bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Mutation in ALK-1 Causes Hereditary Hemorrhagic Telangiectasia Type 2
Authors: Yan Z.M. , Fan Z.P. , Du J. , Hua H. , Xu Y.Y. , Wang S.L.
Published: January 2009

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal-dominant bleeding disorder and has two variants, HHT1 and HHT2, associated with mutations in the ENG and ALK-1 genes, respectively. We identified one Chinese HHT2 family to investigate the pathogenic gene and its possible mechanism of action by mutation screening and functional study. One substitution mutation (1717C>T) in exon 10 of the ALK-1 was found by sequencing of all exons of ENG and ALK-1 and caused a R479X mutation in the ALK-1 protein. ALK-1 mRNA and plasma thrombomodulin were measured by real-time quantitative PCR and ELISA, respectively. There was no significant difference in the expression levels of ALK-1 mRNA between patients and healthy individuals. A significantly higher level of thrombomodulin was found in HHT patients. These findings indicate that the mutation causes truncation of the ALK-1 protein at the post-transcriptional level; the plasma thrombomodulin may provide an easy diagnostic indicator in HHT patients.
Stress and Inflammation as a Detrimental Combination for Peri-implant Bone Loss
Authors: Heckmann S.M. , Linke J.J. , Graef F. , Foitzik Ch. , Wichmann M.G. , Weber H.-P.
Published: January 2009

The causes of peri-implant bone loss continue to be controversial. To determine the impact of biomechanical stress and inflammation, we investigated a total of 80 interforaminal implants in situ for more than 10 years. Two stress groups, with 14 patients each, were established: a low-stress situation with single-standing implants, and an increased-stress situation with splinted implants. To categorize inflammation, we introduced a Composite Inflammation Score using 4 inflammatory parameters. Peri-implant bone loss was calculated from digital panoramic radiographs. To differentiate between the effects of stress and inflammation, we compared bone loss in both stress groups at equivalent levels of inflammation. With greater Composite Inflammation Score values, a clear discrepancy between single-standing and splinted implants was evident (p = 0.117/0.000, regression analysis; p = 0.135/0.000, analysis of variance; p = 0.002, t tests). While stress and inflammation alone may not necessarily be detrimental factors, the presence of stress heightens peri-implant bone loss significantly as inflammation increases.
Nano DCPA-Whisker Composites with High Strength and Ca and PO4 Release
Authors: Xu H.H.K. , Sun L. , Weir M.D. , Antonucci J.M. , Takagi S. , Chow L.C. , Peltz M.
Published: January 2009

The main challenges facing composite restorations are secondary caries and bulk fracture. The objective of this study was to develop nano DCPA (dicalcium phosphate anhydrous)-whisker composites with high strength and Ca and PO4 ion release to combat caries. Flexural strength for the nano DCPA-whisker composites at a nano DCPA:whisker mass ratio of 1:2 ranged from (148 ± 9) MPa to (167 ± 23) MPa, significantly higher than the (103 ± 32) MPa of an inlay/onlay commercial control composite without Ca-PO4 release. The nano DCPA-whisker composite released PO4 to a concentration of (1.95 ± 0.13) mmol/L and Ca of (0.68 ± 0.05) mmol/L. Compared with previous conventional Ca- and PO4-releasing composites, the nano DCPA-whisker composites had strengths two-fold higher, and released comparable or higher levels of Ca and PO4. In conclusion, combining nano-DCPA with whiskers yielded novel composites that released high levels of Ca and PO4 requisite for remineralization. These high-strength composites may provide a unique combination of stress-bearing and caries-inhibiting capabilities.
Contraction Stress in Dentin Adhesives Bonded to Dentin
Authors: Hashimoto M. , de Gee A.J. , Kaga M. , Feilzer A.J.
Published: January 2009

Adhesives cured under constrained conditions develop contraction stresses. We hypothesized that, with dentin as a bonding substrate, the stress would reach a maximum, followed by a continuous decline. Stress development was determined with a tensilometer for two total-etch systems and two systems with self-etching primers. The adhesives were placed in a thin layer between a glass plate and a flat dentin surface pretreated with phosphoric acid or self-etching primer. After an initial maximum shortly after light-curing, the stress decreased dramatically for the total-etch systems (70%) and, to a lesser extent, for the adhesives with self-etching primers (30%). The greater stress decrease for the total-etch systems was ascribed to water and/or solvents released into the adhesives from the fully opened dentinal tubules by the pulling/sucking action of the contraction stress. This happened less with the adhesives with self-etching primers, where the tubules remained mainly closed.
Regulation of Cementoblast Function by P. gingivalis Lipopolysaccharide via TLR2
Authors: Nemoto E. , Darveau R.P. , Foster B.L. , Nogueira-Filho G.R. , Somerman M.J.
Published: January 2009

Although cementoblasts express Toll-like receptors (TLR)-2 and -4, little is known regarding the possible participation of cementoblasts in the inflammatory response. We investigated the effects of Porphyromonas gingivalis lipopolysaccharide (LPS), tetra- and penta-acylated lipid A species (designated PgLPS1435/1449 and PgLPS1690, respectively), on gene expression of osteoclastogenesis-associated molecules in murine cementoblasts. Real-time quantitative RT-PCR analysis revealed that receptor activator of NF-κB ligand (RANKL), interleukin-6, Regulated on activation, normal T-cell expressed, and secreted (RANTES), macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1 were rapidly and dramatically induced upon stimulation with PgLPS1690, but only slightly induced with PgLPS1435/1449. Osteoprotegerin, which was expressed constitutively, was not altered significantly. ELISA demonstrated synthesis of corresponding proteins. PgLPS1690 significantly induced transcripts for NF-κB, and this activation was inhibited by pre-treatment with anti-TLR-2 but not with TLR-4 antibodies. These results suggest that cementoblasts participate in the recruitment of osteoclastic precursor cells by up-regulation of chemokines/cytokines.
RANKL Increase in Compressed Periodontal Ligament Cells from Root Resorption
Authors: Yamaguchi M. , Aihara N. , Kojima T. , Kasai K.
Published: January 2009

