMD. Relative risks were calculated overall, and by each decade of life, in univariate and multivariate analyses. The incidence of TMD in subjects with and without third molar removal were 7 and 5 per thousand person-years, respectively. Third molar removal among subjects of all ages resulted in a statistically insignificant increased relative risk for TMD (1.4, 95% confidence interval (CI): 0.9–2.2). The relative risk was slightly higher in those under 21, but was also not statistically significant (1.6, CI: 0.8–3.1).
Distribution and Excretion of BisGMA in Guinea Pigs
Authors: Reichl F.X. , Seiss M. , Kleinsasser N. , Kehe K. , Kunzelmann K.H. , Thomas P. , Spahl W. , Hickel R.
Published: January 2009

Bisphenol-A-glycidyldimethacrylate (BisGMA) is used in many resin-based dental materials. It was shown in vitro that BisGMA was released into the adjacent biophase from such materials during the first days after placement. In this study, the uptake, distribution, and excretion of [14C]BisGMA applied via gastric and intravenous administration (at dose levels well above those encountered in dental care) were examined in vivo in guinea pigs to test the hypothesis that BisGMA reaches cytotoxic levels in mammalian tissues. [14C]BisGMA was taken up rapidly from the stomach and intestine after gastric administration and was widely distributed in the body following administration by each route. Most [14C] was excreted within one day as 14CO2. The peak equivalent BisGMA levels in guinea pig tissues examined were at least 1000-fold less than known toxic levels. The peak urine level in guinea pigs that received well in excess of the body-weight-adjusted dose expected in humans was also below known toxic levels. The study therefore did not support the hypothesis.
DLX3 Mutation in a New Family and Its Phenotypic Variations
Authors: Lee S.-K. , Lee Z.H. , Lee S.-J. , Ahn B.-D. , Kim Y.-J. , Lee S.-H. , Kim J.-W.
Published: January 2009

Tricho-dento-osseous syndrome (TDO) is an autosomal-dominant disease characterized by curly hair at birth, enamel hypoplasia, taurodontism, and a thick cortical bone. A common DLX3 gene mutation (c.571_574delGGGG) has been identified in multiple families with variable clinical phenotypes. Recently, another DLX3 gene mutation (c.561_562delCT) was reported to cause amelogenesis imperfecta with taurodontism (AIHHT). We identified a Korean family with overlapping phenotypes of TDO and AIHHT. We performed mutational analysis to discover its genetic etiology. The identified mutation was c.561_562delCT mutation in the DLX3 gene. The enamel was hypomature and hypoplastic. The characteristic taurodontic features were not identified. Increased bone density or thickness could not be revealed by cephalometric, hand-wrist, and panoramic radiographs. Affected individuals reported that their nails were brittle, and they had curly hair at birth. This study clearly showed that the c.561_562delCT mutation had not only enamel defects, but also other clinical phenotypes resembling those of TDO syndrome.
Contraction Stress Determinants in Dimethacrylate Composites
Authors: Gonçalves F. , Pfeifer C.S. , Ferracane J.L. , Braga R.R.
Published: January 2009

The influence of composite organic content on polymerization stress development remains unclear. It was hypothesized that stress was directly related to differences in degree of conversion, volumetric shrinkage, elastic modulus, and maximum rate of polymerization encountered in composites containing different BisGMA (bisphenylglycidyl dimethacrylate) concentrations and TEGDMA (triethylene glycol dimethacrylate) and/or BisEMA (ethoxylated bisphenol-A dimethacrylate) as co-monomers. Stress was determined in a tensilometer. Volumetric shrinkage was measured with a mercury dilatometer. Elastic modulus was obtained by flexural test. We used fragments of flexural specimens to determine degree of conversion by FT-Raman spectroscopy. Reaction rate was determined by differential scanning calorimetry. Composites with lower BisGMA content and those containing TEGDMA showed higher stress, conversion, shrinkage, and elastic modulus. Polymerization rate did not vary significantly, except for the lower value of the 66% TEGDMA composite. We used linear regressions to evaluate the association between polymerization stress and conversion (R2 = 0.905), shrinkage (R2 = 0.825), and modulus (R2 = 0.623).
Cortical Representation Area of Human Dental Pulp
Authors: Kubo K. , Shibukawa Y. , Shintani M. , Suzuki T. , Ichinohe T. , Kaneko Y.
Published: January 2009

