bluuebunny/crossref_metadata_2025 huggingface dataset:
Intra-oral Distribution of Dental Fluorosis in Newburgh and Kingston, New York
Authors: Kumar J. , Swango P. , Haley V. , Green E.
Published: January 2009

Previous studies of intra-oral distribution of dental fluorosis in low-fluoride areas reported that teeth that formed later in life were more frequently affected compared with the early-forming teeth. The steady increase of plasma fluoride with age, even under constant fluoride exposure, has been suggested as a possible mechanism for this clinical manifestation. To determine the intra-oral distribution of Dean's Index scores and the effect of fluoride exposure on early- and late-forming teeth, we analyzed data collected on 2193 seven-to 14-year-old lifelong residents of fluoridated or non-fluoridated areas. Logistic regression procedures were used to determine the effects of fluoridation, early brushing, daily supplements, and other socio-demographic variables on early-and late-forming teeth. The results show that the occurrence of very mild or greater levels of fluorosis in the upper anterior teeth was 7 to 10% in the fluoridated area and 5 to 9% in the nonfluoridated area. In the fluoridated area, the occurrence of fluorosis increased from anterior to posterior teeth. Both early- and late-forming teeth were affected by exposure to fluoridation, daily fluoride supplement use, or brushing before the age of two years. This analysis showed that the esthetic consequence of exposure to multiple sources of fluoride was less dramatic, as evidenced by the lower frequency in upper anterior teeth compared with posterior teeth. The longer maturation process of the posterior teeth and the thicker enamel appear to be the likely explanation for the higher occurrence of dental fluorosis in posterior teeth.
Cortical Potentials Associated with Voluntary Mandibular Movements
Authors: Yoshida K. , Kaji R. , Hamano T. , Kohara N. , Kimura J. , Shibasaki H. , Lizuka T.
Published: January 2009

Movement-related cortical potentials (MRCPs) are negative potentials over the scalp, which gradually increase prior to voluntary movements, and might be applied to elucidate the cortical efferent function of the mandibular movements. We compared the MRCPs accompanying various mandibular movements to study the motor control mechanism underlying these movements. Electroencephalograms (EEGs) were recorded from 11 electrodes placed over the scalp (F3, Fz, F4, T3, C3, Cz, C4, T4, P3, Pz, and P4), according to the International 10-20 System, and electromyograms (EMGs) were obtained from surface electrodes over the masseter muscle and the anterior belly of the digastric muscle. Ten healthy subjects were requested to make brisk and self-paced mandibular movements in 4 different directions (mouth-opening and -closing, and left and right lateral movements). We obtained MRCPs by averaging the EEG, using the visually determined EMG onset as a trigger signal. In all the movements, a slowly increasing, bilaterally widespread negativity starting 1.5 to 2.0 sec before the EMG onset (Bereitschaftspotential, or BP proper) was observed, with the maximum over the vertex region. The negative slope (NS') occurred about 300 to 700 msec before the EMG onset. The cortical maps of BP/NS' (BP and NS' combined), immediately prior to the mouth-opening and- closing, showed a symmetrical distribution, whereas that for the lateral movements showed a tendency of predominance over the hemisphere ipsilateral to the direction of the movement. BP/NS' amplitudes at the onset of movement differed significantly or tended to do so between open, close, and lateral movements, suggesting that MRCP recordings may thus provide a means to explore the role of the cerebral cortex in the control of mandibular movements.
Biting and Chewing in Overdentures, Full Dentures, and Natural Dentitions
Authors: Fontijn-Tekamp F.A. , Slagter A.P. , Van Der Bilt A. , Van 'T Hof M.A. , Witter D.J. , Kalk W. , Jansen J.A.
Published: January 2009

It has been suggested that the provision of dental implants can improve the oral function of subjects with severely resorbed mandibles, possibly restoring function to the level experienced by satisfied wearers of conventional complete dentures. Nevertheless, a quantitative comparison has never been made and can be drawn from the literature only with difficulty, since studies differ greatly in methodology. To make such a comparison, we measured bite force and chewing efficiency by using identical methods in subjects with overdentures, complete full dentures, and natural dentitions. Our results indicated that bite forces achieved with overdentures on dental implants were between those achieved with artificial and natural dentitions. Chewing efficiency was significantly greater than that of subjects with full dentures (low mandible), but was still lower than that of subjects with full dentures (high mandible) and overdentures on bare roots. Differences in the height of the mandible revealed significant differences in chewing efficiency between the two full-denture groups. Furthermore, subjects with a shortened dental arch exerted bite forces similar to those of subjects with a complete-natural dentition, but their chewing efficiency was limited due to the reduced occlusal area. For all groups combined, a significant correlation was found between maximum bite force and chewing efficiency. Nearly half of the variation in chewing efficiency was explained by bite force alone.
Use of Radiology Practice Guidelines and Compliance with Accreditation Standards in US and Canadian Dental Schools
Authors: Kantor M.L.
Published: January 2009

