bluuebunny/crossref_metadata_2025 huggingface dataset:
Acute-phase Inflammatory Response to Periodontal Disease in the US Population
Authors: Slade G.D. , Offenbacher S. , Beck J.D. , Heiss G. , Pankow J.S.
Published: January 2009

Moderate elevation of serum C-reactive protein (CRP) is a risk factor for cardiovascular disease among apparently healthy individuals, although factors that create this inflammatory response in the absence of systemic illness have not been clarified. This study aimed to: (1) evaluate associations among periodontal disease, established risk factors for elevated CRP, and CRP levels within the US population; and (2) determine whether total tooth loss is associated with reduced CRP. Data were obtained from the third National Health and Nutrition Examination Survey. A random sample of the US population was interviewed in their homes and examined at mobile examination centers. CRP was quantified from peripheral blood samples and analyzed as a continuous variable and as the prevalence of elevated CRP (≥ 10 mg/L). Some 12,949 people aged 18+ years who had periodontal examinations and an additional 1817 edentulous people aged 18+ years were included in the analysis. Dentate people with extensive periodontal disease (> 10% of sites with periodontal pockets 4+ mm) had an increase of approximately one-third in mean CRP and a doubling in prevalence of elevated CRP compared with periodontally healthy people. Raised CRP levels among people with extensive periodontal disease persisted in multivariate analyses (P < 0.01), with established risk factors for elevated CRP (diabetes, arthritis, emphysema, smoking, and anti-inflammatory medications) and sociodemographic factors controlled for. However, CRP levels were similarly raised in edentulous people. Furthermore, the established risk factors for elevated CRP modified relationships between oral status and CRP levels. Periodontal disease and edentulism were associated with systemic inflammatory response in the US population, most notably among people who had no established risk factors for elevated CRP.
Bond Strength of Resin to Acid-etched Dentin Studied by 13C NMR: Interaction between N-methacryloyl-ω-Amino Acid Primer and Dentinal Collagen
Authors: Nishiyama N. , Asakura T. , Suzuki K. , Komatsu K. , Nemoto K.
Published: January 2009

The application of the hydrophilic methacrylate primer to acid-etched dentin increases the bond strength of the resin to the acid-etched dentin. However, the mechanism for the bonding of the resin to dentinal collagen through the primer remains to be determined. Before a more effective adhesive primer can be developed, we must understand the adsorption behavior of the primer to the dentinal collagen. The purpose of this study was to determine how 5 derivatives of N-methacryloyl-ω-amino acid (NMwA) primers enhance the bonding of the resin to acid-etched dentin. The interaction between the NMwA primers and dentinal collagen was studied by the 13C NMR technique, including the observation of spin-lattice relaxation times, T1. When the dentinal collagen was dispersed into the NMwA solution, the T1 values of the two carbonyl carbons attributed to the amide and the carboxylic acid in the NMwA molecule decreased dramatically. This result was due to the interaction between the amide group and the carboxylic acid group in the NMwA molecule and the dentinal collagen molecule. The T1 values of these carbonyl carbons decreased when the number of methylene groups in the NMωA molecule increased. The interaction became stronger as the number of methylene groups in the NMwA molecule was increased. Further, the bond strength of the resin to the acid-etched dentin primed with NMwA increased with a decrease in the T1 value of the amide carbonyl carbon. The strength of the interaction of the NMwA primer to the dentinal collagen molecule, determined by the 13C NMR technique, showed a direct correlation with the bond strength of the resin to acid-etched dentin that was treated with the NMwA primer.
Antibacterial Activities and Release Kinetics of a Newly Developed Recoverable Controlled Agent-release System
Authors: Ehara A. , Torii M. , Imazato S. , Ebisu S.
Published: January 2009

We attempted to develop a resin with a recoverable antibacterial activity based on the desorption/adsorption of a cationic bactericide by the ion-exchange mechanism. The aims of this study were to investigate the release kinetics of the agent and the antibacterial activity of this newly designed resin system. An experimental resin was prepared by the addition of methacrylic acid as a cation-exchanger and a cationic antibacterial agent, cetylpyridinium chloride (CPC), to triethyleneglycol dimethacrylate. The amount of CPC desorbed from the experimental resin into buffer solutions at pH 4-8 was measured. The adsorption of CPC to control resin and re-adsorption of CPC to the experimental resin, which had once desorbed the agent, were also determined. The antibacterial activity of experimental resin against Streptococcus mutans was evaluated, and the relationship between bacterial acid production and antibacterial effect was assessed. The experimental resin desorbed CPC at pH << 6, and the amount of agent desorbed increased with increasing acidity. The control resin adsorbed CPC when immersed in CPC aqueous solution at a rate determined by the concentration of the agent and immersion time. The experimental resin, once desorbed CPC, could re-adsorb the bactericide by being exposed to a solution of the agent. Less plaque formed on the experimental resin, and the growth and survival of S. mutans was inhibited in the condition in which acid was produced. These results demonstrate that the resin system proposed was able to desorb and re-adsorb the cationic bactericide by an ion-exchange mechanism and could show an inhibitory effect on S. mutans growth and plaque formation.
The Non-collagenous Dentin Matrix Proteins are Involved in Dentinogenesis Imperfecta Type II (DGI-II)
Authors: Thotakura S.R. , Mah T. , Srinivasan R. , Takagi Y. , Veis A. , George A.
Published: January 2009

