bluuebunny/crossref_metadata_2025 huggingface dataset:
Mandibular Bone Formation Rates in Aged Ovariectomized Rats Treated with Anti-resorptive Agents Alone and in Combination with Intermittent Parathyroid Hormone
Authors: Hunziker J. , Wronski TJ , Miller S.C.
Published: January 2009

Anti-resorptive agents-including estrogen (E), calcitonin (CT), and bisphosphonates-are established in the treatment of osteoporosis. Intermittent administration of parathyroid hormone (PTH) stimulates bone formation and is a possible therapeutic agent for the restoration of bone mass. The purpose was to determine the effects of the anti-resorptive agents alone and in combination with intermittent PTH on bone formation in the mandible and a long bone in the aged ovariectomized (Ovx) rat. Female rats were ovariectomized or sham-operated. One year later, groups of Ovx rats were treated with E, CT, or the bisphosphonate, Risedronate (NE). Additional groups of Ovx rats were treated with each of these agents in combination with human PTH for 10 weeks. Estrogen treatment suppressed most indices of bone formation in the humerus and mandible, while NE decreased some indices of formation at the endocortical and endosteal surfaces of the mandible and humerus. Increased double-labeled surface and mineral apposition rates were observed only on the mandibular endosteal surfaces following CT treatment. When the anti-resorptive agents were combined with intermittent PTH, most indices of bone formation at all skeletal sites were substantially greater than those of the untreated Ovx controls as well as the E-, CT-, and NE-treated groups, respectively. These results provide additional evidence that established and emerging therapies for osteoporosis affect osseous tissues in the oral cavity, and this may influence the progression of diseases and/or aging changes at this site.
Interfacial Chemistry of the Dentin/Adhesive Bond
Authors: Spencer P. , Wang Y. , Walker M.P. , Wieliczka D.M. , Swafford J.R.
Published: January 2009

To date, the dentin/adhesive (d/a) bond has primarily been studied by morphologic analysis in conjunction with bond strength measurement. Although these analyses have enhanced our understanding, numerous questions about the chemistry have not been answered. The purpose of this study was to determine, at the molecular level, quantitative differences in the composition of the d/a interface formed under "wet" bonding conditions. The occlusal one-third of the crown was removed from 10 extracted, unerupted human third molars. The prepared dentin surfaces were treated, per manufacturers' instructions, with either Single Bond (3M) or One-Step adhesive (Bisco). Three-micron-thick sections of the d/a interface were cut and stained with Goldner trichrome for light microscopy. Companion slabs were analyzed with micro-Raman spectroscopy; the sample was placed at the focus of a 100x microscope objective, and spectra were acquired at 1-μm intervals across the d/a interface. Reference spectra were collected on model compounds of type I collagen and adhesive; the relative ratios of the integrated intensities of spectral features from adhesive and collagen were determined and plotted as a function of wt% adhesive. The same ratios were determined for the interface samples; by comparing these ratios with the calibration curve generated from the model compounds, we determined the percent of adhesive as a function of spatial position across the d/a interface. The relative percent of Single Bond adhesive was < 50% throughout more than half of the hybrid layer; One Step adhesive was ≥ 50% throughout most of the hybrid. The results from this study provide the first direct chemical evidence of phase separation in a dentin adhesive and its detrimental effect on the dentin/adhesive bond.
Effect of Food Size on the Movement of the Mandibular First Molars and Condyles during Deliberate Unilateral Mastication in Humans
Authors: Miyawaki S. , Ohkochi N. , Kawakami T. , Sugimura M.
Published: January 2009

To date, the effect of food size on the movement of the mandibular first molars and condyles during chewing has not been fully examined due to methodological problems. The purpose of the present study was to examine the previously unknown effect of food size on masticatory jaw movement. Using a face bow, light-emitting diodes, and optical cameras, we recorded, in 16 young adults with good occlusion, mandibular movement for the first 10 strokes during the unilateral chewing of similarly shaped hard gummy jellies weighing 5 g and 10 g, respectively. The chewing cycle time for the 10-g jelly was significantly longer than that for the 5-g jelly. The jaw-closing and -opening maximum velocities, gapes at the maximum velocities, and maximum gape were significantly faster and larger when 10-g gummy jellies were chewed, compared with results with 5-g jellies, at the mandibular first molar on the chewing side and the condyle on the non-chewing side. With the exception of the velocity, similar tendencies were observed at the molar on the non-chewing side. However, such significant differences were not detected at the condyle on the chewing side. The mandibular first molar on the chewing side was that most affected by food size, and the mean value of the maximum gape coincided approximately with the height of each jelly. These results suggest that humans chew hard coherent food such that the mandibular teeth that come into contact with the food open to a height equivalent to that of the food bolus, and that the changes in movement of the other parts of the mandible are minimized, ensuring efficient mastication.
Time-dependent Decrease and Seasonal Variation of the Porosity of Recently Erupted Sound Dental Enamel in vivo
Authors: Ten Bosch J.J. , Fennis-le Y. , Verdonschot E.H.
Published: January 2009

