bluuebunny/crossref_metadata_2025_split huggingface dataset:
Power and Sample Size Calculations for Clinical Trials of Myofascial Pain of Jaw Muscles
Authors: Dao T.T.T. , Lavigne G.J. , Feine J.S. , Tanguay R. , Lund J.P. 
Published: November 2010

When a clinical trial is planned, the approximate number of subjects needed for significant differences between/among groups to be detected must be estimated. Sample-size calculations provide the investigator with this information. This paper discusses the choice of outcome measures and describes the steps used to estimate the numbers of subjects necessary for a study that compares treatments for patients with chronic myofascial pain of jaw muscles. Within- and between-subject variances were estimated for the chosen variables, the subjects' pain ratings on visual analogue scales. Sample sizes were then calculated for theoretical differences between groups by pre-treatment means and overall standard deviations (Cohen, 1977). The results of this analysis can be used by other researchers when planning studies involving these types of patients.
Influence of Initial Flaw Size on Crack Growth in Air-tempered Porcelain
Authors: Anusavice K.J. , Gray A. , Shen C. 
Published: November 2010

Tempering of dental porcelain by forced convective cooling in air has been shown previously to inhibit the sizes of cracks induced in porcelain surfaces. However, the depth of compressive stress that is produced by tempering of feldspathic porcelain has not been determined. It can be assumed that the potential of tempered specimens to inhibit crack formation is reduced as the flaw size exceeds some critical value, since the compressive stress decreases with distance from the surface. The objective of this study was to test the hypothesis that the effectiveness of tempering stress in porcelain decreases with the increasing size of initial surface flaws. Body porcelain discs, 16 mm in diameter and 2 mm in thickness, were tempered (T) by forced convective cooling in air from an initial temperature of 982°C at a pressure of 0.34 MPa for 90 s. Non-tempered control discs (NT) were slowly cooled by termination of power to the furnace. The half crack-lengths (c) of surface cracks induced by a Vickers microhardness indenter at loads ranging from 2.0 to 39.2 N were determined initially and over a period of 24 h. The initial half crack-lengths, co, for the tempered specimens were significantly smaller (p < 0.05) than the corresponding values for the slow-cooled specimens. The mean value of the stress corrosion susceptibility coefficient (n), which is inversely related to the slope of log crack size vs. log time, was only slightly smaller for the NT specimen groups (15.3), compared with the mean value for the T groups (17.1). These results indicate that tempering stress can effectively inhibit the initial sizes of half-penny cracks with initial depths of at least 100 μm. However, in tempered specimens, the growth rate of initial cracks, which varied in length from 21.4 μm to 76.1 μm, was relatively insensitive to the compressive stress (78.1 MPa) produced by tempering.
The Distribution of Magnesium in Developing Rat Incisor Dentin
Authors: Steinfort J. , Driessens F.C.M. , Heijligers H.J.M. , Beertsen W. 
Published: November 2010

Previous studies have shown that rat incisor dentin contains a considerable amount of magnesium that is distributed heterogeneously. The cementum-related dentin, especially its incisal portion, is richest in magnesium. It was the purpose of the present study to investigate the changes that occur in the magnesium content during dentin maturation. Cross-sections were prepared from rat incisors at the apical, middle, and incisal levels. By means of an electron microprobe, tracings were made of the Ca-, Mg-, and P- signal frequencies. Comparison of corresponding dentin layers within and between the cross-sections showed that the Mg/P molar ratio was always higher in the cementum-related dentin (CRD) than in the enamel-related dentin (ERD) and increased from the apex toward the incisal edge. Especially in the incisal cross-section, an increase in Mg/P was found from the older (peripheral) toward the younger (central) dentin layers. As the Mg/P ratio varied from 0.07 to 0.33, the Ca/P ratio was found to fluctuate from 1.48 to 1.15. The two ratios appeared to be highly correlated (r = -0.97; p<0.001), suggesting that Mg replaces Ca and is bound to phosphate.
The Effect of Local Interfacial Geometry on the Measurement of the Tensile Bond Strength to Dentin
Authors: Van Noort R. , Cardew G.E. , Howard I.C. , Noroozi S. 
Published: November 2010