In 1992 and 1997, all US and Canadian dental schools were surveyed by mail regarding the preferred initial radiographic examination prescribed for non-emergency, comprehensive-care patients (dentulous adults, edentulous adults, and children). In both survey years, a minority of US and Canadian dental schools reported using selection criteria for dentulous adults and children, while nearly all schools reported doing so for edentulous adults. The purpose of this secondary analysis was to investigate the relationship between the use of radiology selection criteria (vs. pre-determined routine examinations) in US and Canadian dental school clinics and three factors: (1) the credentials of the chief-of-service, (2) institutional funding, and (3) geographic region. "Credentials of the chief-of-service" is the single factor significantly related to the distributions of radiographic examinations prescribed for dentulous adults in both years (Fisher exact test, p ≤ 0.02). There are no statistically significant relationships for edentulous adults or children in either year. Multivariate analyses (logistic regression) of the 1997 data reveal that institutions with a credentialed chief-of-service are 2.39 times more likely to report using selection criteria than institutions with a non-credentialed chief-of-service; private institutions are 1.13 times more likely than public institutions, and Canadian schools are 3.65 times more likely than US schools. A similar trend was identified for children. Analysis of the 1992 data revealed similar trends for the credentials of the chief-of-service and the geographic region, but showed no association between institutional funding source and the use of selection criteria. Contrary to accreditation standards, most US and Canadian dental schools obtained pre-determined routine radiographic examinations on most new patients. However, the presence of a credentialed chief-of-service had a positive effect on the use of selection criteria for dentulous adults and children.
Cytokine Profiles of T-lymphocytes from Gingival Tissues with Pathological Pocketing
Authors: Takeichi O. , Haber J. , Kawai T. , Smith D.J. , Moro I. , Taubman M.A.
Published: January 2009

Periodontal disease is an infection in which destruction occurs at sites remote from the infection, resulting in pathological pocketing. Intervening between the infection and the destruction is a dense mononuclear inflammatory infiltrate. It has been suggested that this infiltrate might have characteristics and the destructive potential of Th1-type T lymphocytes. To ascertain the nature of the infiltrates we investigated the expression of mRNA for IL-2, IL-5, and IFN-γ by gingival mononuclear cells (GMC) from healthy (n = 8) or adult periodontitis (AP) patients (n = 25) by using cytokine-specific reverse-transcription/polymerasechain-reaction (RT-PCR). GMC, as obtained from patients' tissues, expressed IL-2, IFN-y, or IL-5 mRNA. Significantly higher proportions of GMC from AP patients expressed IL-2 and IFN-γ mRNA than did those from healthy subjects. TFN-γ was the most consistent cytokine message detected. In other experiments, gingival T-lymphocytes (n = 12) and CD4+ and CD8+ gingival T-lymphocytes (n = 16) were isolated from gingival tissues removed surgically from AP patients. AP gingival T-lymphocytes expressed mRNA for IL-2, IFN-γ, or IL-6 prior to stimulation. After stimulation with Con A, the cells significantly up-regulated IL-5 and IL-6 message expression. Both CD4+ and CD8+ gingival T-lymphocytes expressed IFN-γ, IL-5, and some IL-2. This cumulative cytokine profile observed in these experiments is consistent with the predominance of Th1-type cells in pathological tissues and with Th2-type cells, which can also be present, being up-regulated under appropriate stimulation. Importantly, CD4+ and CD8+ lymphocytes were shown to express T1- and T2-type cytokine message, emphasizing the potential for CD8- T-lymphocytes to participate in periodontal disease pathology.
H+-induced Tension Development in Demineralized Dentin Matrix
Authors: Pashley D.H. , Zhang Y. , Carvalho R.M. , Rueggeberg F.A. , Russell C.M.
Published: January 2009

Recent atomic force microscopy studies have shown that acid-etching dentin causes the surface to recede. The purpose of this work was to test the hypothesis that acidic solutions can cause contraction of demineralized dentin matrix. Small beams of dentin were cut from extracted human third molars. The central region of each specimen was completely demineralized in EDTA. Specimens held in a tester were immersed in acidic solutions, and the amount of tension was recorded. Test variables included gauge length, cross-sectional area, pre-strain, and pH. The results showed that immersion of demineralized dentin in acidic solutions caused tension that was directly related both to H+ concentration at pH < 2 and to pre-strain. The contractile stress development ( ca. 0.2-0.4 MPa) was sufficient to cause a collapse of demineralized dentin matrix. The mechanism for this effect probably involves H+-induced conformation changes in the collagen matrix.
Optical Scattering Power for Characterization of Mineral Loss
Authors: Ko C.C. , Tantbirojn D. , Wang T. , Douglas W.H.
Published: January 2009

Mineral loss in early caries cannot be measured without invasive procedures. To quantify mineral loss without sectioning the tooth, one must determine the optical scattering of the enamel. Using enamel white-spot lesions, we hypothesize that the optical scattering power (Sp) of the demineralized enamel would provide a quantitative estimate of mineral loss. Enamel slabs were demineralized to produce artificial white spots. The data were acquired by means of a Charge-Coupled Device (CCD) camera and image-processing software. For the purpose of comparison, mineral loss (ΔZ) of the demineralized samples was determined by the use of a microhardness approach after the samples were sectioned. The scattering power correlated well with AZ (r2 = 0.82). In contrast, simple reflectance of the demineralized samples correlated poorly with AZ (r 2 = 0.22). The validity of using scattering power to measure demineralization has been confirmed by a three-dimensional Monte Carlo Simulation.
Immunohistochemical Detection and Distribution of Enamelysin (MMP-20) in Human Odontogenic Tumors
Authors: Takata T. , Zhao M. , Uchida T. , Wang T. , Aoki T. , Bartlett J.D. , Nikai H.
Published: January 2009