Recently erupted teeth are more sensitive to dental caries than teeth that have remained free from caries lesions for a few years after eruption. It has been hypothesized that this may be ascribed to differences in enamel porosity. The objective of the present work was to assess the time-dependence of electrical conductance, as an indication of porosity, of occlusal enamel in recently erupted permanent molar teeth. Fifty children aged 5-15 years of age, receiving regular dental care at six-month intervals, participated in the study when their first molar teeth (in 5- to 6-year-olds) or their second molar teeth (in 11- to 15-year-olds) had not been exposed to the oral environment for more than six months. On the first semi-annual check-up after eruption of a first or second molar, baseline diagnostic measurements, i.e., visual inspection and electrical conductance measurements (ECMs), were made at three or four pre-defined sites in the fissures. Subsequently, data collection was repeated every six months for three years. Sites were excluded from ECMs when a caries lesion was observed at a site by visual inspection. After 36 months, there were 257 sites in teeth considered sound upon visual examination. The ECM values of these sound sites showed a clear decrease with time after the first examination. The conductance decreased on average from 0.13 (MΩ)-1 to 0.059 (MΩ)-1. Since the conductance is assumed to be proportional to the porosity of the enamel, the latter decreased by a factor of 2.2 over the 36-month period. The results furthermore indicated a higher conductance for maxillary than for mandibular enamel. Almost all sites in that sample appeared to be in teeth that were observed for the first time during the months September to December. Electrical conductance, and therefore enamel porosity, of the sites showed a periodic variation with season of observation: In the fall, the conductance was higher than in the spring. This implies that a dentist should be more prudent in the fall than in the spring when indicating restorative treatment of an incipient caries lesion.
Mandibular Helical Axis Pathways during Mastication
Authors: Gallo L.M. , Fushima K. , Palla S.
Published: January 2009

Condylar and incisor trajectories are often used for the study of mandibular movements. Condylar trajectories, however, depend on the location of the reference point and can be interpreted erroneously. In contrast, the helical axis analysis yields an unequivocal description of rigid body kinematics. The aim of this study was to analyze the mandibular helical axis during mastication. Seven subjects without signs and symptoms of craniomandibular disorders and with class I occlusion were recorded by means of the optoelectronic system Jaws-3D during unilateral mastication of bread cubes (2-cm side). The helical axis was computed every 14 ms with a rotation threshold of 1°. Parameters describing its spatial orientation and position relative to the condyles were calculated. The helical axis changed orientation and position more pronouncedly during the closing than during the opening phases of mastication. The orientation varied significantly from beginning to end of closing but not of opening, indicating less fluctuation of the helical axis on opening than on closing. Also, the distance d CP between helical axis and reference condylar point varied more significantly (p < 0.05) on the working than on the balancing side: On the working side, d CP decreased during both opening and closing, whereas on the balancing side, d CP increased only for closing. Furthermore, the helical axis pathway often showed a bowing ventrally to the balancing condyle, indicating that, during closing, the balancing condyle still translated backward while essentially only rotation occurred around the working condyle. Thus, the helical axis changed its position and orientation continuously during mastication.
No Heritability of Temporomandibular Joint Signs and Symptoms
Authors: Michalowicz B.S. , Pihlstrom B.L. , Hodges J.S. , Bouchard T.J.
Published: January 2009

The causes of temporomandibular joint (TMJ)-rclatcd signs and symptoms are largely unknown. We tested the hypotheses that these signs and symptoms, as well as oral parafunctional habits, are substantially heritable. Questionnaire and clinical data were collected from 494 twins, including pairs of reared-apart and reared-together monozygotic (MZ) and dizygotic (DZ) twins. A history of joint-area pain, joint noises, and clenching and grinding habits was scorcd as present or absent. Twenty-nine percent of the population experienced at least one sign or symptom. Nearly one-quarter of subjects clenched or ground their teeth, and 8.7% reported a history of joint-area pain. Pain was associated with clenching, grinding, and joint noises. MZ twins were no more similar than DZ twins for any outcome, suggesting that genetic factors do not influence these traits in the population. Reared-together MZ twins were no more similar than reared-apart MZ twins, suggesting a negligible effect of the family environment on these outcomes. Environmental factors unique to each twin appeared to be the major determinants of variation in this population.
The Role of Vascular Endothelial Growth Factor in Human Dental Pulp Cells: Induction of Chemotaxis, Proliferation, and Differentiation and Activation of the AP-1-dependent Signaling Pathway
Authors: Matsushita K. , Motani R. , Sakutal T. , Yamaguchi N. , Koga T. , Matsuo K. , Nagaoka S. , Abeyama K. , Maruyama I. , Torii M.
Published: January 2009

Vascular endothelial growth factor (VEGF) is a potent mitogen in endothelial cells, but little is known about its activity in other cell types. To clarify the role of VEGF in human dental pulp cells and pulp tissue, we investigated the effects of VEGF on the chemotaxis, proliferation, and differentiation of human dental pulp cells. VEGF induced a strong chemotactic response in human dental pulp cells in a dose-dependent manner. VEGF also marginally enhanced the proliferation of human dental pulp cells and induced an increase in alkaline phosphatase in human dental pulp cells. However, these effects of VEGF were not observed in reference to human skin fibroblasts. Analyses by the reverse-transcription/polymerase-chain-reaction method and flow cytometry showed that the mRNAs of two VEGF receptors, fms-like tyrosine kinase and kinase insert domain-containing receptor, were expressed in human dental pulp cells, whereas only fms-like tyrosine kinase mRNA was expressed in human skin fibroblasts. VEGF induced the activation of activator protein I (AP-1) and c-fos mRNA expression in human dental pulp cells. The AP-1 inhibitor curcumin strongly inhibited VEGF-induced alkaline phosphatase production in human dental pulp cells. In addition, VEGF antisense oligonucleotide suppressed the production of VEGF and alkaline phosphatase in human dental pulp cells. These results suggest that VEGF produced by human dental pulp cells acts directly upon human dental pulp cells in an autocrine manner, and may promote the chemotaxis, proliferation, and/or differentiation of human dental pulp cells via the utilization of kinase insert domain-containing receptor and in part through AP-1 by increasing c-fos.
Prostaglandin E2 Enhances Bradykinin-evoked iCGRP Release in Bovine Dental Pulp
Authors: Goodis H.E. , Bowles W.R. , Hargreaves K.M.
Published: January 2009

