bluuebunny/crossref_metadata_2025 huggingface dataset:
Age-related Decreases in the Response of Aquaporin-5 to Acetylcholine in Rat Parotid Glands
Authors: Inoue N. , Iida H. , Yuan Z. , Ishikawa Y. , Ishida H.
Published: January 2009

Aquaporin-5 (AQP5) is important in salivary fluid secretion in response to cholinergic and adrenergic stimuli in rat parotid glands. We hypothesized that expression and function of AQP5 might change with age. Acetylcholine and epinephrine induced increases in AQP5 levels in the apical plasma membranes of both young adult and senescent rats. The stimulatory effect of acetylcholine, but not that of epinephrine, on AQP5 levels in the apical plasma membranes of the cells decreased markedly during aging. The quinuclidine derivative, SNI-2011, induced a persistent increase in AQP5 levels in the apical plasma membrane in the cells of both these rats. The amounts of M3-muscarinic receptor and Gq proteins did not decrease during aging. The age-related alteration in the responsiveness of AQP5 in the cells to these stimuli might account for the concomitant changes in nitric oxide synthase activity. These results suggest that SNI-2011 might have therapeutic benefit for the treatment of age-related xerostomia.
Root Resorption Related to Hypofunctional Periodontium in Experimental Tooth Movement
Authors: Sringkarnboriboon S. , Matsumoto Y. , Soma K.
Published: January 2009

Orthodontic movement of non-occluding teeth may result in undesirable apical root resorption. These teeth present with a histologically altered periodontium and are considered to be hypofunctional. The purpose of this study was to compare the amount of root resorption associated with a normal and a hypofunctional periodontium in rats during experimental tooth movement caused by heavy continuous force. The mandibular first molar was induced into a non-occluding condition in the hypofunctional periodontium group. Mesial orthodontic force was applied by means of 50-gram-force closed-coil springs for 15 days in both groups. The active root-resorption lacunae from histological sections, identified by tartrate-resistant acid phosphatase, were measured in terms of length, depth, and area. The results showed that the amount of root resorption was significantly greater in teeth with a hypofunctional periodontium than in those with a normal periodontium (p < 0.05). These results suggest that orthodontic movement of non-occluding teeth should be performed with caution.
Food Texture Differences affect Energy Metabolism in Rats
Authors: Oka K. , Sakuarae A. , Fujise T. , Yoshimatsu H. , Sakata T. , Nakata M.
Published: January 2009

Dietary factors such as taste and nutrients are known to affect satiety and energy balance. We hypothesized that food texture might contribute to the regulation of energy metabolism through the process of mastication in the oral cavity as well. The effects of long-term feeding of different-textured pellets on body weight gain, adiposity, and thermogenesis were assessed. From weaning at 4 wks, rats were divided into 2 groups fed on either standard (controls) or soft pellets (soft-fed) that required less chewing with the same nutritional composition. At 26 wks, the soft-fed rats showed greater adiposity than did the controls. Daily food intake did not differ between the 2 groups. The increase in body temperature following feeding was significantly lower in the soft-fed rats. These results suggested that food texture affected energy metabolism by changing post-prandial thermogenesis. The long-term deficiency of thermogenesis associated with soft foods resulted in a greater tendency toward obesity.
A Longitudinal Study of Streptococcus mutans Colonization in Infants after Tooth Eruption
Authors: Wan A.K.L. , Seow W.K. , Purdie D.M. , Bird P.S. , Walsh L.J. , Tudehope D.I.
Published: January 2009

We previously reported that, before tooth eruption, over one-half of infants aged 6 mos were already infected with Streptococcus mutans. The aim of this investigation was to determine the colonization of S. mutans after tooth eruption in the same cohort of 111 infants (35 pre-term, 76 full-term). Our results showed that S. mutans colonization increased with increasing age, so that by 24 mos of age, 84% harbored the bacteria (p < 0.01). The mean and median ages of S. mutans colonization in dentate infants were 15.7 mos and 16.0 mos, respectively. Factors associated with S. mutans colonization were sweetened fluids taken to bed (p < 0.01), frequent sugar exposure (p < 0.03) and snacking (p < 0.03), sharing of foods with adults (p < 0.03), and maternal S. mutans levels of > 105 CFU/mL (p < 0.02). In contrast, non-colonization of S. mutans was associated with toothbrushing (p < 0.03) and multiple courses of antibiotics (p < 0.001). Analysis of our data establishes the timing of S. mutans colonization in children from birth to 24 mos of age.
Alcohol Consumption Increases Periodontitis Risk
Authors: Pitiphat W. , Merchant A.T. , Rimm E.B. , Joshipura K.J.
Published: January 2009

Alcohol consumption impairs neutrophil, macrophage, and T-cell functions, increasing the likelihood of infections. We examined the association between alcohol consumption and periodontitis, prospectively, among 39,461 male health professionals aged 40 to 75 years and free of periodontitis at the start of follow-up. Alcohol intake was assessed at baseline and updated every 4 years by a food-frequency questionnaire. Periodontal disease status was self-reported and validated against radiographs. Multivariate analysis was adjusted for age, smoking, diabetes, body-mass index, physical activity, time period, and caloric intake. During 406,160 person-years of follow-up, there were 2125 cases of periodontitis. Compared with non-drinkers, the relative risk (95% confidence interval) among men reporting usual alcohol intake of 0.1-4.9 g/day was 1.24 (1.09, 1.42); 5.0 to 14.9 g/day, 1.18 (1.04, 1.35); 15 to 29.9 g/day, 1.18 (1.01, 1.38); and > 30 g/day, 1.27 (1.08, 1.49). The results suggest that alcohol consumption is an independent modifiable risk factor for periodontitis.
Reliability of Clinical Parameters for Predicting the Outcome of Oral Malodor Treatment
Authors: Tanaka M. , Anguri H. , Nishida N. , Ojima M. , Nagata H. , Shizukuishi S.
Published: January 2009

