bluuebunny/crossref_metadata_2025 huggingface dataset:
Validity of Diagnostic and Monitoring Tests Used for Temporomandibular Disorders
Authors: Lund J.P. , Widmer C.G. , Feine J.S.
Published: January 2009

Currently, diagnosis of temporomandibular disorders (TMD) depends on a comprehensive history and physical examination, supplemented, when indicated, by images of hard and soft tissues. However, there are electronic diagnostic devices being marketed to acquire other measures described as relevant to TMD and to use these for diagnosis of TMD and for monitoring the effects of treatment. This paper reviews the capacity of several devices to measure these variables accurately and reliably and to assess the theoretical basis of each of these tests. Diagnostic ability was established, when possible, according to the commonly accepted measures of sensitivity, specificity, and positive predictive values. It was found that many tests lack theoretical validity, that measurement validity tends to be poor, and that diagnostic ability can be even worse than chance, because of a high percentage of false-positive diagnoses. Based on these findings, the use of these instruments in clinical practice is inappropriate at this time and may lead to the treatment of large numbers of subjects who have no disorder.
Oral Candida: Clearance, Colonization, or Candidiasis?
Authors: Cannon R.D. , Holmes A.R. , Mason A.B. , Monk B.C.
Published: January 2009

Candida albicans is frequently isolated from the human mouth, yet few carriers develop clinical signs of candidiasis. Oral candidiasis presents clinically in many forms. This reflects the ability of the yeast to colonize different oral surfaces and the variety of factors which predispose the host to Candida colonization and subsequent infection. Colonization of the oral cavity appears to be facilitated by several specific adherence interactions between C. albicans and oral surfaces which enable the yeast to resist host clearance mechanisms. Thus, Candida has been shown to adhere to complement receptors, various extracellular matrix proteins, and specific sugar residues displayed on host or bacterial surfaces in the oral cavity. Oral candidiasis results from yeast overgrowth and penetration of the oral tissues when the host's physical and immunological defenses have been undermined. Tissue invasion may be assisted by secreted hydrolytic enzymes, hyphal formation, and contact sensing. While these and other phenotypic characteristics may endow certain Candida species or strains with a competitive advantage in the oral cavity, it is the host's immune competence that ultimately determines whether clearance, colonization, or candidiasis occurs.
Effects of Unpolymerized Resin Components on the Function of Accessory Cells Derived from the Rat Incisor Pulp
Authors: Jontell M. , Hanks C.T. , Bratel J. , Bergenholtz G.
Published: January 2009

Monomeric resin components from dental composites are toxic to fibroblasts in culture and thus may interfere with the local immune system of the pulp, reducing its effective defense potential, either by cytotoxicity or by a more specific immune mechanism. Therefore, the present study was undertaken to observe the cytotoxic effects elicited by certain unpolymerized components of resin composites upon the function of accessory pulp cells in mitogen-induced proliferation of T-lymphocytes. Accessory cells from the rat incisor pulp were released following enzymatic digestion with collagenase. The assay included incubation of these cells with purified T-lymphocytes from cervical lymph nodes for 72 h in the presence of different concentrations of the resin components. The proliferative T-lymphocyte response was monitored by 3H-thymidine incorporation. Initially, we conducted experiments on spleen cells to determine the proper concentration intervals for suitable testing of the resin components. To assess the individual susceptibility of accessory cells and T-lymphocytes, we pre-treated each of these cells with some of the test materials prior to assay. At low concentrations, urethane dimethacrylate (UDMA), bisglycidyl methacrylate (bis-GMA), triethylene glycol dimethacrylate (TEGDMA), and bis-phenol A (BPA) increased spleen cell proliferation to concanavalin A (con A). Purified T-lymphocytes stimulated by pulpal cells did not show enhanced responses to UDMA, bis-GMA, glycidyl methacrylate (GMA), or N,N-dihydroxyethyl-p-toluidine (DHEpT). At higher concentrations, all substances except camphoroquinone (CAMP) showed inhibitory effects in both test systems. The in vitro study shows that resin components can evoke either immunosuppression or immunostimulation on mitogen-driven proliferation of purified T-lymphocytes and spleen cells.
Variability in Microleakage Observed in a Total-etch Wet-bonding Technique under Different Handling Conditions
Authors: Tay F.R. , Gwinnett A.J. , Pang K.M. , Wei S.H.Y.
Published: January 2009

Using a stereoscopic clearing protocol and scanning electron microscopy, we investigated the extent and nature of microleakage in a total-etch, current-generation dentin adhesive by a wet-bonding technique under different handling conditions. The hypotheses were that inadequate light curing of the primer or incomplete drying of the primer solvent might adversely affect the sealing ability of an acetone-containing adhesive system. The study consisted of three experimental groups: (I) a control group with an adequate light source and with the primer solvent completely dried; (II) an "inadequate-light" group; and (III) an "incomplete evaporation of primer solvent" group. The extent of microleakage after silver staining and clearing of the specimens was scored based on a modified five-point scale. Nonparametric statistical analysis (Kruskal-Wallis ANOVA) followed by a multiple comparison test (Dunn test) indicated significant differences among the three groups (p < 0.05).