Mediators produced during inflammation are responsible for hyperalgesia and expression of neurotransmitters and receptors in the nervous system. The production of bradykinin (BK) and the prostaglandins (PGs) may regulate initiation of pain. This study tested the hypothesis that BK and prostaglandin E2(PGE2) have a positive interaction in evoking neurosecretion of immunoreactive calcitonin gene-related peptide (iCGRP). Bovine dental pulp was prepared and stimulated by the superfusion method with BK alone and in combination with PGE2. Kinin receptor antagonists to bradykinin-evoked release of iCGRP were also tested. Also tested was the hypothesis that dental pulp contains cither the B, or B2or both BK receptors. Results showed that PGE2enhanced BK-evoked iCGRP release by more than 50%. Western immunoblots revealed detectable B, receptor protein with no detectable B1receptor protein. We conclude that BK evokes iCGRP release from bovine dental pulp which is enhanced by a positive interaction with PGE2. Neurosecretion is evoked from isolated terminals of dental pulp fibers via the bradykinin B2receptor-dependent mechanism.
Myosin Isoform Composition of the Human Medial and Lateral Pterygoid Muscles
Authors: Korfage J.A.M. , Van Eijden T.M.G.J.
Published: January 2009

The medial and lateral pterygoid muscles are different in structure as well as in function. The medial pterygoid muscle is concentrically active during jaw closing, and the superior head of the lateral pterygoid muscle is eccentrically active during jaw closing, while its inferior head is concentrically active during jaw opening. Architecturally, the medial pterygoid can deliver higher forces than the lateral pterygoid. We investigated whether these differences are reflected in the myosin heavy-chain (MyHC) composition and the fiber cross-sectional area (f-csa) of these muscles. The pterygoid muscles from eight cadavers were investigated by means of monoclonal antibodies against different isoforms of MyHC. The proportions of pure MyHC type I fibers did not differ significantly among the muscles (32% in medial pterygoid, 34% in superior head, and 36% in the inferior head of the lateral pterygoid), nor did the total proportions of pure MyHC type IIA and IIX fibers (16% in medial pterygoid, 26% in the superior head, and 19% in the inferior head of the lateral pterygoid). The mean f-csa of type I fibers was 1315 μm2, which did not differ significantly among the muscles, and was significantly larger than the f-csa of type 11A fibers. The relative proportions of hybrid fibers, which expressed more than one MyHC isoform, were 52% in the medial pterygoid, 40% in the superior head, and 45% in the inferior head of the lateral pterygoid and did not differ significantly among the muscles. The most abundant hybrid fiber types found were fibers expressing MyHCs-cardiac α+IIA and MyHCs-cardiac a+I+IIA. Significant regional differences were found in the proportions of MyHC type I fibers in the medial pterygoid and in the inferior head of the lateral pterygoid. Although the form and function of the muscles are different, we conclude that this is not reflected in their myosin isoform composition.
Cytokine Production and Bone Remodeling in Patients wearing Overdentures on Oral Implants
Authors: Schierano G. , Bassi F. , Gassino G. , Mareschi K. , Bellone G. , Preti G.
Published: January 2009

The stability of titanium dental implants is determined by osseointegration. Bone is a dynamic tissue continuously remodeled through resorption and formation, processes controlled by local cytokine production. This study investigated osseotropic cytokine expression in gingival mucosa, in the intraforamina and inferior first molar zones, during rehabilitation with implant-retained overdentures. Specimens were taken from six patients prior to placement of implants in the intraforamina bone; at connection of healing abutments; and 4, 8, and 12 months after prosthetic anchorage. Through semi-quantitative reverse-transcriptase polymerase chain-reaction, the following constitutively expressed cytokines were found at first surgical stage: interleukin-1, -6, and -8; small amounts of interleukin-11; stem cell factor; and transforming growth factor-ß1, -ß2, and -ß3. From the connection of healing abutments to 12 months after prosthetic anchorage, transforming growth factor-ß1, -ß2, and -ß3 were markedly higher than initial values. Expression of interleukin-6 and -8 decreased 8 months after prosthetic anchorage, while that of interleukin-1 increased at 12 months. In cultured gingival fibroblasts, modulation of cytokine secretion was also time-dependent. Cell culture supernatants influenced osteoclast-like multinucleated cell formation in long-term human marrow culture or osteoblast function, depending on the cytokine profile produced. These results are consistent with functional contributions of cytokines to osseointegration and minimization of posterior edentulous zone bone resorption.
Expression of mRNAs Encoding for α and β Integrin Subunits, MMPs, and TIMPs in Stretched Human Periodontal Ligament and Gingival Fibroblasts
Authors: Bolcato-Bellemin A.L. , Elkaim R. , Abehsera A. , Fausser J.L. , Haikel Y. , Tenenbaum H.
Published: January 2009