We conducted the present study to determine which clinical parameters for diagnosing halitosis are most reliable in the development of an accurate prognosis for oral malodor treatment. Clinical evaluation included a questionnaire, oral examination and volatile sulfur compounds (VSC) measurement, and organoleptic test (OLT) at baseline. Ninety-two patients classified with oral pathologic halitosis were treated in a similar manner. Improved treatment outcome was defined as < 0.25 ppm of total VSC, ≤ 2 OLT score, and < 30 on the "sad feeling" scale as subjective stress level by oral malodor 6 months after baseline. Thirty-four patients demonstrated improvement due to the treatment. In a multiple logistic model, pocket depth, OLT score, intra-oral discomfort, and self-perception of oral malodor at baseline displayed significant association with "not improved outcome". These results suggest that malodor- and periodontal-disease-related parameters and self-estimation of malodor at baseline are effective for prediction of outcome.
Occlusal and TMJ Loads in Subjects with Experimentally Shortened Dental Arches
Authors: Hattori Y. , Satoh C. , Seki S. , Watanabe Y. , Ogino Y. , Watanabe M.
Published: January 2009

To determine whether shortened dental arches (SDAs) cause functional overloading of the teeth and the temporomandibular joints, which has been implicated in periodontal diseases and temporomandibular disorders, we investigated the influences of SDA on occlusal and joint loads. Bite force and masticatory muscle electromyograms were recorded in five dentate subjects who clenched maximally on intra-oral appliances, creating symmetrical SDAs experimentally. Muscular forces estimated from the recorded electromyograms were fed into a finite element jaw model for calculating bite forces and joint loads. Comparison between the measured and the calculated bite forces ensured that the joint loads were representative. The bite force on each tooth increased with missing molar occlusions, while joint loads decreased. The bite force per root surface area was always greatest on the most posterior tooth, and these values were most constant. The findings provide no evidence that SDA causes overloading of the joints and the teeth, which suggests that neuromuscular regulatory systems are controlling maximum clenching strength under various occlusal conditions.
Aging Affects Two Modes of Nanoleakage Expression in Bonded Dentin
Authors: Tay F.R. , Hashimoto M. , Pashley D.H. , Peters M.C. , Lai S.C.N. , Yiu C.K.Y. , Cheong C.
Published: January 2009

Water sorption into resin-dentin interfaces precedes hydrolytic degradation. We hypothesized that these processes are morphologically manifested by the uptake of ammoniacal silver nitrate, which is thought to trace hydrophilic domains and water-filled channels within matrices. Water sorption is thought to be nonuniform and can be traced by the use of silver nitrate. Human teeth bonded with an experimental filled-adhesive were aged in artificial saliva (experimental) or non-aqueous mineral oil (control). Specimens retrieved for up to a 12-month period were immersed in 50 wt% ammoniacal silver nitrate and examined by transmission electron microscopy for identification of the changes in their silver uptake. Reticular silver deposits initially identified within the bulk of hybrid layers in the experimental group were gradually reduced over time, but were subsequently replaced by similar deposits that were located along the hybrid layer-adhesive interface. Silver uptake in water-binding domains of the adhesive layers increased with aging, resulting in water tree formation. These water-filled channels may act as potential sites for hydrolytic degradation of resin-dentin bonds.
Expression and Localization of TREK-1 K+ Channels in Human Odontoblasts
Authors: Magloire H. , Lesage F. , Couble M.L. , Lazdunski M. , Bleicher F.
Published: January 2009

During tooth development, odontoblasts are the cells that form dentin and possibly mediate early stages of sensory processing in teeth. It is suggested that ion channels assist in these events. Indeed, mechanosensitive potassium currents, transducing mechanical stimuli into electrical cell signals, have been previously recorded in the human odontoblast cell membrane. Here, we show by RT-PCR that the mechanosensitive potassium channel TREK-1 (a member of the two-pore-domain potassium channel family) is overexpressed in these cultured cells compared with pulp cells in vitro. In situ hybridization showed that transcripts are detected in the odontoblast layer in vivo. The use of antibodies shows that TREK-1 is strongly expressed in the membrane of coronal odontoblasts and absent in the root. This distribution is related to the spatial distribution of nerve endings identified by labeling of the low-affinity nerve growth factor (NGF) receptor (p75NTR). These results demonstrate the expression of TREK-1 in human odontoblasts in vitro and in vivo.
TGF-β3 Decreases Type I Collagen and Scarring after Labioplasty
Authors: Hosokawa R. , Nonaka K. , Morifuji M. , Shum L. , Ohishi M.
Published: January 2009

Cleft lip is a common congenital malformation, and labioplasty performed on infants to repair such defects often results in severe scar formation. Since TGF-β3 has been implicated in wound healing, we therefore hypothesized that TGF-β3 functions to reduce scarring after cleft lip repair. In this investigation, we demonstrated that exogenous TGF-β3 reduced scar formation in an incised and sutured mouse lip in vivo. During labioplasty, endogenous TGF-β3 expression was also elevated. In vitro experiments showed that exogenous TGF-β3 reduced type I collagen accumulation. Furthermore, TGF-β3 inhibited alpha-smooth-muscle actin expression, a marker for myofibroblasts. In tandem, TGF-β3 induced the expression and activity of MMP-9. Analysis of our data suggests that TGF-β3 is normally secreted following labioplastic wound healing. An elevated level of TGF-β3 reduces type I collagen deposition by restricting myofibroblast differentiation and thereby collagen synthesis, and by promoting collagen degradation by MMP-9. In combination, these events lead to TGF-β3-mediated reduced scar formation.
Effects of Implant Healing Time on Crestal Bone Loss of a Controlled-load Dental Implant
Authors: Ko C.C. , Douglas W.H. , DeLong R. , Rohrer M.D. , Swift J.Q. , Hodges J.S. , An K.-N. , Ritman E.L.
Published: January 2009