The ligand receptor activator of NFκB (RANKL) plays an important role in osteoclast formation. However, very little is known about the relationship between external apical root resorption during orthodontic treatment and RANKL. We hypothesized that compressive force is responsible for RANKL formation and up-regulation of osteoclastogenesis in periodontal ligament (PDL) cells from patients with severe orthodontically induced external apical root resorption. RANKL and osteoprotegerin (OPG) production, TRAP-positive cells, and resorptive pits were determined. The increase of RANKL and the decrease of OPG were greater in the severe root resorption group than in the non-resorption group. The numbers of TRAP-positive cells and resorptive pits were also increased in the severe root resorption group than in the non-resorption group. These results support the hypothesis that the compressed PDL cells obtained from tissues with severe external apical root resorption may produce a large amount of RANKL and up-regulate osteoclastogenesis.
Human Immunodeficiency Virus (HIV) Transmission in Dentistry
Authors: Scully C. , Greenspan J.S.
Published: January 2009

HIV transmission in the health-care setting is of concern. To assess the current position in dentistry, we have reviewed the evidence to November 1, 2005. Transmission is evidently rare in the industrialized nations and can be significantly reduced or prevented by the use of standard infection control measures, appropriate clinical and instrument-handling procedures, and the use of safety equipment and safety needles. We hope that breaches in standard infection control will become vanishingly small. When occupational exposure to HIV is suspected, the application of post-exposure protocols for investigating the incident and protecting those involved from possible HIV infection further reduces the likelihood of HIV disease, and also stress and anxiety.
Remineralization of Enamel Caries Can Decrease Optical Reflectivity
Authors: Jones R.S. , Fried D.
Published: January 2009

The remineralization of enamel caries can lead to distinct optical changes within a lesion. We hypothesized that the restoration of mineral volume would result in a measurable decrease in the depth-resolved reflectivity of polarized light from the lesion. To test this hypothesis, we measured optical changes in artificial caries undergoing remineralization as a function of depth, using Polarization-sensitive Optical Coherence Tomography (PS-OCT). Lesions were imaged non-destructively before and after exposure to a remineralization regimen. After imaging, microradiographs of histological thin sections indicated that the significant reflectivity reduction measured by PS-OCT accurately represented the increase in mineral content within a larger repaired surface zone. Mineral volume changes arising from remineralization can be measured on the basis of the optical reflectivity of the lesion.
Static and Dynamic Loading Effects on Temporomandibular Joint Disc Tractional Forces
Authors: Nickel J.C. , Iwasaki L.R. , Beatty M.W. , Moss M.A. , Marx D.B.
Published: January 2009

Mechanical fatigue-related degeneration of the temporomandibular joint (TMJ) disc may be promoted by tractional forces. This study tested the hypotheses that tractional forces following static loading of the TMJ disc: (1) increase with compressive strain at the start of movement, and (2) are velocity-dependent during movement. Sixty-four porcine discs received a 10-N static load via an acrylic indenter for 1 or 30 sec before cyclic movement. Physical data were recorded and analyzed by ANOVA. The results showed that compressive strain and tractional forces were largest for the start of movement following 30 sec of static loading (p ≤ 0.0001) and were correlated (R2 = 0.84). Peak tractional forces were linearly and positively related to velocity of movement (R2 = 0.85), and were highest during Cycle 1 after 30 sec of loading (p ≤ 0.0067). The results demonstrated that tractional forces were strain-related at the start of movement and velocity-dependent during movement. Abbreviations: ANOVA = analysis of variance, PBS = phosphate-buffered physiological saline solution, TMJ = temporomandibular joint, μT =tractional coefficient, μs = static coefficient of friction.
Re-oxygenation Improves Hypoxia-induced Pulp Cell Arrest
Authors: Ueno Y. , Kitamura C. , Terashita M. , Nishihara T.
Published: January 2009

Dental pulp cells can be exposed to hypoxia during severe inflammation or restorative procedures, though their response to hypoxia is not well-understood. We hypothesized that hypoxia has effects on the growth of pulp cells in vitro. When the cells were exposed to hypoxia for 48 hr, cell growth was suppressed, and cell death was detected by Hoechst staining. Western blot analysis revealed that phosphorylation of retinoblastoma protein was inhibited in cells exposed to hypoxia. Analyses of the molecules involved in retinoblastoma protein phosphorylation revealed that hypoxia suppressed cyclin D2 and activated p21CIP1/WAF1. Further, hypoxia-exposed pulp cells showed improvement of cell viability, cell-cycle progression, and expression of cyclin D2 with re-oxygenation. These findings indicate that hypoxia-induced cell cycle arrest in pulp cells is reversible, while cyclin D2 may play an essential role in the improvement of cell proliferation with re-oxygenation.
S100A8 Triggers Oxidation-sensitive Repulsion of Neutrophils
Authors: Sroussi H.Y. , Berline J. , Dazin P. , Green P. , Palefsky J.M.
Published: January 2009