SEM examination of the restorative interface revealed that microleakage appeared to be initiated from the bonding resin-hybrid layer interface in all three groups, representing the weak link in the adhesive system. In addition, microleakage was characterized by 5 zones, each delineating a stage in a continuous array of progressively deleterious microleakage patterns variously distributed among the three groups. It was suggested that, while the bonding resin-hybrid layer interface represented the intrinsic weakness in an already much improved dentin adhesive, extrinsic factors such as the adequacy of the curing light and, more importantly, complete removal of the primer solvents can and should be avoided to preserve the structural integrity of the marginal seal.
Mercury Release from Dental Amalgams: An in vitro Study Under Controlled Chewing and Brushing in an Artificial Mouth
Authors: Berdouses E. , Vaidyanathan T.K. , Dastane A. , Weisel C. , Houpt M. , Shey Z.
Published: January 2009

The release of mercury vapor from class I amalgam restorations prepared in human molar teeth was studied during chewing simulations in an artificial mouth of a bi-axial servo-hydraulic mechanical test system. So that the total mercury released from the restoration over a fixed time could be determined, a closed chamber surrounded the envelope of chewing motion. In addition, the influence of sampling frequency on mercury release was corrected by the use of different sampling frequencies over a fixed time interval of mercury release measurement and extrapolation to zero sampling time. Thus, a combination of a closed environment and an extrapolation method to determine the mercury release under continuous sampling was used to determine the mercury released under normal breathing conditions. The measured mercury release rate data were used to calculate the potential daily mercury dose in a patient due to a single amalgam restoration, following the method previously outlined by Berglund. The mercury release from both a conventional and a high-copper amalgam was evaluated at different age intervals after the restoration was placed in the teeth. The results show that while the age of the amalgam and the amalgam type influence the extent of mercury release during the initial non-steady-state conditions, the steady-state value of mercury daily dose due to a single amalgam filling is 0.03 ug/day, which is well below the calculated threshold-limiting value (TLV) of 82.29 μg/day considered dangerous for occupational exposure in the United States.
Computer-assisted Reconstruction of Enamel Fissures and Carious Lesions of Human Premolars
Authors: Hirano Y. , Aoba T.
Published: January 2009

The origin of cariogenesis in occlusal fissures remains elusive because of limited information about both the fissure structure and the morphologic details of carious lesions occurring there. The present study was aimed at reconstructing the coronal structure of human premolars with the aid of computer-assisted image analysis and, on the basis of the reconstructed structures, investigating the configuration of fissures, their proximity to the enameldentin junction (EDJ), and the occurrence and extension of carious lesions around the fissure walls. The coronal portions of the teeth were embedded in polyester resin and then ground off stepwise by hand. Serial images of the enamel contour on successive ground planes were recorded by objective microscopy after it was distinctly demarcated with either 0.5 w/v% carbol fuchsin or 1 w/v% basic fuchsin. Usually, from 150 to 250 photoprints were collected from a single enamel crown to reproduce the details of the fissure structures. The enamel outline (the occlusal and lateral surfaces, fissure walls, and EDJ) and, if present, the outline of caries-attacked areas were traced accurately on those photoprints by means of a digitizing system. The enamel contour data in series were input into an image analyzing system (Nikon COSMOZONE, 2SA). Observation of the computer-drawn coronal enamel allowed us to view the morphologic features of the fissures (shape, divarication, and proximity to EDJ) and to scrutinize the pathway of enamel caries along fissure walls. The results indicate that the computer-assisted reconstruction of enamel crown, in conjunction with the step-by-step grinding technique, is useful in basic and clinical studies of occlusal fissure caries.
Quantifying the Strength of Bacterial Adhesive Interactions with Salivary Glycoproteins
Authors: Prakobphol A. , Burdsal C.A. , Fisher S.J.
Published: January 2009

We adapted an assay that has been used to estimate the strength of eukaryotic cell-cell and cell-extracellular matrix adhesive interactions (McClay et al., 1981) to quantify the strength of bacterial (streptococci, fusobacteria, actinomyces) interactions with salivary receptors. Bacteria are centrifuged onto human submandibular/sublingual or parotid-saliva-coated microtiter wells. Plates are sealed with pressure-sensitive, double-sided tape which allows them to be inverted and centrifuged again. The force required to remove the bacteria from the coated wells is a direct measure of the adhesive strength of the interaction(s) being disrupted. The bacteria-saliva adhesive forces we detected ranged from 1.6 x 10-8 dynes (Streptococcus sanguis 72-40) to > 1.1 x 10-7 dynes (Actinomyces viscosus T14 V). These forces were in the range to withstand the shear stress produced by salivary flow, which we calculated as approximately 6.1 x 10-7 dynes.
Formation of Differentiated Tissues in vivo by Periodontal Cell Populations Cultured in vitro
Authors: Lang H. , Schiiler N. , Arnhold S. , Nolden R. , Mertens T.
Published: January 2009

