bluuebunny/crossref_metadata_2025 huggingface dataset:
Cerebral Infarcts and Cognitive Performance
Authors: Saczynski Jane S. , Sigurdsson Sigurdur , Jonsdottir Maria K. , Eiriksdottir Gudny , Jonsson Palmi V. , Garcia Melissa E. , Kjartansson Olafur , Lopez Oscar , van Buchem Mark A. , Gudnason Vilmunder , Launer Lenore J.
Published: January 2009

Background and Purpose—

Cerebral infarcts increase the risk for cognitive impairment. The relevance of location and number of infarcts with respect to cognitive function is less clear.

Methods—

We studied the cross-sectional association between number and location of infarcts and cognitive performance in 4030 nondemented participants of the Age Gene/Environment Susceptibility-Reykjavik Study. Composite scores for memory, processing speed, and executive function were created from a neuropsychological battery. Subcortical, cortical, and cerebellar infarcts were identified on brain MRI. We performed linear regression analyses adjusted for demographic and vascular risk factors, depression, white matter lesions, and atrophy.

Results—

Compared to participants with no infarcts, those with infarcts in multiple locations (n=287, 7%) had slower processing speed (β=−0.19;
P
<0.001) and poorer memory (β=−0.16;
P
<0.001) and executive function (β=−0.12;
P
=0.003). Compared to no infarcts, the presence of either subcortical infarcts only (n=275; β=−0.12;
P
=0.016) or cortical infarcts only (n=215; β=−0.17;
P
=0.001) was associated with poorer memory performance. Compared to no infarcts, a combination of cortical and subcortical infarcts (n=45) was associated with slower processing speed (β=−0.38;
P
<0.001) and poorer executive function (β=−0.22;
P
=0.02), whereas a combination of cerebellar and subcortical infarcts (n=89) was associated with slower processing speed (β=−0.15;
P
=0.04). Infarcts in all 3 locations was associated with slower processing speed (β=−0.33;
P
=0.002).

Conclusions—

Having infarcts in >1 location is associated with poor performance in memory, processing speed, and executive function, independent of cardiovascular comorbidities, white matter lesions, and brain atrophy, suggesting that both the number and the distribution of infarcts jointly contribute to cognitive impairment.
Correlates of Common Carotid Artery Lumen Diameter in Black and White Younger Adults
Authors: Ruan Litao , Chen Wei , Srinivasan Sathanur R. , Sun Meihung , Wang Hongwei , Toprak Ahmet , Berenson Gerald S.
Published: January 2009

Background and Purpose—

Vascular remodeling as depicted by increases in arterial lumen diameter occurs in response to development of atherosclerosis. However, data on the correlates of arterial lumen diameter in younger adults by race and sex are limited.

Methods—

The study cohort included 734 white and 306 black subjects, aged 20 to 43 years, enrolled in the Bogalusa Heart Study. The common carotid artery lumen diameter at diastole and intima media thickness (IMT) were measured by M- and B-mode ultrasonography, respectively.

Results—

As a group, blacks versus whites (3.44 mm/m versus 3.37 mm/m,
P
=0.002) and males versus females (3.45 mm/m versus 3.35 mm/m,
P
<0.001) had greater height-adjusted lumen diameter. In multivariate analyses of total sample, body mass index, mean arterial pressure, heart rate, and carotid IMT were independent predictors of height-adjusted lumen diameter. The magnitude of the effects of mean arterial pressure and carotid IMT on height-adjusted lumen diameter was significantly different between races with blacks showing greater slopes (difference in slopes:
P
=0.011 for mean arterial pressure;
P
=0.033 for IMT); interaction effects of body mass index and mean arterial pressure with sex on height-adjusted lumen diameter were also noted with males showing steeper slopes (difference in slopes:
P
=0.003 for body mass index;
P
=0.005 for mean arterial pressure). In addition, the lumen diameter–carotid IMT relationship was stronger in hypertensives than in normotensives (difference in slopes:
P
=0.038).

Conclusions—

Common carotid artery lumen diameter is influenced by carotid artery IMT, adiposity, and blood pressure in a race- and sex-specific manner in asymptomatic younger adults, which may have implications for preventive cardiology.
A 17-Year-Old Male With Pseudotumor Cerebri Secondary to Performance-Enhancing Steroids Triggering Venous Thrombosis in the Brain
Authors: DeSena Allen D. , Weimer Stephen
Published: January 2009

This article is a case report of a 17-year-old male who presented with a headache and blurry vision. He subsequently was noted to have papilledema on a fundoscopic examination and an initial normal magnetic resonance imaging and computed tomography of his head; his condition was, therefore, diagnosed as pseudotumor cerebri. A subsequent magnetic resonance venography of his head revealed venous thrombosis, and other investigations revealed an elevated factor VIII level as well as a mutation at the MTHFR locus, consistent with an elevated risk for hypercoagulability. In addition, he admitted to steroid usage for purposes of performance enhancement in baseball. The patient's condition eventually improved with acetazolamide and serial lumbar punctures. Steroids have been linked to predisposition to hypercoagulable states, but there are no reports identified by these authors that link performance-enhancing steroids with pseudotumor cerebri as a result of a coagulation dyscrasia.
Effect of Settlement Size and Religiosity on Sense of Place in Communal Settlements
Authors: Casakin Hernan , Billig Miriam
Published: January 2009