The inflammatory response to tissue injury is a multi-faceted process. During this process, neutrophils migrate in the extravascular spaces, directed to the site of injury by chemical gradients generated by chemotactic molecules. S100A8, a protein associated with a wide variety of inflammatory conditions, is heavily over-expressed in association with inflammation. We hypothesized that human S100A8 possesses neutrophil-repelling properties that result in an anti-inflammatory effect in vivo. The chemotactic activity of S100A8 on neutrophils was tested in Transwell chemotaxis assays. Analysis of the data indicates that S100A8 causes a repulsion of peripheral neutrophils, an activity that S100A8 loses upon its oxidation. Using a mutant of S100A8 resistant to oxidation and consistent with the in vitro findings, we demonstrated that S100A8 causes a strong anti-inflammatory effect in the rat air-pouch model of inflammation in vivo. These data highlight a naturally occurring novel anti-inflammatory pathway and provide potential molecular targets for the development of novel anti-inflammatory therapeutics. Abbrevations: ethylene diamine tetraacetic acid (EDTA); limulus amoebocyte lysate assay (LAL); pertussis toxin (PTX); forward scatter (FSC); Interleukin-8 (IL-8); formyl-Met-Leu-Phe (fMLP); monocyte chemotactic protein 1 (MCP1).
Ca, Pi, and F in the Fluid of Biofilm Formed under Sucrose
Authors: Tenuta L.M.A. , Del Bel Cury A.A. , Bortolin M.C. , Vogel G.L. , Cury J.A.
Published: January 2009

Calcium (Ca), inorganic phosphorus (Pi), and fluoride (F) concentrations are low in the whole plaque biofilm formed under exposure to sucrose. It was hypothesized that this would be reflected in the biofilm fluid, where these low values should greatly influence the de/remineralization process. Dental biofilms were formed in situ over enamel blocks mounted in palatal appliances and exposed 8 times/day to distilled water, glucose+fructose, or sucrose solutions for 14 days. While Ca, Pi, and F concentrations in the whole biofilms were significantly lower in the glucose+fructose and sucrose groups, no effect on biofilm fluid was observed, even after a cariogenic challenge. An increase in whole biofilm mineral ions was observed 24 hrs after the carbohydrate treatments were suspended, but this effect was also not observed in the fluid. These results suggest that there is a homeostatic mechanism that maintains biofilm fluid mineral ion concentration, regardless of its total concentration in the whole biofilm.
Immobilization Stress Induces BDNF in Rat Submandibular Glands
Authors: Tsukinoki K. , Saruta J. , Sasaguri K. , Miyoshi Y. , Jinbu Y. , Kusama M. , Sato S. , Watanabe Y.
Published: January 2009

Brain-derived neurotrophic factor (BDNF) promotes survival and differentiation of the cells of the central and peripheral nervous systems. BDNF has been identified in non-neural tissue, including the heart, lung, platelets, lymphocytes, and lacrimal glands. Immobilization stress modifies BDNF mRNA expression in some organs. The present study examines the effect of immobilization stress on BDNF, and its receptor TrkB, in male rat submandibular glands. Increased BDNF mRNA and protein expression were observed in duct cells as a result of immobilization stress, as demonstrated by real-time PCR, Western blot, immunohistochemistry, and analysis by microdissection. TrkB mRNA was not detected in salivary gland tissue, or oral or esophageal mucosa, by RT-PCR. Rat submandibular gland was thus identified as an organ which expresses BDNF. Furthermore, the results of this study suggest that increased salivary BDNF expression occurs following immobilization stress.
Genetic and Cellular Toxicology of Dental Resin Monomers
Authors: Schweikl H. , Spagnuolo G. , Schmalz G.
Published: January 2009

Monomers are released from dental resin materials, and thus cause adverse biological effects in mammalian cells. Cytotoxicity and genotoxicity of some of these methacrylates have been identified in a vast number of investigations during the last decade. It has been well-established that the co-monomer triethylene glycol dimethacrylate (TEGDMA) causes gene mutations in vitro. The formation of micronuclei is indicative of chromosomal damage and the induction of DNA strand breaks detected with monomers like TEGDMA and 2-hydroxyethyl methacrylate (HEMA). As a consequence of DNA damage, the mammalian cell cycle was delayed in both G1 and G2/M phases, depending on the concentrations of the monomers. Yet, the mechanisms underlying the genetic and cellular toxicology of resin monomers have remained obscure until recently. New findings indicate that increased oxidative stress results in an impairment of the cellular pro- and anti-oxidant redox balance caused by monomers. It has been demonstrated that monomers reduced the levels of the natural radical scavenger glutathione (GSH), which protects cell structures from damage caused by reactive oxygen species (ROS). Depletion of the intracellular GSH pool may then significantly contribute to cytotoxicity, because a related increase in ROS levels can activate pathways leading to apoptosis. Complementary, cytotoxic, and genotoxic effects of TEGDMA and HEMA are inhibited in the presence of ROS scavengers like N-acetylcysteine (NAC), ascorbate, and Trolox (vitamin E). Elevated intracellular levels of ROS can also activate a complex network of redox-responsive macromolecules, including redox-sensitive transcription factors like nuclear factor kappaB (NF-κB). It has been shown that NF-κB is activated probably to counteract HEMA-induced apoptosis. The induction of apoptosis by TEGDMA in human pulp cells has been associated with an inhibition of the phosphatidylinositol 3-kinase (PI3-K) cell-survival signaling pathway. Although the details of the mechanisms leading to cell death, genotoxicity, and cell-cycle delay are not completely understood, resin monomers may be able to alter the functions of the cells of the oral cavity. Pathways regulating cellular homeostasis, dentinogenesis, or tissue repair may be modified by monomers at concentrations well below those which cause acute cytotoxicity.
The Effectiveness of School Dental Screening: a Cluster-randomized Control Trial
Authors: Milsom K. , Blinkhorn A. , Worthington H. , Threlfall A. , Buchanan K. , Kearney-Mitchell P. , Tickle M.
Published: January 2009