The universally accepted concept of delay-loaded dental implants has recently been challenged. This study hypothesizes that early loading (decreased implant healing time) leads to increased bone formation and decreased crestal bone loss. We used 17 minipigs to study implants under a controlled load, with non-loaded implants for comparison. Radiographic and histological assessments were made of the osseointegrated bone changes for 3 healing times (between implant insertion and loading), following 5 months of loading. The effect of loading on crestal bone loss depended on the healing time. Early loading preserved the most crestal bone. Delayed loading had significantly more crestal bone loss compared with the non-loaded controls (2.4 mm vs. 0.64 mm; P < 0.05). The histological assessment and biomechanical analyses of the healing bone suggested that loading and bioactivities of osteoblasts exert a synergistic effect on osseointegration that is likely to support the hypothesis that early loading produces more favorable osseointegration.
Adhesive Resin Induces Apoptosis and Cell-cycle Arrest of Pulp Cells
Authors: Mantellini M.G. , Botero T.M. , Yaman P. , Dennison J.B. , Hanks C.T. , Nör J.E.
Published: January 2009

The application of an adhesive resin near or directly over the pulp was shown to induce pulp inflammation and lack of dentin regeneration. We hypothesize that the absence of dentin bridging is due to adhesive-resin-induced apoptosis of cells responsible for pulp healing and dentin regeneration. Mouse odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD-21), or macrophages (RAW 264.7) were exposed to SingleBond polymerized for 0–40 seconds. Annexin V and propidium iodide assays demonstrated that SingleBond induced apoptosis of MDPC-23, OD-21, and macrophages. The proportion of apoptotic cells was dependent on the degree of adhesive resin polymerization. Adhesive-resin-induced death of pulp cells was associated with activation of the pro-apoptotic cysteine protease Caspase-3. Interestingly, most cells exposed to adhesive resin that did not undergo apoptosis showed cell-cycle arrest. We conclude that an adhesive resin induces apoptosis and cell-cycle arrest of cells involved in the regeneration of the dentin-pulp complex in vitro.
Expression of an Inhibitor of Apoptosis, Survivin, in Oral Carcinogenesis
Authors: Tanaka C. , Uzawa K. , Shibahara T. , Yokoe H. , Noma H. , Tanzawa H.
Published: January 2009

A novel inhibitor of apoptosis, survivin, plays a role in oncogenesis. To determine the potential involvement of survivin in oral carcinogenesis, we investigated the distribution of survivin protein expression in oral squamous cell carcinomas (OSCCs) and oral pre-malignant lesions. The mRNA expression level and methylation status of the gene also were evaluated in OSCCs and OSCC-derived cell lines. In immunohistochemistry, 58% of tumors and 37% of pre-malignant lesions examined were positive for survivin, while no immunoreaction was observed in corresponding normal tissues. The reverse-transcription/polymerase chain-reaction revealed similar changes in survivin gene expression levels. Furthermore, of the 9 normal oral tissues with no survivin gene expression, 4 showed methylation of the gene, while no methylation was detected in the corresponding tumorous tissues. The results suggest that survivin plays an important role during oral carcinogenesis, and that the gene expression may be regulated by an epigenetic mechanism.
Task-dependence of Jaw Elevator and Depressor Co-activation
Authors: Proeschel P.A. , Raum J.
Published: January 2009

Elevator muscle activity per unit bite-force has been shown to be higher in chewing than in isometric biting. We tested the hypothesis that surplus elevator activity is evoked in response to a possible co-activation of jaw-opener muscles during the masticatory power stroke. In 32 subjects, digastric and bilateral masseter and temporalis activities were recorded during unilateral chewing of test foods, isometric biting on a force transducer, and during balancing of the jaw against maximum effort of depressor muscles. During elevator peak effort in chewing, the digastric activity was 113% higher than during peak effort in isometric biting. Comparison of balancing and chewing trials revealed that a 6% increase of elevator activity would suffice to compensate for this increased depressor action. Elevator activity in chewing, however, was up to 130% higher than in clenching. We conclude that depressor counteraction could have only a minor influence on the generation of surplus muscle activity in chewing.
Expression of MMP-8 and MMP-13 Genes in the Periodontal Ligament during Tooth Movement in Rats
Authors: Takahashi I. , Nishimura M. , Onodera K. , Bae J.-W. , Mitani H. , Okazaki M. , Sasano Y. , Mitani H.
Published: January 2009

Periodontal ligament tissue is remodeled on both the tension and compression sides of moving teeth during orthodontic tooth movement. The present study was designed to clarify the hypothesis that the expression of MMP-8 and MMP-13 mRNA is promoted during the remodeling of periodontal ligament tissue in orthodontic tooth movement. We used the in situ hybridization method and semi-quantitative reverse-transcription/polymerase chain-reaction analysis to elucidate the gene expression of MMP-8 and MMP-13 mRNA. Expression of MMP-8 and MMP-13 mRNA transiently increased on both the compression and tension sides during active tooth movement in vivo. The gene expression of MMP-8 and MMP-13 was induced by tension, while compression indirectly promoted the gene expression of MMP-8 and MMP-13 through soluble factors in vitro. Thus, we concluded that the expression of MMP-8 and MMP-13 is differentially regulated by tension and compression, and plays an important role in the remodeling of the periodontal ligament.
TGF-β1 Induces Accumulation of Dendritic Cells in the Odontoblast Layer
Authors: Farges J.-C. , Romeas A. , Melin M. , Pin J.-J. , Lebecque S. , Lucchini M. , Bleicher F. , Magloire H.
Published: January 2009