Enamelysin is a tooth-specific protease that was initially isolated from porcine enamel organ and subsequently from human odontoblasts. Since this protease is thought to play important roles in tooth development, the evaluation of enamelysin in odontogenic tumors may aid our understanding of the histogenesis and cell differentiation of such lesions. A monoclonal antibody (203-lC7) was generated against synthesized human enamelysin oligopeptide and was used to assess the immunolocalization of enamelysin in healthy developing tooth germs and various types of odontogenic lesions. In tooth germs, enamelysin expression was detected only in the secretory enamel. Thus, 203-1C7 may serve as an enamel-specific marker in the late stage of enamel matrix development and calcification. In odontogenic lesions, strong enamelysin staining was demonstrated in the immature enamel matrix of ameloblastic fibro-odontomas and odontomas. Furthermore, enamelysin was also detected in globular amyloid masses and calcified foci in calcifying epithelial odontogenic tumors, hyaline droplets, small and large mineralized areas in adenomatoid odontogenic tumors, and a portion of ghost cells in calcifying odontogenic cysts. Positive reactivity was also observed in selected tumor cells in some of these tumors. No intracellular staining for enamelysin was detected in ameloblastomas or the ameloblastic portion of ameloblastic fibro-odontomas. Also, enamelysin was not detected in dentin, dysplastic dentinoid hyaline matrices, and cementum that were present within the tumors examined. Thus, taken together, our results suggest that the enamelysin-specific monoclonal antibody (203-1C7) may be utilized as a marker of early enamel development and that enamelysin may be involved in the pathogenesis of specific odontogenic tumors.
Jaw-Tongue Reflex: Afferents, Central Pathways, and Synaptic Potentials in Hypoglossal Motoneurons in the Cat
Authors: Ishiwata Y. , Ono T. , Kuroda T. , Nakamura Y.
Published: January 2009

The tongue position is reflexively controlled by the jaw position (the jaw-tongue reflex). The purpose of this study was to clarify the mechanism of this reflex in terms of afferents, central pathways, and synaptic potentials in hypoglossal motoneurons in the cat. Intracellular recordings from hypoglossal motoneurons revealed that electrical stimulation of the temporalis muscle nerve evoked excitatory and inhibitory post-synaptic potentials in hypoglossal motoneurons. The threshold of temporalis muscle nerve stimulation for evoking the synaptic potentials was higher than 2.0 times the nerve threshold. The amplitude of the potentials increased with stimulus intensity up to 5.0 times the nerve threshold. Punctate light pressure applied to the temporalis muscle induced a tonic depolarizing potential in hypoglossal motoneurons on which action potentials as well as depolarizing synaptic activation noise were superimposed. On the other hand, electrical stimulation of the temporalis muscle during jaw-opening could slightly inhibit the electromyographic activities in the genioglossus and styloglossus muscles. Lesions including the Probst's tract at the level caudal to the trigeminal motor nucleus abolished both excitation and inhibition in hypoglossal motoneurons induced by tonic depression of the lower jaw, but exerted no effects on either the tonic stretch reflex or the trigemino-hypoglossal reflex. In contrast, lesions including the trigeminal spinal tract produced no changes in either excitation or inhibition of hypoglossal motoneurons induced by temporalis muscle afferents, whereas the excitation of hypoglossal motoneurons was abolished by the lesions. We conclude that the group II muscle spindle afferents from the temporalis muscle are primarily responsible for evoking the jaw-tongue reflex.
Relaxation vs. Cognitively Oriented Therapies for Dental Fear
Authors: Berggren U. , Hakeberg M. , Carlsson S.G.
Published: January 2009

Cognitive therapy has been reported for the treatment of dental phobia, but comparisons with other behavioral treatments are scarce. This study investigated the outcome of two modes of treatment for phobic dental fear. Relaxation and cognitively oriented therapy were compared in a sample of 112 adult fearful dental patients. The patient made questionnaire assessments of background and outcome variables, and the specialist dentist rated successful/non-successful outcome. It was shown that a higher number of patients who received cognitively oriented therapy completed the treatment program, while anxiety was more reduced among patients who received relaxation-oriented therapy. Dropout during the initial phobia therapy with a psychologist was related to lower motivation (willingness to engage in treatment), while failures during dental treatment after the completion of therapy were related to higher levels of general fear and anxiety. A multiple logistic regression model explaining 67% of the variance revealed that the risk of failure was only slightly increased by general fears, while patients with low (below median) motivation ran a 3.6-times-higher risk of dropping out. In conclusion, it was shown that the two treatment methods were both effective in reducing dental phobic reactions. However, while cognitively oriented therapy resulted in a higher number of patients completing therapy, relaxation-oriented treatment generally resulted in a more significant reduction in dental fear as well as in general anxiety and fear. Motivation was found to be a significant predictor of successful treatment outcome.
Low Unstimulated Salivary Flow and Subjective Oral Dryness: Association with Medication, Anxiety, Depression, and Stress
Authors: Bergdahl M. , Bergdahl J.
Published: January 2009

Medication and psychological processes may affect salivary flow and cause subjective oral dryness. The importance of these factors is unclear. The aim of this study was to evaluate the association of medication, anxiety, depression, and stress with unstimulated salivary flow and subjective oral dryness. We studied 1202 individuals divided into three groups, and controls. Intake of medication was evaluated. Anxiety, depression, and stress were assessed. Unstimulated salivary flow < 0.1 mL/min and subjective oral dryness were significantly associated with age, female gender, intake of psychotropics, anti-asthmatics, and diuretics. Unstimulated salivary flow < 0.1 mL/min and no subjective oral dryness were significantly associated with age, intake of antihypertensives, and analgesics. Subjective oral dryness and unstimulated salivary flow > 0.1 mL/min were significantly associated with depression, trait anxiety, perceived stress, state anxiety, female gender, and intake of antihypertensives. Age and medication seemed to play a more important role in individuals with hyposalivation, and female gender and psychological factors in individuals with subjective oral dryness.
Prevalence of Specific Genotypes of Porphyromonas gingivalis fimA and Periodontal Health Status
Authors: Amano A. , Kuboniwa A.M. , Nakagawa I. , Akiyama S. , Morisaki I. , Hamada S.
Published: January 2009