Dental screening of children in schools is undertaken in many countries. There is no evidence that this activity is effective. The objective of our study was to determine if school dental screening of children reduces untreated disease or improves attendance at the population level. A four-arm cluster-randomized controlled trial was undertaken in the northwest of England. In total, 16,864 children aged 6–9 years in 168 schools were randomly allocated to 3 test groups, which received screening according to different models, and a control, which received no intervention. There were no significant differences in caries increment in the primary and secondary dentitions or in the proportions of children attending a dentist after screening between the control group and the 3 intervention arms. School dental screening delivered according to 3 different models was not effective at reducing levels of active caries and increasing attendance in the population under study.
ART and Conventional Root Restorations in Elders after 12 Months
Authors: Lo E.C.M. , Luo Y. , Tan H.P. , Dyson J.E. , Corbet E.F.
Published: January 2009

Successful use of atraumatic restorative treatment (ART) in children has been reported, but little information is available regarding its use in older adults. The hypothesis of this study was that survival rates of root restorations placed by both ART and the conventional technique were similar. Root-surface caries lesions in 103 institutionalized elders in Hong Kong were treated randomly by either: (1) the conventional approach—caries removed by dental burs, and the cavity filled with light-cured resin-modified glass ionomer; or (2) the ART approach—caries removed by hand instruments, and the cavity filled with chemically cured high-strength glass ionomer. In total, 84 conventional and 78 ART restorations were placed. After 12 months, 63 conventional and 59 ART restorations were reviewed, and the respective 12-month survival rates were 91.7% and 87.0% (p > 0.05). It is concluded that the survival rates of both types of root restorations were high and similar.
Salivary LL-37 Secretion in Individuals with Down Syndrome is Normal
Authors: Bachrach G. , Chaushu G. , Zigmond M. , Yefenof E. , Stabholz A. , Shapira J. , Merrick J. , Chaushu S.
Published: January 2009

Antimicrobial peptides play an important role in the innate immune response. Deficiency in salivary LL-37 antimicrobial peptide has been implicated in periodontitis in patients with morbus Kostman syndrome. Down syndrome is associated with periodontitis, diminished salivary flow, and salivary immunoglobulin deficiency. In the present study, levels of LL-37 and its hCAP18 precursor were measured in saliva samples from young individuals with Down syndrome and compared with levels in those from age-matched healthy controls. LL-37 and human cathelicidin antimicrobial protein (hCAP18) were detected in whole but not in parotid saliva. hCAP18 was more abundant than LL-37. The concentrations of salivary hCAP18 and LL-37 were found to be higher in individuals with Down syndrome than in healthy controls, but their secretion rates were similar. We concluded that, while the adaptive immunity of individuals with Down syndrome is impaired at the oral mucosa, the secretion rate of the LL-37 component of the innate immune system is normal.
Controlled Release of Chlorhexidine from UDMA-TEGDMA Resin
Authors: Anusavice K.J. , Zhang N.-Z. , Shen C.
Published: January 2009

Chlorhexidine salts are available in various formulations for dental applications. This study tested the hypothesis that the release of chlorhexidine from a urethane dimethacrylate and triethylene glycol dimethacrylate resin system can be effectively controlled by the chlorhexidine diacetate content and pH. The filler concentrations were 9.1, 23.1, or 33.3 wt%, and the filled resins were exposed to pH 4 and pH 6 acetate buffers. The results showed that Fickian diffusion was the dominant release mechanism. The rates of release were significantly higher in pH 4 buffer, which was attributed to the increase of chlorhexidine diacetate solubility at lower pH. The higher level of filler loading reduced the degree of polymerization, leading to a greater loss of organic components and higher chlorhexidine release rates.
Magnification—a New Look at a Long-known Optical Property of Dentin
Authors: Kienle A. , Michels R. , Hibst R.
Published: January 2009

Light propagation in human dentin exhibits a strong directional dependence featuring the long-known optical magnification property. We hypothesized that this anisotropic effect is caused by multiple scattering at the dentin tubules, and not by fiberoptic effects, as had been previously assumed. We performed measurements of the transmitted intensity from dentin disks and compared them with Monte Carlo simulations of light propagation in dentin, considering the scattering by the tissue’s microstructure. We found that the optical anisotropy of dentin can be fully explained with this model. We concluded that the magnification property of dentin is due to multiple scattering by the dental microstructure.
Craniofacial Tissue Engineering by Stem Cells
Authors: Mao J.J. , Giannobile W.V. , Helms J.A. , Hollister S.J. , Krebsbach P.H. , Longaker M.T. , Shi S.
Published: January 2009