The biological mechanisms of tooth movement result from the cellular responses of connective tissues to exogenous mechanical forces. Among these responses, the degradation of the extracellular matrix takes place, but the identification of the molecular basis as well as the components implicated in this degradation are poorly understood. To contribute to this identification, we subjected human fibroblasts obtained from the periodontal ligament (PDLs) and from the gingiva (HGFs) to a continuous stretch to quantify the mRNAs encoding for various metalloproteinases (MMPs), their tissue inhibitors (TIMPs), and a and β integrin subunits. Both cell lines reacted by inducing the expression of the mRNAs encoding for MMP-1, MMP-2, TIMP-1, and TIMP-2, while other mRNAs did not vary (MTI-MMP, TIMP-3) or were not expressed (MMP-9). PDLs expressed selectively the mRNAs encoding for a4 and av, with no difference measurable under stretching, while the mRNAs encoding for a6 and β1 were increased and the one encoding for a5 was decreased. HGFs increased the mRNAs encoding for α2, α6, β1, and β3 and decreased the one encoding for a3. Analysis of our data indicated that stretched HGFs and PDLs induced the same pattern of mRNAs encoding for MMPs and TIMPs but differed for those encoding various integrin subunits, known to act as protein receptors in mechanotransduction.
Effects of Low-energy CO2 Laser Irradiation and the Organic Matrix on Inhibition of Enamel Demineralization
Authors: Hsu C.-Y.S. , Jordan T.H. , Dederich D.N. , Wefel J.S.
Published: January 2009

In the past two decades, accumulated evidence has clearly demonstrated the inhibitory effects of laser irradiation on enamel demineralization, but the exact mechanisms of these effects remain unclear. The purpose of this study was to investigate the effects of low-energy CO2 laser irradiation on demineralization of both normal human enamel and human enamel with its organic matrix removed. Twenty-four human molars were collected, cleaned, and cut into two halves. One half of each tooth was randomly selected and its lipid and protein content extracted. The other half of each tooth was used as the matched control. Each tooth half had two window areas. All the left windows were treated with a low-energy laser irradiation, whereas the right windows served as the non-laser controls. After caries-like lesion formation in a pH-cycling environment, microradiographs of tooth sections were taken for quantification of demineralization. The mean mineral losses (with standard deviation) of the enamel control, the lased enamel, the non-organic enamel control, and the lased non-organic enamel subgroups were 3955 (1191), 52(49), 4565(1311), and 1191 (940), respectively. A factorial ANOVA showed significant effects of laser irradiation (p = 0.0001), organic matrix (p - 0.0125), and the laser-organic matrix interaction (p = 0.0377). The laser irradiation resulted in a greater than 98% reduction in mineral loss, but the laser effect dropped to about 70% when the organic matrix in the enamel was removed. The results suggest that clinically applicable CO2 laser irradiation may cause an almost complete inhibition of enamel demineralization.
The Real Performance of Bitewing Radiography and Fiber-Optic Transillumination in Approximal Caries Diagnosis
Authors: Vaarkamp J. , Ten Bosch J.J. , Verdonschot E.H. , Bronkhorst E.M.
Published: January 2009

For both general practitioners and researchers in caries diagnostics, the true validity of available diagnostic techniques is of considerable interest. Yet, for both bitewing radiography and fiber-optic transillumination, this is still not accurately known, nor is it clear which of the two techniques performs best clinically. This study's purpose was to estimate the clinical performance of the two techniques in diagnosing approximal caries lesions in low-caries-prevalence populations. Clinical studies that compare the two techniques were selected from literature. We determined 2 x 2 contingency tables from these studies and calculated one overall contingency table. The cut-off for decay was at dentinal caries. Assuming that erroneous outcomes from both techniques are mutually independent, we expressed diagnostic sensitivity and specificity of the two techniques as functions of the contingency table cell contents, with caries prevalence as the parameter. Because the caries prevalence was unknown, every sensitivity and specificity value was possible. From the conditions that sensitivity, specificity, and caries prevalence are always between one and zero, a limited range of sensitivity and specificity values was obtained. Three situations were examined: Bitewing radiography specificity is 1, fiber-optic transillumination specificity is 1, and both specificities are equal. Under these conditions, the bitewing radiography sensitivity was between 1.00 and 0.71 ± 0.01, and the fiber-optic transillumination sensitivity was between 0.70 ± 0.01 and 0.50 ± 0.02. Both specificities were between 1.00 and 0.99. We concluded that the two techniques have comparable specificities, but that the fiber-optic transillumination sensitivity is significantly lower than that for bitewing radiography.
Evidence of Genetic Heterogeneity for Hereditary Gingival Fibromatosis
Authors: Hart T.C. , Pallos D. , Bozzo L. , Almeida O.P. , Marazita M.L. , O'Connell J.R. , Cortelli J.R.
Published: January 2009