Dentinogenesis Imperfecta type II (DGI-II) is a localized form of mesodermal dysplasia of the dentin affecting both the primary and permanent dentitions. This is an autosomal-dominant disease in which there is a disorder in dentin mineralization. Several studies have localized DGI-II to human chromosome 4 in the region 4q 12-21. Many ECM genes—such as OPN, DMP1, DMP2, DMP3 (DSPP), and BSP—have been mapped to the same locus. Biochemical studies indicated that dentin phosphophoryn (DMP2) might be a candidate gene in DGI-II. In this study, we have used histological and RFLP analyses of tissues from a DGI-II-affected patient, as compared with two normal controls, to determine if DMP1, 2, or 3 was linked to DGI-II. The histology of the affected tooth was very different in the DGI-II patient as compared with the normals. In particular, the dentinal tubules in the DGI-1I patient were very irregular, which could be the result of perturbations in the process of dentin formation. Patient and control DNA samples were digested with EcoRI or Pstl and Southern-hybridized with the DMP1, DMP2, and DMP3 cDNAs. Few differences in the restriction pattern were observed between affected and normal samples for DMP1 and DMP3-3' region (phosphophoryn-like sequences) probes. On the other hand, DMP2 showed a dramatic shift in the restriction pattern in DGI-II. This study suggests that the different restriction enzyme digestion profiles of the DNA from the DGI-II patient, as probed by DMP2, might be related to the defective mineralization of dentin in DGI-II.
Choline Acetyltransferase, Acetylcholinesterase, and Nicotinic Acetylcholine Receptors of Human Gingival and Esophageal Epithelia
Authors: Thuong Nguyen V. , Hall L.L. , Gallacher G. , Ndoye A. , Jolkovsky D.L. , Webber R.J. , Buchli R. , Grando S.A.
Published: January 2009

A non-neuronal cholinergic system that includes neuronal-like nicotinic acetylcholine receptors (nAChRs) has recently been described in epithelial cells that line the skin and the upper respiratory tract. Since the use of nicotine-containing products is associated with morbidity in the upper digestive tract, and since nicotine may alter cellular functions directly via nAChRs, we sought to identify and characterize a non-neuronal cholinergic system in the gingival and esophageal epithelia. mRNA transcripts for a3, α5, α7, and β2 nAChR subunits, choline acetyltransferase, and the asymmetric and globular forms of acetylcholinesterase were amplified from gingival keratinocytes (KC) by means of polymerase chain-reactions. These proteins were visualized in the gingival and esophageal epithelia by means of specific antibodies. Variations in distribution and intensity of immunostaining were found, indicating that the repertoire of cholinergic enzymes and receptors expressed by the cells changes during epithelial maturation, and that an upward concentration gradient of free acetylcholine exists. Blocking of the nAChRs with mecamylamine resulted in reversible loss of cell-to-cell adhesion, and shrinking and rounding of cultured gingival KC. Activation of the receptors with acetylcholine or carbachol caused stretching and peripheral ruffling of the cytoplasmic aprons, and formation of new intercellular contacts. These results demonstrate that both the keratinizing epithelium of attached gingiva and the non-keratinizing epithelium lining the upper two-thirds of the esophageal mucosa possess a non-neuronal cholinergic system. The nAChRs expressed by these epithelia are coupled to regulation of cell adhesion and motility, and may provide a target for the deleterious effects of nicotine.
The Three-dimensional Cancellous Bone Architecture of the Human Mandibular Condyle
Authors: Giesen E.B.W. , Van Eijden T.M.G.J.
Published: January 2009

In the present study, we tested the hypothesis that the cancellous bone of the mandibular condyle is inhomogeneous and anisotropic. For this purpose, 11 mandibular condyles from embalmed human cadavers were scanned in a micro-CT system. Within each condyle, 9 volumes of interest were selected from different mediolateral and superoinferior regions. Several bone parameters were calculated to describe the morphology. It appeared that the cancellous bone of the condyle could be approximated by parallel plates. These plates were almost vertically oriented at an angle of 17° relative to the sagittal plane, i.e., perpendicular to the condylar axis. In the superior regions of the condyle, the cancellous bone had the largest bone volume fraction (0.19), associated with the thickest trabeculae (0.11 mm), and the highest trabecular number (1.72 mm-1 ). The lowest bone volume fraction (0.15) was found more inferiorly. The degree of anisotropy increased from superior to inferior across the condyle. No mediolateral differences in bone morphology were found, but superiorly central regions contained more bone than peripheral regions. The plate-like trabeculae could indicate that the condyle is optimally adapted to sustain loads from all directions in a plane perpendicular to the condylar axis. The high bone mass and lower anisotropy in the superior regions could enable the condyle to sustain multiple load directions. Toward the collum, the trabeculae are more aligned. This could point to stresses acting predominantly in one direction.
Use of Dental Care by HIV-infected Medical Patients
Authors: Coulter I.D. , Marcus M. , Freed J.R. , Der-Martirosian C. , Cunningham W.E. , Andersen R.M. , Maas W.R. , Garcia I. , Schneider D.A. , Genovese B. , Shapiro M.F. , Bozzette S.A.
Published: January 2009