Porphyromonas gingivalis fimA gene encoding fimbrillin, a subunit of fimbriae, has been classified into 5 genotypes (types I to V) based on their nucleotide sequences. Here, we investigated the relationship between the prevalence of these fimA genotypes and periodontal health status in adults. Dental plaque specimens obtained from 380 periodontally healthy adults and 139 periodontitis patients were analyzed by the PCR method. P. gingivalis was detected in 36.8% of the healthy subjects and in 87.1% of the periodontitis patients. Among the P. gingivalis-positive healthy adults, the most prevalent fimA type was type I (76.1%), followed by type V. In contrast, a majority of the periodontitis patients carried type II fimA organisms (66.1%), followed by type IV. The univariate analysis illustrated that periodontitis was associated with the occurrences of type I fimA (OR 0.16), type II (OR 44.44), type III (1.96), type IV (13.87), and type V (1.40). These findings clearly indicate that there are both disease-associated and non-disease-associated strains of P. gingivalis, and that their infectious traits influencing periodontal health status could be differentiated based on the clonal variation of fimA genes.
Meal Pattern Analysis in Response to Temporomandibular Joint Inflammation in the Rat
Authors: Harper R.P. , Kerins C.A. , Talwar R. , Spears R. , Hutchins B. , Carlson D.S. , Mclntosh J.E. , Bellinger L.L.
Published: January 2009

Inflammation of the temporomandibular joint (TMJ) can alter behavioral responses such as food intake and mobilize stress hormones. The hypothesis of this study was that food intake and diurnal corticosterone analysis can be used as indicators of adjuvant-induced TMJ inflammation. Groups of rats received adjuvant or no injections at the beginning of the resting (AM) or activity (PM) phase. Forty-eight hours (early) or 6 weeks (late) after adjuvant injection, plasma corticosterone was assayed and food intake was recorded. Food intake was suppressed up to 4 days post-injection. As expected, the non-injected group showed low AM and high PM corticosterone. AM corticosterone was elevated, but PM corticosterone was attenuated in both early- and late-stage-injected rats. A computerized pair-fed experiment showed that adjuvant-induced hypophagia did not alter corticosterone levels. Meal pattern analysis revealed decreased food intake due to a decrease in the number of meals taken. Notably, meal size remained the same but meal duration increased. This model demonstrated that food intake and stress hormone analysis could be used as indicators for sequelae of adjuvant-induced TMJ inflammation.
Local and Chronic Application of PTH Accelerates Tooth Movement in Rats
Authors: Soma S. , Matsumoto S. , Higuchi Y. , Takano-Yamamoto T. , Yamashita K. , Kurisu K. , Iwamoto M.
Published: January 2009

We previously reported that whereas systemic continuous infusion of parathyroid hormone (PTH) accelerated orthodontic tooth movement, systemic but intermittent injection of PTH did not increase the rate of tooth movement. Analysis of these data suggested that continuous administration of PTH could be applicable for orthodontic therapy. In the present study, we investigated whether local and chronic application of PTH(1-34) would accelerate orthodontic tooth movement. To increase the residence time of PTH in the injected area, we used methylcellulose (MC) gel (2% w/v) for a slow-release formulation of PTH. MC gel containing PTH (PTH-MC) continuously released biologically active PTH into the acceptor medium for more than 72 hrs in vitro. When male rats received a local injection of PTH-MC into the subpcriosteum in the mesio-palatal region of the maxillary first molar (M1) every other day, M1 movement, which was mesially drawn by an orthodontic coil spring attached to the maxillary incisors, was accelerated in a dose-dependent manner. PTH-MC injection at 1 μg/400 g body weight caused a 1.6-fold increase in the rate of tooth movement. The acceleration of tooth movement by PTH-MC injection was marked on days 6, 9, and 12. Local injection of PTH dissolved in saline without MC did not significantly accelerate tooth movement on day 6 or later. Histological examination revealed active osteoclastic bone resorption and a widened periodontal space on the compression side of the periodontal tissue in the PTH-MC-injected rats. These results suggest that local injection of PTH in a slow-release formulation is applicable to orthodontic therapy.
Antibodies against Mycobacterial Antigens in the Synovial Fluid of Patients with Temporomandibular Disorders
Authors: Adachi N. , Matsumoto S. , Tokuhisa M. , Kobayashi K. , Yamada T.
Published: January 2009

