bluuebunny/crossref_metadata_2025 huggingface dataset:
Dominant Cross-reactive Antibodies Generated during the Response to a Variety of Oral Bacterial Species Detect Phosphorylcholine
Authors: Gmür R. , Thumheer T. , Guggenheim B.
Published: January 2009

The intraperitoneal immunization of Balb/c mice with subgingival plaque from advanced periodontal pockets or with certain strains of Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Actinomyces israelii, Streptococcus mitis, or Streptococcus oralis yielded frequently indistinguishable IgM monoclonal antibodies which were reactive with antigens from a variety of oral bacteria. This study aimed to characterize the specificity of such monoclonal antibodies and the diversity of oral bacteria expressing this target antigen or epitope. Using a competitive enzyme-linked immunosorbent assay to study a variety of competitor substances for their capacity to bind to the monoclonal antibodies, we identified phosphorylcholine as the recognized epitope. The concentration of positive bacteria with extraordinarily bright cell wall fluorescence in indirect immunofluorescence assays varied between 0.1% and 15% in subgingival and from 10 to 40% in supragingival plaque samples. Labeled bacteria belonged to different morphotypes, including cocci, rods, and filaments. Of 75 species tested in vitro, 14 Gram-positive and four Gram-negative species were found to harbor positive strains. Haemophilus aphrophilus, Streptococcus mitis, Actinomyces georgiae, Actinomyces gerencseriae, Actinomyces israelii, and Actinomyces odontolyticus were human oral species of which all tested strains were capable of binding the cross-reactive monoclonal antibodies. In contrast, Actinomyces naeslundii was consistently negative. These data provide evidence for a much more common expression of phosphorylcholine by oral bacteria than hitherto believed but do not indicate an obvious association of phosphorylcholine expression with oral health or inflammatory periodontal diseases.
Glass-ionomer Restoratives: A Systematic Review of a Secondary Caries Treatment Effect
Authors: Randall R.C. , Wilson N.H.F.
Published: January 2009

It is generally accepted that glass ionomers inhibit secondary caries in vivo, and data from in vitro studies support this effect. The aim of this review was a systematic assessment, from the literature, of clinical evidence for the ability of glass-ionomer restoratives to inhibit secondary caries the restoration margin. Inclusion and exclusion criteria for selection of the review papers were established prior to commencement of the literature search. Papers which conformed to these criteria, and reported on secondary caries as an outcome, were selected (N = 52). Primary and secondary of systematic for use in the assessment of the papers were drawn up. The primary list of 14 criteria was applied to each paper. No paper fulfilled all these criteria, necessitating the use of the secondary measures: (i) a prospective study and (ii) use of an appropriate control. This yielded 28 papers. Tabulation of these papers by occurrence of secondary caries in the glass-ionomer or control groups demonstrated an even distribution between positive and negative outcomes. Valid evidence is to be best obtained from randomized, controlled of sufficient sample size. No conclusive evidence for or against a treatment effect of inhibition of secondary caries by the glass-ionomer restoratives was obtained from the systematic review. There is a need for appraisal of the methods currently adopted for the clinical of glass-ionomer restorative materials, for further development of the methodology to support future systematic reviews.
Clinical Predictability of Temporomandibular Joint Disc Displacement
Authors: Orsini M.G. , Kuboki T. , Terada S. , Matsuka Y. , Yatani H. , Yamashita A.
Published: January 2009

Single items from a typical clinical examination have proved disappointing in their predictive value for temporomandibular joint (TMJ) disc displacement. Only one criterion (the 12 o'clock) is used to diagnose normal disc position. According to this criterion, the posterior band of the disc should be located at the top of the condyle, at the 12 o'clock position. The purpose of this study was to determine which signs and symptoms provide a valid prediction of the condition of the joint based on 4 magnetic resonance imaging (MRI) criteria used to define normal disc position. Sagittal MRI and clinical findings of 137 temporomandibular disorder patients and 23 normal asymptomatic volunteers were used. Three calibrated and blinded observers interpreted the images. Disc position with the mouth closed was evaluated based on 4 MRI criteria: 12, 11, 10 o'clock, and the intermediate zone. Disc position with the mouth open was determined based on one criterion. It was considered normal if the intermediate zone of the disc was located between the condyle and the articular eminence. Joints were classified as normal or as having disc displacement with or without reduction. The sensitivity and specificity of multiple clinical parameters for predicting the condition of the joint established by each of these 4 gold-standard MRI criteria were then determined. Regarding disc displacement with reduction, significant differences were observed in the sensitivity and specificity of all of the clinical parameters used to predict the imaging diagnosis established by each of the criteria. Concerning disc displacement without reduction, no significant differences were observed. The intermediate zone criterion was the criterion that most accurately reflected the condition of the joint. The clinical predictability of the disorder diagnosed according to this criterion suggests that clinical findings alone are too often nonspecific as predictors of the imaging stage of disc displacement. However, we found that combining the most sensitive clinical items to predict the disorder and using an overall criterion for positivity to interpret the results led to an impressive increase in the specificity of the combination, enabling false-positive diagnoses to be excluded.
The Influence of Antagonist Standardization on Wear
Authors: Krejci I. , Albert P. , Lutz F.
Published: January 2009