The effect of religiosity and settlement size on sense of place was studied among residents of Jewish communal settlements in Judea and Samaria. Sense of place was defined as a multidimensional concept of cognitive, affective, and conative dimensions. Sense of place was found to be significantly higher for religious than for secular residents. Sense of place was found to be higher for religious residents in small settlements, whereas for secular residents it was higher in large settlements. The study suggests reasons for these findings.
Architecture of Intact Natural Human Plaque Biofilms Studied by Confocal Laser Scanning Microscopy
Authors: Wood S.R. , Kirkham J. , Marsh P.D. , Shore R.C. , Nattress B. , Robinson C.
Published: January 2009

Determination of the structure of human plaque will be of great benefit in the prediction of its formation and also the effects of treatment. However, a problem lies in the harvesting of undisturbed intact plaque samples from human volunteers and the viewing of the biofilms in their natural state. In this study, we used an in situ device for the in vivo generation of intact dental plaque biofilms on natural tooth surfaces in human subjects. Two devices were placed in the mouths of each of eight healthy volunteers and left to generate biofilm for 4 days. Immediately upon removal from the mouth, the intact, undisturbed biofilms were imaged by the non-invasive technique of confocal microscopy in both reflected light and fluorescence mode. Depth measurements indicated that the plaque formed in the devices was thicker round the edges at the enamel/nylon junction (range = 75-220 μm) than in the center of the devices (range = 35-215 μm). The reflected-light confocal images showed a heterogeneous structure in all of the plaque biofilms examined; channels and voids were clearly visible. This is in contrast to images generated previously by electron microscopy, suggesting a more compact structure. Staining of the biofilms with fluorescein in conjunction with fluorescence imaging suggested that the voids were fluid-filled. This more open architecture is consistent with recent models of biofilm structure from other habitats and has important implications for the delivery of therapeutics to desired targets within the plaque.
Quantification of Periapical Bone Destruction in Mice by Micro-computed Tomography
Authors: Balto K. , Muller R. , Carrington D.C. , Dobeck J. , Stashenko P.
Published: January 2009

Bacterial infections of the dental pulp result in tissue destruction and periapical bone resorption. The availability of genetically engineered mouse strains is a major advantage in the use of this model system for studies of periapical pathogenesis. The main limitation of the mouse model is its small size, and the necessity for laborious histologic analyses to quantify periapical bone destruction. In the present study, we evaluated the use of a new technology, high-resolution micro-computed tomography (micro-CT), for the rapid and non-invasive quantification of periapical bone destruction. Periapical lesions were induced in the lower first molars of mice by exposing the pulp to the oral environment. Mandibles were harvested on day 21 after pulp exposure, and were subjected to micro-CT analysis, with 17-μm-thick radiographic sections. Samples were then decalcified, embedded, and sectioned for histology. The cross-sectional area of periapical lesions was determined by image analysis of corresponding micro-CT and histologic sections. The results showed a highly significant correlation between micro-CT and histology (p < 0.0001), with mean differences of 4.1% (range, 0.9 to 7.2%) between the two methods. The mean error associated with image analysis was 4.9% for images obtained by both micro-CT and histology. The variability of replicate (n = 5) independent micro-CT determinations was 3.4%, less than that associated with the image analysis error. These results demonstrate that micro-CT imaging is a rapid, reproducible, and non-invasive method, that gives results that are closely comparable with those obtained by histology. Micro-CT appears to have utility for the accurate quantification of changes in bone architecture in small biological specimens.
Nominal Shear or Fracture Mechanics in the Assessment of Composite-Dentin Adhesion?
Authors: Tantbirojn D. , Cheng Y.-S. , Versluis A. , Hodges J.S. , Douglas W.H.
Published: January 2009

This study addresses the anticipated problem of discriminating among high-performing dentin adhesives. The simplicity of the nominal shear bond test, despite being heavily criticized, has made it a routine procedure for the determination of bonding efficacy. A fracture mechanics approach has been suggested as a better assessment of bonding efficacy (Versluis et al., 1997). However, experimental complexity is a major limitation. It is hypothesized that a new, simplified interfacial fracture toughness test (Lin, 1994) will evaluate bonding agents differently if compared with the traditional shear bond test. Therefore, the objective of this study was to compare the performances of six dentin bonding agents subjected to the interfacial fracture toughness test (critical plane strain energy release rate) or to the nominal shear bond test (shear bond strength). Their performances were also characterized by scanning electron micrography of the fracture surfaces for evidence of dentin cohesive failure. Statistical analyses showed only marginal differences between these determinants of the two tests. However, when the analysis was applied only to the materials that had 100% frequency of dentin cohesive failure in shear testing, which also had high bonding efficacy, the difference in adhesive strengths between the two tests became significant. The reliability of the nominal shear test is questioned when dentin cohesive failure occurs, which usually is associated with high bonding efficacy. Since it is expected that bonding efficacy will increase further, the interfacial fracture toughness test is the preferred methodology to distinguish among high-performing dentin adhesives.
Regional Differences of Metabolism in Human Masseter Muscle by Two-dimensional 31P-Chemical Shift Imaging
Authors: Kanayamd T. , Minowa K. , Inoue N. , Yamaguchi T. , Yoshida S. , Kawasaki T.
Published: January 2009