TGF-β1 released from dentin degraded by bacterial or iatrogenic agents is suspected to influence dental pulp response, including the modulation of cell migration. To determine the consequences of TGF-β1 action on pulp immune cells, we analyzed, by immunohistochemistry, the effect of transdentinally diffusing TGF-β1 on their localization in a human tooth slice culture model. TGF-β1 induced an accumulation of HLA-DR-positive cells in both odontoblast and subodontoblast layers of the stimulated zone. Together with HLA-DR, these cells co-expressed Factor XIIIa and CD68, two features of immature antigen-presenting dendritic cells (DC), as well as the TGF-β1 specific receptor TβRII. In contrast, no effect could be detected on the localization of either mature DC-LAMP-positive DC or of T- and B-lymphocytes. Analysis of these data suggests that TGF-β1 released from dentin degraded by bacterial or iatrogenic agents could be involved in the immune response of the dental pulp resulting from tooth injury.
Age-related Changes in Brain Regional Activity during Chewing: A Functional Magnetic Resonance Imaging Study
Authors: Onozuka M. , Fujita M. , Watanabe K. , Hirano Y. , Niwa M. , Nishiyama K. , Saito S.
Published: January 2009

Age-related changes in mastication-induced brain neuronal activity have been suggested. However, in humans, little is known about the anatomical regions involved. Using fMRI during cycles of rhythmic gum-chewing and no chewing, we have examined the effect of aging on brain regional activity during chewing in young adult (19–26 yrs), middle-aged (42–55 yrs), and aged (65–73 yrs) healthy humans. In all subjects, chewing resulted in a bilateral increase in the BOLD signals in the sensorimotor cortex, cerebellum, thalamus, supplementary motor area, and insula, and a unilateral increase in the right prefrontal area. In the first three regions, the signal increases were attenuated in an age-dependent manner, whereas, in the right prefrontal area, the converse was seen. The remaining two regions showed no significant differences with ages. These results indicate that chewing causes regional increases in neuronal activity in the brain, some of which are age-dependent.
Galanin-immunoreactive Nerve Fibers in the Periodontal Ligament during Experimental Tooth Movement
Authors: Deguchi T. , Takeshita N. , Balam T.A. , Fujiyoshi Y. , Takano-Yamamoto T.
Published: January 2009

Neuropeptides have been suggested to play a role in pain transmission during orthodontic tooth movement. We examined this hypothesis by examining the effect of orthodontic tooth movement on the expression of galanin (GAL)-immunoreactive (ir) nerve fibers in the periodontal ligament (PDL) of one mesial root (MR) and two distal roots (DRs) of the rat maxillary first molar. In control rats, GAL-ir fibers were very rare in the PDL. One day after the insertion of the elastic band, the number of GAL-ir fibers increased, becoming most numerous at 3 days. From 5 to 28 days, GAL-ir fibers tended to decrease. Electron microscopic observation showed that all of the GAL-ir fibers were unmyelinated. These findings suggest that GAL-containing nerve fibers in the PDL may play an important role in the response of the tissue to experimental tooth movement.
Effects of Echistatin and an RGD Peptide on Orthodontic Tooth Movement
Authors: Dolce C. , Vakani A. , Archer L. , Morris-Wiman J.A. , Holliday L.S.
Published: January 2009

We tested whether orthodontic tooth movement (OTM) could be blocked by local administration of echistatin or an arginine-glycine-aspartic acid (RGD) peptide, agents known to perturb bone remodeling, adjacent to maxillary molars in rats. These molecules were incorporated into ethylene-vinyl acetate (ELVAX), a non-biodegradable, sustained-release polymer. In vitro experiments showed that the echistatin and RGD peptide were released from ELVAX in active forms at levels sufficient to disrupt osteoclasts. Biotinylated RGD peptide was released from ELVAX into the PDL after surgical implantation. ELVAX loaded with either RGD peptide or echistatin and surgically implanted next to the maxillary molars inhibited orthodontic tooth movement (p < 0.01). The RGD peptide also reduced molar drift (p < 0.05). This study shows the feasibility of using ELVAX to deliver integrin inhibitors adjacent to teeth to limit local tooth movement in response to orthodontic forces.
Effects of Matrix Metalloproteinase Inhibitors on Bone Resorption and Orthodontic Tooth Movement
Authors: Holliday L.S. , Vakani A. , Archer L. , Dolce C.
Published: January 2009

Matrix metalloproteinases are involved in the regulation of bone remodeling. The hypothesis that matrix metalloproteinase inhibitors may be useful for experimentally limiting orthodontic tooth movement, a process involving perturbations of normal bone remodeling, was tested. General matrix metalloproteinase inhibitors limited the resorption of bone slices by mouse marrow cultures stimulated by calcitriol, parathyroid hormone, and basic-fibroblast growth factor. Pre-coating dentin slices with short arginine-glycine aspartic acid (RGD) peptides, but not arginine-glycine-glutamic acid (RGE) controls, restored bone resorption in the presence of matrix metalloproteinase inhibitors. Orthodontic tooth movement was inhibited by local delivery of Ilomastat, a general matrix metalloproteinase inhibitor, with the use of ethylene-vinyl-acetate (ELVAX) 40, a non-biodegradable, non-inflammatory sustained-release polymer. This study shows that orthodontic tooth movement can be inhibited with the use of matrix metalloproteinase inhibitors, and suggests a mechanistic link between matrix metalloproteinase activity and the production of RGD peptides.
Behavior of SaOS-2 Cells Cultured on Different Titanium Surfaces
Authors: Postiglione L. , Di Domenico G. , Ramaglia L. , Montagnani S. , Salzano S. , Di Meglio F. , Sbordone L. , Vitale M. , Rossi G.
Published: January 2009