For differences among materials to be easily detected, low variation in in vitro wear tests is desirable. The working hypothesis of this paper was that antagonists standardized for shape and size and according to materials would show mean values similar to those found in natural, non-standardized cusps, and that standardization would lead to a reduction in mean variation. First, the shapes and sizes of palatal cusps of non-erupted human upper third molars were measured. The cusp cupola was best described by the formula y = 0.001 x2 and was symmetrical around the axis of rotation. Up to 200 μm of the y-axis, this parabola corresponded best to a ball radius of 0.6 mm. Based on this information, standardized antagonists were fabricated from both human enamel and steatite. Wear in the occlusal contact area and the wear of opposing conventional ceramic and fine hybrid composite, respectively, were quantified in a computerized chewing simulator. As a control, natural human enamel cusps were used. Standardization of enamel cusps did not reduce the variation of the resulting wear compared with that of non-standardized enamel antagonists. Furthermore, standardization led to significantly different results both in the antagonists and in the opposing restorative materials. Thus, natural enamel antagonists are preferable for the simulation of wear in the occlusal contact area.
Characterization of Recombinant Pig Enamelysin Activity and Cleavage of Recombinant Pig and Mouse Amelogenins
Authors: Ryu O.H. , Fincham A.G. , Hu C.-C. , Zhang C. , Qian Q. , Bartlett J.D. , Simmer J.P.
Published: January 2009

Enamelysin (MMP-20) is a tooth-specific matrix metalloproteinase that is initially expressed by ameloblasts and odontoblasts immediately prior to the onset of dentin mineralization, and continues to be expressed throughout the secretory stage of amelogenesis. During the secretory stage, enamel proteins are secreted and rapidly cleaved into a large number of relatively stable cleavage products. Multiple proteinases are present in the developing enamel matrix, and the precise role of enamelysin in the processing of enamel proteins is unknown. We have expressed, activated, and purified the catalytic domain of recombinant pig enamelysin, and expressed a recombinant form of the major secreted pig amelogenin rP172. These proteins were incubated together, and the digestion products were analyzed by SDS-PAGE and mass spectrometric analyses. We assigned amelogenin cleavage products by selecting among the possible polypeptides having a mass within 2 Daltons of the measured values. The polypeptides identified included the intact protein (amino acids 2-173), as well as 2-148, 2-136, 2-107, 2-105, 2-63, 2-45, 46-148, 46-147, 46-107, 46-105, 64-148, 64-147, and 64-136. These fragments of rP172 include virtually all of the major amelogenin cleavage products observed in vivo. We propose that enamelysin is the predominant proteinase that processes enamel proteins during the secretory phase of amelogenesis.
Langerhans Cells from Oral Epithelium are More Effective in Stimulating Allogeneic T-cells in vitro than Langerhans Cells from Skin Epithelium
Authors: Hasseus B. , Jontell M. , Bergenholtz G. , Eklund C. , Dahlgren U.I.
Published: January 2009

Dendritic cells, such as Langerhans cells (LC), in different ectodermal compartments may have different functional capabilities. The present study was undertaken to compare oral Langerhans cells (LC) with those of the epidermis in terms of their ability to co-stimulate T-cells in vitro. A Mixed Epithelial Cell Lymphocyte Reaction (MELR) and a mitogen-driven (concanavalin A) T-cell proliferation assay were used. In both assays, LC in a crude cell suspension of freshly isolated oral epithelial cells were found to be five times more effective in mediating T-cell proliferation than freshly isolated epidermal LC. Twenty-four-hour cell culture at 37°C enhanced the T-cell response in the MELR compared with cells cultured at 4°C. This applied to both skin and oral epithelial cells. Oral and skin epithelial cell suspensions depleted of LC lost the capacity to stimulate allogeneic T-cells. Incubation of the epithelial cell suspensions with recombinant Granulocyte/Macrophage-Colony Stimulating Factor (rGM-CSF) did not enhance the co-stimulating capacity of the LC. Titration of different numbers of oral and skin LC to T-cells showed that skin LC were never able to reach more than 44% of the maximal stimulatory capacity of oral LC. Data show that oral LC are more efficient than skin LC in providing co-stimulatory signals to T-cells, suggesting a difference in functional capacity between the two cell populations.
Age of Onset of Dental Anxiety
Authors: Locker D. , Liddell A. , Dempster L. , Shapiro D.
Published: January 2009

Little attention has been given to the issue of the age of onset of dental anxiety, even though it may have a bearing on the origins of this type of fear. This study aimed to identify the age of onset of dental anxiety and to identify differences by age of onset with respect to potential etiological factors, such as negative dental experiences, family history of dental anxiety, and general psychological states. Data were collected by means of two mail surveys of a random sample of the adult population. Of 1420 subjects returning questionnaires, 16.4% were dentally anxious. Half, 50.9%, reported onset in childhood, 22.0% in adolescence, and 27.1% in adulthood. Logistic regression analyses indicated that negative dental experiences were predictive of dental fear regardless of age of onset. A family history of dental anxiety was predictive of child onset only. Adolescent-onset subjects were characterized by trait anxiety and adult-onset subjects by multiple severe fears and symptoms indicative of psychiatric problems. The three groups were similar in terms of their physiological, cognitive, and behavioral responses to dental treatment. However, adolescent- and adult-onset subjects were more hostile toward and less trusting of dentists. These results indicate that child-onset subjects were more likely to fall into the exogenous etiological category suggested by Weiner and Sheehan (1990), while adult-onset subjects were more likely to fall into the endogenous category.
Sequence Variations of the CST2 Gene Related to the Polymorphism of Salivary Cystatin SA
Authors: Haga T. , Minaguchi K.
Published: January 2009