The local detail of the geometry of the adhesive interface can have a significant effect on the measurement of dentin bond strengths and may be a contributory factor in the discrepancies among data in the published literature. The potential effect on the dentin bond strength due to modifications of the local stress distribution at the adhesive/dentin interface has been assessed. Tensile bond strength measurements for specimens with and without an adhesive flash were carried out and compared with the stress distribution at the adhesive interface determined by finite element stress analysis. The results showed that when the adhesive was constrained to the interface only, the tensile bond strength was 3.10 MPa, which increased to 6.90 MPa when a flash of adhesive was present. For a realistic measurement of dentin bond strength, the adhesive should be constrained to the interface only. Extension of the adhesive beyond the interface will result in an artificially high value for the dentin bond strength. A standardized method for the measurement of dentin bond strength is urgently needed, but must take these as well as all other known factors into account if results from different testing centers are to be directly comparable.
Adhesion to Bovine Dentin-Surface Characterization
Authors: Ruse N.D. , Smith D.C. 
Published: November 2010

X-ray photo-electron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were used to characterize the dentin surface, to determine the effects of different pre-conditioning procedures on the elemental composition of the dentin surface, and to investigate the interaction between dentin and a dentin bonding agent (ScotchBond) by studying the changes in the elemental composition of dentin as a result of the interaction. Scanning electron microscopy (SEM) was used to characterize sample surface morphology, which was then correlated with surface elemental composition. The results showed that: (a) the elemental composition of the smear layer was similar to that of the underlying dentin; (b) cleaning with hydrogen-peroxide did not produce any modification in the elemental composition of the dentin surface; and (c) acid-etching led to an almost complete demineralization of the dentin, leaving behind an organic-rich surface. The results suggest that bonding systems that use acid-etching as a pre-conditioning procedure should be based on agents able to interact with the organic components of dentin, since bonding agents that rely on a chelation-to-calcium reaction are unlikely to be successful. The investigation of the interaction between the bonding agent and dentin led to a postulated adhesive-bonding reaction mechanism and suggested a partially cohesive failure in the bonding agent during fracturing of a dentin-bonding-agent-bonded assembly.
The Severity of Dental Fluorosis in Children Exposed to Water with a High Fluoride Content for Various Periods of Time
Authors: Ish T. , Suckling G. 
Published: November 2010

Inhabitants of the Ikeno district of Japan were accidentally exposed to drinking water containing 7.8 ppm fluoride (F) for 12 years, after which water with 0.2 ppm F was substituted. Dental examinations of local inhabitants revealed that only children aged seven years or less at the introduction or aged 11 months or more at the removal of the high-F water had fluorosis. Regular inspections were made of the 86 children between those age limits. The severity of fluorosis in three tooth types (first permanent molars, upper central incisors, and first premolars) was assessed and related to the period of use of the high-F water. Continuous exposure throughout tooth development resulted in severe changes in all three tooth types. With limited exposure, the age at the beginning and at the end was an important factor in determining the severity of the fluorosis. The pattern of change from normal to severe fluorosis differed in the three tooth types, influenced by their respective times of formation. Two 'at-risk' periods for the production of moderate or severe fluorosis were evident. One started at birth and ended early in tooth development, while the other started later and ended at eruption. The duration of F exposure, although determining the initial degree of fluorosis, did not influence the rate of post-eruptive enamel loss.
The Areas of Various Surfaces in the Human Mouth from Nine Years to Adulthood
Authors: Kerr W.J.S. , Kelly J. , Geddes D.A.M. 
Published: November 2010