Many reports have demonstrated significant region-dependent differences in the fiber-type composition of the human masseter muscle. Therefore, it is considered that there is intramuscular heterogeneity of metabolic activity in the muscle. The present study was carried out, with two-dimensional Chemical Shift Imaging, to detect differences between the deep and superficial parts of the human masseter muscle at rest. Masseter muscle from 11 volunteers, from 20 to 27 years old, was examined, and characteristic spectra of the inorganic phosphate (Pi), phosphocreatine (PCr), and a-, β-, and γ-adenosine triphosphate (ATP) from each part of the muscles were obtained. In this study, the deep and superficial parts of the masseter muscle were distinguished by the existence of aponeurosis. The Pi/PCr, PCr/β-ATP, and Pi/β-ATP ratios as well as the pH in the deep and superficial parts were calculated from the peak spectra. Compared with the deep part, the Pi/PCr of the superficial part was lower (p < 0.05) and the PCr/β-ATP was higher (p < 0.01). The Pi/β-ATP and pH showed no significant differences between the two parts. The results indicate that the superficial part of the masseter muscle contains more PCr than the deep part, and this may be related to functional differences between these two parts. In future examinations of the metabolic activity of the human masseter muscle, the deep and superficial parts must be measured separately.
Design and Wear Testing of a Temporomandibular Joint Prosthesis Articulation
Authors: Van Loon J.-P. , Verkerke G.J. , De Vries M.P. , De Bont L.G.M.
Published: January 2009

As part of the development of a total temporomandibular joint prosthesis, a prosthesis articulation was designed. The articulation consists of a spherical head (ball) of the mandibular part, rotating against an enveloping ultra-high-molecular-weight polyethylene (UHMWPE) disc with a flat cranial side, which slides along the opposing skull part. The aim of this study was to determine the in vitro wear rate of the articulation, and to predict the in vivo wear rate from the results. Based on a disc thickness of 5 mm and a ball diameter of 8 mm, the stresses within the disc were calculated by means of a finite element computer model. The wear rate of the ball-disc articulation was determined by in vitro wear tests, with a stainless-steel ball rotating against a UHMWPE disc in a serum-based lubricant. Eight discs were tested for seven million cycles each. The in vitro wear rate of the disc-skull part articulation was calculated from the test results of the ball-disc articulation. The maximum Von Mises' stress was less than the yield strength of UHMWPE and, therefore, was sufficiently low. The in vitro wear rate of the ball-disc articulation was 0.47 mm3 per million cycles. The in vivo expected total wear rate is 0.65 mm3 per year, corresponding with a yearly decrease of disc thickness of 0.0094 mm. Although it is difficult to judge whether this wear rate is sufficiently low, because the influence of UHMWPE wear particles in the TMJ region is unknown, both the expected wear rate and the decrease of thickness appear to be acceptable.
Molecular Mapping of Statherin- and Histatin-binding Domains in Human Salivary Mucin MG1 (MUC5B) by the Yeast Two-hybrid System
Authors: lontcheva I. , Oppenheim F.G. , Offner G.D. , Troxler R.F.
Published: January 2009

MG1 is a high-molecular-weight mucin secreted by mucous acinar cells in human submandibular and sublingual glands. We have recently shown that the tracheobronchial mucin MUC5B is a major component of MG1. MUC5B is organized into cysteine-rich N- and C-terminal regions that flank a central tandem-repeat region containing cysteine-rich subdomains and imperfect 29-residue tandem repeats. In earlier work, we have shown that this mucin selectively forms heterotypic complexes with amylase, proline-rich proteins, statherin, and histatins in salivary secretions, and the aim of this study was to identify specific binding domains within MUC5B using the yeast two-hybrid system. Interactions of cysteine-rich domains in the tandem-repeat region (Cysl-Cys4) and C-terminal region (Cys8a, Cys8b, Cys8c) of MUC5B with statherin and histatins were investigated. These studies indicated that histatin 1 selectively bound to Cysl and Cys2, whereas statherin and histatin 1, 3, and 5 selectively bound to Cys8a. Analysis of the primary sequences of the identified binding domains suggests that these domains most probably can fold into globular-like structures in the native mucin. A ProDom blast search revealed that sequences in Cys1, Cys2, and Cys8a exhibit similarity to domains in evolutionarily diverse extracellular proteins known to participate in a wide variety of protein-protein interactions.
Prostaglandin E2 Predominantly Induces Production of Hepatocyte Growth Factor/Scatter Factor in Human Dental Pulp in Acute Inflammation
Authors: Ohnishi T. , Suwa M. , Oyama T. , Arakaki N. , Torii M. , Daikuhara Y.
Published: January 2009

Hepatocyte growth factor (HGF), which is also known as the scatter factor, is a broad-spectrum and multifunctional cytokine, mediates epithelial-mesenchyme interaction, and is shown to be involved in the development and regeneration of various tissues, including tooth. Here, we report that HGF was present in adult human dental pulps, and its levels increased during acute inflammation of the tissue. Levels of HGF mRNA in dental pulps also increased with inflammation, as determined by reverse-transcription/polymerase chain-reaction. The production of HGF in fibroblasts from dental pulps in culture was dose-dependently stimulated by inflammatory cytokines such as interleukin (IL)-la and tumor necrosis factor (TNF)-a, and by prostaglandin (PG) E2, as determined by an enzyme-linked immunosorbent assay. We also showed that indomethacin did not affect the increase in HGF production by the cells with IL-la, TNF-a, and PGE2. The levels of HGF mRNA in the cells were simultaneously increased by these stimulants, as determined by Northern blotting. Since the production of PGs is known to increase at the beginning of inflammation, PGE2 may be involved in the regeneration of dental pulps by the induction of HGF expression after inflammation.
The Effects of a Break in Water Fluoridation on the Development of Dental Caries and Fluorosis
Authors: Burt B.A. , Keels M.A. , Heller K.E.
Published: January 2009