The periodontium contains heterogeneous mesenchymal cell populations with various differentiation potentials. The capacity of these cells for tissue formation as well as the origin of their precursors are still not entirely defined. In this study, cells originating from different periodontal tissues were cultured in vitro, and tissue formation in vivo following orthotopic re-implantation was investigated. Cells were recovered from the alveolar bone and periodontal ligament tissue of six minipigs, and cultured cells were then grown on extracted dental roots from the homologous animals by means of co-culture in vitro. Each minipig received 2 roots covered with alveolar bone cells, 2 roots covered with periodontal ligament cells, and 2 control roots (without cells) implanted into palatal bone defects. Intravital fluorochrome labeling was performed, and two minipigs were histologically examined after 2, 4, and 12 weeks in each case. Controls showed widespread resorption and ankylosis, whereas roots covered with cultured periodontal cells exhibited tissue formation in vivo. Alveolar bone cells synthesized a calcified cellular tissue resembling cellular cementum, suggesting that cells within this population might differentiate into cementoblasts when re-implanted with a dental substrate in vivo. Periodontal ligament cells exhibited no calcified tissue formation in vivo, but cells synthesized a connective tissue with orientated fiber bundles attached to both host bone and root, resembling periodontal ligament. Results indicate that cultured cells retain the capacity to form differentiated periodontal tissues after re-implantation, depending on the cells' origin. Our findings also suggest that the alveolar bone contains cementogenic precursors with the potential to differentiate into active cementoblasts in the presence of a dental substrate.
Expression of Basement Membrane Type IV Collagen and Type IV Collagenases (MMP-2 and MMP-9) in Human Fetal Teeth
Authors: Heikinheimo K. , Salo T.
Published: January 2009

Formation and degradation of dental basement membrane (BM) are important for tooth development. Data on the expression of genes for type IV collagen (the major structural component of the BM) and type IV collagenases [MMP-2 (72 kDa) and MMP-9 (92 kDa)], enzymes that degrade type IV collagen during human tooth development, are lacking. We studied expression of type IV collagen and the MMP-2 and MMP-9 in human fetal teeth (from the 13th to the 20th gestational weeks, covering cap stage through early hard tissue formation). During cap and bell stages, in situ hybridization located transcripts for al type IV collagen chain in the fibroblasts surrounding the enamel organ. No al type IV collagen chain mRNA was detected in tooth germ epithelium or dental papilla. However, type IV collagen immunoreactivity was observed in BM underlying the dental epithelium up to the appositional stage. Transcripts for MMP-2 were located mostly in the cells of the dental papilla and follicle. Transient expression of MMP-2 mRNA was observed in the inner enamel epithelium of late cap/early bell-stage teeth. During early apposition, a high level of MMP-2 was confined to secretory odontoblasts. Transcripts for MMP-9 were detected by the sensitive reverse-transcription polymerase chain reaction (RT-PCR) in developing teeth. Thus, in dental BM, al type IV collagen chain may be of mesenchymal cell origin. Further, MMP-2 but not MMP-9 may participate in remodeling and degradation of BM during human tooth morphogenesis.
Effect of Lung Inflation on Levator Veli Palatini Muscle Activity
Authors: Koizumi H. , Kogo M. , Matsuya T.
Published: January 2009

Palatal movements play a critical role in regulating oropharyngeal airflow during breathing. We hypothesized that these movements are coordinated with breathing movements via afferent signals from the lung. However, the control of palatal movements in relation to the lung remains unclear. This study was designed to define, by electromyographic techniques, the relationship between palatal movement and lung action during respiration.

We performed tracheotomies on 12 mongrel dogs anesthetized with sodium pentobarbital and found that lung inflation augmented the activity of the levator veli palatini muscle (LVP). Two kinds of discharges were recognized during the expiratory pause following lung inflation. One was a continuous, low-amplitude discharge induced during apnea following lung inflation. The other was a transient, high-amplitude discharge which appeared immediately after lung inflation. Both of these response activities were eliminated by bilateral vagotomy. We thus concluded that palatal movements, which can regulate expiratory airflow resistance and cause switching from nasal to oral airflow, are under the control of vagal afferent signals from the lung.
Isothermal Anneal Effect on Leucite Content in Dental Porcelains
Authors: Mackert J.R. , Twiggs S.W. , Evans-Williams A.L.
Published: January 2009

Porcelain thermal expansion behavior is a function of leucite content, and leucite changes can produce porcelain-metal incompatibilities. The purpose of the present study was to determine whether isothermal anneal treatments (such as are encountered during "post-soldering" operations) could result in alterations of leucite content of dental porcelain. Six commercial dental porcelains and the "Component No. 1" frit of the Weinstein et al. patent (1962) were studied. Twenty-eight coupon specimens of each porcelain were fired and divided randomly into seven groups of four specimens each. One group served as a control, while the other six groups were subjected to isothermal anneal treatments-three groups at 500°C and three groups at 750°C, for 4, 8, and 16 min, respectively. Leucite volume fraction was measured via quantitative x-ray diffraction. From an equation for the growth of particles in competition for diffusing material, an expression was derived for the potential simultaneous processes of leucite crystallization and reaction of leucite + glass to form sanidine or other compounds. This exponential growth/decay curve was fit through the experimental data for each porcelain by minimization of the sum of the squares of the residuals through iteration. For each porcelain, a statistically significant correlation was obtained between leucite volume fraction and isothermal anneal duration at 750°C (p < 0.01), whereas at 500°C, only CII exhibited a statistically significant correlation (p < 0.01). The control (non-annealed) leucite volume fractions for the commercial porcelains ranged from (mean ± SD) 0.155 ± 0.002 for WIL to 0.442 ± 0.003 for Component No. 1. The 750°C isothermal anneal increased the leucite volume fraction by between 6.1% and 21.3%. These increases in leucite could be responsible for the porcelain fracture that sometimes occurs during post-soldering.
Hypermineralization of Dentinal Lesions Adjacent to Glass-ionomer Cement Restorations
Authors: ten Cate J.M. , van Duinen R.N.B.
Published: January 2009