In the absence of active pulmonary disease, mycobacterial infection frequently causes arthritis and can be considered to initiate autoimmune diseases such as rheumatoid arthritis. Temporomandibular disorder (TMD) is a disease in which pain and impaired mandibular movement appear to arise directly from degenerative or inflammatory changes within the temporomandibular joint, but its precise pathogeny has not been elucidated. Here we examined whether mycobacterial infection is related to the pathology of TMD. The antibody levels against mycobacterial antigen in the synovial fluid (SF) of patients with TMD were assessed by enzyme-linked immunosorbent assay (ELISA). Six of 17 TMD patients (35%) were found to possess mycobacterial antigen-specific immunoglobulin (lg) G but not IgM, while the six healthy volunteers possessed neither. Western-blot analysis was used to isolate the reacted antigen, and the IgG reacted strongly to 44-kDa antigen. The first 14 N-terminal amino acid sequences were determined, and computer analysis revealed that it was homologous to translational elongation factor Tu (EF-Tu) of Mycobacterium tuberculosis, which was a major target antigen for these antibodies. The 44-kDa protein of Mycobacterium bovis BCG (BCG) was identical with the EF-Tu of M. tuberculosis. We cloned the gene encoding the EF-Tu of BCG by using the synthesized oligonucleotide primers by means of polymerase chain-reaction. The gene was expressed in Escherichia coli. The protein was purified, and the antibody levels against this recombinant protein in the SF of TMD patients were assessed by ELISA. Our findings suggest that some cases of TMD are concerned with the synovial IgG against the EF-Tu of M. tuberculosis, and that the existence of the antibody is a clinical indication of TMD.
Immunoquantification of Human Salivary Mucins MG1 and MG2 in Stimulated whole Saliva: Factors Influencing Mucin levels
Authors: Payment S.A. , Liu B. , Offner G.D. , Oppenheim F.G. , Troxler R.F.
Published: January 2009

While more and more is known about the structure and function of human salivary mucins, there is relatively little information on quantification of these glycoconjugates in whole saliva and on factors influencing their secretion. The goal of the present work was to develop capture ELISAs that would allow for rapid, inexpensive, and reliable measurement of the salivary mucins MG1 and MG2, and to use these immunological procedures to investigate the significance of age, gender, flow rate, and protein concentration on mucin levels in whole saliva. Previously, we described a rabbit polyclonal antibody against MG1 (Troxler et al., 1995) and a rabbit polyclonal peptide antibody against an epitope in the N-terminal region of MG2 (Liu et al., 1999) which were used to develop the capture ELISAs. We verified the accuracy and specificity of these assays by showing correct measurement of known quantities of purified MG1 or MG2 added to whole saliva and lack of cross-reactivity between mucins and heterologous antisera on Western blots or in ELISAs. Whole saliva was collected from 60 subjects under conditions of masticatory stimulation, flow rates were recorded, and mucin concentrations were determined. The results showed that the mean concentration of MG1 and MG2 was 23.3 ± 14.6 mg% and 13.3 ± 11.6 mg%, respectively, and that mucins constitute approximately 16% of the total protein in whole saliva. No significant correlations were found between mucin levels and age or flow rate; however, a significant correlation was found between MG2 levels and total protein concentration. Furthermore, there were statistically significant gender differences in flow rate and MG1 levels, but not in MG2 levels. The availability of these immunoassays for quantification of MG1 and MG2 will help to elucidate the role of mucin in oral health and disease.
Between-subject and within-subject Statistical Information in Dental Research
Authors: Mancl L.A. , Leroux B.G. , DeRouen T.A.
Published: January 2009

The evaluation of risk factors in dental research frequently uses observations at multiple sites in the same patient. For this reason, statistical methods that accommodate correlated data are generally used to assess the significance of the risk factors (e.g., generalized estimating equations, generalized linear mixed models). In applications of these methods, it is typically assumed (implicitly, if not explicitly) that between-subject and within-subject comparisons will produce the same estimated effect of the risk factor. When between- and within-subject comparisons conflict, the statistical methods can give biased estimates or results that are difficult to interpret. For illustration, we present two examples from periodontal disease studies in which different statistical methods give different estimates and significance levels for a risk factor. Statistical analyses in dental research should assess whether different sources of information give similar conclusions about risk factors or treatments.
Local Injection of IFN-gamma Reduces the Number of Myofibroblasts and the Collagen Content in Palatal Wounds
Authors: Cornelissen A.M.H. , Maltha J.C. , Von den Hoff J.W. , Kuijpers-Jagtman A.M.
Published: January 2009

Wound contraction and scar formation after cleft palate surgery impair maxillary growth and dentoalveolar development. Since myofibroblast numbers and scar formation are reduced by interferon-gamma (IFN-γ) in the healing of dermal wounds, the hypothesis was tested that local administration of IFN-γ reduces the numbers of myofibroblasts and the elevated amount of collagen during palatal mucoperiosteal wound healing. Standardized mucoperiosteal excision wounds were made in the palatal mucoperiosteum of young rats. Either IFN-γ or vehicle alone (sham group) was repeatedly injected into the wound site between 4 and 29 days post-wounding. The results were compared with unmanipulated control wounds. Samples of wound tissue were prepared for biochemical and microscopic analysis. The hydroxyproline, sulfated glycosaminoglycan and DNA contents of the wound tissues were analyzed biochemically. The degree of re-epithelialization, tissue thickness, the numbers of myofibroblasts, and the amounts of elastin and collagen types I and III were evaluated on histological sections. Injection of vehicle alone affected almost all healing parameters, compared with the controls, and delayed the wound-healing process. IFN-γ stimulated re-epithelialization and decreased the numbers of myofibroblasts when compared with vehicle-treated wounds. It also decreased the hydroxyproline and glycosaminoglycan contents of 60-day-old wound tissue, but the histological characteristics of scar tissue persisted. Therefore, IFN-γ is able to reduce the numbers of myofibroblasts and the collagen content of scar tissue after palatal wound healing. It may be a promising pharmaceutical agent for the reduction of wound contraction and scarring after cleft palate surgery.
The Interactions of Human Neutrophils with the Constituents of an Experimental Dental Biofilm
Authors: Shapira L. , Tepper P. , Steinberg D.
Published: January 2009