Durham, NC, fluoridated since 1962, had an 11-month cessation of fluoridation between September, 1990, and August, 1991. The purpose of this study was to assess the effects of this break on the development of caries and fluorosis in children. Study participants were continuously-resident children in Kindergarten through Grade 5 in Durham's elementary schools. There were 1696 children, 81.4% of those eligible, for whom a questionnaire was completed and clinical data recorded. Age cohorts were defined by a child's age at the time that fluoridation ceased. Caries was recorded in children in the Birth Cohort through Cohort 3, and fluorosis for children in Cohorts 1 through 5. Caries was assessed in the primary first and second molars according to the decayed-filled index; fluorosis on the labial surfaces of the upper permanent central and lateral incisors was assessed by the Thylstrup-Fejerskov (TF) index. Mother's education was associated with caries; higher education of the mother had an odds ratio of 0.53 (95% CI 0.40, 0.76) for caries in the child. No cohort effects could be discerned for caries. Overall prevalence of fluorosis was 44%. Prevalence in Cohorts 1, 2, 3, 4, and 5 was 39.8%, 32.3%, 33.0%, 62.3%, and 57.1%, respectively. These cohort differences remained statistically significant in regression analysis. It was concluded that while the break had little effect on caries, dental fluorosis is sensitive to even small changes in fluoride exposure from drinking water, and this sensitivity is greater at 1 to 3 years of age than at 4 or 5 years.
The pH of Dental Plaque in its Relation to Early Enamel Caries and Dental Plaque Flora in Humans
Authors: Lingström P. , Van Ruyven F.O.J. , Van Houte J. , Kent R.
Published: January 2009

Dental caries appears to result from the action of multiple, interrelated factors. A companion study dealt with the plaque-flora/caries relationship (van Ruyven et al., 2000). The plaque-pH/caries relationship is the subject of this study. Since both studies involve the same subjects, plaques, and tooth surfaces, data on the examined factors have also been integrated. In vivo plaque pH determinations (microelectrode) were done on buccal sound (s) and "white-spot" (ws) caries surfaces in a selected dentition area in a low-caries (no ws) and higher-caries subject group. The pH response to sugar was evaluated before and after a sugar rinse, a local sugar application, or sucking on a sugary lozenge. pH profiles with sugar rinsing and normal or limited salivary flow conditions, showed progressively decreasing plaque pH values at various time points in the order of: low-caries subjects (s sites), higher-caries subjects (s sites), higher-caries subjects (s + ws sites), and higher-caries subjects (ws sites). The minimum pH values showed the same trend. Analyses of all data indicated only a statistical difference for minimum values for s sites in low-caries subjects vs. ws sites in higher-caries subjects, and for s and ws sites in the latter. Local sugar application and sucking on a sugary lozenge induced smaller pH drops than sugar rinsing; such suboptimal sugar exposure caused a disappearance of the difference between the minimum pH values for s and ws sites observed with sugar rinsing in the higher-caries subjects. Initial plaque pH values were similar regardless of subject or tooth caries status. The values were also not correlated with the plaque levels of strongly iodophilic polysaccharide-storing bacteria. Collectively, both studies indicate that increasing subject caries status is characterized by increasing plaque levels of highly-acid-tolerant, acidogenic bacteria and an increasing plaque-pHlowering potential and support the dynamic relationship between these parameters.
Campylobacter Species in Health, Gingivitis, and Periodontitis
Authors: Macuch P.J. , Tanner A.C.R.
Published: January 2009

At least seven Campylobacter species have been identified from subgingival sites. Campylobacter rectus has been implicated as a periodontal pathogen; however, association with periodontal infections of other Campylobacter species, especially the newly described Campylobacter showae, is unclear. This study examined which Campylobacter species were associated with periodontal health and disease. Subgingival Campylobacter species from initial and established periodontitis were compared with species from periodontally healthy subjects, including subjects with gingivitis. Campylobacter species were isolated on selective media and identified by whole-cell protein profiles (SDS-PAGE). Except for C. rectus, Campylobacter levels were frequently below the detection limit (2-5% of the microbiota) of non-selective culture methods. C. rectus and C. showae, including Campylobacter X, were found more frequently and in higher levels from diseased than from healthy periodontal sites. C. gracilis was the dominant Campylobacter species found in relatively shallow pockets; however, its presence was unrelated to periodontal health or disease. C. concisus was isolated in higher proportions from relatively shallow and healthy sites, compared with deeper pockets. C. curvus was unrelated to periodontal health or disease. Analysis of the study data confirmed the relationship of C. rectus with diseased subgingival sites and indicated that C. showae may also be associated with periodontal disease.
Visco-elastic Parameters of Dental Restorative Materials during Setting
Authors: Dauvillier B.S. , Feilzer A.J. , De Gee A.J. , Davidson C.L.
Published: January 2009