Hereditary Gingival Fibromatosis (HGF) is the most common genetic form of gingival fibromatosis. The condition is most frequently reported to be transmitted as an autosomal-dominant trait, but autosomal-recessive inheritance has also been reported. The clinical presentation of HGF is variable, both in the distribution (number of teeth involved) and in the degree (severity) of expression. It is unknown if the variable clinical expression of HGF in different families is due to variable expression of a common gene mutation, allelic mutations, or non-allelic mutations. The apparently different modes of Mendelian inheritance of HGF suggest genetic heterogeneity. A gene locus for HGF has been localized to a 37-cM genetic interval on chromosome 2p21-p22 (D2S1352, Zmax = 5.10, θ = 0.00) flanked by D2S1788 and D2S441. To evaluate the generality of this linkage, we tested linkage with 9 markers from this candidate region in another large family, segregating for an autosomal-dominant form of generalized HGF, and found no support for linkage with any of these markers. Furthermore, statistical tests of this apparent heterogeneity were highly significant. Analysis of these data provides direct evidence that at least two genetically distinct loci are responsible for autosomal-dominant hereditary gingival fibromatosis.
Role of MAP Kinases p42erk-2/p44erk-1 in Cementum-derived Attachment-protein-mediated Cell Attachment
Authors: Komaki M. , Kang M. , Narayanan A.S.
Published: January 2009

Cementum-derived attachment protein (CAP) is a collagenous protein which promotes the attachment and spreading of periodontal cell types. We examined the role of the MEK/MAPK pathway in CAP-mediated fibroblast attachment. Human gingival fibroblasts were labeled with 35S-methionine, and the effect of MAP kinase pathway inhibitor PD98059 on attachment and spreading on CAP-coated dishes was examined. Effect on cell proliferation on CAP-coated plates was determined by [3H]-thymidine uptake. Attachment of human gingival fibroblasts to CAP-containing surfaces activated extracellular-signal-regulated kinases (ERK) ERK-2 and ERK-1. In the absence of serum, the ERKs were activated 15 min after attachment, reaching peak levels after 3 hours, and the activity was sustained for at least 12 hours. The enzyme levels were inhibited in cells treated with PD98059. The PD98059 did not significantly affect the kinetics of fibroblast attachment or the number of cells attaching to CAP-coated plates. However, cell spreading was retarded. DNA synthesis as indicated by [3H]-thymidine uptake was not significantly affected. In contrast to PD98059, attachment, spreading, and [3H]-thymidine uptake were inhibited by the protein tyrosine kinase inhibitor genestein. Our results indicate that the MEK/MAPK pathway participates in CAP-mediated fibroblast spreading, but cell attachment and proliferation do not appear to require ERK-2.
Cytokine Responses of Oral Epithelial Cells to Porphyromonas gingivalis Infection
Authors: Sandros J. , Karlsson C. , Lappin D.F. , Madianos P.N. , Kinane D.F. , Papapanou P.N.
Published: January 2009

Accumulating evidence indicates that epithelia are not merely mechanical barriers but also important elements of the innate immune system. The present study was performed to examine cytokine responses of oral epithelial cells after infection with the periodontal pathogen Porphyromonas gingivalis. The KB-cell line and primary cultures of periodontal pocket epithelium were infected with P. gingivalis for assessment of bacterial invasion by an antibiotic protection assay, and examinination of expression of interleukin-1 beta, interleukin-6, interleukin-8, and tumor necrosis factor-alpha by in situ hybridization and immunohistochemistry. We observed that P. gingivalis induces a strong cytokine response, positively correlated with the adhesive/invasive potential of the infecting strain, in both KB cells and primary cultures. These findings indicate that the epithelial cells of the periodontal pocket are an integral part of the immune system, eliciting cytokine responses to a bacterial challenge. In this context, the adhesive/invasive phenotype of P. gingivalis appears to contribute to pathogenicity.
Estrogenicity of Fissure Sealants and Adhesive Resins Determined by Reporter Gene Assay
Authors: Tarumi H. , Imazato S. , Narimatsu M. , Matsuo M. , Ebisu S.
Published: January 2009

It is controversial whether the dental resinous materials containing 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl] propane (BisGMA), which is synthesized from the estrogenic compound bisphenol A (BPA), include unreacted BPA and/or can mimic the effects of natural steroid hormones. In the present study, the estrogenic activities of 3 fissure sealants and 5 adhesive resins, which were all unpolymerized, were determined by means of a reporter gene assay, and the relevance of the components to the estrogenicity was investigated. Two commercially available sealants were confirmed to have estrogenic activity, although none of the tested materials contained BPA. In contrast, hydrophobic monomer bisphenol A dimethacrylate (BPA-DMA), which is also estrogenic, was found to be included in these estrogenic sealants in an amount greater than the minimum concentration to show estrogenicity. This suggests that the estrogenicity of the two proprietary sealants was associated with BPA-DMA rather than with BPA.
Collagenases in Different Categories of Peri-implant Vertical Bone Loss
Authors: Ma J. , Kitti U. , Teronen O. , Sorsa T. , Husa V. , Laine P. , Rönkä H. , Salo T. , Lindqvist C. , Konttinen Y.T.
Published: January 2009

The loosening of dental implants is associated with peri-implant vertical bone loss. The mechanisms and mediators of this bone destruction are not known. To test the hypothesis that collagenase-2 and collagenase-3 might be markers or maybe even mediators in this process, we measured collagenase-2 (time-resolved immunofluorometric assay) and collagenase-3 (quantitative immunoblot) in peri-implant sulcus fluid in 49 implant sites in 13 patients. Vertical bone loss was graded as being < 1 mm, from 1 to 3 mm, or > 3 mm. The severity of inflammation, as rated according to Gingival Index, did not correlate with the category of bone loss (p > 0.05). Collagenase-2 and collagenase-3 were higher (p < 0.05) in the group which had lost > 3 mm of bone than in the two other groups. Gingival Index is not a clinically important marker for bone loss, but collagenase-2 and collagenase-3 in peri-implant sulcus fluid are. They might participate in peri-implant osteolysis.
Osteoprotegerin and Osteoclast Differentiation Factor in Tooth Eruption
Authors: Wise G.E. , Lumpkin S.J. , Huang H. , Zhang Q.
Published: January 2009