Previous reports have shown a release of fluoride from glass-ionomer cement (GIC) restorations into the oral fluids. Fluoride in the ambient fluids has a caries-preventive effect by enhancing remineralization and inhibiting demineralization of the dental hard tissues. Therefore, the current investigation was undertaken to determine whether GIC fillings could contribute to the remineralization of caries lesions in dentin. Small circular preparations were made in disks of dentin which had incipient caries-like lesions in the remaining tissue. The preparations were filled with amalgam or composite materials (as controls) or with GIC. The specimens thus contained a restoration close to a dentinal caries-like lesion. The specimens were placed contralaterally in the buccal surfaces of removable partial dentures and were worn intra-orally by volunteers for a 12-week experimental period, after which the specimens were sectioned and analyzed by microradiography. All specimens with GIC restorations exhibited hypermineralization in the tissue bordering the filling and in the wall of the preparation which had been in contact with the restoration. The (caries-like) lesions were remineralized, even under conditions of heavy plaque formation. In contrast, specimens with amalgam or composite restorations showed further extensive demineralization. This study demonstrates a significant remineralization potential exerted by the fluoride-releasing GIC restorative material. Consequently, the choice of the restorative material might be crucial for the occurrence or prevention of recurrent caries around restorations.
Anticariogenicity of Calcium Phosphate Complexes of Tryptic Casein Phosphopeptides in the Rat
Authors: Reynolds E.C. , Cain C.J. , Webber EL , Black C.L. , Riley P.F. , Johnson I.H. , Perich J.W.
Published: January 2009

Casein phosphopeptides (CPP) stabilize calcium phosphate through the formation of casein-phosphopeptide amorphous calcium-phosphate complexes (CPP-CP). The ability of CPP-CP to reduce caries activity was investigated by use of specific-pathogen-free rats inoculated with Streptococcus sobrinus. The animals consumed a defined cariogenic diet free of dairy products. Solutions (100 pL) of the CPP-CP (0.1, 0.2, 0.5, 1.0% w/v) were applied to the animals' molar teeth twice daily. Other groups of animals received solutions containing 500 ppm F, the non-phosphorylated peptides of a casein tryptic digest (0.5% w/v), or the calcium-phosphate complex of a synthetic octapeptide, Ac-Glu-Ser(P)-Ile-Ser(P)-Ser(P)-Ser(P)-Glu-Glu-NHMe, corresponding to the common sequence in the CPP. The CPP-CP significantly reduced caries activity in a dose-response fashion, with 1.0% CPP-CP producing 55% and 46% reductions in smooth surface and fissure caries activity, respectively, being similar to that of 500 ppm F. The anticariogenic effects of CPP-CP and fluoride were additive, since animals receiving 0.5% CPP-CP plus 500 ppm F had significantly lower caries activity than those animals receiving either CPP-CP or fluoride alone. The tryptic digest of casein with the phosphopeptides selectively removed showed no anticariogenic activity. The synthetic octapeptide-calcium phosphate complex significantly reduced caries activity, confirming that this calcium-phosphate-stabilizing portion of the casein phospho-peptides is associated with anticariogenicity. The CPP-CP did not significantly affect the level of S. sobrinus in fissure plaque. The proposed mechanism of anticariogenicity for CPP-CP complexes is that they substantially increase the level of calcium phosphate in plaque, depressing enamel demineralization and enhancing remineralization.
Saliva Protein Binding to Layers of Oral Streptococci in vitro and in vivo
Authors: Rudney J.D. , Ji Z. , Larson C.J. , Liljemark W.F. , Hickey K.L.
Published: January 2009

This paper reports a system for measuring saliva protein binding to oral streptococci. Enamel chips with layers of Streptococcus gordonii Blackburn or Streptococcus oralis 10557 were incubated in vitro with whole saliva from eight persons. Blackburn bound significantly more amylase than 10557; no strain differences were seen for lysozyme or lactoferrin. There were significant correlations between saliva and bound amylase and lactoferrin. Blackburn and 10557 chips were then placed in ten subjects. Sites included the buccal left and right upper premolars and molars (UL, UR), labial upper central incisors (UC), and lingual lower central incisors (LL). That study was repeated three months later; chips with Streptococcus sanguis 13379 were also placed then. Blackburn bound significantly more amylase than the other strains. Blackburn and 10557 both bound the most amylase at UL and UR, and the least amylase at UC. However, strain 13379 bound less amylase at UL. That strain also bound significantly less sIgA at UL. All three strains bound the least sIgA at UC. Lysozyme and lactoferrin binding showed few differences among sites or strains. Bound protein concentrations were significantly correlated across sites and strains within subjects, but not correlated with whole saliva. Strain differences may reflect species differences in amylase binding, or differences in species-specific sIgA titers. Site differences may indicate local variation in protein availability. Differences between chip correlations with whole saliva in vitro and in vivo suggest that the salivary film may be modified as it flows over tooth surfaces.
Isolation, Purification, and Partial Characterization of an Autocrine Periodontal Ligament Cell Chemotactic Factor
Authors: Ye J. , Nishimura F. , Orman R. , Terranova V.P.
Published: January 2009