Contraction stresses generated in restoratives during setting are among the major problems in adhesive dentistry, since they often result in loss of adhesion from the cavity walls or in post-operative pain. The rate of stress development and the ultimate magnitude of the stress, which determine the seriousness of these problems, depend on the relatively unknown visco-elastic behavior of the restoratives during setting. The aim of this study was to determine the visco-elastic parameters during setting, to aid our understanding of the process of contraction stress development. A dynamic mechanical method was used in which the materials were subjected to periodic strain cycles in a universal testing machine during the first 60 min of setting. The visco-elastic parameters (viscosity η and Young's modulus E) were calculated by analysis of the experimental stress-strain data with a simple mechanical model according to Maxwell. Two restorative materials from different classes were investigated: a two-paste resin composite and a conventional glass-ionomer cement. A comparison of the results showed significant differences in the development of viscosity and stiffness in the early stage of setting. The resultant relaxation time (η/E) of the glass ionomer remained at a low level during the first 15 min, whereas that of the resin composite increased markedly. This is of clinical importance, since it implies that, during the early setting stage, glass ionomers are better capable of reducing the contraction stresses than resin composites, thus increasing the likelihood that the bond with the cavity walls will form and survive during setting.
Feasibility of Computer-assisted Recognition of Different Dental Hard Tissues
Authors: Kocher T. , Strackeljan J. , Behr D.
Published: January 2009

For pattern recognition, fuzzy set theory has been proven to be highly useful. The aim of the present investigation was to combine the fuzzy set with an ultrasonic scaler, to test its suitability for automatic detection of different tooth substances. An experienced operator placed the tip of a piezoceramic ultrasonic scaler on a tooth, thereby inducing oscillations in the contact area around the ultrasonic tip. Each surface showed a characteristic oscillatory behavior in the immediate vicinity of the tip. The oscillations were then re-transmitted to the scaler tip and recorded by the measurement of variations in current and voltage. Because the ultrasonic scaler is driven by piezoceramics, it can be used as both an oscillatory excitation and a sensor system. The data were processed with Fast Fourier transformation and analyzed by means of a fuzzy pattern recognition algorithm. Re-classification of the different measurements was carried out by the experienced operator's assessment. With a combination of six features (frequencies), re-classification was correct for 99% of all surfaces. The diagnostic reliability of the system was tested by the assessment of 50 teeth for which no learning data had previously been recorded. The unknown samples were correctly classified to 100%. The excellent results of these experiments suggest promising possibilities for the implementation of new diagnostic and therapeutic instruments in periodontology practice.
Oral Colonization with Actinomyces Species in Infants by Two Years of Age
Authors: Sarkonen N. , Könönen E. , Summanen P. , Kanervo A. , Takala A. , Jousimies-Somer H.
Published: January 2009

In early childhood, the human mouth is already colonized by actinomycetes. Due to recent taxonomic changes within the genus Actinomyces, up-to-date data are warranted on the time and succession of different Actinomyces species in the oral cavity. By using a longitudinal study design and culture techniques, we examined the age-related occurrence of Actinomyces species in saliva from 39 healthy infants at 2, 6, 12, 18, and 24 months of age. Altogether 428 Actinomyces isolates were available for this study. Identification was based on biochemical tests and gas chromatographic demonstration of metabolic end-products, and when needed, cellular fatty acid profiles were determined. The frequency of the total actinomycetal flora increased from 31% to 97% within 2 years. A. odontolyticus was the most prominent Actinomyces colonizer at all five sampling occasions. A. naeslundii was the second most common Actinomyces sp. but was not detected before the age of 1 year. As a novel observation, we found A. graevenitzii in the oral cavity. The number of A. graevenitzii isolates indicates that this species is not just occasionally present in infants' mouths. We also found A. viscosus, A. gerencseriae, A. israelii, and A. georgiae. Based on the present results, we suggest that A. odontolyticus is the main primary Actinomyces species on oral mucosal surfaces in infants up to 2 years of age.
Caries in Five-year-old Children and Associations with Family-related Factors
Authors: Mattila M.-L. , Rautava P. , Sillanpää M. , Paunio P.
Published: January 2009

It is generally understood that the teeth of pre-school-aged children are healthy, but the improvement in the dmft index has halted in the industrialized countries. Those few children who have caries have more of it than before. Little is known of the family-related factors which are associated with this polarization of caries. A representative population-based sample consisted of 1443 mothers expecting their first child. The children were followed at well-baby clinics and public dental health clinics for over five years. The objective was to study the prevalence of dental caries and its predictors in five-year-old children and to assess children's own dental health habits and the meaning of family-related factors in dental health. The findings were based on questionnaire data from parents and on clinical dental examinations of the five-year-old children as completed by 101 public health dentists. In firstborn five-year-old children, dental health was found to be good in 72%, fair in 20%, and poor in 8% of the cases. The final multivariate analysis illustrated that the dmft index > 0 was independently associated with the mother's irregular toothbrushing (OR 2.2; 95% CI 1.4-3.5), annual occurrence of several carious teeth in the father (OR 2.6; 95% CI 1.9-3.6), daily sugar consumption at the age of 18 months (OR 2.4; 95% CI 1.4-4.1), occurrence of child's headaches (OR 3.7; 95% CI 1.5-8.8), parents' cohabitation (OR 3.3; 95% CI 1.5-7.6), rural domicile (OR 2.4; 95% CI 1.2-4.5), and mother's young age (OR 5.0; 95% CI 1.3-19.8). The findings indicated that attention should be paid not only to the child's dental health care but also to that of the whole family. Parents should be supported in their upbringing efforts and encouraged to improve their children's dental health habits. In everyday life, parents function as role models for their children, and therefore, parents' own dental hygiene habits are very meaningful.
Influence of Maternal Xylitol Consumption on Acquisition of Mutans Streptococci by Infants
Authors: Soderling E. , Isokangas P. , Pienihäkkinen K. , Tenovuo J.
Published: January 2009