Although increasing attention has been paid to the use of dental care by HIV patients, the existing studies do not use probability samples, and no accurate population estimates of use can be made from this work. The intent of the present study was to establish accurate population estimates of the use of dental services by patients under medical care. The study, part of the HIV Cost and Services Utilization Study (HCSUS), created a representative national probability sample, the first of its kind, of HIV-infected adults in medical care. Both bivariate and logistic regressions were conducted, with use of dental care in the preceding 6 months as the dependent variable and demographic, social, behavioral, and disease characteristics as independent variables. Forty-two percent of the sample had seen a dental health professional in the preceding 6 months. The bivariate logits for use of dental care show that African-Americans, those whose exposure to HIV was caused by hemophilia or blood transfusions, persons with less education, and those who were employed were less likely to use dental care (p < 0.05). Sixty-five percent of those with a usual source of care had used dental care in the preceding 6 months. Use was greatest among those obtaining dental care from an AIDS clinic (74%) and lowest among those without a usual source of dental care (12%). We conclude that, in spite of the high rate of oral disease in persons with HIV, many do not use dental care regularly, and that use varies by patient characteristics and availability of a regular source of dental care.
Antigenic Specificity of Gingival Crevicular Fluid Antibody to Actinobacillus actinomycetemcomitans
Authors: Ebersole J.L. , Cappelli D. , Steffen M.J.
Published: January 2009

Elevated antibody levels to periodontopathogens in GCF have been identified and used as support for local antibody synthesis in periodontitis. This study examined both cross-sectional and longitudinal GCF samples for the antigenic specificity of antibody in the fluid. GCF samples were collected from each tooth of 27 periodontitis patients infected with A. actinomycetemcomitans. Levels of IgG antibody in the GCF were assessed by means of an ELISA and compared with serum for determination of local elevations. A proportion of those GCF samples that exhibited significantly elevated antibody were examined by Western immunoblotting to outer membrane antigens from A. actinomycetemcomitans. Homologous sera were also examined for comparison of antibody specificities. Of the sites with elevated IgG antibody, 87% were colonized by A. actinomycetemcomitans; however, 46% of sites with A. actinomycetemcomitans infection did not have elevated antibody. Cross-sectional studies identified a 78 to 100% agreement between the antibody specificities in GCF and those in serum. Additionally, patterns of antibody reactivity in both GCF and serum in the subjects were often very distinctive. Longitudinal alterations in GCF antibody were examined in 15 patients through a monitoring interval of up to 2 years and showed a general conservation of specificities. However, 7/15 patients exhibited a definite acquisition of different antibody specificities during the monitoring. These results describe a relationship between elevated local antibody and A. actinomycetemcomitans infection. Furthermore, the antibody specificities in serum appear to reflect generally the local response to this pathogen.
Co-ordinated Mandibular and Head-Neck Movements during Rhythmic Jaw Activities in Man
Authors: Eriksson P.-O. , Häggman-Henrikson B. , Nordh E. , Zafar H.
Published: January 2009

Recent observations in man of concomitant mandibular and head movements during single maximal jaw-opening/-closing tasks suggest a close functional relationship between the mandibular and the head-neck motor systems. This study was aimed at further testing of the hypothesis of a functional integration between the human jaw and neck regions. Spatiotemporal characteristics of mandibular and associated head movements were evaluated for 3 different modes of rhythmic jaw activities: self-paced continuous maximal jaw-opening/-closing movements, paced continuous maximal jaw-opening/-closing movements at 50 cycles/minute, and unilateral chewing. Mandibular and head-neck movements were simultaneously recorded in 12 healthy young adults, by means of a wireless opto-electronic system for 3-D movement recordings, with retro-reflective markers attached to the lower (mandible) and upper (head) incisors. The results showed that rhythmic mandibular movements were paralleled by head movements. An initial change in head position (head extension) was seen at the start of the first jaw-movement cycle, and this adjusted head position was retained during the following cycles. In addition to this prevailing head extension, the maximal jaw-opening/-closing cycles were paralleled by head extension-flexion movements, and in general the start of these head movements preceded the start of the mandibular movements. The results support the idea of a functional relationship between the temporomandibular and the cranio-cervical neuromuscular systems. We therefore suggest a new concept for human jaw function, in which "functional jaw movements" are the result of activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlantooccipital, and cervical spine joints.
Three-dimensional Analysis of Root Canal Geometry by High-resolution Computed Tomography
Authors: Peters O.A. , Laib A. , Rüegsegger P. , Barbakow F.
Published: January 2009

A detailed understanding of the complexity of root canal systems is imperative to ensure successful root canal preparation. The aim of this study was to evaluate the potential and accuracy of a three-dimensional, non-destructive technique for detailing root canal geometry by means of high-resolution tomography. The anatomy of root canals in 12 extracted human maxillary molars was analyzed by means of a micro-computed tomography scanner (μCT, cubic resolution 34 μm). A special mounting device facilitated repeated precise repositioning of the teeth in the μCT. Surface areas and volumes of each canal were calculated by triangulation, and means were determined. Model-independent methods were used to evaluate the canals' diameters and configuration. The calculated and measured volumes and the areas of artificial root canals, produced by the drilling of precision holes into dentin disks, were well-correlated. Semi-automated repositioning of specimens resulted in near-perfect matching (< 1 voxel) when outer canal contours were assessed. Root canal geometry was accurately assessed by this innovative technique; therefore, variables and indices presented may serve as a basis for further analyses of root canal anatomy in experimental endodontology.
Immunolocalization and Adenoviral Vector-mediated Manganese Superoxide Dismutase Gene Transfer to Experimental Oral Tumors
Authors: Lam E.W.N. , Hammad H.M. , Zwacka R. , Darby C.J. , Baumgardner K.R. , Davidson B.L. , Oberley T.D. , Engelhardt J.F. , Oberley L.W.
Published: January 2009