Periodontal ligament (PDL) cells are believed to play a critically important role in the regeneration of the periodontium. We have suggested that polypeptide growth factors can enhance periodontal regeneration by stimulating PDL cell chemotaxis and mitogenesis. This manuscript describes the identification of a novel chemotactic factor isolated from human PDL cells which we named PDL-CTX. PDL-CTX induces the directed migration of human PDL cells in vitro and was found to be a more potent chemotactic agent than other known growth factors. Additionally, PDL-CTX has no chemotactic effect on gingival fibroblasts or gingival epithelial cells. Both tryptic digestion and boiling abolished PDL-CTX's biological activity. The designed purification method included Mono-S cation exchange, heparin-sepharose affinity, and microbore reverse-phase HPLC. The purified factor has a relative molecular weight of approximately 7000 daltons based on sodium dodecyl sulfate (SDS) gel analysis. The amino acid composition and partial amino acid sequence were determined from HPLCpurified material. These were determined to be unique. Further investigation of the biological functions of PDL-CTX on PDL cells and other ligament cells should help improve our understanding of ligament repair.
A Topographical and Ultrastructural Study of Sensory Trigeminal Nerve Endings in the Rat Temporomandibular Joint as Demonstrated by Anterograde Transport of Wheat Germ Agglutinin-Horseradish Peroxidase (WGA-HRP)
Authors: Kido M.A. , Kiyoshima T. , Ibuki T. , Shimizu S. , Kondo T. , Terada Y. , Tanaka T.
Published: January 2009

To extend our previous light microscopic observations concerning the distribution of trigeminal sensory nerves in the synovium of the rat temporomandibular joint, we investigated the detailed distribution and fine structure of sensory nerve endings at the light and electron microscopic level by the anterograde transport method using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injected into the trigeminal ganglion. At the light microscopic level, HRP-labeled nerve fibers were observed in the joint capsule and peripheral portion of the disc. The anterior portion of the disc was more densely innervated than the posterior portion, while no nerves were found in the central portion. At the electron microscopic level, HRP reaction products were observed intra-axonally in the thinly myelinated (AS) and unmyelinated (C) axons in the anterior portion of the joint capsule, and were also localized in the extracellular space surrounding the unmyelinated fibers and terminals. In the subsynovial layer of the synovial membrane, the majority of labeled axons located near blood vessels or among the collagenous fibrils were covered by Schwann cell sheaths, although some naked axon terminals without sheaths were also found. These unsheathed terminals contained mitochondria, small clear vesicles, and large granular vesicles, and were close to the synovial A and/or B cells near the joint cavity. The minimum distance between the terminals and synovial cells was 75 nm. This is the first demonstration of trigeminal sensory nerve terminals close to synovial lining cells or joint cavity and suggests that neuropeptides such as substance P may be released close to the synovial lining cells or joint cavity.
Salivary Amylase Promotes Adhesion of Oral Streptococci to Hydroxyapatite
Authors: Scannapieco F.A. , Torres G.I. , Levine M.J.
Published: January 2009

Recent studies have demonstrated that several species of oral streptococci, such as Streptococcus gordonii, bind soluble salivary a-amylase. The goal of the present study was to determine if amylase immobilized onto a surface such as hydroxyapatite can serve as an adhesion receptor for S. gordonii. Initially, human parotid saliva was fractionated on Bio-Gel P60, and fractions were screened for their ability to promote adhesion of S. gordonii to hydroxyapatite. Fractions containing a-amylase and proline-rich proteins promoted the adhesion of [3H]-labeled S. gordonii to hydroxyapatite. Similar findings were obtained with purified amylase and acidic proline-rich protein 1 (PRP1). Incubation of S. gordonii G9B in the presence of starch and maltotriose increased the binding of this strain to amylase-coated hydroxyapatite, while the adhesion of S. sanguis 10556 to amylase-coated hydroxyapatite was not affected by these saccharides. These results suggest that amylase may serve as a hydroxyapatite pellicle receptor for amylase-binding streptococci. Furthermore, starch and starch metabolites may enhance the adhesion of amylase-binding streptococci to amylase in dental pellicles to augment the formation of dental plaque.
Relation between Clinical Dental Status and Subjective Impacts on Daily Living
Authors: Leao A. , Sheiham A.
Published: January 2009