A critical cellular event in tooth eruption is the formation of osteoclasts that are needed for bone resorption to form an eruption pathway. To analyze molecular regulation of osteoclast formation and activation, we examined the expression of osteoprotegerin (OPG), an inhibitor of osteoclast formation. In vivo, the gene expression of OPG is reduced in the dental follicle of the first mandibular molar of the rat at day 3 post-natally and in the mouse at day 5. This correlates with the days of maximal mononuclear cell influx and osteoclast numbers in the rat and mouse. Thus, inhibition of OPG gene expression on these days might allow osteoclasts to be formed and/or activated. In vitro studies demonstrated that both colony-stimulating factor-1 and parathyroid hormone-related protein reduced OPG gene expression in follicle cells, suggesting that these are candidate molecules for the in vivo inhibition of OPG expression. Osteoclast differentiation factor (ODF) immunolocalizes to the alveolar bone stromal cells adjacent to the follicle, whereby it might act to stimulate fusion of the mononuclear cells in the follicle.
Evidence for Charge Domains on Developing Enamel Crystal Surfaces
Authors: Kirkham J. , Zhang J. , Brookes S.J. , Shore R.C. , Wood S.R. , Smith D.A. , Wallwork M.L. , Ryu O.H. , Robinson C.
Published: January 2009

The control of hydroxyapatite crystal initiation and growth during enamel development is thought to be mediated via the proteins of the extracellular matrix. However, the precise nature of these matrix-mineral interactions remains obscure. The aim of the present study was to use a combination of atomic and chemical force microscopy to characterize developing enamel crystal surfaces and to determine their relationship with endogenous enamel matrix protein (amelogenin). The results show regular and discrete domains of various charges or charge densities on the surfaces of hydroxyapatite crystals derived from the maturation stage of enamel development. Binding of amelogenin to individual crystals at physiological pH was seen to be coincident with positively charged surface domains. These domains may therefore provide an instructional template for matrix-mineral interactions. Alternatively, the alternating array of charge on the crystal surfaces may reflect the original relationship with, and influence of, matrix interaction with the crystal surfaces during crystal growth.
Butyric-acid-induced Apoptosis in Murine Thymocytes and Splenic T- and B-cells Occurs in the Absence of p53
Authors: Kurita-Ochiai T. , Ochiai K. , Fukushima K.
Published: January 2009

Butyric acid, an extracellular metabolite from periodontopathic bacteria, induces apoptosis in murine thymocytes, splenic T-cells, and human Jurkat T-cells. The present study examines the contributions of apoptosis-related proteins (Bcl-2, Bcl-XL, Bax, and p21 WAFI/CIP1) in the regulation of T-cell death induced by butyric acid, using p53 knock-out (p53-/-) and wild-type (p53+/+) mice. The results of a DNA fragmentation assay indicated that thymocytes, splenic T-cells, and B-cells from p53-/- mice were susceptible to butyric-acid-induced apoptosis to a degree similar to those from p53+/+ mice. Moreover, butyric acid significantly induced apoptosis in lymphocytes from both p53 +/+ and p53-/- mice in a concentration- and time-dependent fashion. Experiments with fractionated subpopulations of splenic T-cells revealed that DNA fragmentation was equally observed in CD4+ and CD8+ splenic T-cells from both p53+/+ and p53-/- lymphocytes. Activation of caspase-3, caspase-6, and caspase-8, but not of caspase-1, in butyric-acid-induced T-cell apoptosis occurred regardless of the presence of p53. Western blotting analysis of splenic T-cells showed that butyric acid treatment decreased Bcl-2 and Bcl-XL expressions in p53+/+ and p53-/- cells. Splenic T-cells had barely detectable Bax and p21WAF1/CIP1, regardless of whether butyric acid and/or p53 was present. These results suggest that butyric-acid-mediated apoptosis of murine T-cells takes place via a pathway that is independent of p53, and is followed by the p53-regulated proteins Bax and p21WAF1/CIP1, which lower the levels of the apoptosis antagonists Bcl-2 and Bcl-XL in cells.
Collagen XII Mutation Disrupts Matrix Structure of Periodontal Ligament and Skin
Authors: Reichenberger E. , Baur S. , Sukotjo C. , Olsen B.R. , Karimbux N.Y. , Nishimura I.
Published: January 2009