The anti-oxidant enzyme system protects cellular macromolecules against damage from reactive oxygen species. One component of this system, manganese superoxide dismutase (MnSOD), has also been shown to display tumor suppressor gene-like activity. The purpose of this study was to examine changes in MnSOD expression during hamster cheek pouch carcinogenesis, and the effects of MnSOD overexpression using an adenoviral vector. Tumor induction was carried out using 7,12-dimethylbenz[α]anthracene. Animals were killed at periodic intervals, and check pouch tissues were excised and examined for MnSOD expression by immunohistochemistry and digital image analysis. We observed a reduction in MnSOD expression as early as 2 weeks after the start of carcinogen application. Low MnSOD expression persisted until the end of the 23-week experimental period. Solid hamster cheek pouch carcinoma xenografts were then established in nude mice. An adenoviral vector encoding the human MnSOD gene was delivered to the xenografts by direct injection. We observed high, immediate expression of MnSOD in the xenografts that persisted for 10 days following cessation of viral construct delivery. Delivery of the MnSOD construct resulted in a maximal 50% reduction in tumor growth compared with untreated controls. Our results suggest that MnSOD may be a tumor suppressor gene in the hamster cheek pouch model system.
Temperature Dependence of the Electrical Resistance of Sound and Carious Teeth
Authors: Huysmans M.C.D.N.J.M. , Longbottom C. , Christie A.M. , Bruce P.G. , Shellis R.P.
Published: January 2009

Temperature variations are expected to influence measurement error in electrical resistance of teeth. It was the aim of this study to determine the changes in electrical behavior of extracted human teeth due to temperature changes in the range of room temperature to intra-oral temperature. Nine extracted teeth were selected, and the occlusal or an approximal surface was chosen for measurement. Carious involvement of the surfaces ranged from sound to cavitated. Electrical impedance spectroscopy sweeps in a frequency range of about 100 kHz to 10 Hz were completed at selected temperatures between 22°C and 40°C. After fitting the data to equivalent circuits that yielded parameter values for components of the equivalent circuit, we calculated the dc bulk resistance ( Rb). The temperature dependence of Rb of the surfaces with different carious involvement was very similar, and the mean drop of Rb from 20 to 35°C was 45% (SD 2%). It was concluded that the electrical resistance of sound and carious tooth surfaces is inversely related to temperature.
Clinical, Radiographic, and Genetic Evaluation of a Novel Form of Autosomal-dominant Oligodontia
Authors: Goldenberg M. , Das P. , Messersmith M. , Stockton D.W. , Patel P.I. , D'Souza R.N.
Published: January 2009

A frameshift mutation recently identified within the paired domain of the transcription factor, PAX9, has been linked to a unique form of oligodontia in a single, multigenerational family (Stockton et al., 2000). We now describe the phenotypic and segregation analyses of this remarkable kindred, the initial approach taken to identify a candidate gene involved in this form of oligodontia, and the power of this single-family pedigree to generate significant linkage in a genome search. Of the 43 family members enrolled in this study, 21 individuals were affected with several congenitally missing permanent teeth. The pattern of inheritance of the oligodontia trait suggested the involvement of a single gene bearing a dominant mutation. To various degrees, affected members lacked permanent first, second, and third molars in all four quadrants. Several individuals with missing molars also lacked second premolars-most commonly, maxillary second premolars and mandibular central incisors. To the best of our knowledge, this pattern of non-syndromic, familial tooth agenesis has not been previously described in the literature. Since a missense mutation in the homeobox gene, MSX1, was previously linked to tooth agenesis in a single family lacking second premolars and third molars, we performed a mutational analysis of MSX1 by PCR. The absence of a mutation in exons 1 and 2 of MSX1 suggested that allelic mutations in the coding region of MSX1 are not associated with this phenotypically distinct form of oligodontia. Computer simulation of linkage analysis further proved that this pedigree alone was sufficient to generate a significant result for a total genome scan.
Cementum Attachment Protein Enriches Putative Cementoblastic Populations on Root Surfaces in vitro
Authors: BarKana I. , Narayanan A.S. , Grosskop A. , Savion N. , Pitaru S.
Published: January 2009

We tested the capacity of cementum attachment protein (CAP) to recruit putative cementoblastic populations to root surfaces in vitro by determining the phenotypic expression of periodontal ligament cloned cell populations. The clones were derived from cells that attached to either CAP-coated (experimental) or uncoated (control) root slices. Root slices were co-cultured with primary human periodontal ligament cells. Cloned and parent populations were analyzed for their capacity to express alkaline phosphatase (AP), osteopontin, bone sialoprotein (BSP), and CAP and to form mineralized tissue in vitro. The percentage of CAP- and BSP-positive clones was significantly higher in the experimental clones than in the controls. The percentage of cells positive for AP, BSP, and CAP was higher in the experimental clones than in their control counterparts. Mineralized tissue formation was observed only in the cell populations derived from the CAP-coated root slices. These results indicate that CAP is capable of recruiting putative cementoblastic populations on root slices in vitro and therefore might play an important role in cementogenesis during periodontal homeostasis and wound healing.
Reactive Oxygen Species Participation in Experimentally Induced Arthritis of the Temporomandibular Joint in Rats
Authors: Kawai Y. , Kubota E. , Okabe E.
Published: January 2009