Although clinical dental status has weak correlations with subjective impacts, some of them are significant. Those variables which had significant correlations could be used as a starting point to understand clinical and social characteristics of people who experience dental problems. This is indeed the basis for the current research. The study compares psychosocial impacts on the quality of people's life with their respective oral status. To that end, a socio-dental indicator, the 'Dental Impact of Daily Living' (DIDL), involving five dimensions, together with a scale which assesses dimension impacts, was developed. The resulting instrument was validated and the reliability tested. The instrument generates a total final score, in addition to scores for each dimension. The method was tested in Brazil on a sample of 662 people, aged from 35 to 44 years, of two social classes, both sexes, and with three different levels of dental caries status or with a full upper denture. To test whether DIDL discriminated between groups with different levels of subjective impact, we analyzed how oral status, social class, and gender varied according to impacts. Different levels of oral status had different impacts on people's daily life. On the basis of the results, it is reasonable to suggest that oral status and social and psychological dimensions should be considered simultaneously when in assessment of people's dental needs.
Fracture Toughness of Experimental Dental Composites Aged in Ethanol
Authors: Ferracane J.L. , Berge H.X.
Published: January 2009

Fracture toughness (KIc) is an intrinsic property which may be related to the ability of a restorative material to resist fracture and abrasion. This property may change for a dental composite restorative due to the effects of various oral solvents. The hypothesis to be tested was that aging in ethanol would cause a reduction in the fracture toughness of dental composites, and that the extent of this reduction might be dependent upon certain compositional variables. The fracture toughnesses of three series of experimental composites with various degrees of conversion, filler volume, and percent of silane-treated fillers were compared after the composites were aged for periods of one month and six months in 75% ethanol/water, a solvent which serves as a food-simulating liquid. An unfilled Bis-GMA/TEGDMA resin served as the control. All composites, with the exception of one subjected to a post-light-curing heat treatment, experienced a significant reduction (from 30 to 56%) in KIc after being aged in 75% ethanol for six months. A similar reduction in KIc of 58% for the unfilled resin suggested that the reduction for the composites was due to a weakening of the resin matrix, which facilitated crack propagation. A simultaneous reduction in microhardness was also demonstrated. One month of aging in ethanol also produced large reductions in KIc for specimens with insufficient cure and minimal filler volume, suggesting that the properties of the resin matrix predominated for these composites. Aging in ethanol for one month increased KIc by from 5 to 10% for three partially silanated composites, but further aging caused a large reduction in their resistance to crack propagation. This study verified that the KIc and hardness of Bis-GMA-based composites was reduced after long-term aging in an effective solvent. In addition, insufficient curing and severely compromised filler/matrix adhesion, which caused the properties of the resin matrix to dominate, contributed to a reduction in the fracture toughness of composites.
The Prevalence of Dental Anxiety in Children from Low-income Families and its Relationship to Personality Traits
Authors: Raadal M. , Milgrom P. , Weinstein P. , Mancl L. , Cauce A.M.
Published: January 2009

The prevalence of dental anxiety and the association between dental anxiety and personality traits were examined in a population-based sample of 895 US urban children, from 5 to 11 years of age, from low-income families. Dental anxiety was reported by the child using the Dental Subscale (DS) of the Children's Fear Survey Schedule, and behavioral problems and personality traits were evaluated by parent report on the Child Behavior Checklist (CBCL). Mean DS scores were 31.1 (SD = 10.3) for boys and 34.3 (SD = 11.0) for girls. CBCL score means were 33.3 (SD = 23.2) for boys and 28.5 (SD = 19.1) for girls. The hypothesized relationship between DS and CBCL scores in this population was not demonstrated.
Effects of Protein Deficiency and Diet Consistency on the Parotid Gland and Parotid Saliva of Rats
Authors: Johnson D.A. , Lopez H. , Navia J.M.
Published: January 2009

Protein deficiency results in an increased susceptibility to dental caries, suggesting that oral host-defense properties are compromised. An important component of oral host defense is salivary gland function, which is affected by both protein deficiency and diet consistency. This study describes the effects on rat parotid gland growth and secretory function induced by feeding rats diets of normal (20%) or moderately low (7%) protein content, provided in either a powdered or solid form. In addition, since protein deficiency may result in a secondary zinc deficiency which, in turn, may affect salivary gland function, the effects of these diets on liver zinc concentration were also measured. From 22 to 47 days of age, rats (18/group) were fed the following diets: normal protein, powdered; normal protein, solid; low protein, powdered; and low protein, solid. With each diet consistency, liver zinc was higher for the normal protein group. Within each protein level, liver zinc was higher for the solid diet. This latter observation suggests that food mastication and the resultant stimulation of salivary gland function may also play a role in zinc metabolism. With the normal-protein diet, parotid gland weight was higher for the solid diet; with the low-protein diet, parotid gland weight was similar for both consistencies and did not differ from that of the group fed the "normal protein, powdered" diet. For both consistencies, parotid saliva protein concentration was greater for malnourished rats. Parotid saliva protein composition, measured by quantitative scans of SDS-PAGE gels, showed that basic proline-rich proteins were increased several-fold in both groups of malnourished rats, while proteins identified as deoxyribonuclease, parotid secretory protein, acidic epididymal glycoprotein, and common salivary protein 1b were reduced. Within each dietary protein level, only minor differences in protein composition were found between the solid and powdered consistencies. These studies show that protein deficiency has a marked effect on the protein composition of rat parotid saliva.
Definitive vs. Exploratory Periodontal Trials: A Survey of Published Studies
Authors: Hujoel P.P.
Published: January 2009