Collagen XII has been postulated to organize the extracellular matrix (ECM) architecture of dense connective tissues such as the periodontal ligament (PDL) and skin. The objective of this study was to test this hypothesis in transgenic mice carrying a dominant interference mutation of collagen XII. The truncated α1(XII) collagen minigene construct MXIINC3(-), driven by the mouse α2(I) collagen promoter, was prepared and used to generate transgenic mouse lines. The PDL matrix fibers of molar teeth lost the ordered architecture characteristic of ligament tissue without noticeable inflammation. Cellular cement appeared to be disrupted at the PDL insertion. By confocal laser scanning microscopy, the PDL of transgenic mice demonstrated swollen and irregularly arranged collagen fibers associated with internal porosity. The skin of transgenic mice revealed the lack of matrix fiber structure in the papillary dermis. These results indicated that the dominant interference mutation of collagen XII disorganized the ECM architecture of PDL and skin.
Detection of a Novel Mutation in X-linked Amelogenesis Imperfecta
Authors: Kindelan S.A. , Brook A.H. , Gangemi L. , Lench N. , Wong F.S.L. , Fearne J. , Jackson Z. , Foster G. , Stringer B.M.J.
Published: January 2009

Amelogenesis imperfecta (AI) is a heterogeneous group of inherited disorders of defective enamel formation. The major protein involved in enamel formation, amelogenin, is encoded by a gene located at Xp22.1-Xp22.3. This study investigated the molecular defect producing a combined phenotype of hypoplasia and hypomineralization in a family with the clinical features and inheritance pattern of X-linked amelogenesis imperfecta (XAI). Genomic DNA was prepared from buccal cells sampled from family members. The DNA was subjected to the polymerase chain-reaction (PCR) in the presence of a series of oligonucleotide primers designed to amplify all 7 exons of the amelogenin gene. Cloning and sequencing of the purified amplification products identified a cytosine deletion in exon VI at codon 119. The deletion resulted in a frameshift mutation, introducing a premature stop signal at codon 126, producing a truncated protein lacking the terminal 18 amino acids. Identifying mutations assists our understanding of the important functional domains within the gene, and finding another novel mutation emphasizes the need for family-specific diagnosis of amelogenesis imperfecta.
Dentists' Judgment Strategies on Prophylactic Removal of Mandibular Third Molars
Authors: Knutsson K. , Lysell L. , Rohlin M.
Published: January 2009

The number of molars selected for prophylactic removal varies widely among general dental practitioners and oral surgeons. To understand the basis for such variations, we investigated two hypotheses: (1) Individual judgment strategies will differ concerning the use of cues (items of information), and (2) few dentists will integrate the cues according to evidence in the literature. To analyze 30 general dental practitioners' (GDPs) and 10 oral surgeons' use of cues in the judgment preceding the treatment decision, we used the Brunwik's lens as a conceptual model. The cues were the patient's age, and the angular position and the degree of impaction of the molar. The clinical situation was simulated by written case descriptions. The proportion of variation explained by the cues and their combinations (total model) varied between 61% and 100% and between 4% and 76% as main effects. Two GDPs and one oral surgeon integrated the cues additively, i.e., any of the cues is independent of the other cues in the judgment. In general, the dentists integrated the cues interactively, i.e., the impact of one cue depends on the levels of some other cues. Even though most variations in judgments were accounted for by the cues, the dentists did not integrate the cues according to evidence in the literature and lacked insight into their decision-making thought processes.
Consive Review: Analysis of Ordinal Dental Data: Evaluation of Conflicting Recommendations
Authors: Cohen M.E.
Published: January 2009

Although recommendations for the appropriate analysis of non-normal and ordinal-scaled data have appeared in the dental research literature for many years, there is no consensus. When one is conducting statistical tests for differences between groups, the central concern is whether it is safe to use parametric tests ( e. g., analysis of variance), or if only non-parametric ranking tests should be considered. Relevant statistical and scientific issues associated with non-normality and measurement scale are reviewed, and three conclusions are reached regarding the analysis of dental data: (1) Parametric tests are sufficiently robust relative to typical violations of normality; (2) presumed statistical prohibitions against the application of parametric methods to ordinal data do not actually exist; and (3) 'ordinal' dental indices have sufficient quantitative meaning to be considered quasi-interval. For these reasons, parametric tests should not be avoided; they will be valid and usually more powerful and more easily applied to complex designs than nonparametric alternatives.
Biological Organization of Hydroxyapatite Crystallites into a Fibrous Continuum Toughens and Controls Anisotropy in Human Enamel
Authors: White S.N. , Luo W. , Paine M.L. , Fong H. , Sarikaya M. , Snead M.L.
Published: January 2009

Enamel forms the outer surface of teeth, which are of complex shape and are loaded in a multitude of ways during function. Enamel has previously been assumed to be formed from discrete rods and to be markedly aniostropic, but marked anisotropy might be expected to lead to frequent fracture. Since frequent fracture is not observed, we measured enamel organization using histology, imaging, and fracture mechanics modalities, and compared enamel with crystalline hydroxyapatite (Hap), its major component. Enamel was approximately three times tougher than geologic Hap, demonstrating the critical importance of biological manufacturing. Only modest levels of enamel anisotropy were discerned; rather, our measurements suggest that enamel is a composite ceramic with the crystallites oriented in a complex three-dimensional continuum. Geologic apatite crystals are much harder than enamel, suggesting that inclusion of biological contaminants, such as protein, influences the properties of enamel. Based on our findings, we propose a new structural model.
Mass Properties of the Pig Mandible
Authors: Zhang F. , Langenbach G.E.J. , Hannam A.G. , Herring S.W.
Published: January 2009