Craniofacial tissue engineering promises the regeneration or de novo formation of dental, oral, and craniofacial structures lost to congenital anomalies, trauma, and diseases. Virtually all craniofacial structures are derivatives of mesenchymal cells. Mesenchymal stem cells are the offspring of mesenchymal cells following asymmetrical division, and reside in various craniofacial structures in the adult. Cells with characteristics of adult stem cells have been isolated from the dental pulp, the deciduous tooth, and the periodontium. Several craniofacial structures—such as the mandibular condyle, calvarial bone, cranial suture, and subcutaneous adipose tissue—have been engineered from mesenchymal stem cells, growth factor, and/or gene therapy approaches. As a departure from the reliance of current clinical practice on durable materials such as amalgam, composites, and metallic alloys, biological therapies utilize mesenchymal stem cells, delivered or internally recruited, to generate craniofacial structures in temporary scaffolding biomaterials. Craniofacial tissue engineering is likely to be realized in the foreseeable future, and represents an opportunity that dentistry cannot afford to miss.
Lesions of Endodontic Origin and Risk of Coronary Heart Disease
Authors: Caplan D.J. , Chasen J.B. , Krall E.A. , Cai J. , Kang S. , Garcia R.I. , Offenbacher S. , Beck J.D.
Published: January 2009

A paucity of epidemiologic research exists regarding systemic health consequences of endodontic disease. This study evaluated whether incident radiographically evident lesions of endodontic origin were related to development of coronary heart disease (CHD) among 708 male participants in the VA Dental Longitudinal Study. At baseline and every three years for up to 32 years, participants (who were not VA patients) received complete medical and dental examinations, including full-mouth radiographs. Cox regression models estimated the relationship between incident lesions of endodontic origin and time to CHD diagnosis. Among those ≤ 40 years old, incident lesions of endodontic origin were significantly associated with time to CHD diagnosis (p < 0.05), after adjustment for covariates of interest, with hazard ratios decreasing as age increased. Among those > 40 years old, no statistically significant association was observed. These findings are consistent with research that suggests relationships between chronic periodontal inflammation and the development of CHD, especially among younger men.
Head Immobilization can Impair Jaw Function
Authors: Häggman-Henrikson B. , Nordh E. , Zafar H. , Eriksson P.-O.
Published: January 2009

Findings that jaw-opening/-closing relies on both mandibular and head movements suggest that jaw and neck muscles are jointly activated in jaw function. This study tested the hypothesis that rhythmic jaw activities involve an active repositioning of the head, and that head fixation can impair jaw function. Concomitant mandibular and head-neck movements were recorded during rhythmic jaw activities in 12 healthy adults, with and without fixation of the head. In four participants, the movement recording was combined with simultaneous registration of myoelectric activity in jaw and neck muscles. The results showed neck muscle activity during jaw opening with and without head fixation. Notably, head fixation led to reduced mandibular movements and shorter duration of jaw-opening/-closing cycles. The findings suggest recruitment of neck muscles in jaw activities, and that head fixation can impair jaw function. The results underline the jaw and neck neuromuscular relationship in jaw function.
Mechanical Work during Stress-field Translation in the Human TMJ
Authors: Gallo L.M. , Chiaravalloti G. , Iwasaki L.R. , Nickel J.C. , Palla S.
Published: January 2009

The pathomechanics of degenerative joint disease of the temporomandibular joint (TMJ) may involve fatigue produced by mechanical work on the articulating tissues. This study tested the hypotheses that mechanical work in the TMJ (i) varies with the type of mandibular activity, and (ii) is evenly distributed over TMJ surfaces. Ten healthy human participants were recorded with Magnetic Resonance Imaging (MRI) and jaw tracking. The data were used to reconstruct and animate TMJ activity. Aspect ratios, instantaneous velocities, and distances of stress-fields translation were used to calculate work (mJ). The results were analyzed by least-squares polynomial regression and ANOVA. Work magnitudes were related to peak velocity (R2 = 0.92) and distance of stress-field translation (R2 = 0.83), and were distributed over the joint surfaces (p < 0.03). During mandibular laterotrusion, average mechanical work was 1.5 times greater in the contralateral joint. Peak magnitudes of work (> 3000 mJ) were 4 times that previously reported.
Effects of Resin Hydrophilicity on Dentin Bond Strength
Authors: Nishitani Y. , Yoshiyama M. , Donnelly A.M. , Agee K.A. , Sword J. , Tay F.R. , Pashley D.H.
Published: January 2009

The purpose of this study was to determine if hydrophobic resins can be coaxed into dentin wet with ethanol instead of water. The test hypothesis was that dentin wet with ethanol would produce higher bond strengths for hydrophobic resins than would dentin wet with water. This study examined the microtensile bond strength of 5 experimental adhesives (50 wt% ethanol/50% comonomers) of various degrees of hydrophilicity to acid-etched dentin that was left moist with water, moist with ethanol, or air-dried. Following composite buildups, hourglass-shaped slabs were prepared from the bonded teeth for microtensile testing. For all 3 types of dentin surfaces, higher bond strengths were achieved with increased resin hydrophilicity. The lowest bond strengths were obtained on dried dentin, while the highest bond strengths were achieved when dentin was bonded moist with ethanol. Wet-bonding with ethanol achieved higher bond strengths with hydrophobic resins than were possible with water-saturated matrices.
Tissue pH and Temperature Regulate Pulpal Nociceptors
Authors: Goodis H.E. , Poon A. , Hargreaves K.M.
Published: January 2009