The CST2 locus has two polymorphic alleles, CST2*1 and CST2*2, which produce cystatin proteins SAI and SA2, respectively (Shintani et al., 1994). The purpose of this study was to define nucleotide sequence variations of the protein-coding region of the two alleles. The variations were investigated by direct sequencing of amplified DNA from individuals with different CST2 phenotypes. The sequence of three exons obtained from DNA of the CST2 1 phenotype was found to be identical to the published sequence of the CST2 gene (Saitoh et al., 1987), whereas two-point mutations were found in the sequence obtained from DNA of the CST2 2 phenotype. One of the mutations was a G → A transition in exon 2, resulting in loss of a commonly occurring Acil restriction site. This mutation resulted in a Gly59 → Asp59 substitution in the protein. The other mutation was an A → T transversion in exon 3, resulting in the generation of a SfaNI restriction site. This mutation also produced a Glu120 → Asp120 substitution in the protein. PCR-RFLP assay with Acil and SfaNI restriction enzymes revealed that the two-point mutations were always correlated with cystatin SA polymorphism. The difference in the electrophoretic positions of the two proteins, SA1 and SA2, in a basic gel and in an isoelectric focusing gel agreed with the expected mobilities of the proteins with the SA2 variant at a more anodal position. The CST2*2 allele is a unique allele, which shows amino acid substitution in one of the most conserved regions responsible for cysteine proteinase inhibitory activity.
Damage Modes in Dental Layer Structures
Authors: Jung Y.-G. , Wuttiphan S. , Peterson I.M. , Lawn B.R.
Published: January 2009

Natural teeth (enamel/dentin) and most restorations are essentially layered structures. This study examines the hypothesis that coating thickness and coating/substrate mismatch are key factors in the determination of contact-induced damage in clinically relevant bilayer composites. Accordingly, we study crack patterns in two model "coating/substrate" bilayer systems conceived to simulate crown and tooth structures, at opposite extremes of elastic/plastic mismatch: porcelain on glass-infiltrated alumina ("soft/hard"); and glass-ceramic on resin composite ("hard/soft). Hertzian contacts are used to investigate the evolution of fracture damage in the coating layers, as functions of contact load and coating thickness. The crack patterns differ radically in the two bilayer systems: In the porcelain coatings, cone cracks initiate at the coating top surface ; in the glass-ceramic coatings, cone cracks again initiate at the top surface, but additional, upward-extending transverse cracks initiate at the internal coating/substrate interface, with the latter dominant. The substrate is thereby shown to have a profound influence on the damage evolution to ultimate failure in the bilayer systems. However, the cracks are highly stabilized in both systems, with wide ranges between the loads to initiate first cracking and to cause final failure, implying damage-tolerant structures. Finite element modeling is used to evaluate the tensile stresses responsible for the different crack types. The clinical relevance of these observations is considered.
Long-term Durability of Dentin Bonds Made with a Self-etching Primer, in vivo
Authors: Sano H. , Yoshikawa T. , Pereira P.N.R. , Kanemura N. , Morigamui M. , Tagami J. , Pashley D.H.
Published: January 2009

The long-term durability of bonds between adhesive resins and dentin is of significant importance for the longevity of bonded restorations. We carried out an in vivo one-year study to evaluate the durability of resin-dentin bonds in the oral cavity, as well as to test the hypothesis that the adhesive interface would show morphological changes in vivo over time. Very shallow saucer-shaped dentin cavities were prepared in 12 intact teeth of one Japanese monkey ( Macaca fuscata) under general anesthesia. The cavities were restored with Clearfil Liner Bond II and Clearfil Photo Posterior resin composite. The teeth were extracted at three different times: immediately, and 180 and 360 days after placement of the restorations. One day after the monkey was killed, specimens of the three time periods were subjected to the micro-tensile bond test at a crosshead speed of 1 mm/min. The surfaces of the failed bonds were observed under a field emission scanning electron microscope (FE-SEM). Bond strength measurements in this study were successfully performed and were stable at approximately 19 MPa during the one-year testing. Scanning electron microscopic observations of the failed surfaces revealed, at the top of the hybrid layer and within the adhesive resin, porosity which increased over time. Long-term bonds can be assessed in vivo by the combined evaluation of the microtensile bond strength and SEM morphological examination of the adhesive interface.
Occlusal Disharmonies Modulate Central Catecholaminergic Activity in the Rat
Authors: Areso M.P. , Giralt M.T. , Sainz B. , Prieto M. , Garcia-Vallejo P. , Gómez F.M.
Published: January 2009