Surface properties may affect the clinical outcome of titanium dental implants. The aim of the present study was to investigate the effects of 3 different titanium surfaces—smooth (S), sandblasted (SB), and titanium plasma-sprayed (TPS)—on proliferation, differentiation, and apoptosis of human osteoblast-like cells, SaOS-2. Cell proliferation was significantly (p < 0.05) higher on the S surface, and synthesis of extracellular matrix proteins was more abundant on TPS and SB than on S surfaces. Analysis of integrin receptors showed a higher expression of α2, α5, αVβ3, and ß1 on TPS as compared with SB and S surfaces. An increase in alkaline phosphatase activity was detected only on SB and TPS surfaces. Analysis of cell apoptosis did not demonstrate any significant difference among the 3 different surfaces. The results indicate that titanium surface topography affects proliferation and differentiation of osteoblast-like SaOS-2 cells, suggesting that surface properties might be important for bone response around dental implants in vivo.
Spectroscopic Imaging of Mineral Maturation in Bovine Dentin
Authors: Verdelis K. , Crenshaw M.A. , Paschalis E.P. , Doty S. , Atti E. , Boskey A.L.
Published: January 2009

Dentin is a useful model for the study of mineral maturation. Using Fourier Transform Infrared Imaging (FTIRI), we characterized distinct regions in developing dentin at 7-μm spatial resolution. Mineral-to-matrix ratio and crystallinity in bovine dentin from cervical and incisal parts of 3rd-trimester fetal compared with one-year-old incisor crowns showed that virtually all maturation stages in dentin could be spectroscopically isolated and analyzed. In the fetal incisors, mantle and circumpulpal dentin presented distinct patterns of mineral maturation. Gradients in both mineral properties examined were observed at the mineralization front and at the dentino-enamel junction.
Integrating Oxalate Desensitizers with Total-etch Two-step Adhesive
Authors: Tay F.R. , Pashley D.H. , Mak Y.F. , Carvalho R.M. , Lai S.C.N. , Suh B.I.
Published: January 2009

Compromised bonding of total-etch adhesives to dentin treated with oxalate desensitizers results from the interference of a surface layer of acid-resistant crystals of calcium oxalate. We hypothesize that effective tubular occlusion and dentin bonding may be simultaneously achieved by depleting dentin surfaces of calcium with acids before desensitizer application. Dentin specimens treated with 4 oxalate desensitizers before or after being acid-etched were bonded with a two-step adhesive. Microtensile bond strengths (μTBS) were significantly lower, compared with the control, when oxalates were used before the specimens were acid-etched; in contrast, when oxalates were used after acid-etching. μTBS were similar to nonoxalate-treated controls. Dentin surfaces and tubular orifices were covered with a surface layer of crystals when desensitizers were applied to fractured dentin and smear-layer-covered dentin before specimens were acid-etched. However, when the dentin was acid-etched prior to the application of oxalate desensitizers, the crystals were largely limited to the subsurface of dentinal tubules, where they did not interfere with subsequent resin bonding.
Oral Health Indicators Poorly Predict Coronary Heart Disease Deaths
Authors: Tuominen R. , Reunanen A. , Paunio M. , Paunio I. , Aromaa A.
Published: January 2009

Several earlier studies have suggested that development of coronary heart disease (CHD) is causally related to oral infections. The aim of this study was to investigate the association between oral health indicators and CHD deaths. Out of a nationally representative sample, 6527 men and women aged 30–69 years participated in the health examination with a dental check. Detailed oral health data included caries, periodontal and dental plaque status, presence of remaining teeth, and various types of dentures. Over a mean 12-year follow-up, persons dying of CHD were older and more often smoked, had hypertension, hypercholesterolemia, diabetes, and only a basic education compared with other persons. In univariate analyses, several oral health indicators were associated with CHD deaths. Adjustment for the established CHD risk factors reduced all these associations to statistical non-significance. The associations between oral health indicators and CHD are mostly explained by confounding factors, particularly those relating to health behavior.
Forward Mandibular Positioning Up-regulates SOX9 and Type II Collagen Expression in the Glenoid Fossa
Authors: Rabie A.B.M. , She T.T. , Harley V.R.
Published: January 2009

Regulatory factors governing the formation of bone in the glenoid fossa in response to functional appliance therapy have not been identified. Therefore, the purpose of this study was to investigate the temporal pattern of expression of two key chondrogenesis markers—SOX9 and its target gene, type II collagen—in the glenoid fossa by immunostaining in a 35-day-old Sprague Dawley rat model during both natural growth and forward mandibular positioning. The expression of both factors was up-regulated when the mandible was positioned forward, indicating an enhancement of chondrocyte differentiation and chondroid matrix formation. Our results indicate that chondroid bone formation in the glenoid fossa in response to forward mandibular positioning is regulated by molecular markers indicative of endochondral ossification.
A Repetitive, Steady Mouth Opening Induced an Osteoarthritis-like Lesion in the Rabbit Temporomandibular Joint
Authors: Fujisawa T. , Kuboki T. , Kasai T. , Sonoyama W. , Kojima S. , Uehara J. , Komori C. , Yatani H. , Hattori T. , Takigawa M.
Published: January 2009