To elucidate the dental pulp-representing area in the human primary somatosensory cortex and the presence of A-beta fibers in dental pulp, we recorded somatosensory-evoked magnetic fields from the cortex in seven healthy persons using magnetoencephalography. Following non-painful electrical stimulation of the right maxillary first premolar dental pulp, short latency (27 ms) cortical responses on the magnetic waveforms were observed. However, no response was seen when stimulation was applied to pulpless teeth, such as devitalized teeth. The current source generating the early component of the magnetic fields was located anterior-inferiorly compared with the locations for the hand area in the primary somatosensory cortex. These results demonstrate the dental pulp representation area in the primary somatosensory cortex, and that it receives input from intradental A-beta neurons, providing a detailed organizational map of the orofacial area, by adding dental pulp to the classic “sensory homunculus”.
Oral Manifestations of Sjögren’s Syndrome
Authors: Mathews S.A. , Kurien B.T. , Scofield R.H.
Published: January 2009

Sjögren’s syndrome is a common autoimmune rheumatic disease. The most common symptoms of Sjögren’s syndrome are extreme tiredness, along with dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia). Saliva plays an essential role in numerous functions of the mouth. Xerostomia can be caused by medications, chronic diseases like Sjögren’s syndrome, and medical treatments, such as radiation therapy and bone marrow transplant. Xerostomia can eventually lead to difficulty in swallowing, severe and progressive tooth decay, or oral infections. Despite having excellent oral hygiene, individuals with Sjögren’s syndrome have elevated levels of dental caries, along with the loss of many teeth, early in the disease. Sjögren’s syndrome alters the protein profile and brings about a change in the composition of saliva. There is an increase in the levels of lactoferrin, β2-microglobulin, sodium, lysozyme C, and cystatin C, and a decrease in salivary amylase and carbonic anhydrase. Up to 90% of individuals with Sjögren’s syndrome have antibodies targeting the Ro 60 and La autoantigens. Natural aging, regardless of Sjögren’s syndrome, is also another factor that brings about a significant change in the composition of saliva. The most prevailing cause of xerostomia in elderly persons is the use of anticholinergic medications. Currently, there is no cure for Sjögren’s syndrome, and treatment is mainly palliative.
Periodontal Pathogens and Gestational Diabetes Mellitus
Authors: Dasanayake A.P. , Chhun N. , Tanner A.C.R. , Craig R.G. , Lee M.J. , Moore A.F. , Norman R.G.
Published: January 2009

In previous cross-sectional or case-control studies, clinical periodontal disease has been associated with gestational diabetes mellitus. To test the hypothesis that, in comparison with women who do not develop gestational diabetes mellitus, those who do develop it will have had a greater exposure to clinical and other periodontal parameters, we measured clinical, bacteriological (in plaque and cervico-vaginal samples), immunological, and inflammatory mediator parameters 7 weeks before the diagnosis of gestational diabetes mellitus in 265 predominantly Hispanic (83%) women in New York. Twenty-two cases of gestational diabetes mellitus emerged from the cohort (8.3%). When the cases were compared with healthy control individuals, higher pre-pregnancy body mass index (p = 0.004), vaginal levels of Tannerella forsythia (p = 0.01), serum C-reactive protein (p = 0.01), and prior gestational diabetes mellitus (p = 0.006) emerged as risk factors, even though the clinical periodontal disease failed to reach statistical significance (50% in those with gestational diabetes mellitus vs. 37.3% in the healthy group; p = 0.38).
Fluoride Uptake by Plaque from Water and from Dentifrice
Authors: Pessan J.P. , Silva S.M.B. , Lauris J.R.P. , Sampaio F.C. , Whitford G.M. , Buzalaf M.A.R.
Published: January 2009

It has been suggested that fluoride retention in plaque is limited by available binding sites. We determined the effects of fluoridated or placebo dentifrices on plaque and salivary fluoride concentrations [F]s in communities with different water fluoride concentrations (0.04, 0.85, 3.5 ppm). After one week of dentifrice use, samples were collected 1.0 and 12 hrs after the last use of dentifrices. After the use of fluoridated dentifrice, plaque fluoride concentrations were higher at both times, except at 12 hrs in the 3.5-ppm community. Plaque concentrations at 1.0 hr after the use of fluoridated dentifrice increased almost constantly (6.5 mmol/kg), but then decreased approximately 50% at 12 hrs in each community. Unlike previous studies, the present findings suggest that the use of fluoridated dentifrice is likely to increase plaque fluoride concentrations significantly for up to 12 hrs in areas where the water contains fluoride close to 1.0 ppm. As previously reported, plaque fluoride concentrations were directly related to calcium concentrations.
Dental Amalgam and Antibiotic- and/or Mercury-resistant Bacteria
Authors: Roberts M.C. , Leroux B.G. , Sampson J. , Luis H.S. , Bernardo M. , Leitão J.
Published: January 2009