Xylitol is effective as a non-cariogenic sugar substitute. Habitual xylitol consumption appears to select for mutans streptococci (MS) with impaired adhesion properties, i.e., they shed easily to saliva from plaque. One hundred sixty-nine mother-child pairs participated in a two-year study exploring whether the mothers' xylitol consumption could be used to prevent mother-child transmission of mutans streptococci. All mothers showed high salivary levels of mutans streptococci during pregnancy. The mothers in the xylitol group (n = 106) were requested to chew xylitol-sweetened gum (65% w/w) at least 2 or 3 times a day, starting three months after delivery. In the two control groups, the mothers received either chlorhexidine (n = 30) or fluoride (n = 33) varnish treatments at 6, 12, and 18 months after delivery. The children did not chew gum or receive varnish treatments. MS were assessed from the mothers' saliva at half-year intervals and from the children's plaque at the one- and two-year examinations. The MS were cultured on Mitis salivarius agars containing bacitracin. The salivary MS levels of the mothers remained high and not significantly different among the three study groups throughout the study. At two years of age, 9.7% of the children in the xylitol, 28.6% in the chlorhexidine, and 48.5% in the fluoride varnish group showed a detectable level of MS. In conclusion, therefore, habitual xylitol consumption by mothers was associated with a statistically significant reduction of the probability of mother-child transmission of MS assessed at two years of age. The effect was superior to that obtained with either chlorhexidine or fluoride varnish treatments performed as single applications at six-month intervals.
MALDI-TOF MS Analysis of a Library of Polymerizable Cyclodextrin Derivatives
Authors: Bowen R.L. , Farahani M. , Dickens S.H. , Guttman C.M.
Published: January 2009

Polymerizable cyclodextrin derivatives (PCDs) have been proposed as candidates for use in dental therapeutics (Bowen, 1996; Bowen and Reed, 1997). Here, PCD "libraries" were synthesized by quasi-random reactions of 6 moles of methacrylic anhydride plus 6 moles of cyclic glutaric anhydride per mole of beta-cyclodextrin (BCD) in solution. BCD has 21 reactive sites on each of its molecules. These proportions were based on probability calculations, which predicted that the products should have a minimum of 2 polymerizable substituents and acidic ligand groups on practically every one of the diverse product molecules. Matrix-assisted laser desorption/ionization (MALDI) time of flight (TOF) mass spectrometry (MS) gave valuable information regarding the masses of molecular ions representing the molecules that made up the PCD libraries. For the MALDI-TOF MS analyses, small samples were analyzed by the successive application of 3 solutions to the sample holder: the matrix in acetone, the products in water, and sodium trifluoroacetate in water. The resulting spectra had > 40 envelopes of mass peaks above background. The ionic-abundance peak heights had quasi-Gaussian configurations, with central peaks having masses in the neighborhood of 2000 g/mol (Daltons). Regardless of structural permutations within each peak, the range of these peaks was between about 1500 g/mol and 2900 g/mol. This range of masses was in accord with, but perhaps somewhat more narrow than, that predicted by the statistical method, which was based on equal reactivity of all hydroxyl groups. Analysis by MALDI-TOF MS gave valuable data regarding the masses, structures, and characteristics of the products formed and provided unanticipated information to facilitate improvements in future PCD syntheses.
Cloning Human Enamelin cDNA, Chromosomal Localization, and Analysis of Expression during Tooth Development
Authors: Hu C.-C. , Hart T.C. , Dupont B.R. , Chen J.J. , Sun X. , Qian Q. , Zhang C.H. , Jiang H. , Mattern V.L. , Wright J.T. , Simmer J.P.
Published: January 2009

Enamelin is the largest protein in the enamel matrix of developing teeth. In the pig, enamelin is secreted as 186-kDa phosphorylated glycoprotein, which is rapidly processed by enamel proteinases into smaller cleavage products. During the secretory stage of enamel formation, enamelin is found among the crystallites in the rod and interrod enamel and comprises roughly 5% of total matrix protein. Although the function of enamelin is unknown, it is thought to participate in enamel crystal nucleation and extension, and the regulation of crystal habit. Here we report the results of enamelin in situ hybridization in a day 1 mouse developing incisor that shows that enamelin is expressed by ameloblasts, but not by odontoblasts or other cells in the dental pulp. The restricted pattern of enamelin expression makes the human enamelin gene a prime candidate in the etiology of amelogenesis imperfecta (AI), a genetic disease in which defects of enamel formation occur in the absence of non-dental symptoms. We have cloned and characterized a full-length human enamelin cDNA and determined by radiation hybrid mapping and fluorescent in situ hybridization (FISH) that the gene is located on chromosome 4q near the ameloblastin gene in a region previously linked to local hypoplastic AI in six families. These findings will facilitate the search for specific mutations in the enamelin gene in kindreds suffering from amelogenesis imperfecta.
Inhibition of Wnt Signaling by Exogenous Mfrzbl Protein Affects Molar Tooth Size
Authors: Sarkar L. , Sharpe P.T.
Published: January 2009