Although excessive mechanical stress is assumed to be one of the factors contributing to pathogenesis of temporomandibular joint (TMJ) osteoarthritis (OA), no pure mechanical-stress-induced OA model has been developed without surgical manipulation or puncture of the joint cavity. The purpose of this study was to establish a genuine mechanical-stress-induced OA model of the rabbit TMJ. In the experimental rabbits, repetitive, forced jaw-opening, 3 hrs/day for 5 days, was applied with the use of a general anesthesia protocol. By histological assessment of the TMJ articular tissues, partial eburnation of the articular cartilage, reactive marginal proliferation of the articular cartilage chondrocytes, and nested proliferation of chondrocytes in the subchondral bone area were observed at 7 days after the repetitive, forced-jaw-opening period. These results suggest that the repetitive, forced-jaw-opening protocol without surgical intervention can induce evident OA-like lesions in the rabbit TMJ, and this OA model may greatly contribute to the elucidation of the cartilage degradation mechanism in TMJ OA.
Multiple Dendritic Cell (DC) Subpopulations in Human Gingiva and Association of Mature DCs with CD4+ T-cells in situ
Authors: Jotwani R. , Cutler C.W.
Published: January 2009

Gingival epithelium is a site of active trafficking of Langerhans cells (LCs), while the lamina propria in chronic periodontitis (CP) contains CD83+ mature dendritic cells (mDCs) and CD4+ T-cells. The immune cells that contribute to the mDCs, and whether mDCs engage with T-cells in situ, are unclear. Using several immunohistochemical approaches, combined with fluorescence-, light-, and scanning laser confocal-microscopy, we show that, in addition to LCs, the gingiva contains dermal DCs (DDCs) in the lamina propria; moreover, DDCs increase in number during CP. Furthermore, DDCs, LCs, and B-cells co-express CD83 in CP and contribute to the mDC pool. Double-staining for CD83 and CD4 revealed that mDCs associate with clusters of CD4+ T-cells in the lamina propria. Analysis of these data suggests that multiple DC subsets mature in the gingiva and that mature DCs engage in antigen presentation with T-cells in chronic periodontitis.
Degradation of Antimicrobial Histatin-variant Peptides in Staphylococcus aureus and Streptococcus mutans
Authors: Groenink J. , Ruissen A.L.A. , Lowies D. , van ’t Hof W. , Veerman E.C.I. , Nieuw Amerongen A.V.
Published: January 2009

Histidine-free variants of salivary histatin 5 have a broad antimicrobial activity against various bacteria. In relation to a possible therapeutic application, we were interested in the susceptibility of these small peptides (14 amino acids long) to microbial proteinases and whether this affects their antimicrobial activity. Analyses by SDS-PAGE of supernatants of peptide-bacteria incubation showed a reduction in protein bands within 15 minutes’ incubation, as a result of cellular internalization. Degradation products of dhvar1 and dhvar2 appeared within one hour in the supernatants of Streptococcus mutans and Staphylococcus aureus. In contrast, the variants dhvar3 and dhvar4 were more resistant to degradation under the same conditions. MALDI-TOF analyses identified cleavage of dhvar1 and dhvar2 at Glu6. The N-terminal peptide part (1–6) of dhvar1 and 2 showed no bactericidal activity, while peptide fragment (7–14) showed a highly reduced bactericidal activity.
The Dentin Matrix Protein 1 (Dmp1) is Specifically Expressed in Mineralized, but not Soft, Tissues during Development
Authors: Feng J.Q. , Huang H. , Lu Y. , Ye L. , Xie Y. , Tsutsui T.W. , Kunieda T. , Castranio T. , Scott G. , Bonewald L.B. , Mishina Y.
Published: January 2009

Dentin Matrix Protein 1 ( Dmp1) was originally identified from dentin. However, its expression and function in vivo are not clear. To clarify these two issues, we have generated mice carrying a truncated Dmp1 gene by using gene targeting to replace exon 6 with a lacZ gene. Northern blot analysis shows the expected 5.8-kb Dmp1-lacZ fusion transcript and loss of the wild-type 2.8-kb Dmp1 transcript, confirmed by a lack of immunostaining for the protein. Using heterozygous animals, we demonstrate that Dmp1 is specific for mineralized tissues. Not previously shown, Dmp1 is also expressed in pulp cells. Dmp1-deficient embryos and newborns display no apparent gross abnormal phenotype, although there are a modest expansion of the hypertrophic chondrocyte zone and a modest increase in the long bone diameter. This suggests that DMP1 is not essential for early mouse skeletal or dental development.
Genetic Mapping of the Absence of Third Molars in EL Mice to Chromosome 3
Authors: Nomura R. , Shimizu T. , Asada Y. , Hirukawa S. , Maeda T.
Published: January 2009

We noted the absence of all 4 third molars (M3) in Epilepsy-Like disorder (EL) mice, an animal model for the study of epilepsy. This study was conducted to identify the major candidate chromosome and to detect the region that included the candidate gene causing the absence of M3 in EL mice. Linkage analysis was performed on genetic crosses of EL mice and MSM ( Mus musculus molossinus) strain mice, which had a normal complement of teeth. Genome-wide screening by individual genotyping of F2 intercross mice identified mouse chromosome 3 as one of the candidate chromosomes. Based on high linkage scores in detailed genotyping of F2 intercross and N2 backcross mice, the candidate locus for the absence of M3 in EL mice was mapped on the middle of chromosome 3.
Apoptosis in Human Oral Squamous Cell Carcinomas is Induced by 15-Deoxy-Δ12,14-Prostaglandin J2 but not by Troglitazone
Authors: Fukuchi K. , Date M. , Azuma Y. , Shinohara M. , Takahashi H. , Ohura K.
Published: January 2009