Mercury emitted from dental amalgam may select for increased numbers of antibiotic- or mercury-resistant commensal bacteria in patients and increase their risk for bacterial diseases that are resistant to common therapies. We hypothesized that the presence of dental amalgams would increase the level of mercury-, tetracycline-, ampicillin-, erythromycin-, or chloramphenicol-resistant oral and urinary bacteria as compared with levels in children receiving composite fillings. Samples were collected at baseline, 3–6 months after the initial dental treatment, and annually for 7 years of follow-up. There were no statistically significant differences between treatment groups in the numbers of bacteria growing on antibiotic- or mercury-supplemented plates. This study provided no evidence that amalgam fillings on posterior teeth influenced the level of antibiotic- or mercury-resistant oral or urinary bacteria as detected by culture.
Effects of Ethanol Consumption on Periodontal Inflammation in Rats
Authors: Irie K. , Tomofuji T. , Tamaki N. , Sanbe T. , Ekuni D. , Azuma T. , Maruyama T. , Yamamoto T.
Published: January 2009

Studies suggest a correlation between ethanol consumption and periodontal disease. We hypothesized that elevated levels of blood reactive oxygen species following ethanol consumption may increase inflammation in periodontal tissue. Rats were divided into 4 groups (6–7 rats/group). Two groups were fed an ethanol-containing liquid diet, and 2 groups were fed a pair-fed control diet. In one of each dietary group, periodontitis was ligature-induced, while the other group was left unligated. Chronic ethanol feeding alone decreased the ratio of reduced/oxidized glutathione and increased 8-hydroxydeoxy-guanosine and tumor necrosis factor (TNF)-α levels in the gingiva. Blood hydroperoxides were also increased. In ligature-induced periodontitis lesions, ethanol feeding enhanced polymorpho-nuclear leukocyte infiltration and TNF-α expression. The results suggest that chronic alcohol consumption increased periodontal inflammation, oxidative damage, and TNF-α production and had an additive effect on polymorphonuclear leukocyte infiltration and gingival oxidative damage, increasing the severity of periodontal inflammation in the ligature model.
Ca Pre-rinse Greatly Increases Plaque and Plaque Fluid F
Authors: Vogel G.L. , Schumacher G.E. , Chow L.C. , Takagi S. , Carey C.M.
Published: January 2009

Previous studies demonstrated that a Ca pre-treatment greatly increases salivary F from a subsequent NaF rinse. This study examines if these increases are found in plaque and plaque fluid F. Thirteen individuals accumulated plaque before rinsing with: (1) 12 mmol/L NaF (228 μg/g F), (2) 150 mmol/L Ca rinse, or (3) the Ca rinse followed by the F rinse. One hr later, plaque samples were collected, the plaque fluid was recovered, and the plaque residues were extracted 5 times with pH 6.8 or pH 4.8 buffers, and then by acid. The F in each extract after the Ca rinse/F rinse greatly exceeded the corresponding F from the NaF rinse. Consequently, the Ca rinse/F rinse increased the total plaque F and the plaque fluid F by 12x and 5x, compared with the NaF rinse alone. These and the previous salivary results suggest that a Ca pre-treatment may increase the cariostatic effects of topical F agents.
Professional Oral Health Care Reduces the Number of Oropharyngeal Bacteria
Authors: Ishikawa A. , Yoneyama T. , Hirota K. , Miyake Y. , Miyatake K.
Published: January 2009

Silent aspiration of oropharyngeal pathogenic organisms is a significant risk factor causing pneumonia in the elderly. We hypothesized that regular oral hygiene care will affect the presence of oropharyngeal bacteria. Professional cleaning of the oral cavity and/or the gargling of a disinfectant liquid solution was performed over a five-month period in three facilities for the dependent elderly. Total oropharyngeal bacteria, streptococci, staphylococci, Candida, Pseudomonas, and black-pigmented Bacteroides species were monitored. The levels of these oropharyngeal bacteria decreased or disappeared after weekly professional oral health care, i.e., cleaning of teeth, dentures, tongue, and oral mucous membrane by dental hygienists. After lunch, gargling with povidone iodine was shown to be less effective than professional oral care. These findings indicate that weekly professional mechanical cleaning of the oral cavity, rather than a daily chemical disinfection of the mouth, can be an important strategy to prevent aspiration pneumonia in the dependent elderly.
The Seven-year Outcome of an Early Orthodontic Treatment Strategy
Authors: Kerosuo H. , Väkiparta M. , Nyström M. , Heikinheimo K.
Published: January 2009