Occlusal disharmonies have classically been thought to be involved in the etiopathogenesis of bruxism, as have, more recently, alterations in central neurotransmission, particularly dopaminergic neurotransmission. However, the connection between these two factors has still not been established. In this study, we assessed the effects of diverse occlusal disharmonies, maintained for either 1 day or 14 days, on neurochemical indices of dopaminergic and noradrenergic activity in the striatum, frontal cortex, and hypothalamus of the rat. The in vivo activity of tyrosine hydroxylase, determined as the accumulation of 3,4-dihydroxyphenylalanine (DOPA), 30 min after the administration of 3-hydroxybenzylhydrazine, a DOPA decarboxylase inhibitor, and dopamine and noradrenaline contents were quantified by high-performance liquid chromatography with electrochemical detection. The wearing of an acrylic cap on both lower incisors for 1 day induced a significant increase in DOPA accumulation in the regions analyzed, with parallel increases in dopamine levels in the hypothalamus and dopamine and noradrenaline in the frontal cortex. After the cap was maintained for 14 days, DOPA accumulation tended to return to control values, except in the left striatum, thereby causing an imbalance between hemispheres. In contrast, 1 or 14 days after the lower left and the upper right incisors were cut, less pronounced changes in catecholaminergic neurotransmission were found in the brain areas studied. Moreover, the cutting of one lower incisor did not modify either DOPA accumulation or dopamine and noradrenaline contents in the striatum or hypothalamus. These results provide experimental evidence of a modulation of central catecholaminergic neurotransmission by occlusal disharmonies, being dependent on the nature of the incisal alteration and on the time during which it was maintained.
Root Development in Mice Lacking Functional Tissue Non-specific Alkaline Phosphatase Gene: Inhibition of Acellular Cementum Formation
Authors: Beertsen W. , VandenBos T. , Everts V.
Published: January 2009

Tissue non-specific alkaline phosphatase (TNAP) is richly present in developing teeth including the cells of the periodontal ligament. Here, we investigated tooth and root development in mice lacking the TNAP gene. Heterozygous mutants were obtained from The Jackson Laboratory, Animal Resources (Bar Harbor, ME, USA) and bred. TNAP-deficient mice and their littermates were killed from 6 to 25 days after birth and their molar blocks processed for light and electron microscopy. It was observed that the eruption of the incisors into the oral cavity was delayed for 2 to 3 days. Also, the onset of mineralization of the mantle dentin in the roots of the developing molars was delayed for 2 to 3 days. Yet, dentin and enamel formation in the homozygous mutants showed a more or less normal pattern, with the exception of localized enamel hypoplasias. The most conspicuous finding was the defective formation of acellular cementum along the molar roots. Instead of a continuous layer, the cementum was deposited as very thin and irregularly shaped patches around the bases of the periodontal ligament fibers. Sharpey's fibers were short and poorly developed. In contrast, the development of the alveolar bone, the periodontal ligament, and the cellular cementum was seemingly unaffected. It is concluded that TNAP represents an essential factor in mantle dentin mineralization and in the formation of acellular cementum.
Kinetics of Enamel Demineralization in vitro
Authors: Margolis H.C. , Zhang Y.P. , Lee C.Y. , Kent R.L. , Moreno E.C.
Published: January 2009

Previously, we reported that the rate (R) of hydroxyapatite dissolution in acetic, lactic, and phosphoric acid solutions is a function of the degree of saturation with respect to the dissolving mineral, DS (defined as the ratio of the mean ionic activity product for hydroxyapatite [Ca5OH(PO 4)3] in solution to its solubility product constant), and the sum of the acid activities (ΣBiH) in solution: R = K(l-DS) m(ΣBiH)n. The present study was undertaken to explore the general validity of this model in describing the kinetics of enamel demineralization. Thin sections of human enamel were exposed to partially saturated 0.1 mol/L lactic acid solutions, at two different DS levels, and at pH values of 4.3 to 6.0. Thin sections of human enamel were also exposed to solutions with four different concentrations of acetic and lactic acids (pH 4.3) with three different DS values and, at one DS value, to solutions of propionic acid. Mineral loss was monitored by quantitative microradiography. In solutions with pH values of 4.3 and 5.0, "lesions" were formed with well-defined surface layers, whereas, in solutions with pH 6.0, "lesions" were produced with no apparent surface layers. The formation of relatively intact surface layers was consistent with predicted phase transformations. Rates of mineral loss were found to be inversely proportional to both the degree of saturation with respect to enamel mineral, DSEn, and the pH of the solution and increased with increased activities of each organic acid, consistent with the proposed model. However, at the same DSEn and acid activity, rates of demineralization were the same in the acetic and propionic acid solutions, whereas rates of demineralization in lactic acid were greater. It is suggested that specific interactions of acid species with enamel mineral may modify the rate of enamel demineralization. These in vitro findings suggest that relatively small differences in DS En values found in plaque fluid may result in very significant differences in the rate of enamel demineralization in vivo.
Expression of Cell Cycle and Apoptosis-related Proteins in Sporadic Odontogenic Keratocysts and Odontogenic Keratocysts Associated with the Nevoid Basal Cell Carcinoma Syndrome
Authors: Lo Muzio L. , Staibano S. , Pannone G. , Bucci P. , Nocini P.F. , Bucci E. , De Rosa G.
Published: January 2009