Definitive and exploratory randomized controlled trials (RCTs) have different goals as well as different design and analysis characteristics. The goal of definitive studies is to provide unequivocal evidence of a treatment's tangible benefit to the patient; a pre-trial-specified hypothesis is tested by use of a pre-trial-specified method.The goal of exploratory studies is to elucidate biological treatment mechanisms, to identify promising treatments, and to generate hypotheses for definitive studies; multiple hypotheses are evaluated to extract as much information from the data as possible. The purposes of this study were: (1) to survey selected design and analysis characteristics of randomized controlled periodontal trials published between 1988 and 1992 (n = 86), and (2) to classify trials as exploratory or definitive studies. The periodontal RCTs surveyed were typical of exploratory studies whose primary goal was to elucidate biological treatment mechanisms. Trial reports indicated the testing of multiple hypotheses (≥ 6 hypothesis tests in 70 of the 86 trials) on a variety of biological markers (86 out of 86 trials). The sample size (≤ 30 subjects in 67 out of 86 trials), duration (< 6 months in 65 out of 86 trials), and design and analysis characteristics (e.g., an absence of masking in 57 out of 86 trials) were also typical of exploratory studies which strive to obtain quick answers (short duration) at a low cost (small sample size; accept bias for increased efficiency and a lower cost). No definitive trials were identified. Promising, biologically active, treatments identified in exploratory trials should be evaluated in definitive studies where the primary goal is the procurement of unequivocal evidence of a treatment's tangible benefit to the patient. The costs and benefits of conducting definitive periodontal RCTs to provide such evidence should be investigated.
Architecture of the Human Pterygoid Muscles
Authors: van Eijden T.M.G.J. , Koolstra J.H. , Brugman P.
Published: January 2009

Muscle force is proportional to the physiological cross-sectional area (PCSA), and muscle velocity and excursion are proportional to the fiber length. The length of the sarcomeres is a major determinant of both force and velocity. The goal of this study was to characterize the architecture of the human pterygoid muscles and to evaluate possible functional consequences for muscle force and muscle velocity. For the heads of the lateral and medial pterygoid, the length of sarcomeres and of fiber bundles, the PCSA, and the three-dimensional coordinates of origin and insertion points were determined. Measurements were taken from eight cadavers, and the data were used as input for a model predicting sarcomere length and active muscle force as a function of mandibular position. At the closed-jaw position, sarcomeres in the lateral pterygoid (inferior head, 2.83 ± 0.1 um; superior head, 2.72 ± 0.11 μm) were significantly longer than those in the medial pterygoid (anterior head, 2.48 ± 0.36 um; posterior head, 2.54 ± 0.38 μm). With these initial lengths, the jaw angle at which the muscles were capable of producing maximum active force was estimated to be between 5° and 10°. The lateral pterygoid was characterized by relatively long fibers (inferior, 23 ± 2.7 mm; superior, 21.4 ± 2.2 mm) and a small PCSA (inferior, 2.82 ± 0.66 cm2; superior, 0.95 ± 0.35 cm2), whereas the medial pterygoid had relatively short fibers (anterior, 13.5 ± 1.9 mm; posterior, 12.4 ± 1.5 mm) and a large PCSA (anterior, 2.47 ± 0.57 cm2; posterior, 3.53 ± 0.97 cm2). The mechanical consequence is that the lateral pterygoid is capable of producing 1.7 times larger displacements and velocities than the medial pterygoid, whereas the medial pterygoid is capable of producing 1.6 times higher forces. The model showed that jaw movement had a different effect on active force production in the muscles.
Contributions of Facial Morphology, Age, and Gender to EMG Activity Under Biting and Resting Conditions: A Canonical Correlation Analysis
Authors: Fogle L.L. , Glaros A.G.
Published: January 2009

Theoretical studies suggest that facial morphology may confer a mechanical advantage to particular individuals during force production, but not during rest. However, prior studies on the relationship between facial morphology and EMG suffer from various methodological limitations. We examined the hypothesis that facial morphology variables contribute significantly and meaningfully to the variance in masticatory muscle EMG when subjects produce specific levels of interocclusal force, but not when subjects are at rest. Measures of facial morphology included gonial angle, ramus height, and maxillary height, as determined from lateral cephalograms. EMG data were obtained from surface electrodes placed on masseter and temporalis sites. Subjects (N = 96) sat in a darkened, sound-attenuated room while they watched a seven-minute segment of a movie. EMG activity obtained during the last two minutes was used as a baseline period. Using the central incisors, subjects then provided five different force levels ranging from 6.5 to 48 1b in random order on a bite-force device while EMG data were collected. A canonical correlation analysis, performed on the set of predictor variables (age, gender, and facial morphology measurements) and the set of criterion variables (EMG data), showed a significant canonical correlation between the two variable sets while biting, but not at rest. Age, but not the facial morphology variables, was highly related to the canonical variate. The data suggest that facial morphology variables examined in this study do not exert a meaningful influence on EMG data, at least when the task involves biting with the incisors over a broad range of bite forces obtained from a sample of subjects who vary deliberately with respect to age and gender.
Properties of Ca2+-dependent K+ Channels of Human Gingival Fibroblasts
Authors: Takahashi A. , Ikehara T. , Hosokawa K. , Ogura R. , Yamaguchi H. , Nakaya Y. , Miyamoto H.
Published: January 2009