The benefits of early orthodontic treatment are continuously discussed, but studies are few. We examined whether definite need for orthodontic treatment could be eliminated in public health care by systematically focusing on early intervention. One age cohort living in a rural Finnish municipality (N = 85) was regularly followed from ages 8 to 15 years, and persons with malocclusions were treated according to a pre-planned protocol. Treatment need was assessed according to the Dental Health Component (DHC) of the Index of Orthodontic Treatment Need, and treatment outcome by the Peer Assessment Rating Index (PAR). Fifty-two percent of the cohort received treatment, and definite treatment need decreased from 33% to 9%. In the treated group, the mean PAR score reduction was 63%, and 51% showed more than 70% improvement. The results suggest that an early treatment strategy may considerably reduce the need for orthodontic treatment in public health care with limited specialist resources.
Ectopic Maxillary Canines: Segregation Analysis and a Twin Study
Authors: Camilleri S. , Lewis C.M. , McDonald F.
Published: January 2009

The etiology of ectopic canines is controversial, with opinion divided as to a genetic or environmental mechanism. This study addressed the hypothesis that genetic factors play a role in the etiology of ectopic maxillary canines. Sixty-three probands were identified, and information on the dental status of 395 relatives was determined. Pedigrees were constructed and the Relative Risk calculated. Complex segregation analysis was carried out by means of the Pedigree Analysis Package. The best mathematical model obtained was a single dominant gene with autosomal transmission, incomplete penetrance, and highly variable expression. Only two of seven pairs of monozygotic twins were concordant for ectopic canines. This is consistent with environmental or epigenetic variables affecting the phenotype. The low concordance rate is consistent with the low penetrance determined by the segregation analysis and further supports the existence of environmental factors.
SCPP Gene Evolution and the Dental Mineralization Continuum
Authors: Kawasaki K. , Weiss K.M.
Published: January 2009

Many genes critical to vertebrate skeletal mineralization are members of the secretory calcium-binding phosphoprotein (SCPP) gene family, which has evolved by gene duplication from a single ancestral gene. In humans, mutations in some of these SCPP genes have been associated with various diseases related to dentin or enamel hypoplasia. Recently, systematic searches for SCPP genes of various species have allowed us to investigate the history of phylogenetically variable dental tissues as a whole. One important conclusion is that not all disease-associated SCPP genes are present in tetrapods, and teleost fish probably have none, even in toothed species, having acquired their complement of SCPP genes through an independent duplication history. Here, we review comparative analyses of mineralized dental tissues, with particular emphasis on the use of SCPPs, within and between tetrapods and teleosts. Current knowledge suggests a close relationship among bone, dentin, teleost fish enameloid (enamel-like hard tissue), and tetrapod enamel. These tissues thus form a mineralized-tissue continuum. Contemporary dental tissues have evolved from an ancestral continuum through lineage-specific modifications.
Quantifying the Strength of a Resin-coated Dental Ceramic
Authors: Addison O. , Marquis P.M. , Fleming G.J.P.
Published: January 2009

Resin luting all-ceramic restorations increases clinical performance; however, the strengthening mechanisms are not fully understood. The authors have previously proposed the existence of a resin-ceramic hybrid layer, and the hypothesis tested was that ceramic strength enhancement was conferred by the characteristics of the resin-ceramic hybrid layer. Dentin porcelain discs were polished with a P4000-grade abrasive paper, and half were centrally indented at 9.8 N. Further discs were alumina-air-abraded. Groups of 30 specimens were coated with resin cement thicknesses varying from 0 to 250 ± 20 μm before bi-axial flexure testing. Following investigation of residual stresses by annealing, regression analysis enabled us to calculate the magnitude of ’actual’ strengthening for a theoretical ’zero’ thickness of resin cement on each surface texture. Accounting for resin bulk strengthening, resin cement coating significantly increased the mean strength that was attributed to a resin-ceramic hybrid layer sensitive to surface texture.
Damage Maps for Layered Ceramics under Simulated Mastication
Authors: Kim J.-H. , Kim J.-W. , Myoung S.-W. , Pines M. , Zhang Y.
Published: January 2009