In the temporomandibular joint (TMJ), it has been hypothesized that mechanical stresses lead to the oxidative stress of articular tissues. It has also been postulated that cells pertinent to arthritis-including endothelial cells and synovial cells-when stimulated by mechanical stresses and/or pro-inflammatory cytokines, promote oxidative damage. To determine the involvement of reactive oxygen species (ROS) in the diseased joint, we studied the generation of ROS in synovial fluid (SF) from interleukin-1α (IL-1α)-induced TMJ arthritis by electron spin resonance (ESR) spectroscopy, using the spin trap 5,5-dimethyl-l-pyrroline N-oxide (DMPO). The TMJ arthritis was experimentally induced in rats by the injection of human recombinant IL-1α into the TMJ; control rats were treated with normal saline solution. We found that the detected radicals in the collected SF were identified as a 1:2:2:1 quartet, characteristic of the hydroxyl radical-DMPO spin adduct. The ESR signal intensity of the hydroxyl radical-DMPO spin adduct in the SF from IL-1-treated rats was significantly higher than that from the control rats (P < 0.01). The results of ESR study also showed that hydroxyl radical (HO') was increased in a time-dependent fashion in the presence of superoxide anion radical (O2·-) scavenger superoxide dismutase (SOD); the formation of DMPO-HO' was strongly inhibited by the iron chelater deferoxamine. We could measure higher levels of free iron (Fe2+and Fe3+) in the SF from TMJ arthritis than in that from controls (P < 0.05). Analysis of the data obtained from the present study suggests that the HO' radical detected in SF from IL-1-induced TMJ arthritis is generated via a modified Haber-Weiss reaction (biological Fenton reaction) in which O2·-can subsequently result in the production of H2O2through dismutation reaction by SOD. Thus, HO' may be generated from the reaction of resultant H2O2with free iron ions. The results presented here provide the first evidence of involvement of ROS in IL-1-induced TMJ arthritis.
The Prevalence of Xerostomia and Salivary Gland Hypofunction in a Cohort of HIV-positive and At-risk Women
Authors: Navazesh M. , Mulligan R. , Komaroff E. , Redford M. , Greenspan D. , Pkelan J.
Published: January 2009

The association of xerostomia and salivary gland hypofunction with HIV infection has been established for men but not for women. We investigated the prevalence of these conditions in a national cohort (n = 733) of HIV-positive and at-risk HIV-negative women. Participants in this prospective cross-sectional study were recruited from the Women's Interagency HIV Study (WIHS) at five outpatient USA clinics. Xerostomia was assessed based on "yes" responses to a dry-mouth questionnaire. Samples of unstimulated whole and chewing-stimulated whole saliva were collected under standardized conditions. The major salivary glands were also evaluated clinically. The prevalence of dry-mouth complaint, the absence of saliva upon palpation, and zero unstimulated whole saliva (flow rate = 0 mL/min) were significantly (p = 0.001) higher in HIV-positive women. Adjusted odds of zero unstimulated whole saliva were significantly (p = 0.02) higher in HIV-positive women vs. HIV-negative women (OR = 2.86; 95% CI, 1.23 to 6.63). Significant (p = 0.03) univariate association was found between zero unstimulated whole saliva and CD4 counts. Adjusted odds of zero unstimulated whole saliva were significantly (p = 0.02) higher for HIV-positive women with CD4 < 200 compared with those with CD4 > 500 (OR = 2.61; 95% CI, 1.17 to 5.85). Chewing-stimulated flow rates were not significantly different between seropositive and seronegative women. The prevalence of xerostomia and salivary gland hypofunction appears to be significantly higher in HIV-positive women relative to a comparable group of at-risk seronegative women. Immunosuppression levels measured by CD4 cell counts are significantly associated with xerostomia and salivary gland hypofunction in a population of HIV-positive women.
Association of Salivary Flow Rates with Maximal Bite Force
Authors: Yeh C.-K. , Johnson D.A. , Dodds M.W.J. , Sakai S. , Rugh J.D. , Hatch J.P.
Published: January 2009

Mean salivary secretion and bite force decrease with advancing age. Previous studies have shown that salivary flow rates are influenced by mastication. In the present study, we examined the relationship between salivary flow rates and maximal bite force in a community-based sample of men and women 35 years of age or older. Salivary flow rates for unstimulated whole and unstimulated submandibular/sublingual (SMSL) saliva as well as citrate-stimulated parotid and SMSL saliva were measured in 399 subjects. Bite force was assessed with a bilateral force transducer. Pearson correlation analysis yielded significant positive correlations between bite force and flow rates for unstimulated whole saliva (r = 0.24, p < 0.0001), stimulated parotid saliva (r = 0.13, p < 0.03), unstimulated SMSL (r = 0.14, p < 0.0001), and stimulated SMSL (r = 0.16, p < 0.003). When adjusted for age and gender, the partial correlations between bite force and salivary flow rates remained significant for unstimulated whole saliva (r = 0.10, p < 0.05), stimulated parotid saliva (r = 0.13, p < 0.02), and stimulated SMSL saliva (r = 0.14, p < 0.006). Subjects were divided into four groups based on their maximal bite force score (low, medium low, medium high, and high). For each saliva type, the flow rate of the high-bite-force group was significantly greater than that of the low-bite-force group as well as that of the medium-high-bite-force group. These results confirm an age-related decrease in bite force and salivary flow rates and show that, regardless of age or gender, bite force is correlated with salivary flow.
High-temperature X-ray Diffraction Measurement of Sanidine Thermal Expansion
Authors: Mackert J.R. , Twiggs S.W. , Williams A.L.
Published: January 2009