The TRPV1 receptor acts as a sensor for environmental changes in pH and temperature. Since many nociceptors express TRPV1, it is possible that local tissue-cooling may inhibit nociceptor activity via reduction of TRPV1 activation. The present study used isolated superfused rat dental pulp to test the hypothesis that capsaicin receptors are activated in inflamed tissue, as measured by alterations in neuropeptide release. We tested the hypothesis that alterations in the tissue temperature and pH of isolated superfused rat dental pulp regulate capsaicin-induced release of calcitonin gene-related peptide (CGRP). Application of capsaicin with increased proton concentration ( i.e., lowered pH) produced a nearly two-fold increase in peak immunoreactive CGRP release, as compared with capsaicin applied at a pH of 7.4. Reduction in tissue temperature from 37°C to 26°C completely blocked the capsaicin effect. The study indicates that environmental stimuli regulate the activity of capsaicin-sensitive neurons innervating dental pulp, and these factors may be significant clinically in the development and amelioration of dental pain.
Characterization of Fibroblasts with Son of Sevenless-1 Mutation
Authors: Lee E.J. , Jang S.I. , Pallos D. , Kather J. , Hart T.C.
Published: January 2009

Although non-syndromic hereditary gingival fibromatosis (HGF) is genetically heterogeneous, etiologic mutations have been identified only in the Son of Sevenless-1 gene ( SOS1). To test evidence of increased cell proliferation, we studied histological, morphological, and proliferation characteristics in monolayer and three-dimensional cultures of fibroblasts with the SOS1 g.126,142–126,143insC mutation. Histological assessment of HGF gingiva indicated increased numbers of fibroblasts (30%) and increased collagen (10%). Cell proliferation studies demonstrated increased growth rates and 5-bromo-2-deoxyuridine incorporation for HGF fibroblasts. Flow cytometry showed greater proportions of HGF fibroblasts in the G2/M phase. Attachment of HGF fibroblasts to different extracellular matrix surfaces demonstrated increased formation of protrusions with lamellipodia. HGF fibroblasts in three-dimensional culture showed greater cell proliferation, higher cell density, and alteration of surrounding collagen matrix. These findings revealed that increased fibroblast numbers and collagen matrix changes are associated with mutation of the SOS1 gene in vitro and in vivo.
Influence of Alveolar Support on Stress in Periodontal Structures
Authors: Ona M. , Wakabayashi N.
Published: January 2009

The influence of alveolar bone support on the functional capability of a tooth remains unclear. It was hypothesized that a reduction in alveolar support causes an increase of maximum stress in the periodontal structures. Mathematical models of the maxillary incisor to simulate in vivo tooth movement were constructed with periodontium of normal or reduced bone height, and normal or widened periodontal ligament (PDL) space. Under simulated bite force, the maximum tensile stress at the lingual cervical region in the PDL increased with bone height reduction, but decreased with PDL widening. The compressive stress at the cervical region in the cortical bone was no more than 22% of the yield strength of bone, and did not increase by the height reduction with widened PDL. The result suggests that the height reduction potentially causes mechanical damage to the PDL, but, of itself, is not likely to have a negative effect on the bone.
Antagonist Enamel Wears More Than Ceramic Inlays
Authors: Krämer N. , Kunzelmann K.-H. , Taschner M. , Mehl A. , Garcia-Godoy F. , Frankenberger R.
Published: January 2009

Wear phenomena of ceramic inlays are not fully understood. The aim of the present study was to evaluate ceramic wear, antagonist enamel wear, and luting cement wear over 8 years. The two-fold null hypothesis was that there would be (1) no difference in wear behavior between ceramic and enamel, and (2) no influence of filler content of luting composites on composite wear. From 96 restorations, 36 Class II inlays from 16 participants were selected. For inlays with opposing enamel cusps (n = 17), replicas of inlays and enamel were scanned with a 3-D laser scanner. Luting gaps of inlays (n = 36) were analyzed with a profilometer, including 3-D data analysis. Ceramic and enamel wear increased between 4 and 8 years, with significantly higher values for enamel after 6 years (p < 0.05). Luting gap wear increased continuously up to 8 years (p < 0.05), with no influence of luting composites (p > 0.05) and location of teeth (p > 0.05).
Roles of CLCA and CFTR in Electrolyte Re-absorption from Rat Saliva
Authors: Ishibashi K. , Yamazaki J. , Okamura K. , Teng Y. , Kitamura K. , Abe K.
Published: January 2009

A molecular basis for Cl− re-absorption has not been well-characterized in salivary ductal cells. Previously, we found strong expression of a rat homologue proposed to be Ca2+-dependent Cl− channels (rCLCA) in the intralobular ducts of the rat submandibular gland. To address the question as to whether rCLCA and cystic fibrosis transmembrane conductance regulator (CFTR) are involved in Cl− re-absorption, we evaluated the electrolyte content of saliva from glands pre-treated with a small interfering RNA (siRNA). Retrograde injection into a given submandibular duct of an siRNA designed to knock down either rCLCA or CFTR reduced the expression of each of the proteins. rCLCA and CFTR siRNAs significantly increased Cl− concentration in the final saliva during pilocarpine stimulation. These results represent the first in vivo evidence for a physiological significance of rCLCA, along with CFTR, in transepithelial Cl− transport in the ductal system of the rat submandibular gland.
Effects of Phenylephrine on Transplanted Submandibular Gland
Authors: Xiang B. , Zhang Y. , Li Y.M. , Zhang K. , Zhang Y.Y. , Wu L.L. , Yu G.Y.
Published: January 2009