Despite the antibacterial properties of neutrophils, their ability to prevent colonization of the dental biofilm by pathogenic bacteria is limited. The present study examined the ability of human neutrophils to attach to an experimental dental biofilm and tested their antibacterial functions following adhesion. Neutrophil adhesion was greatest to hydroxyapatite (HA) in the absence of biofilm. Among the biofilms, glucosyltransferase or fructosyltransferase adsorbed onto saliva-coated HA showed the highest adhesion of cells. The adhesion of neutrophils was directly related to their initial concentration in the solution and to the duration of incubation. Plasma was found to reduce neutrophil attachment significantly, while stimulation of the cells had no effect. Stimulation of attached neutrophils induced superoxide secretion with levels significantly lower than that secreted by suspended cells. The presence of neutrophils on the biofilm reduced the number and the viability of Streptococcus mutans attached to the beads. The present findings suggest that neutrophils are able to attach to dental biofilms and that the attached neutrophils retained their antibacterial activity.
Improved Sealant Retention with Bonding Agents: A Clinical Study of Two-bottle and Single-bottle Systems
Authors: Feigal R.J. , Musherure P. , Gillespie B. , Levy-Polack M. , Quelhas I. , Hebling J.
Published: January 2009

Recent in vitro work and a short clinical study suggest that adding a bonding agent layer between sealant and saliva-contaminated enamel allows for adequate bond strength and retention of resin sealants and may improve success of all sealant applications. This five-year clinical study scored 617 occlusal and 441 buccal/lingual molar sealants, with use of a split-mouth design, with half receiving sealant alone and half bonding agent plus sealant. Treatment effects and potential risk factors for sealant failure were tested by means of a Cox regression model. Three bonding agent groups were analyzed for treatment effect: Tenure primer, Scotchbond Multi-Purpose, and 3 single-bottle dentin bonding agents as a third group. The single-bottle group was successful in reducing risk of sealant failure, with a hazard ratio (HR) of 0.53 (p = 0.014) for occlusal and 0.35 (p = 0.006) for buccal/lingual sealants. Scotchbond was detrimental to occlusal sealant success, with a HR of 2.96 (p = 0.0003). Tenure primer was neutral, showing HRs close to 1.0. Variables that affected success differed between occlusal and buccal/lingual sealants, suggesting that failures on these two surfaces may be dependent upon differing factors. Early eruption stage was a significant risk factor for both surfaces (HR = 2.91, p = 0.00001, occlusal; and HR = 1.52, p = 0.015, buccal/lingual). Behavior (HR = 1.96, p = 0.0007), salivary problems (HR = 1.73, p = 0.002), and visually apparent variations in enamel (HR = 1.51, p = 0.018) were significant risk factors for occlusal sealants only. In addition to completing detailed analyses of risk factors for sealant survival, this study shows that single-bottle bonding agents protect sealant survival, yielding half the usual risk of failure for occlusal sealants and one-third the risk of failure for buccal/lingual sealants.
Biomechanical Evaluation of Osseous Implants Having Different Surface Topographies in Rats
Authors: Ogawa T. , Ozawa S. , Shih J.-H. , Ryu K.H. , Sukotjo C. , Yang J.-M. , Nishimura I.
Published: January 2009

Biomechanical and biological factors can co-dependently influence the establishment of implant-tissue integration; thus, concurrent evaluation of these factors should provide a better understanding of osseointegration. This study aimed to establish and validate an in vivo rat model frequently used in molecular/cellular biology for implant biomechanical studies. We tested the hypotheses that the implant push-in test assesses the degree of osseointegration by the breakpoint load at the implant-tissue interface and that it sensitively differentiates between the effects of different implant surface topographies. The implant push-in test, which produces a consistent load-displacement measurement, was used to test miniature cylindrical titanium implants placed at the distal edge of the adult rat femur. The push-in test values obtained at each post-implantation healing point (weeks 0, 2, 4, and 8) significantly increased in a time-dependent manner. The implant surface after the push-in test was associated with remnant tissues containing host-derived elements, such as calcium, phosphate, and sulfate. In this model, acid-etched implants (average roughness, 0.159 μm) showed significantly greater push-in test values than did turned implants (average roughness, 0.063 μm) throughout the experimental period (p < 0.0001). These results support the validity of the push-in test in rats, which may be used as a rapid and sensitive biomechanical assay system for implant osseointegration research.
Polymorphisms in the IL-1A Gene are Correlated with Levels of Interleukin-1α Protein in Gingival Crevicular Fluid of Teeth with Severe Periodontal Disease
Authors: Shirodaria S. , Smith J. , McKay I.J. , Kennett C.N. , Hughes F.J.
Published: January 2009