Dental porcelains that are designed to be fused to PFM (porcelain-fused-to-metal) alloys are formulated by their manufacturers to be closely matched in thermal expansion to these alloys. The high thermal expansion of the mineral leucite has been exploited to regulate porcelain expansion. Leucite, however, has been observed to convert to the sanidine polymorph of feldspar during certain heat treatments within the normal firing range of dental porcelain. The effects of this conversion on porcelain thermal expansion and porcelain-metal thermal compatibility have been uncertain, due to the paucity of published data on the thermal expansion of sanidine. The purpose of this study was to measure the thermal expansion of sanidine by high-temperature x-ray diffraction over the temperature range in which thermal mismatch stresses can develop in porcelain-fused-to-metal restorations, i.e., from room temperature to 700°C. The lattice parameters a, b, c, and /3 were determined from the d-spacings and hkl values of multiple reflections by means of a least-squares iteration. The dependence of each lattice parameter on temperature was determined via analysis of variance, and the coefficient of thermal expansion, a, was obtained from this analysis. The lattice parameters of sanidine at room temperature were determined to be: a = 0.8524 ± 0.0015 nm, b = 1.3020 ± 0.0004 nm, c = 0.7165 ± 0.0002 nm, and β = 116.02° ± 0.01° (mean ± 95% confidence interval). The linear thermal expansion coefficient, α, over the range from room temperature to 700°C was determined to be 4.1 X 10-6 K-1 ± 0.6X 106 K-1 (mean ± 95% confidence interval). Because the coefficient of thermal expansion for sanidine is substantially lower than that of leucite (the effective linear thermal coefficient of thermal expansion of leucite over the range of 25° to 700°C is 28×10-6 K-1), the conversion of leucite to sanidine during porcelain heat treatments would produce a detrimental lowering of the porcelain thermal expansion.
High Glucose Suppresses Cathepsin Activity in Periodontal-ligament-derived Fibroblastic Cells
Authors: Nishimura F. , Naruishi K. , Yamada H. , Kono T. , Takashiba S. , Murayama Y.
Published: January 2009

The accumulation of extracellular matrices and integrins by high glucose has been reported in relation to diabetic complications. We previously reported that PDL cells expressed a higher amount of VLA-5 when cultured in high-glucose (4500 mg/L) medium than those cultured in low-glucose (1100 mg/L) medium. In this study, we aimed to address (1) whether this effect was mediated by the transcriptional level of the gene or the degradative level of the protein, and (2) whether this effect was mediated by TGF-β. The results indicated that the level of mRNA encoding a5 integrin did not change in PDL cells regardless of the concentration of glucose. Alternatively, high glucose suppressed cathepsin B+L activity. Additionally, the level of mRNA encoding TGF-β was not affected by high glucose, nor did an anti-TGF-β neutralizing antibody have an effect on the expression of β5 gene or cathepsin activity. Therefore, the effects of high glucose appeared to be mediated by impaired protein degradation, but not by autocrine TGF-β.
Measuring the Effect of Intra-oral Implant Rehabilitation on Health-related Quality of Life in a Randomized Controlled Clinical Trial
Authors: Awad M.A. , Locker D. , Korner-Bitensky N. , Feine J.S.
Published: January 2009

The importance of assessing the impact of treatments for chronic conditions on an individual's quality of life has been well-established. In this randomized clinical trial, oral-health-rclated quality of life, measured with the Oral Health Impact Profile (OHIP), was compared between two groups of edentulous patients. One group (n = 54) received mandibular implant-supported overdentures, and the other group (n = 48) received conventional dentures. Assessments were performed pre-treatment and two months after the prostheses were delivered. The multivariate model showed that implant treatment was significantly associated with lower post-treatment OHIP scores (p = 0.0002), indicating a better quality of life. In addition, pre-treatment OHIP scores, treatment allocation, age, sex, and marital status explained 31% of the variation in post-treatment OHIP scores (F = 0.0001). These results suggest that implant treatment provides significant short-term improvement over conventional treatment in oral-health-related quality of life.
Expression of the Antimicrobial Peptide, Human β-defensin 1, in Duct Cells of Minor Salivary Glands and Detection in Saliva
Authors: Sahasrabudhe K.S. , Kimball J.R. , Morton T.H. , Weinberg A. , Dale B.A.
Published: January 2009