Autotransplantation of the submandibular gland is a potential treatment for severe kerato-conjunctivitis sicca. However, one of the major barriers to this procedure is that secretions from the transplanted gland decrease shortly after the operation, which may lead to obstruction of Wharton’s duct, or even to transplantation failure. Using a rabbit model, we investigated whether phenylephrine could improve the secretion from the transplanted gland. We found that phenylephrine treatment significantly reversed the decrease in salivary secretion after transplantation, enhanced the expressions of α1A-, α1B-, and α1D-adrenoceptor mRNA, and ameliorated atrophy of acinar cells. Furthermore, phenylephrine also induced translocation of aquaporin-5 from the cytoplasm to the apical membrane, and increased the levels of phospho-ERK1/2, ERK1/2, phospho-PKCζ, and PKCζ in the transplanted gland. These results indicate that phenylephrine treatment moderates structural injury and improves secretory function in the transplanted submandibular gland through promoting α1-adrenoceptor expression and post-receptor signal transduction.
Bilateral TMJ Disk Displacement Induces Mandibular Retrognathia
Authors: Bryndahl F. , Eriksson L. , Legrell P.E. , Isberg A.
Published: January 2009

Unilateral non-reducing TMJ disk displacement has been shown to retard mandibular growth on the ipsilateral side, with facial asymmetry a sequela. We hypothesized that bilateral affliction would impair mandibular growth bilaterally, generating mandibular retrognathia. Non-reducing TMJ disk displacement was surgically created in 10 growing New Zealand White rabbits. Ten additional rabbits served as a sham-operated control group. Facial growth was followed in serial cephalograms, with tantalum implants, during a period corresponding to childhood and adolescence in man. The results verified that bilateral non-reducing TMJ disk displacement retarded mandibular growth bilaterally, the extent corresponding to mandibular retrognathia in man. Maxillary growth was also retarded, but to a lesser degree. Growth impairment fluctuated over time, the most striking retardation occurring during periods of general growth acceleration. This should be taken into consideration when orthodontic treatment, aimed at stimulating mandibular growth, is initiated in adolescent individuals with non-reducing TMJ disk displacement.
Human Saliva Proteome and Transcriptome
Authors: Hu S. , Li Y. , Wang J. , Xie Y. , Tjon K. , Wolinsky L. , Loo R.R.O. , Loo J.A. , Wong D.T.
Published: January 2009

This paper tests the hypothesis that salivary proteins and their counterpart mRNAs co-exist in human whole saliva. Global profiling of human saliva proteomes and transcriptomes by mass spectrometry (MS) and expression microarray technologies, respectively, revealed many similarities between saliva proteins and mRNAs. Of the function-known proteins identified in saliva, from 61 to 70% were also found present as mRNA transcripts. For genes not detected at both protein and mRNA levels, we made further efforts to determine if the counterpart is present. Of 19 selected genes detected only at the protein level, the mRNAs of 13 (68%) genes were found in saliva by RT-PCR. In contrast, of many mRNAs detected only by microarrays, their protein products were found in saliva, as reported previously by other investigators. The saliva transcriptome may provide preliminary insights into the boundary of the saliva proteome.
Plaque Removal by Young Children Using Old and New Toothbrushes
Authors: van Palenstein Helderman W.H. , Kyaing M.M. , Aung M.T. , Soe W. , Rosema N.A.M. , van der Weijden G.A. , van ’t Hof M.A.
Published: January 2009

There is inconclusive evidence about the relationship between toothbrush wear and plaque removal. This randomized cross-over clinical trial aimed to validate or invalidate non-inferiority in the plaque-removal efficacy of old vs. new toothbrushes in the hands of 7- and 8-year-old children. The lower limit for non-inferiority was set a priori as a difference in plaque score < 15%. Children (n = 101) brushed, in the first session, with either their 14-month-old toothbrush or a new one, and in the second session vice versa. The mean Quigley-Hein plaque score, before and after children brushed with old brushes, was 2.9 and 2.4, and with new brushes 2.8 and 2.1. The plaque score after they brushed with the new toothbrush was 10.9% lower (p < 0.001) than after they brushed with the old toothbrush. The confidence interval of 7.6%–13.9% was within the acceptance band (< 15%), and non-inferiority of old toothbrushes in the hands of these children was validated.
A Novel Missense Mutation in Van der Woude Syndrome: Usefulness of Fingernail DNA for Genetic Analysis
Authors: Matsuzawa N. , Shimozato K. , Natsume N. , Niikawa N. , Yoshiura K.
Published: January 2009

Van der Woude syndrome (VWS) is an autosomal-dominant oral facial disorder. To find a gene mutation in a Japanese family using fingernail DNA samples, we performed this study. We hypothesized that a gene mutation in IRF6 might be involved in VWS, and that fingernail DNA samples may be valuable for detecting such mutations. Linkage and haplotype analyses of the family mapped the disease locus to the 1q32-q41 region. Mutation analysis with an improved extraction method for fingernail DNA detected a novel missense mutation (1046A>T, E349V) in exon 7 of IRF6 in all the affected members of the family. Since the E349V change may disturb the hydrophobic core and affect regulatory activity of IRF6, it is most likely that the mutation is causative for VWS in this family. Fingernail DNA is thus useful for linkage and mutation analyses, since the fingernail can be easily obtained non-invasively, sent through the mail, and stored for a long period. We emphasize here the usefulness of fingernail DNA for the genetic analysis of a disease.
Predicting Clustered Dental Implant Survival Using Frailty Methods
Authors: Chuang S.-K. , Cai T.
Published: January 2009