Interleukin-1 (IL-1) is a potent stimulator of bone resorption and is strongly implicated in the destruction due to bystander damage seen in periodontal disease. Recent studies suggest that polymorphisms of the (IL-1) gene complex may be significant risk factors for a number of chronic inflammatory diseases. The severity of periodontal disease has been positively associated with carriage of allele 2 at position -889 of the IL-1A gene in conjunction with allele 2 of the 1L-1B gene at position +3953. In this study, we tested the hypothesis that allele 2 of the IL-1A gene at position -889 might act to elevate levels of IL-la protein in patients with periodontal disease. Since levels of IL-la protein are low in healthy individuals, we used a group of patients with severe periodontal disease to investigate if levels of IL-1α protein in gingival crevicular fluid can be correlated to patient genotype. IL-la levels were measured by enzyme immunoassay in 46 patients with severe periodontal disease. These patients were genotyped by PCR and allele-specific restriction digests. The carriage rate for allele 2 in the diseased population was 68%. Overall, the carriage of allele 2 was associated with almost a four-fold increase in IL-la protein levels. Differences were most pronounced in non-smokers, while heavy smokers showed reduced levels of IL-1α protein regardless of genotype. These results suggest a mechanism whereby this genetic polymorphism acts to modulate IL-la protein production and may influence the pathogenesis of periodontal disease by affecting the extent of IL-1-associated bystander damage.
Occurrence of Dental Decay in Children after Maternal Consumption of Xylitol Chewing Gum, a Follow-up from 0 to 5 Years of Age
Authors: Isokangas P. , Soderling E. , Pienihakkinen K. , Alanen P.
Published: January 2009

Studies have shown that prevention of mutans streptococci (MS) colonization in early childhood can lead to prevention of dental decay. In the microbiological part of the present study in Ylivieska, Finland, with 195 mothers with high salivary MS levels, regular maternal use of xylitol chewing gum resulted in a statistically significant reduction in MS colonization in their children's teeth at the age of 2 years compared with teeth in children whose mothers received fluoride or chlorhexidine varnish treatment. The children did not chew gum or receive varnish treatments. For the present study, the children were examined annually for caries occurrence by experienced clinicians who did not know whether the children were colonized with MS. Regardless of the maternal prevention group, the presence of MS colonization in children at the age of 2 years was significantly related to each child's age at the first caries attack in the primary dentition. In children at the age of 5 years, the dentinal caries (dmf) in the xylitol group was reduced by about 70% as compared with that in the fluoride or chlorhexidine group. We conclude that maternal use of xylitol chewing gum can prevent dental caries in their children by prohibiting the transmission of MS from mother to child.
Occlusal Contacts during lateral Excursions in Children with Primary Dentition
Authors: Okamoto A. , Hayasaki H. , Nishijima N. , Iwase Y. , Yamasaki Y. , Nakata M.
Published: January 2009

The presence of non-working occlusal contacts in adults is considered abnormal and may initiate parafunctional activity. Few studies have looked for non-working occlusal contacts in children with primary dentition. The purposes of this study were (1) to prove the existence of non-working-side occlusal contacts, and (2) to quantify their area during lateral excursion in children with primary dentition. To achieve this purpose, we developed a measurement system that combined a tracking system for mandibular movements with a three-dimensional digitizer for tooth shape. Ten children were selected for this study. Estimated occlusal contact area of the primary second molar on the non-working side was 0.8 mm2, in contrast to 2.0 mm2 on the working side, at 3.0 mm of movement of the lower incisor. All children examined had some occlusal contacts on the non-working side during the first part of lateral excursion.
Immunohistochemical Localization of Gaq, PLCβ, Gαi1-2, PKA, and the Endothelin B and Extracellular Ca2+-sensing Receptors during Early Amelogenesis
Authors: Moran R.A. , Brown E.M. , Bawden J.W.
Published: January 2009

Antibodies specific to Gaq, PLCβ, Gai 1-2, and PKA were immunohistochemically (IHC) localized in the pre-ameloblasts up to initial dentin matrix deposition and continued in the distal ends of the pre-secretory ameloblasts to the beginning of enamel matrix secretion. It was hypothesized that the endothelin B receptor (ETBR) and/or the extracellular Ca2+-sensing receptor (CaR) would localize in the same locations as their known downstream signal transduction pathway (STP) effectors during events related to early amelogenesis. Localization was similar for the 4 signal transduction pathway elements and the CaR. The ETBR was not localized in any of the cells of the enamel organ. These findings indicate that the CaR and its related STPs are expressed in the pre-ameloblasts and pre-secretory ameloblasts in positions where they may be able to detect increases in extracellular Ca2+ concentrations observed in the pre-dentin matrix in a previous study. These observations are consistent with the hypothesis that increased levels of free Ca2+ in the pre-dentin matrix serve as a primary signal for modification of gene expression important to amelogenesis.
Region-specific Bone Mass Changes in Rat Mandibular Condyle following Ovariectomy
Authors: Tanaka M. , Ejiri S. , Kohno S. , Ozawa H.
Published: January 2009

The effects of estrogen deficiency on the mandible have been indicated; however, there have been only a few reports on the mandibular condyle. To clarify the region-specific changes of condyles following estrogen deficiency, we histomorphometrically studied the anterior and posterior regions of condyles in sham-operated (Sham) and ovariectomized (Ovx) female Fischer rats, since it has been reported that rat occlusal force loads mainly onto the anterior part of the condyle. The anterior and posterior regions of condyles showed significantly different bone dynamics. The bone volume in the anterior region of the Sham group increased to 79.9% with aging, but that of the posterior region remained at ca. 60%. In the Ovx group, the bone volume of the posterior region significantly declined to 42.7% until 60 days post-ovariectomy, although no changes occurred in the anterior region. As compared with the Sham counterparts, both regions of the Ovx group showed high bone turnover and revealed significantly low bone volume at 60 days (p < 0.01). Regional differences between anterior and posterior regions were more emphasized in the Ovx than in the Sham group. The osteoclast number and amount of eroded surface in the Ovx were higher in the posterior than in the anterior region, with significance at 30 and/or 60 days (p < 0.05). The mineralized surface at 14 days and the bone formation rate at 60 days in the Ovx posterior region were significantly lower than those in the Ovx anterior region (p < 0.05). Consequently, a net bone loss occurred in the posterior region of the mandibular condyle in ovariectomized rats, owing to region specificity and estrogen deficiency.
Delayed Embryonic Development of Mouse Masseter Muscle Correlates with Delayed MyoD Family Expression
Authors: Yamane A. , Ohnuki Y. , Saeki Y.
Published: January 2009