Odontogenic keratocysts are occasionally (4-5%) associated with the nevoid basal cell carcinoma syndrome, a pleiotropic, autosomal disorder presenting a spectrum of developmental abnormalities and a predisposition for the development of different neoplasms. The aim of this study was to establish whether keratocysts showing clinically aggressive behavior associated with nevoid basal cell carcinoma syndrome reflect differences in cellular proliferation rate and/or in the expression of oncoproteins and tumor suppressor genes. For this reason, formalin-fixed paraffin-embedded sections of odontogenic keratocysts associated with the nevoid basal cell carcinoma syndrome (16 cases) and sporadic odontogenic keratocysts (16 cases) were compared for expression of proliferating cell nuclear antigen (PCNA) and p53, bcl-2, and bcl-1 (cyclin Dl) onco-proteins. Most of the epithelial lining of odontogenic keratocysts associated with the nevoid basal cell carcinoma syndrome showed nuclear immunopositivity for p53 protein and overexpression of cyclin Dl with various degrees of staining intensity. All sporadic odontogenic keratocysts were negative for p53 and cyclin Dl. The expressions of bcl-2 oncoprotein were found to be substantially similar between the two groups of lesions, with a cytoplasmic immunopositivity localized only in the resting reserve basal layer of the epithelium. PCNA expression showed no statistically significant difference between the two groups of lesions. In conclusion, the finding of cyclin Dl and p53 overexpression in odontogenic keratocysts associated with the nevoid basal cell carcinoma syndrome could be considered a hallmark of a mutated cellular phenotype, thus leading to the hypothesis that their aggressive clinical behavior could be due to a dysregulation of the expression of cyclin Dl and p53 proteins, involved in a check-point control of cellular proliferation.
Detection and Quantification of MUC7 in Submandibular, Sublingual, Palatine, and Labial Saliva by Anti-peptide Antiserum
Authors: Bolscher J.G.M. , Groenink J. , van der Kwaak J.S. , van den Keijbus P.A.M. , van't Hof W. , Veerman E.C.I. , Nieuw Amerongen A.V.
Published: January 2009

The large carbohydrate moiety of low-Mr salivary mucin MUC7 (originally referred to as MG2) is subject to variations. Biochemical analysis and quantification of MUC7 in saliva samples require recognition tools that are independent of the carbohydrate moiety. Therefore, we have evoked three antisera to synthetic peptides of MUC7. One of these (CpMG2), raised against the C-terminal peptide, recognized native MUC7 in saliva and was characterized further. Recognition of MUC7 by CpMG2 turned out to be specific, resistant to dissociating and reductive treatments, and independent of glycosylation differences, as indicated by Western analysis and ELISA. The antiserum could be used to monitor MUC7 during purification procedures. MUC7 was demonstrated in small volumes of saliva from all (sero)mucous glands, including the palate and lip. Analysis with antibodies and lectins indicated large variations in amount as well as in glycosylation of MUC7. An ELISA was developed to determine the relative quantity of MUC7 in the glandular salivas: mean values of approximately 220, 980, and 100 μg mucin per mL were found in submandibular, sublingual, and palatine saliva, respectively.
Oral Microflora in Subjects with Reduced Salivary Secretion
Authors: Almstahl A. , Wikstrom M.
Published: January 2009

It is generally assumed that a decreased salivary secretion rate will promote plaque accumulation and increase the risk for caries, gingival inflammation, and mucosal infections. In this study, the effect of hyposalivation on the oral microflora was examined. The following microorganisms were analyzed in rinsing samples from 14 subjects with hyposalivation: the total number of anaerobically growing micro-organisms, a-hemolytic streptococci, mutans streptococci, lactobacilli, Fusobacterium nucleatum, Prevotella intermedia/Prevotella nigrescens, Staphylococcus aureus, Candida albicans, and enterics. The study group, age 53 ± 7 years, had no history of radiation therapy and showed no signs of inflammation in their salivary glands on biopsy. All were dentate with a mean of 24 ± 3 teeth. Their salivary secretion rates were 0.03 ± 0.02 mL/min (unstimulated) and 0.84 ± 0.65 mL/min (stimulated). The control group was matched to the hyposalivation group according to age, sex, and number of teeth. There was a significantly increased number of lactobacilli, and a tendency, not statistically significant and with large variations within the groups, toward a higher proportion of mutans streptococci and a lower proportion of a-hemolytic streptococci in the hyposalivation group. The presence of micro-organisms associated with gingival inflammation and mucosal infections was comparable with that in the healthy controls. The results indicated that a low salivary secretion rate mainly promotes a flora associated with the development of caries.
Myogenic Determination and Differentiation of the Mouse Palatal Muscle in Relation to the Developing Mandibular Nerve
Authors: Zhang L. , Yoshimura Y. , Hatta T. , Otani H.
Published: January 2009