Wnt extracellular signaling molecules have essential roles as regulators of cell proliferation, migration, differentiation, and in epithelial-mesenchymal interactions involved in tissue morphogenesis. Frizzled integral membrane proteins have been shown to function as receptors for Wnt signaling molecules. Vertebrates also produce secreted proteins related to Frizzled receptors, Frizzled-related proteins (FRPs), which contain the cysteine-rich domain of Frizzleds and appear to function as Wnt antagonists. Tooth development is regulated by a reciprocal series of epithelial-mesenchymal interactions, and many Wnt signaling pathway genes are expressed in the developing tooth at these sites. Here we report the expression of one FRP gene, Mfrzbl, in the rostral mesenchyme of the mandibular primordium. Using explant cultures, we show that expression of Mfrzbl in the mandibular mesenchyme is under the control of signals derived from the overlying epithelium. Bead implantation experiments in vitro show that FGF8 induces Mfrzbl expression, whereas BMP4 and SHH proteins have no effect. We studied the effect of ectopic MFrzbl protein on the developing tooth germs by transplanting explants treated with Mfrzbl protein into renal capsules, and found it to retard tooth development. This suggests that Wnt signaling is required early in tooth germ formation and that interference with signaling via addition of an antagonist results in retarded development and formation of smaller teeth.
Low Levels of GRP-Ca Expression in Transgenic Mice
Authors: Ten Hagen K.G. , Balys M.M.
Published: January 2009

The GRP-Ca gene of the rat encodes a member of the glutamine/glutamic-acid-rich protein (GRP) family. This gene is expressed in a highly tissue-specific fashion, with transcription being found only in the acinar cells of the submandibular gland (SMG). To begin to define the cis-acting elements governing GRP-Ca expression, we constructed transgenic mice containing the rat GRP-Ca gene plus 9.5 kb of 5' genomic sequence and 1 kb of 3' genomic sequence. Expression of GRP-Ca was detectable in progeny from only 1 of 3 independent founders. Expression levels of the transgenic GRP-Ca were much lower than the native GRP-Ca found in the rat SMG. Furthermore, GRP-Ca in transgenic mice was not tissue-specifically expressed, being found in both the SMG/SLG complex and the liver. These results indicate that the genomic region of GRP-Ca included in these transgenic mice is not sufficient to confer the high levels of tissue-specific expression seen in the rat.
The Relationship Between the Density of the Alveolar Processes and that of Post-cranial Bone
Authors: Southard K.A. , Southard T.E. , Schlechte J.A. , Meis P.A.
Published: January 2009

Skeletal mass declines in all populations with age, and the literature suggests that changes in oral bone may be linked to the status of the post-cranial (systemic) skeleton. However, there is a lack of information defining the relationship between alveolar process bone and the post-cranial skeleton in healthy individuals. The purpose of this study was to determine: (1) if the bone densities of the maxillary and mandibular alveolar processes are related to the bone density of the spine, hip, or radius in healthy women; and (2) if the alveolar process densities decline with age. Forty-one dentate Caucasian women aged 20 to 78 years underwent assessment of post-cranial (systemic) and alveolar process bone. D-speed vertical bitewing and periapical radiographs incorporating aluminum stepwedges, controlled exposure and processing conditions, and a density correction algorithm were used to make alveolar process density assessments with regions of interest (ROIs) apical to crestal bone and intrabony defects. Anteroposterior lumbar (L1 to L4) and lateral lumbar (L2 to L4) spine, total hip (and subregions), and radius bone densities were determined by dual-energy x-ray absorptiometry (DEXA). Correlation analysis revealed significant relationships between maxillary alveolar process bone density and the density of the mandibular alveolar process (r = 0.57, p ≤ 0.001), anteroposterior lumbar spine (r = 0.53, p ≤ 0.001), lateral lumbar spine (r = 0.52, p ≤ 0.001), total hip (r = 0.39, p = 0.01), total radius (r = 0.39, p = 0.01), and age (r = -0.38, p = 0.01). A two-tailed t test comparison revealed significantly greater maxillary alveolar process bone density in women younger than 50 years of age than in those 50 and older (p ≤ 0.01). We conclude that the density of maxillary alveolar process bone is significantly related to the density of the mandibular alveolar process, lumbar spine, hip, and radius in healthy women and that maxillary alveolar process bone density declines with age.
Self-perceived Oral Health Status, Psychological Well-being, and Life Satisfaction in an Older Adult Population
Authors: Locker D. , Clarke M. , Payne B.
Published: January 2009

Numerous studies have demonstrated that many older adults have problems chewing, pain, difficulties in eating, and problems in social relationships because of oral disorders. However, it is not clear if these functional and psychosocial outcomes affect broader psychological well-being and life satisfaction. Consequently, this paper begins to address the question, 'Does poor oral health compromise the quality of life?'. Initial cross-sectional analyses used data derived from the seven-year follow-up of the Ontario Study of the Oral Health of Older Adults. As at baseline and three-year follow-up, oral health was measured by self-ratings of oral health and five oral health indices. Psychological well-being and life satisfaction were assessed according to the Morale Index, the Perceived Life Stress Questionnaire, The Life Satisfaction Scale, and the General Health Questionnaire. All oral health variables were significantly associated with scores from the first three of these measures in the expected direction. These associations remained after we controlled for other potential influences on the quality of life. In addition, prospective analysis indicated that self-perceived oral health at three years had a significant independent effect on psychological well-being and life satisfaction at seven years. These results suggest that poor self-perceived oral health and relatively poor quality of life co-exist in the same subgroup of older adults.
In vivo Degradation of Resin-Dentin Bonds in Humans Over 1 to 3 Years
Authors: Hashimoto M. , Ohno H. , Kaga M. , Endo K. , Sano H. , Oguchi H.
Published: January 2009