While the masseter muscle is known to have several unique developmental characteristics as compared with other skeletal muscles, little is known about its myogenesis. Thus, we examined the expression of myogenic marker and of myoD family gene mRNA from embryonic day (E) 11 to birth. The obtained results were compared with our earlier results of the mouse tongue muscle, which is also involved in oral functions. The mRNA quantities were determined by means of the reverse-transcription and competitive-polymerase chain-reaction techniques. The expression of myogenic marker mRNA indicated that differentiation and maturation in the masseter began at E13 as in the tongue, and were not yet completed at birth, although they were completed in the tongue. The expression of myoD, myogenin, and myf5 mRNA peaked later in the masseter (E17) than in the tongue (E13). The expression of MRF4 mRNA began later in the masseter (E15) than in the tongue (E13). These results suggest that the delayed expression of the myoD family genes in the masseter correlates with delayed differentiation and maturation, probably due to the later functional requirements of the masseter than of the tongue.
Cyclooxygenase-2-dependent Prostaglandin E2 Down-regulates Intercellular Adhesion Molecule-1 Expression via EP2/EP4 Receptors in Interleukin-1ß-stimulated Human Gingival Fibroblasts
Authors: Noguchi K. , Iwasaki K. , Shitashige M. , Endo H. , Kondo H. , Ishikawa I.
Published: January 2009

Prostaglandin E2 (PGE2), which exerts its actions via EP receptors (EP,, EP2, EP3, and EP4), is a bioactive metabolite of arachidonic acid produced by cyclooxygenase (COX)-l and/or COX-2. We have previously demonstrated that PGE, downregulates intercellular adhesion molecule-1 (ICAM-1) expression in interleukin-1β (IL-1β)-stimulated human gingival fibroblasts (HGF). In the present study, we investigated which COX was involved in down-regulation of ICAM-1 expression by PGE2in IL-1β-stimulated HGF and which subtypes of EP receptors modulated the ICAM-1 expression. NS-398, a specific COX-2 inhibitor, completely inhibited PGE2production by IL-1β-stimulated HGF, as did indomethacin, a COX-1/COX-2 inhibitor. Northern blot analysis and immunocytochemical staining showed that mRNA and protein of COX-2 were expressed in IL-1β-challenged HGF, but not in unstimulated HGF, and that the expression of mRNA and protein of COX-1 was similar both in unstimulated and in stimulated cells. NS-398 and indomethacin enhanced ICAM-1 expression in IL-1β-challenged HGF. EP1, EP2, and EP4receptor mRNA was expressed in HGF according to reverse-transcription/polymerase chain-reaction. PGE2, 11-deoxy-PGE1(a selective EP2/EP4agonist), and Butaprost (a selective EP2agonist) attenuated IL-1β-elicited ICAM-1 expression, although Butaprost was less potent than PGE2and 11-deoxy-PGE1. AH-23848B, an EP4 antagonist, antagonized the inhibitory effect of IL-1β-elicited ICAM-1 expression by PGE2. Sulprostone, an EP1/EP3agonist, had no effect on IL-1β-elicited ICAM-1 expression. Analysis of these data suggests that COX-2-derived PGE2downregulates ICAM-1 expression via EP2/EP4receptors in IL-1β-stimulated HGF.
The in vivo Expression of the Collagenolytic Matrix Metalloproteinases (MMP-2, -8, -13, and -14) and Matrilysin (MMP-7) in Adult and Localized Juvenile Periodontitis
Authors: Tervahartiala T. , Pirilä E. , Ceponis A. , Maisi P. , Salo T. , Tuter G. , Kallio P. , Törnwall J. , Srinivas R. , Konttinen Y.T. , Sorsa T.
Published: January 2009

Periodontal inflammation is characterized by irreversible degradation of periodontal ligament collagen fibers leading to loss of tooth attachment. Cultured gingival keratinocytes and fibroblasts express, in vitro, various matrix metalloproteinases (MMPs) which can degrade fibrillar collagens. We hypothesized that several MMPs are also synthesized in vivo by sulcular epithelium, and analyzed the collagenolytic MMPs (MMP-2, -8, -13, and -14) and matrilysin (MMP-7) in gingival tissue specimens and gingival crevicular fluid from adult and localized juvenile periodontitis patients by in situ hybridization, immunohistochemistry, and Western immunoblotting. MMP-2, -7, -8, and -13 were expressed in gingival sulcular epithelium. MMP-7 and -13 were also located in fibroblasts and macrophages, and MMP-8 in neutrophils. MMP-8- and -13-positive cells/mm2 were higher in periodontitis gingiva when compared with healthy control tissue (p < 0.01). In periodontal diseases, gingival sulcular epithelium expresses several, rather than a single, collagenolytic MMPs, and this proteolytic cascade is evidently responsible for the tissue destruction characteristic of adult and juvenile periodontitis.