The vertebrate palatal muscles are derived from the cranial paraxial mesoderm and start myogenesis by the expression of myogenic regulatory factors (MRFs). Predetermined myogenic cells migrate from the cranial paraxial mesoderm into the branchial arches, followed by myogenic differentiation. The objective of this study was to elucidate whether the determination, migration, and differentiation of myogenic cells during the myogenesis of the palatal muscles, particularly the tensor veli palatini (TVP), are related to the extending mandibular nerve in mouse embryos. By immunohistochemical staining at embryonic day (E) 9.5, MyoDl and myogenin have been expressed in the mandibular arch, into which the mandibular nerve had not yet extended. At E11.5, these myogenic cells encircled the extending mandibular nerve and were distributed from the distal and lateral to the trigeminal ganglion and into the mandibular arch to form the muscle plate, a girdle-like structure. By E12.5, these myogenic cells lost their girdle-like pattern, vacated the trunk area of the mandibular nerve, and were separated into several incompletely divided masses encircling the collateral branches of the mandibular nerve. The TVP started differentiation at E13.5 with the appearance of myofilaments and acetylcholinesterase (AchE), whereas the other palatal muscles began differentiation at E14.5. We defined the differentiation process of mouse palatal muscles into five stages based on the present findings. These results suggest that the determination and initial migration of the palatal myogenic cells into the mandibular arch occur before the mandibular nerve extends out of the trigeminal ganglion, whereas the myogenic cells migrating into the final sites of differentiation intimately relate to the extending nerve.
Mandibulofacial Adaptations in a Juvenile Animal Model of Temporomandibular Joint Arthritis
Authors: Tavakkoli-Jou M. , Miller A.J. , Kapila S.
Published: January 2009

Juvenile rheumatoid arthritis (JRA) is a chronic systemic disease of childhood that affects synovial joints including the temporomandibular joint (TMJ). Individuals with JRA of the TMJ frequently show aberrations in mandibulofacial development. Since the basis for these developmental perturbations is poorly understood, they remain a perplexing clinical problem to manage. To begin dissecting the mechanisms for altered craniofacial development in JRA of the TMJ, we characterized the gross morphologic adaptations in the facial skeleton in a juvenile animal model of TMJ arthritis. Arthritis was induced in ten 87-day-old male rabbits by intra-articular challenge with ovalbumin. Eight sham-challenged and 4 unchallenged rabbits were used as controls. Serial lateral head cephalograms, taken at 73 (T1), 87 (T2), 108 (T3), 129 (T4), and 150 (T5) days of age, were evaluated by linear measures of maxillary, mandibular, and posterior dental height dimensions. Differences in the absolute dimensions and relative percent incremental changes were compared by ANOVA and Fisher's test. The body weights, as well as the absolute measures and incremental changes in maxillary and posterior dental height dimensions, were not significantly different between the antigen-challenged and control groups. In contrast, absolute measures of posterior mandibular height, condylar neck height, and total mandibular length were significantly smaller (P < 0.05) in antigen-challenged rabbits than in both control groups at T5. Furthermore, the antigen-challenged rabbits demonstrated significantly smaller (P < 0.05) relative increases in all measures of mandibular length, and in total posterior mandibular and condylar neck heights. Cephalometric superimpositions on the cranial base and tantalum implants confirmed these quantitative observations. This investigation demonstrates mandibulofacial developmental aberrations in experimental JRA-like disease of the TMJ that are similar to those observed in humans with this disease.
The Smallest Detectable Difference of Mandibular Function Impairment in Patients with a Painfully Restricted Temporomandibular Joint
Authors: Kropmans Th.J.B. , Dijkstra P.U. , van Veen A. , Stegenga B. , de Bont L.G.M.
Published: January 2009

Mandibular functions such as speech, laughing, yawning, mastication, and taking a large bite may be impaired if temporomandibular disorders exist. The Mandibular Function Impairment Questionnaire is a validated instrument that scores perceived difficulty of representative mandibular functions in relation to jaw complaints. However, the reliability of the Mandibular Function Impairment Questionnaire has never been adequately tested. Generalizability and decision studies are currently proposed to assess the reliability of a measurement device. The smallest detectable difference is the smallest statistically significant amount of change to be detected with a measurement device. The purpose of this study was to assess the reliability of the Mandibular Function Impairment Questionnaire in terms of the smallest detectable difference. Twenty-five consecutive patients with painfully restricted temporomandibular joints completed the Mandibular Function Impairment Questionnaire on two separate measurement days, one week apart, using two consecutive sessions per day. Spearman's r was calculated for test-retest reliability. Variance components such as patients, measurement days, repetitions, and all their interactions were analyzed in the generalizability study. In the decision study, the smallest detectable difference was calculated for different days and repetitions. Spearman's r varied from 0.69 to 0.96. The between-patient variance and the error variance contributed 81% and 19% to total variance, respectively. The Mandibular Function Impairment Questionnaire is a reliable instrument for the assessment of mandibular function impairment. The minimal amount of change to be detected is 14 units on a scale of 0 to 68. Reliability in terms of the smallest detectable difference increases if the measurement ' is repeated twice on two separate days: The smallest detectable difference improves to 10 units.
In vitro Lymphoproliferative Assays with HgCl2 Cannot Identify Patients with Systemic Symptoms Attributed to Dental Amalgam
Authors: Cederbrant K. , Gunnarsson L.-G. , Hultman P. , Norda R. , Tibbling-Grahn L.
Published: January 2009