The purpose of this study was to predict future implant survival using information on risk factors and on the survival status of an individual’s existing implant(s). We considered a retrospective cohort study with 677 individuals having 2349 implants placed. We proposed to predict the survival probabilities using the Cox proportional hazards frailty model, with three important risk factors: smoking status, timing of placement, and implant staging. For a non-smoking individual with 2 implants placed, an immediate implant and in one stage, the marginal probability that 1 implant would survive 12 months was 85.8% (95%CI: 77%, 91.7%), and the predicted joint probability of surviving for 12 months was 75.1% (95%CI: 62.1%, 84.7%). If 1 implant was placed earlier and had survived for 12 months, then the second implant had an 87.5% (95%CI: 80.3%, 92.4%) chance of surviving 12 months. Such conditional and joint predictions can assist in clinical decision-making for individuals.
Hereditary Gingival Fibromatosis: Characteristics and Novel Putative Pathogenic Mechanisms
Authors: Häkkinen L. , Csiszar A.
Published: January 2009

Hereditary gingival fibromatosis (HGF) is a rare condition that can occur as an isolated disease or as part of a syndrome or chromosomal abnormality. In severe cases, the gingival enlargement may cover the crowns of teeth and cause severe functional and esthetic concerns. Histological and cell culture studies have uncovered some of the molecular and cellular changes associated with HGF. However, the pathogenesis of the disease is still largely unknown. Recent studies about the genetic characteristics of HGF have provided novel clues about the potential pathogenic mechanisms. In particular, mutation in the son-of-sevenless ( SOS-1) gene has been associated with one form of the disease. However, HGF displays genetic heterogeneity, and mutations in other genes are also likely involved. This review outlines the current knowledge about the histological, cellular, and genetic characteristics of HGF. In addition, the potential role of the SOS-1 molecule and related novel intracellular signaling pathways in the pathogenesis of HGF will be discussed.
Enamel Matrix Derivative Stimulates Human Gingival Fibroblast Proliferation via ERK
Authors: Zeldich E. , Koren R. , Nemcovsky C. , Weinreb M.
Published: January 2009

Emdogain®, a formulation of Enamel Matrix Proteins, is used clinically for periodontal regeneration to stimulate PDL (periodontal ligament), cementum, and bone formation. Its effects on gingival fibroblasts and tissue have not been thoroughly studied. Therefore, we investigated the mechanisms by which Emdogain affects the cell cycle of human gingival fibroblasts. Without serum, Emdogain (50 μg/mL) induced human gingival fibroblast entry into the S phase and DNA synthesis, but not completion of the cell cycle. With low serum concentrations (0.2–0.5%), Emdogain synergistically induced completion of the cell cycle, resulting in increased cell numbers. The mitogenic response to Emdogain depended on Extracellular Regulated Kinase (ERK) activation, which occurred in two waves, peaking after 15 min and 4 to 6 hrs, since it was abolished by U0126, a specific MAPK inhibitor. Inhibition of the second wave was sufficient to abrogate mitogenesis. This study characterized the mitogenic effect of Emdogain on primary human gingival fibroblasts, its cooperation with serum growth factors, and the key mediatory role of the ERK cascade.
Effects of Occlusal Stimuli on Alveolar/Jaw Bone Formation
Authors: Shimomoto Y. , Chung C.J. , Iwasaki-Hayashi Y. , Muramoto T. , Soma K.
Published: January 2009

Occlusion is known to influence the growth and development of the craniofacial complex. However, the consequences of occlusal hypofunction, or its recovery, on the amount of formation and development of alveolar bone and the jaw are not fully understood. Therefore, the present study was designed to elucidate the relationship between the occlusal stimuli and alveolar and jaw bone growth by the use of a hypofunction/recovered occlusal function model in growing rats. Bone histomorphometric analyses, including bone apposition rate and mineral apposition rate, were evaluated in double-labeled frontal sections of mandibular second molars. Results showed that occlusal hypofunction significantly suppressed alveolar and jaw bone formation compared with that in animals growing normally (p < 0.05). However, recovered occlusal function induced an enhancement in jaw bone formation. These results indicate the influence of occlusal function on alveolar and jaw bone formation during the growth period.
Randomized Effectiveness Study of Four Therapeutic Strategies for TMJ Closed Lock
Authors: Schiffman E.L. , Look J.O. , Hodges J.S. , Swift J.Q. , Decker K.L. , Hathaway K.M. , Templeton R.B. , Fricton J.R.
Published: January 2009

For individuals with temporomandibular joint (TMJ) disc displacement without reduction with limited mouth opening (closed lock), interventions vary from minimal treatment to surgery. In a single-blind trial, 106 individuals with TMJ closed lock were randomized among medical management, rehabilitation, arthroscopic surgery with post-operative rehabilitation, or arthroplasty with post-operative rehabilitation. Evaluations at baseline, 3, 6, 12, 18, 24, and 60 months used the Craniomandibular Index (CMI) and Symptom Severity Index (SSI) for jaw function and TMJ pain respectively. Using an intention-to-treat analysis, we observed no between-group difference at any follow-up for CMI (p ≥ 0.33) or SSI (p ≥ 0.08). Both outcomes showed within-group improvement (p < 0.0001) for all groups. The findings of this study suggest that primary treatment for individuals with TMJ closed lock should consist of medical management or rehabilitation. The use of this approach will avoid unnecessary surgical procedures.