15-deoxy-Δ12,14-prostaglandin J2 (15-d-PGJ2) and troglitazone have been shown to induce apoptosis in several carcinoma cell lines. However, apoptotic signaling pathways of these agents are poorly understood. We tested the hypothesis that peroxisome proliferator-activated receptor-γ ligands such as these two agents will induce caspase-mediated apoptosis in human oral squamous cell carcinomas (SCC). Treatment of these cell lines with 15-d-PGJ2 or troglitazone decreased cell viability in a time- and dose-dependent manner. 15-d-PGJ2, but not troglitazone, induced apoptosis, and this effect was time-dependent. Exposure of cells to 20 μM of 15-d-PGJ2 initiated early cytochrome c release, followed by late caspase activation. Furthermore, co-treatment with caspase inhibitors such as Z-VAD-FMK or Z-DEVD-FMK of oral SCC cells that had been treated with 20 μM of 15-d-PGJ2 blocked apoptosis. Our study demonstrates that treatment with 15-d-PGJ2, but not troglitazone, induces apoptosis in human SCC cell lines, and 15-d-PGJ2 appears to work through cytochrome c release and caspase activation.
A Determination of Tumor Necrosis Factor Expression in TMJ Inflammation with the Use of Microarray Analysis
Authors: Spears R. , Oakes R. , Moore C. , Bellinger L.L. , Hutchins B.
Published: January 2009

Many different factors can lead to inflammatory changes within temporomandibular joint tissues. This investigation examined if the expression of TNF-α and its receptors was altered in TMJ tissues during inflammation. Adult male rats were injected bilaterally with complete Freund’s adjuvant (CFA) into the TMJ or served as uninjected controls and were killed two days after CFA treatment. TMJ tissues were removed, and expression of TNF-α and its receptors was examined via gene microarray analysis, RT-PCR, Western blot, and ELISA. Gene microarray analysis provided evidence for changes in gene expression, notably that TNF-α and TNF-R1, but not TNF-R2, were significantly elevated in CFA-treated TMJ tissues. However, protein levels of TNF-α, TNF-R1, and TNF-R2 were all significantly increased in CFA-treated TMJ tissues. These results indicate that the pro-inflammatory cytokine TNF-α may play a significant role in the onset of inflammatory conditions associated with adjuvant-induced arthritis of the TMJ.
Prediction of Mechanical Properties of the Cancellous Bone of the Mandibular Condyle
Authors: van Ruijven L.J. , Giesen E.B.W. , Farella M. , van Eijden T.M.G.J.
Published: January 2009

The mechanical properties of cancellous bone depend on the bone structure. The present study examined the extent to which the apparent stiffness of the cancellous bone of the human mandibular condyle can be predicted from its structure. Two models were compared. The first, a structure model, used structural parameters such as bone volume fraction and anisotropy to estimate the apparent stiffness. The second was a finite element model (FEM) of the cancellous bone. The bone structure was characterized by micro-computed tomography. The calculated stiffnesses of 24 bone samples were compared with measured stiffnesses. Both models could predict 89% of the variation in the measured stiffnesses. From the stiffness approximated by FEM in combination with the measured stiffness, the stiffness of the bone tissue was estimated to be 11.1 ± 3.2 GPa. It was concluded that both models could predict the stiffness of cancellous bone with adequate accuracy.
Fluoride Release from a Resin-modified Glass-ionomer Cement in a Continuous-flow System: Effect of pH
Authors: Carey C.M. , Spencer M. , Gove R.J. , Eichmiller F.C.
Published: January 2009

Fluoride is added to many dental restorative materials, including glass-ionomer cements, for the specific purpose of leaching fluoride into the surrounding tissues to provide secondary caries inhibition. During the caries process, an acidic environment attacks the dental tissues as well as the glass-ionomer cement. We hypothesized that pH significantly affects the rate of release of fluoride from the glass-ionomer cement. A continuous-flow fluoride-measuring system that monitors the amount of fluoride released over time was used to determine the release of fluoride from a resin-modified glass-ionomer cement (KetacFil®). The results show that the release rate began with a fast burst of fluoride which quickly diminished to low levels in 3 days. Under neutral pH conditions, the rate of fluoride release at 72 hrs was significantly slower than at pH 4.
Intracellular Calcium in Signaling Human β-Defensin-2 Expression in Oral Epithelial Cells
Authors: Krisanaprakornkit S. , Jotikasthira D. , Dale B.A.
Published: January 2009

Expression of human β-defensins is correlated with differentiation in the oral epithelium, consistent with their function as part of the epithelial antimicrobial barrier. Because calcium is a known regulator of epithelial differentiation, we tested the hypothesis that calcium concentration mediates β-defensin expression. Gingival epithelial cells were cultured in medium containing low calcium concentration (0.03 mM), then either changed to high extracellular calcium concentrations or stimulated with thapsigargin to release intracellular calcium stores in the presence or absence of BAPTA-AM, a calcium chelator. Human β-defensin-2 (hBD-2) mRNA expression was rapidly induced by thapsigargin, and more slowly induced by high extracellular calcium. Induction of hBD-2 peptide was confirmed by immunofluorescence. BAPTA-AM inhibited hBD-2 induction by both thapsigargin and calcium in a dose-dependent fashion. In addition, BAPTA-AM inhibited hBD-2 induction by a bacterial stimulant. Collectively, these findings demonstrate that intracellular calcium is a critical mediator of hBD-2 expression. Abbreviations used in this study are: BAPTA-AM, 1,2-bis(2-aminophenoxy)-ethane-N,N,N′,N′-tetra-acetic acid tetrakis (acetoxymethyl ester); DMSO, dimethylsulfoxide; F. nucleatum, Fusobacterium nucleatum; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; HBDs, human β-defensins; HGECs, human gingival epithelial cells; MAP, mitogen-activated protein; and RT-PCR, reverse-transcriptase/polymerase chain-reaction.
Involvement of CD73 (ecto-5′-nucleotidase) in Adenosine Generation by Human Gingival Fibroblasts
Authors: Hashikawa T. , Takedachi M. , Terakura M. , Saho T. , Yamada S. , Thompson L.F. , Shimabukuro Y. , Murakami S.
Published: January 2009