Dental amalgam is suspected, by some exposed individuals, to cause various systemic psychological, sensory, and neurological symptoms. Since not all amalgam-bearers experience such reactions, an individual characteristic—for example, a susceptible immune system—might explain these conditions. In vitro lymphocyte proliferation is a valuable tool in the diagnosis of allergy. With HgCl2 as the antigen, however, the test is hampered, because Hg2+ can cause unspecific lymphocyte proliferation, optimal at 1.4 to 9.5 μg HgCl2/mL. Recently, the use of suboptimal HgCl2 concentrations (≤ 0.5 μg/mL) has been suggested to circumvent these problems. The main aim of this study was to investigate whether patients with systemic symptoms alleged to result from the presence of dental amalgam differ from healthy controls, with reference to in vitro lymphoproliferative responses to HgCl2 ≤ 0.5 μg/mL. Three different test protocols—lymphocyte transformation test (LTT) in micro- and macro-cultures, and the memory lymphocyte immunostimulation assay (MELISA®)—were used. Other immune parameters—such as a standard patch test for dental materials, the number of T- and B-lymphocytes, monocytes, granulocytes, and NK cells in peripheral blood, allergic symptoms, and predisposition-were also investigated. Twenty-three amalgam patients, 30 healthy blood donors with amalgam, ten healthy subjects without amalgam, and nine patients with oral lichen planus (OLP) adjacent to dental amalgam and a positive patch test to Hg0 were tested. None of the investigated immune parameters revealed any significant differences between amalgam patients and controls. The sensitivity of in vitro lymphocyte proliferation ranged from 33 to 67%, with the OLP patients as a positive control group, and the specificity from 0 to 70% for healthy controls with a negative patch test to Hg°. Thus, despite the use of HgCl2 ≤ 0.5 μg/mL, a high frequency of positive results was obtained among healthy subjects with or without dental amalgam. Consequently, in vitro lymphocyte proliferation with HgCl2 cannot be used as an objective marker for mercury allergy in dental amalgam-bearers.
The Effects of Light Intensity, Temperature, and Comonomer Composition on the Polymerization Behavior of Dimethacrylate Dental Resins
Authors: Lovelh L.G. , Newman S.M. , Bowman C.N.
Published: January 2009

One of the most common combinations for the organic phase of dental restorative materials is BisGMA (2,2 bis[4-(2-hydroxy-3-methacryloyloxypropoxy) phenylJpropane) and TEGDMA (triethylene glycol dimethacrylate). However, this copolymer has some drawbacks, such as volume shrinkage during cure and lack of complete double-bond conversion. If the properties of this system are to be improved, an attempt must be made to understand the underlying kinetics of the reaction. This work examines the effects of light intensity, temperature, and composition on the polymerization behavior of BisGMA/TEGDMA copolymerizations. Using differential scanning calorimetry, we monitored the rates of photopolymerization for various experimental conditions. The BisGMA/TEGDMA copolymerization behaved similarly to other dimethacrylate systems and exhibited diffusion-controlled kinetics. It was found that the maximum rate of polymerization was significantly affected by the intensity of the light, and the temperature of the polymerization affected the conversion at which the maximum rate occurred. When the composition of the mixture was varied, it was discovered that the viscosity of the system played a significant role in the polymerization rate and the onset of reaction-diffusion-controlled termination. Mixtures which contained from 50 wt% to 75 wt% BisGMA displayed the highest maximum rate. This feature suggests that TEGDMA is an excellent diluent, since it increases the mobility of the reacting medium; however, the high reactivity is due to the presence of BisGMA. Therefore, based on compositional dependence, we conclude that the BisGMA portion of the mixture largely controls the polymerization mechanisms and kinetics.
Enhancement by Recombinant Human Bone Morphogenetic Protein-2 of Bone Formation by Means of Porous Hydroxyapatite in Mandibular Bone Defects
Authors: Yoshida K. , Bessho K. , Fujimura K. , Konishi Y. , Kusumoto K. , Ogawa Y. , Iizuka T.
Published: January 2009

Hydroxyapatite is osteoconductive and can maintain an original biocompatible form. It is useful, in the reconstruction of bone defects, to enhance the osteoconduction of hydroxyapatite with an osteogenic protein. The aim of this study was to evaluate the bone formation in surgically created defects of rabbit mandibles by a combination of recombinant human bone morphogenetic protein-2 (rhBMP-2), with porous hydroxyapatite and atelopeptide type I collagen used as the carrier for rhBMP-2. A 10-μg rhBMP-2-implanted group (n = 15) and a control group (n = 15), in which only atelopeptide type I collagen and porous hydroxyapatite were implanted, were histologically examined 3, 7, and 21 days after implantation. The alkaline phosphatase activity was also quantitatively analyzed. No new bone formation was observed in either the tested or the control group after 3 days. At 7 days, immature bone tissue was observed in some pores of the rhBMP-2implanted group, while in the control group, immature mesenchymal cells were observed. At 21 days, trabecular bone lined some pore walls. In the central portion, the bone marrow, including angioid tissue, was observed. New trabecular bone formation was observed on portions of the external surface of the hydroxyapatite disk. On the other hand, the control group showed infiltration of immature mesenchymal cells into some pores. Marginal bone formation was found in the pores close to the surface of the disk which opposed mandibular bone. The control group showed a slow, small increase in alkaline phosphatase activity in this study, while the experimental group showed a marked increase at 21 days. This increase was significantly higher in the tested group than in the control group at both 7 and 21 days. The findings indicate that rhBMP-2 accelerated bone formation by osteoconduction from porous hydroxyapatite. The combination of rhBMP-2, atelopeptide type I collagen, and porous hydroxyapatite is suggested to be advantageous for clinical application in reconstructing mandibular bone defects.
The Predominant Actinomyces spp. Isolated from Infected Dentin of Active Root Caries Lesions
Authors: Brailsford S.R. , Tregaskis R.B. , Leftwich H.S. , Beighton D.
Published: January 2009