Ceramic restorations, whether monolithic (single layer) or porcelain-veneered, often chip and fracture from repeated occlusal loading. Occlusion involves the opposing tooth sliding along the cuspal incline surface with an applied biting force (off-axis loading). We hypothesized that off-axis contact–load–slide–liftoff fatigue, as compared with normal axial fatigue loading, produces different fracture modes and fatigue lifespans of layered ceramics. Monolithic glass plates were epoxy-bonded to polycarbonate substrates as a transparent model for an all-ceramic crown on dentin. Off-axis and axial (control) cyclic loading was applied through a hard sphere in water, with a mouth-motion machine. The off-axis loading is more deleterious for contact-induced occlusal surface fracture, but less harmful for flexure-induced cementation surface fracture of brittle layers than the axial loading. This is because of the tangential load component associated with the off-axis loading. Clinical relevance is discussed.
Salivary Procalcitonin and Periodontitis in Diabetes
Authors: Bassim C.W. , Redman R.S. , DeNucci D.J. , Becker K.L. , Nylen E.S.
Published: January 2009

Periodontitis and type 2 diabetes are co-morbid conditions, both characterized by infectious susceptibility. We investigated procalcitonin (ProCT) levels in the serum and saliva of persons with periodontitis and type 2 diabetes (n = 20), to determine if these levels are altered by periodontitis activity or by hyperglycemia. Persons with severe periodontitis showed higher levels of salivary-ProCT than did those with moderate periodontitis (241 ± 71 vs. 77 ± 516 pg/mL, p = 0.02) and higher levels than did healthy control individuals (118 ± 26 pg/mL, p = 0.05). Salivary-ProCT levels were correlated with bleeding-on-probing (r = 0.45, p = 0.05), as well as with HgbA1c (r = 0.49, p = 0.03). Salivary levels of ProCT were higher than serum levels for the periodontitis/diabetes group (152 ± 37 vs. 78 ± 17 pg/mL, p = 0.02) and the control group (118 ± 146 vs. 48 ± 17 pg/mL, p = 0.01). Persons with periodontitis and type 2 diabetes have salivary-ProCT levels that reflect their degree of periodontitis activity and hyperglycemia. This study demonstrates, for the first time, the presence of procalcitonin (ProCT), an established serum marker of infection, in saliva.
Synergism between TLRs and NOD1/2 in Oral Epithelial Cells
Authors: Uehara A. , Takada H.
Published: January 2009

Oral epithelium is the first barrier against oral bacteria in periodontal tissue. Oral epithelial cells constitutively express Toll-like receptors (TLRs) and NOD1/2, functional receptors which induce the production of antibacterial factors such as peptidoglycan recognition proteins (PGRPs) and β-defensin 2, but not pro-inflammatory cytokines such as interleukin (IL)-8. In this study, we hypothesized that innate immune responses in the oral epithelium are enhanced in inflamed tissue. We found that NOD1 and NOD2 agonists, in combination with TLR agonists, synergistically induced production of PGRPs and of β-defensin 2 in human oral epithelial cells via NF-κB. In contrast, co-stimulation with NOD1/2 and TLR ligands had no effect on the production of pro-inflammatory cytokines (IL-6, IL-8, and monocyte chemoattractant protein-1). These findings indicate that, in innate immune responses to invading microbes, a combination of signaling through TLRs and NODs leads to the synergistic activation of antibacterial responses in the oral epithelium.
Analysis of the Degradation of a Model Dental Composite
Authors: Koin P.J. , Kilislioglu A. , Zhou M. , Drummond J.L. , Hanley L.
Published: January 2009

Dental composites undergo material property changes during exposure to the oral environment and may release compounds of potential toxicity, such as bisphenol A. Degradation of dental composites was studied in a simplified overlayer model in which bisphenol A diglycidyl methacrylate (BisGMA) was covalently bound to a porous silicon oxide surface. It was hypothesized that the chemical structure of this overlayer would allow release of bisphenol A, BisGMA, and the decomposition products thereof, upon exposure to water for an extended period. Liquid chromatography mass spectrometry found leaching of intact BisGMA and several degradation products that contained the bisphenol A moiety from the overlayer into distilled water after 2 wks of aging. The absence of bisphenol A release from the overlayer reduces concerns regarding its potential health risk in dental composites. Nevertheless, health concerns might arise with respect to BisGMA and the leached degradation products, since they all contain the bisphenol A moiety. Abbreviations: BisGMA, bisphenol A diglycidyl methacrylate; HPLC, high-performance liquid chromatography; LCMS, liquid chromatography mass spectrometry; MA, methacrylic acid; MPS, 3-(trimethoxysilyl) propyl methacrylate; m/z, mass-to-charge ratio; and TIC, total ion chromatogram.