Adenosine has various biological effects on human gingival fibroblasts (HGF) and epithelial cells closely associated with inflammation, such as cytokine production and cell adhesion. However, the mechanism of adenosine formation in periodontal tissues is not yet defined. In this study, we examined the involvement of CD73 (ecto-5′-nucleotidase) in adenosine generation by HGF. CD73 was detected on in vitro-maintained HGF by immunocytochemistry and flow cytometric analysis. Adenosine production was observed following the addition of 5′-AMP, the substrate of CD73-associated ecto-5′-nucleotidase. Moreover, the addition of 5′-AMP to cultured HGF resulted in the elevation of cyclic adenosine monophosphate (cAMP). The 5′-AMP-induced increase in intracellular cAMP level was inhibited markedly by xanthine amine congener, an adenosine receptor antagonist, and partially by α,β-methylene adenosine 5′-diphosphate, an ecto-5′-nucleotidase inhibitor. These results suggest that CD73 on HGF is a critical enzyme responsible for the generation of adenosine, an immunomodulator that activates adenosine receptors.
Induction of CD13 on T-lymphocytes by Adhesive Interaction with Gingival Fibroblasts
Authors: Saho T. , Kishida T. , Hirano H. , Hashikawa T. , Shimabukuro Y. , Murakami S.
Published: January 2009

Lymphocytes in peripheral blood do not express CD13 (aminopeptidase N), a membrane alanyl metallopeptidase. However, it has been demonstrated that locally infiltrated lymphocytes in chronic inflammatory sites can be CD13-positive, and possible involvement of stromal cell adherence in the induction of CD13 has been suggested. In this study, we examined whether T-lymphocyte/gingival-fibroblast interaction can activate T-lymphocytes to express CD13. CD13 expression was induced on PMA-activated T-lymphocytes only when they adhered directly to human gingival fibroblasts (HGF) at 2 hrs after the co-culture began, while an increase in the enzyme activity of CD13 was also confirmed in activated T-lymphocytes that had been co-cultured with HGF. Furthermore, CD13-positive T-lymphocytes were detected in inflamed gingival tissues in vivo. Analysis of these results indicates that direct interaction with HGF is essential for the induction of CD13 expression on T-lymphocytes that was also observed in periodontitis lesions.
How Does Fluoride Concentration in the Tooth Affect Apatite Crystal Size?
Authors: Vieira A. , Hancock R. , Limeback H. , Schwartz M. , Grynpas M.
Published: January 2009

Despite fluoride’s (F) well-documented ability to prevent caries, the effects of F concentrations on enamel and dentin apatite crystals are unknown. The present study examined the hypothesis that tooth F concentration and tooth crystallite size correlate. One hundred human unerupted third molars were studied—53 from Fortaleza-Brazil (F water 0.7 ppm), 23 from Toronto (1.0 ppm), and 24 from Montreal (0.2 ppm). F concentration was analyzed by Neutron Activation Analysis and apatite crystal size by powder x-ray diffraction. A positive correlation between dentin F concentration and enamel crystallite length and width was found. Enamel crystallite length was significantly greater in teeth from Fortaleza than in teeth from Toronto (p = 0.011) and Montreal (p = 0.003). Enamel crystallite widths were significantly greater in Fortaleza teeth compared with those from Toronto (p = 0.020) and Montreal (p < 0.001). No difference in the dentin crystallite size was seen in the 3 regions. Thus, tooth F concentration and crystallite size correlate.
Anti-cardiolipin Antibodies in Sera from Patients with Periodontitis
Authors: Schenkein H.A. , Berry C.R. , Burmeister J.A. , Brooks C.N. , Barbour S.E. , Best A.M. , Tew J.G.
Published: January 2009

Antiphospholipid antibodies are commonly found in patients with systemic lupus erythematosus or the antiphospholipid syndrome, and a subset of such antibodies is associated with prothrombotic events such as stroke and with adverse pregnancy outcomes and fetal loss. We examined sera from 411 patients who were clinically characterized as to their periodontal disease status for serum levels of β2-glycoprotein I-dependent anti-cardiolipin autoantibodies (anti-CL). The prevalence of patients with chronic periodontitis (CP) and generalized aggressive periodontitis (GAgP) positive for anti-CL (16.2% and 19.3%, respectively) was greater than that in healthy controls (NP) and localized aggressive periodontitis (LAgP) patients (6.8% and 3.2%). Patients with these autoantibodies demonstrated increased pocket depth and attachment loss compared with patients lacking the antibodies. Analysis of the data indicates that patients with generalized periodontitis have elevated levels of autoantibodies reactive with phospholipids. These antibodies could be involved in elevated risk for stroke, atherosclerosis, or pre-term birth in periodontitis patients.
Survivin, a Potential Early Predictor of Tumor Progression in the Oral Mucosa
Authors: Lo Muzio L. , Pannone G. , Leonardi R. , Staibano S. , Mignogna M.D. , De Rosa G. , Kudo Y. , Takata T. , Altieri D.C.
Published: January 2009

Survivin is a recently described apoptosis inhibitor selectively over-expressed in most tumors. Immunohistochemistry was used to investigate a potential role of survivin as an early predictor of malignant transformation in precancerous and cancerous lesions of the oral cavity. Survivin was present in 10/30 cases (33%) of oral precancerous lesions without malignant progression, and in 15/16 cases (94%) of oral precancerous lesions evolved into full-blown squamous cell carcinoma. Tumors that progressed from these precancerous lesions retained widespread survivin positivity (100%). Variations among group means were highly statistically significant (p < 0.001). No significant correlation was found between survivin expression and the degree of dysplasia. High expression of cytoplasmic/nuclear survivin is an early event during oral carcinogenesis and may provide a useful tool for the identification of precancerous lesions at higher risk of progression into invasive carcinoma.