The longevity of resin restorations is currently an area of great interest in adhesive dentistry. However, no work has been conducted to investigate the durability of resin-dentin bond structures using human substrate in vivo. The purpose of this study was to investigate the degradation of the resin-dentin bond structures aged in an oral environment for 1, 2, or 3 years. Cavities were prepared in primary molars, and an adhesive resin system (Scotchbond Multi-Purpose) was applied to the cavity. After I to 3 years, following the eruption of the succedaneous permanent teeth, the resin-restored teeth were extracted. Immediately after extraction, those teeth were sectioned perpendicular to the adhesive interface and trimmed to produce an hourglass-shaped specimen. Then, a micro-tensile test was performed at a crosshead speed of 1.0 mm/min. The mean bond strengths were statistically compared with one-way ANOVA and Fisher's PLSD test (p < 0.05). Further, all fractured surfaces were observed by SEM, and the area fraction of failure mode was calculated by means of a digital analyzer on SEM photomicrographs. There were significant differences in tensile-bond strength among all 3 groups (p < 0.05), with mean values ranging from 28.3 ± 11.3 MPa (control), to 15.2 ± 4.4 MPa (1 to 2 years), to 9.1 ± 5.1 MPa (2 to 3 years). Moreover, under fractographic analysis, the proportion of demineralized dentin at the fractured surface in specimens aged in an oral environment was greater than that in control specimens. Furthermore, degradation of resin composite and the depletion of collagen fibrils was observed among the specimens aged in an oral environment. Analysis of the results of this study indicated that the degradation of resin-dentin bond structures occurs after aging in the oral cavity.
Whisker-reinforced Heat-cured Dental Resin Composites: Effects of Filler Level and Heat-cure Temperature and Time
Authors: Xu H.H.K.
Published: January 2009

Currently available dental resin composites are inadequate for use in large stress-bearing crown and multiple-unit restorations. The aim of this study was to reinforce heat-cured composites with ceramic whiskers. It was hypothesized that whiskers substantially strengthen heat-cured composites. It was further hypothesized that whisker filler level and heat-cure temperature and time significantly influence composite properties. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whiskers for improved retention in the matrix. The whisker filler mass fraction was varied from 0% to 79%, the heat-cure temperature from 80°C to 180°C, and cure time from 10 min to 24 hrs. Flexural strength, work-of-fracture, and fracture toughness of the composites were measured, and specimen fracture surfaces were examined with scanning electron microscopy. Filler level had a significant effect on composite properties. The whisker composite with 70% filler level had a flexural strength in MPa (mean ± SD; n = 6) of 248 ± 23, significantly higher than 120 ± 16 of an inlay/onlay composite control and 123 ± 21 of a prosthetic composite control (Tukey's multiple comparison test; family confidence coefficient = 0.95). Heat-cure time also played a significant role. At 120°C, the strength of composite cured for 10 min was 178 ± 17, lower than 236 ± 14 of composite cured for 3 hrs. The strength of whisker composite did not degrade after water-aging for 100 d. In conclusion, heat-cured composites were substantially reinforced with whiskers. The reinforcement mechanisms appeared to be whiskers bridging and resisting cracks. The strength and fracture toughness of whisker composite were nearly twice those of currently available inlay/onlay and prosthetic composites.
Interleukin-1α-dependent Regulation of Matrix Metalloproteinase-9 (MMP-9) Secretion and Activation in the Epithelial Cells of Odontogenic Jaw Cysts
Authors: Kubota Y. , Ninomiya T. , Oka S. , Takenoshita Y. , Shirasuna K.
Published: January 2009

Interleukin-la (IL-1α) and matrix metalloproteinase-9 (MMP-9) are thought to be involved in odontogenic cyst expansion. In this study, we investigated the effects of IL-1α on the secretion and activation of MMP-9 in odontogenic jaw cysts. An active form of MMP-9 was present in odontogenic keratocyst (6 of 8 cases) fluids more frequently than dentigerous cyst (3 of 10 cases) and radicular cyst (3 of 10 cases) fluids, although proMMP-9 was present in all cyst fluids. Odontogenic keratocyst fragments in explant culture secreted a larger amount of IL-1α than dentigerous cyst and radicular cyst fragments in explant culture, and spontaneously secreted both proMMP-9 and an active form of MMP-9. The fragments of dentigerous cysts and radicular cysts secreted a small amount of proMMP-9, but no active form of MMP-9. Exogenously added recombinant human IL-1α (rhIL-la) increased the secretion and activation of proMMP-9 in the fragments of dentigerous cysts and radicular cysts. The epithelial cells isolated from odontogenic keratocysts secreted IL-la and proMMP-9 without stimulation. Under the cultivation on a fibronectin-coated dish, rhIL-la increased the secretion of proMMP-9 from the epithelial cells in a dose-dependent manner. Moreover, rhIL-la induced the secretion of proMMP-3 and plasminogen activator urokinase (u-PA) from the epithelial cells, and converted the secreted proMMP-3 to the active form in the presence of plasminogen. The secreted proMMP-9 was also activated in the presence of rhIL-la and plasminogen. Hence, our results suggest that IL-1α may up-regulate not only proMMP-9 secretion but also proMMP-9 activation by inducing proMMP-3 and u-PA production in the cyst epithelial cells by autocrine/paracrine regulatory mechanisms.