Actinomyces are Gram-positive pleomorphic rods (GPPR) which form a large proportion of the oral microflora of all mammals. They have been implicated in root caries, although their role in dental caries initiation and progression is not well-understood. Many studies have focused on Actinomyces naeslundii, but few reports have documented other members of the GPPR. Therefore, we investigated the GPPRs isolated from infected dentin of active root caries lesions (n = 9) to determine which species were the most frequently isolated. The GPPR were isolated under both aerobic and anaerobic conditions and identified by biochemical and physiological tests to the species level according to the new taxonomy. Of 654 GPPR isolates investigated, 607 were identified as belonging to the genus Actinomyces. Of these, 242 were identified as A. israelii, 225 as A. gerencseriae, 109 as A. naeslundii, 15 as A. odontolyticus, and 13 as A. georgiae. Individual strains of A. israelii (n = 56) and A. gerencseriae (n = 46) were also investigated at the DNA level by means of Repetitive Extragenic Palindromic polymerase chain-reactions (REP-PCR) for the study of clonal diversity. Although only a small number of isolates was investigated, REP-PCR showed that the genotypes of both A. gerencseriae and A. israelii populations were heterogeneous within individual root caries lesions. A. gerencseriae and A. israelii strains from the same lesions did not share the same REP-PCR patterns, showing the robustness of the identification scheme. A significantly greater proportion of A. gerencseriae was isolated from the aerobic plates (p < 0.05), while the proportion of A. israelii was significantly (p < 0.05) greater from anaerobic plates. The role of individual Actinomyces spp. in the root caries process remains unclear, since various populations of GPPRs were isolated from individual active root caries lesions.
Capsaicin Induces Cystatin S-like Substances in Submandibular Saliva of the Rat
Authors: Katsukawa H. , Ninomiya Y.
Published: January 2009

Irritating dietary substances such as tannin and papain have been reported to alter the morphology of salivary glands and their secretions. Such alterations can be one line of protection from toxic or irritating substances in food. We investigated the effects of dietary capsaicin (a pungent ingredient of hot red pepper) on the rat submandibular gland and its secretions. Several groups of animals were offered either control diets or diets containing capsaicin (from 0.0001 to 0.1%) for seven days. Higher concentrations suppressed food consumption for two days, after which only the highest concentration continued to reduce intake. The relative weight of the salivary glands in capsaicin-diet groups increased in a dose-dependent fashion, and new proteins appeared in the submandibular saliva. Chromatographic and electrophoretic properties of these proteins were identical or similar to those of isoproterenol-induced proteins. After affinity chromatography of the new protein fraction on a Cm-papain Sepharose 4B column, SDS-electrophoresis of the eluate revealed three major bands (15,500, 16,500, and 28,000 kDa). Hydrolysis of N-benzoyl-D,L-arginine-p-nitroanilide by papain (a cysteine protease) decreased in the presence of the new protein fraction, suggesting that these proteins have cystatin-like activity (inhibition of cysteine protease). Denervation of the glossopharyngeal nerve suppressed induction of these proteins. The results suggest that dietary capsaicin induces cystatin S-like substances in submandibular saliva by stimulating the reflex arc involving the glossopharyngeal nerve. These proteins likely facilitate ingestion of diets containing the irritating substance.
Establishment of Oral Anaerobes during the First Year of Life
Authors: Könönen E. , Kanervo A. , Takala A. , Asikainen S. , Jousimies-Somer H.
Published: January 2009

Anaerobic species constitute a significant part of the bacterial community of the mouth. Although the time and species involved in the primary colonization of infants are of great importance by forming the basis for further colonization, the development of the oral anaerobic microflora with age is still inadequately understood. In the present study, time and succession of colonization of oral anaerobes were longitudinally examined in 44 healthy Caucasian infants at 2, 6, and 12 months of age. Unstimulated saliva samples were quantitatively cultured on non-selective Brucella blood agar and several selective media for the isolation of anaerobic micro-organisms. The most frequent anaerobic finding in two-month-old infants was Veillonella spp. The Prevotella melaninogenica group also represented early colonizing species, and the frequency increased remarkably during the first year of life, whereas the Prevotella intermedia group organisms seemed to be late colonizers. Fusobacterium nucleatum, non-pigmented Prevotella spp., and Porphyromonas catoniae were occasional findings in subjects at 2 months but frequent findings in those at one year of age. F. nucleatum was the most frequent strictly anaerobic species in one-year-old infants; other fusobacteria were also occasionally found. The frequency of facultative/micro-aerophilic corroding rods and Capnocytophaga spp. started to increase toward the end of the first year. Except for the common presence of facultative/micro-aerophilic Actinomyces spp., other anaerobic Gram-positive species were only occasionally present in these infants. Once established, early-colonizing species tended to persist in the mouth. Our longitudinal study demonstrated the establishment of several anaerobic species with steadily increasing frequencies during the first year of life.