Specification of mass properties is an essential step in the modeling of jaw dynamics, but obtaining them can be difficult. Here, we used three-dimensional computed tomography (CT) to estimate jaw mass, mean bone density, anatomical locations of the mass and geometric centers, and moments of inertia in the pig jaw. High-resolution CT scans were performed at one-mm slice intervals on specimens submerged in water. The mean estimated jaw mass was 12% greater than the mean wet weight, and 33% more than the mean dry weight. Putative bone marrow accounted for an extra 13% of mass. There was a positive correlation between estimated mean bone density and age. The mass center was consistently in the midline, near the last molar. The mean distance between the mass center and geometric center was small, especially when bone marrow was taken into account (0.58 ± 0.21 mm), suggesting that mass distribution in the pig jaw is almost symmetrical with respect to its geometric center. The largest moment of inertia occurred around each mandible's superoinferior axis, and the smallest around its anteroposterior axis. Bone marrow contributed an extra 9% to the moments of inertia in all three axes. Linear relationships were found between the actual mass and a mass descriptor (product of the bounding volume and mean bone density), and between the moments of inertia and moments of inertia descriptors (products of the mass descriptor and two orthogonal dimensions forming the bounding box). The study suggests that imaging modalities revealing three-dimensional jaw shape may be adequate for estimating the bone mass properties in pigs.
Influence of Dentition Status on Physical Disability, Mental Impairment, and Mortality in Institutionalized Elderly People
Authors: Shimazaki Y. , Soh I. , Saito T. , Yamashita Y. , Koga T. , Miyazaki H. , Takehara T.
Published: January 2009

The loss of teeth is known to influence the mastication of foods and nutritional status. Therefore, we hypothesize that poor dentition status can impair the systemic health of the aged. To clarify the influence of dentition status on deterioration in physical ability, mental impairment, and mortality, we conducted a six-year prospective cohort study of the institutionalized elderly living in 29 of the 30 institutions for the elderly in Kitakyushu, Japan. Bivariate analysis revealed that worse dentition status at baseline led to significantly worse physical and mental impairment, and higher mortality. In a multiple logistic regression analysis, the physical ability of edentulous subjects without dentures significantly deteriorated compared with that of dentate subjects with 20 or more teeth. The six-year mortality rate of the edentulous subjects without dentures was significantly higher than that of the subjects with 20 or more teeth. Poorer dentition status, especially edentulousness without dentures, may therefore be related to deterioration in the systemic health of the aged.
New in vitro Model for the Acquired Enamel Pellicle: Pellicles Formed from Whole Saliva Show Inter-subject Consistency in Protein Composition and Proteolytic Fragmentation Patterns
Authors: Lamkin M.S. , Migliari D. , Yao Y. , Troxler R.F. , Oppenheim F.G.
Published: January 2009

The present investigation was undertaken to investigate the variability of proteins in whole saliva which adsorb to hydroxyapatite and are thus likely to be precursors of the acquired enamel pellicle. Whole-saliva proteins from 18 subjects were absorbed to hydroxyapatite, and the gel filtration patterns of released proteins revealed four major peaks and three minor peaks eluting between the major peaks. Amino acid analysis indicated that minor peaks contained fragments of proteins in major peaks, and this was confirmed by sequence analysis. Major peaks comprised 95% and minor peaks comprised 5% of protein absorbed to hydroxyapatite, suggesting a limited proteolytic capacity of whole saliva. HPLC elution patterns of components in minor peaks suggested that proteolysis is not totally random but is an orderly and consistent process. These studies suggest that whole saliva may be suitable as a model system for the investigation of post-secretory modifications of salivary proteins important for the formation of the acquired enamel pellicle.
Innervation of Human Tooth Pulp in Relation to Caries and Dentition Type
Authors: Rodd H.D. , Boissonade F.M.
Published: January 2009

The neural status of carious teeth, particularly those associated with a painful pulpitis, is largely unknown. This study sought to determine differences in the innervation density of human primary and permanent teeth and whether caries or painful pulpitis was associated with anatomical changes in pulpal innervation. Coronal pulps were removed from 120 primary and permanent molars with a known pain history. Teeth were categorized as intact, moderately carious, or grossly carious. Using indirect immunofluorescence, we labeled sections for the general neuronal marker, protein gene product 9.5. Using image analysis, we found permanent teeth to be significantly more densely innervated than primary teeth. While there was no significant correlation with reported pain experience, neural density in both dentitions increased significantly with caries. Analysis of these data suggests that caries-induced changes in neural density may be functionally more important in the regulation of pulpal inflammation and healing than in the processing and perception of dental pain.
The Relationship among Dental Status, Nutrient Intake, and Nutritional Status in Older People
Authors: Sheiham A. , Steele J.G. , Marcenes W. , Lowe C. , Finch S. , Bates C.J. , Prentice A. , Walls A.W.G.
Published: January 2009

Dental health status may influence nutrition. The objective of this part of the National Diet and Nutrition Survey was to assess if there is a relationship between dental status in people 65 years and older and intake of certain nutrients and any link between dental status and blood-derived values of key nutrients. Random national samples of independently living subjects and those living in institutions had dental examinations, interviews, four-day food diaries, and blood and urine analyzed. In the sample living independently, intakes of most nutrients were lower in edentate than dentate subjects. Intake of non-starch polysaccharides, protein, calcium, non-heme iron, niacin, and vitamin C was significantly lower in edentate subjects. People with 21 or more teeth consumed more of most nutrients, particularly of non-starch polysaccharide. This relationship in intake was not apparent in the hematological analysis. Plasma ascorbate and plasma retinol were the only analytes significantly associated with dental status.