The oral cavity is exposed to a variety of environmental insults. Salivary secretions play a critical role in maintaining oral health via innate host defense mechanisms and secretion of secretory IgA. Human B-defensins (hBD) are antimicrobial peptides that are a component of the innate immune response; they are expressed in epithelia and are proposed to have a role in mucosal defense. hBD-1 mRNA is constitutively expressed in numerous mucosal tissues, including human gingiva and submandibular and parotid glands. Our objective was to detect the expression and localization of hBD-1 peptide in human salivary glands and in saliva. Minor salivary gland tissue was obtained from biopsies of patients with mucoceles (n = 20). hBD-1 peptide was detected by immunohistochemistry; expression was localized to the ductal cells and not the acinar cells of these glands. The peptide was located apically, toward the lumen in the duct cells. Further evaluation showed stronger hBD-1 expression in ducts with periductal inflammation, as indicated by the immunostaining of serial sections with anti-CD45 specific for B- and T-lymphocytes. Statistical analysis showed a strong correlation of hBD-1 staining and inflammation. Results of immunolocalization suggest that hBD-1 functions to protect salivary glands from retrograde infection, that expression of the peptide is enhanced in inflamed sites, and that post-transcriptional regulatory mechanisms may be involved in hBD-1 peptide expression. Western immunoblot analysis also detected hBD-1 peptide in unstimulated, whole, acidified saliva from normal volunteers. However, hBD-1 peptide associated with salivary mucin resulted in loss of the detection in a dot-immunoblot assay. Association of hBD-1 with salivary mucin may facilitate peptide distribution and adherence to oral surfaces and aid its function within the oral cavity.
Induction of Intracellular Interleukin-1 β Signals via Type II Interleukin-1 Receptor in Human Gingival Fibroblasts
Authors: Chou H.-H. , Takashiba S. , Maeda H. , Naruishi K. , Nishimura F. , Arai H. , Lu H.-k. , Murayama Y.
Published: January 2009

The type II interleukin-1 receptor (IL-1RII) has been thought to be incapable of transducing signals to cells because of its short intracellular domain, while type I IL-1 receptor (IL-1RI) does transduce signals. Since over-expression of IL-1RII has been demonstrated to inhibit cytokine production in the fibroblastic cell line, it has been proposed to use IL-1RII to prevent IL-1-induced inflammation in connective tissue. In this study, trace amounts of IL-1RII mRNA expression were detected in human gingival fibroblasts (HGFs), which are affected by cytokines in inflammatory periodontal disease. Cloning of the cDNA encoding IL-1RII expressed in HGFs revealed 3 amino acid substitutions in the extracellular domain, when compared with the 408 residues predicted from human B-cells. Over-expression of IL-1RII on HGFs by gene transfer down-regulated the expression of IL-1β mRNA and IL-6 mRNA in response to IL-1β stimulation, while the expression of IL-8 mRNA was not affected. In the IL-1RII-transfected HGFs, phosphorylation of 25-and 74-kDa proteins was up-regulated upon IL-1β stimulation in the transfected HGFs. The phosphorylation of these proteins was suppressed by the addition of a neutralizing antibody against IL-1RII. These results suggest that the IL-1RII may regulate HGFs expression of cytokine mRNA upon IL-1β stimulation, possibly by altering the IL-1RI-dependent signals.
Effects of TGFβ 1 on Dental Pulp Cells in Cultured Human Tooth Slices
Authors: Melin M. , Joffre-Romeas A. , Farges J.-C. , Couble M.-L. , Magloire H. , Bleicher F.
Published: January 2009

Transforming Growth Factor-betal (TGFβ1) is a potent modulator of tissue repair in various tissues. To analyze its role during human dental repair, we used thick-sliced teeth cultured as described previously (Magloire et al., 1996). The supply of TGFβ1 to the pulp tissue was accomplished by means of a small tube glued onto the dentin. We show that this device allowed the growth factor to diffuse locally through dentinal tubules and to bind to the cells present in the coronal pulp opposite the TGFβ1-delivery tube. The tube was filled with 20 ng/mL TGFβ1, and slices were cultured for 4 days. Results show a preferential accumulation of cells in the odontoblastic and subodontoblastic layers in the vicinity of the tube. Cell proliferation increased in the subodontoblastic layer and in the underlying pulp, and BrdU-positive cells were abundant around the blood vessels. TGFβ1 induced type I collagen production by the odontoblastic/subodontoblastic/pulp cells in the stimulated zone, as demonstrated by in situ hybridization. These results suggest that TGFβ1 could be directly involved in the regulation of cell proliferation, migration, and extracellular matrix production in the human dental pulp and eventually in the repair process occurring after tooth injury.
Cloning, Characterization, and Expression Analysis of Mouse Enamelysin
Authors: Catering J. , Shi J. , Sun X. , Qian Q. , Yamada S. , Liu Y. , Krakora S. , Bartlett J.D. , Yamada Y. , Engler J.A. , Birkedal-Hansen H. , Simmer J.P.
Published: January 2009

Enamelysin is a recently isolated member of the matrix metalloproteinase (MMP) family of extracellular matrix (ECM)-degrading enzymes. Here we describe the isolation and characterization of the mouse enamelysin cDNA. Expression of mouse enamelysin was detectable only in ameloblasts and odontoblasts of developing teeth. Characterization of mouse enamelysin demonstrated that it is highly conserved in both its sequence content and pattern of expression relative to the porcine, human, and bovine homologues previously described.
Stress-field Translation in the Healthy Human Temporomandibular Joint
Authors: Gallo L.M. , Nickel J.C. , Iwasaki L.R. , Palla S.
Published: January 2009