Cells in the oral cavity are normally exposed to different temperatures. Ion transport systems are influenced by temperature in other tissues: In particular, changes in intracellular K+ ion can affect cell growth and synthesis of macromolecules. The purpose of this investigation was to identify K+ channels in human gingival fibroblast cells and analyze the effect of temperature on their K+ conduction properties. Ca2+-dependent K+ channels with a large conductance (125 pS in symmetrical K+-rich solutions) were identified in human gingival fibroblasts and studied by the patch-clamp technique. The open probability of the channels varied with membrane potential between +40 and -100 mV. When the bath temperature was decreased from 40 to 4°C, channel conductance was reduced, but the mean open time of the channels was increased. The activation energies for the conductance and the reciprocal of the mean open time were estimated to be 9.1 and 22.9 kj/mol, respectively. These values are lower than those reported for these and other types of channels in cells from other tissues. The open probability of the channels was nearly constant in the temperature range studied. These results suggest that the properties of Ca2+-dependent K+ channels of gingival fibroblasts remain relatively unchanged when the cells are exposed to a wide range of temperatures.
Transcription and Translation of CSF-1 in the Dental Follicle
Authors: Wise G.E. , Lin F. , Zhao L.
Published: January 2009

The dental follicle, a loose connective tissue sac which surrounds the unerupted tooth, is required for eruption to occur. Injection of colony-stimulating factor-1 (CSF-1) will accelerate molar eruption in rats, as well as stimulate tooth eruption in osteopetrotic rats. Utilizing in situ hybridization and reverse- transcription polymerase chain-reaction techniques, we show here that CSF-1 mRNA is present in vivo in the dental follicle of the first mandibular molar of the rat. Analysis of the molars from day 0 through day 10 post-natally demonstrates that the maximal expression of CSF-1 mRNA is at day 3 post-natally. Immunostaining also reveals that the CSF-1 mRNA is translated, with immunostaining for the CSF-1 itself, being heavy in early post-natal days and absent by day 9 post-natally. In view of the fact that there is a maximal influx of mononuclear cells (monocytes) into the dental follicle at day 3 post-natally-an influx which increases the numbers of osteoclasts needed to form a tooth eruption pathway-it is probable that the maximal expression of CSF-1 mRNA by day 3 post-natally contributes to this monocyte influx. Thus, this study establishes a relationship among a molecule (CSF-1), cell (monocyte), and tissue (dental follicle) that appear to play a major role in tooth eruption.
Hypertriglyceridemia associated with Tumor Necrosis Factor-α in Hamster Cheek-pouch Carcinogenesis
Authors: Nakajima J. , Mogi M. , Kage T. , Chino T. , Harada M.
Published: January 2009

We demonstrated for the first time that 9,10-dimethyl-l,2-benzanthracene (DMBA)-treated hamsters showed hypertriglyceridemia followed by cachexia. Hypertriglyceridemia is believed to be caused in part by the decreased lipoprotein lipase (LPL) activity, and by cytokines such as tumor necrosis factor (TNF)-a. In addition, TNF-a action is associated with the LPL activity. Therefore, we determined the content of triglyceride (TG), LPL, and TNF-a in the serum from DMBA-treated hamsters. Elevated TG concentration in the serum of tumor-bearing hamsters was more remarkable and preceded the increase in other lipids, whereas the activity of LPL, the key enzyme of TG metabolism in vivo, was drastically reduced. TNF-a, known as an endogenous inhibitor of LPL activity, was detected in both the sera and the extract of tumors from DMBA-treated hamsters, whereas it was not detectable in any control samples. Pre-incubation of control sera with exogenous recombinant human TNF-a resulted in a potent inhibition of endogenous LPL activity in a dose-dependent manner in vitro. Therefore, the presence of TNF-a might lead to the increase in plasma TG mediated by LPL in tumor-bearing hamsters.
Self-estimation of Oral Malodor
Authors: Rosenberg M. , Kozlovsky A. , Gelernter I. , Cherniak O. , Gabbay J. , Baht R. , Eli I.
Published: January 2009

Bad breath (halitosis, oral malodor) is a common condition, usually the result of microbial putrefaction within the oral cavity. Often, people suffering from bad breath remain unaware of it, whereas others remain convinced that they suffer from foul oral malodor, although there is no evidence for such. The purpose of the present investigation was to determine whether objective self-measurement of oral malodors is possible. Each of 52 volunteers was asked to sample the odor from his/her mouth, tongue, and saliva. Results were compared with (i) self-assessments prior to (preconception) and following (post-measurement) self-measurements; (ii) odor judge scores; (iii) dental measurements (plaque index, gingival index, and probing depth); (iv) volatile sulphide levels; (v) salivary cadaverine levels; and (vi) intra-oral trypsin-like activity. Among the self-measurements, only saliva self-scores yielded significant correlations with objective parameters. Despite the partial objectivity of saliva self-estimates, subsequent post-measurement self-assessments failed to correlate with objective parameters. The results suggest that (i) preconceived notions confound the ability to score one's own oral malodors in an objective fashion; and (ii) partial objectivity can be obtained in the case of saliva self-measurement, presumably because the stimulus is removed from the body proper.