Movement over the surface of the temporomandibular joint (TMJ) disc produces tractional forces. These forces potentially increase the magnitude of shear stresses and contribute to wear and fatigue of the disc. Theoretically, tractional forces in all synovial joints are the result of frictional forces, due to rubbing of the cartilage surfaces, and plowing forces, due to translation of the stress-field through the cartilage matrix as the joint surface congruency changes during motion. For plowing forces to occur in the TMJ, there must be mediolateral translation of the stress-field as the condyle moves dorsoventrally during jaw function. To test whether mediolateral stress-field translation occurs in the intact TMJ, we measured stress-field position and translation velocities in ten normal individuals during rhythmic jaw opening and closing. Magnetic resonance imaging and jaw tracking were combined to animate the three-dimensional position of the stress-field between the articulating surfaces. This allowed for mediolateral translation velocity measurements of the centroid of the stress-field. The results showed that during jaw opening and closing at 0.5 Hz, the average peak mediolateral translation velocity was 35 ± 17 mm/sec. When opening and closing increased to 1.0 Hz, the average peak velocity was 40 ± 19 mm/sec. Theoretical model estimates of the work done during such translation ranged from 6 to 709 mJ between the individual joints studied. The potential clinical importance of this measure is that long-term exposure of the TMJ disc to high work may result in fatigue failure of the TMJ disc.
Morning Breath Odor: Influence of Treatments on Sulfur Gases
Authors: Suarez F.L. , Furne J.K. , Springfield J. , Levitt M.D.
Published: January 2009

We assessed the effects of several treatments on the concentrations of oral sulfur-containing gases, compounds thought to be responsible for morning breath. Upon awakening in the morning, healthy volunteers collected oral gas samples before and for eight hours after the following treatments: no treatment, brushing the teeth with toothpaste, brushing the tongue, rinsing with 5 mL of 3% hydrogen peroxide, breakfast ingestion, or swallowing two BreathAsureR capsules. The gas samples were analyzed for sulfur-containing volatiles via gas chromatography. Baseline collections usually contained three sulfur gases: hydrogen sulfide, methanethiol, and dimethylsulfide. The effectiveness of a treatment was determined via comparison of the areas under gas concentrations-time curves with and without treatment. Brushing the teeth or ingestion of BreathAsureR had no apparent influence on the sulfur gases. Ingestion of breakfast and tongue brushing resulted in strong trends toward decreased sulfur gases. Hydrogen peroxide significantly reduced the sulfur gas concentrations for eight hours.
Inositol Hexasulphate, a Casein Kinase Inhibitor, Alters Enamel Formation in Cultured Embryonic Mouse Tooth Germs
Authors: Torres-Quintana M.A. , Lecolle S. , Septier D. , Palmier B. , Rani S. , MacDougall M. , Goldberg M.
Published: January 2009

Post-translational modification of enamel proteins is regulated by casein kinases (CK) and results in binding sites for calcium ions that subsequently play a key role during the initial stages of mineralization. Phosphorylation may also influence the secretion and extracellular organization of enamel proteins. Previous studies indicated that inositol hexasulphate inhibited the activity of CK-1 and/or CK-II in mouse tooth germs (Torres-Quintana et al., 1998). We hypothesized that inositol hexasulphate would also inhibit the activity of the specific casein kinase(s) identified in secretory ameloblasts, and would prove useful for determination of the extent to which phosphorylation might influence the organization of enamel proteins at early stages of enamel formation. To test this hypothesis, we dissected mandibular first molars from 18-day-old mouse embryos and cultured them for 11 days in the presence of 0-0.1 mM inositol hexasulphate. Ultastructural analysis revealed that the formation of enamel was largely impaired at an inhibitor concentration ≥ 0.08 mM. Quantitative radioautographic analysis of [33P]phosphate incorporation indicated that radiolabeled phosphate normally secreted into forming enamel was retained within ameloblasts. In contrast, no significant difference was observed between control and inositol-hexasulphate-treated tooth germs when cultures were labeled with [3H]serine and [3H]proline. SDS-PAGE and Western blot analysis confirmed that while inositol hexasulphate inhibited CK-mediated phosphorylation, it did not significantly alter protein synthesis. We conclude that impairment of phosphorylation leads to intracellular accumulation of [3H]phosphate-containing material by ameloblasts. We also conclude that when non-phosphorylated enamel matrix proteins are secreted, they are either unable to form an enamel matrix that supports mineralization, or they diffuse throughout a poorly mineralized dentin.
Elevated Intramuscular Concentration of Bradykinin in Jaw Muscle Increases the Fusimotor Drive to Neck Muscles in the Cat
Authors: Hellström F. , Thunberg J. , Bergenheim M. , Sjölander P. , Pedersen J. , Johansson H.
Published: January 2009

Patients suffering from temporomandibular dysfunction exhibit clinical findings such as fatigue, painful muscles, and muscles that are tender to palpation, not only in the temporomandibular area, but also in the neck/shoulder region. The mechanisms behind this are not known, although previous studies of similar spreading phenomena have revealed a possible involvement of the fusimotor system. In the present study, we evaluated the activity of this system by recording the activity of muscle spindle afferents from dorsal neck muscles after intramuscular injections of 6 μg to 25 μg bradykinin in the ipsilateral masseter muscle. A total of 23 muscle spindle afferents from the trapezius and splenius muscles was recorded at the C3-C4 level in 7 adult cats anesthetized with a-chloralose. Of these 23 afferents, 17 (74%) showed significantly different responses to bradykinin injections compared with control injections (dissolving agent, Tyrode), and the majority of the effects were compatible with an increased static fusimotor drive to the muscle spindle system. Thus, the results demonstrate potent reflex connections from groups III and IV masseter muscle afferents to fusimotor neurones on the C3-C4 level. It is concluded that the fusimotor system might play a significant role in the mechanisms behind the spread of muscle pain and tension from the temporomandibular region to the neck.