Surface area measurements of five regions of the oral cavity were made from study casts of 57 subjects with an age range from 9.3 to 19 years. While the longitudinal pattern of growth exhibited by the total of the five areas, when subgroups were compared, was characterized by a steady increase to around puberty (13 years), followed by a plateau, different areas showed different patterns of growth. Increase in the surface area of the teeth was associated with the eruption of the second and third molars, whereas the area of the buccal lingual mucosa continued to increase into adult life. The palate, buccal vestibular mucosa, and dorsum of the tongue demonstrated a typically skeletal pattern of growth, i.e., increase until puberty with a rapid cessation thereafter. The results of this study indicate the need for longitudinal data to further knowledge concerning growth of the oral cavity.
A Longitudinal Radiographic Study of the Periosteal Migration along the Growing Rabbit Mandible
Authors: Frankenhuis-Van Den Heuvel T.H.M. , Maltha J.C. , Kuijpers-Jagtman A.M. , Van't hof M.A. 
Published: November 2010

In the present study, the role of the periosteum in mandibular growth was investigated. The orientation of the superficial bony spicules of rabbit mandibles was determined on dry skulls after perfusion of the animals with an India ink solution. The spicular orientation in the ramus area appeared to be toward the condyle, rostrally toward the incisors, and caudally toward the angular region. The behavior, during growth, of the periosteum in the caudal mandibular half was studied by implantation of metal periosteal and bone markers. A series of cephalograms revealed the migration pattern of the periosteal markers, and by that the migration pattern of the periosteum. It can be concluded that both the pattern of the superficial bony spicules and the periosteal migration pattern suggest a possible influence of the periosteum on mandibular growth.
Acute and Chronic Fluoride Toxicity
Authors: Whitford G.M. 
Published: November 2010

Compared with the latter half of the 19th century and the first half of the 20th century, the frequency of fatalities stemming from the ingestion of fluoride compounds has declined dramatically. Since 1978, there have been four fatalities caused by the ingestion of fluoride, all in dental products. The numbers of exposures to fluoride doses that cause concern, however, has increased, as judged by the annual reports of the American Association of Poison Control Centers. The number of reports made to poison control centers has increased from approximately 7700 in 1984 to 10,700 in 1989. Over 3700 persons have been treated in health care facilities for exposure to fluoride during this period, and there have been 133 cases for which the medical outcomes were classified as moderate or major. The sources of fluoride have been limited almost exclusively to fluoride-containing vitamins and dental products. Based on a review of the doses involved in the four fatalities, three of which involved young children, the "probably toxic dose" of fluoride has been set at 5 mg F/kg body weight. For children who are 6 years of age or less, the PTD can be found in single containers of several kinds of dental products. Recommendations that should reduce the frequency of over-exposures to fluoride are described. Regarding adverse effects due to the chronic intake of fluoride (excluding dental fluorosis), there is no evidence for risk in the US up to the level of intake that is associated with drinking water containing 4 ppm. This statement is based on 1990 or 1991 reports by the NY State Department of Health, the USPHS, and the National Cancer Institute. Two new reports, however, have implicated chronic fluoride intake at relatively low levels in a higher incidence of bone fractures. This relationship requires further study.
ESCA Study on Dental Alloy Surfaces Modified by Ga-Sn Alloy
Authors: Ohno H. , Araki Y. , Endo K. 
Published: November 2010

A new, simple surface modification method for adherend metals has been developed. It gives high bond strength and superior water durability to dental precious-metal alloys bonded with 4-META/ MMA-TBB resin. However, there was no effect on the bonding of Ag-In-Zn alloy and base-metal alloys. In the present study, the alloy surfaces modified by the new method were analyzed by ESCA and SEM for determination of details of the modification effect. A new alloying layer containing Ga and Sn was formed on the precious-metal alloys. The main factor for excellent adhesion to be achieved was the formation of a very thin layer of Ga 2O3 and SnO2, less than 1-2 nm thick, on the alloy surface. A thicker modified layer, as formed on the Ag-In-Zn and Ni-Cr alloys, led to low bonding ability.
Initial Dissolution Rate Studies on Dental Enamel after CO2 Laser Irradiation
Authors: Fox J.L. , Yu D. , Otsuka M. , Higuchi W.I. , Wong J. , Powell G.L. 
Published: November 2010

The influence of CO 2 laser irradiation on the dissolution behavior of human dental enamel has been investigated. Human enamel was irradiated by a continuous-wave CO 2 laser at 10.6 μm and initial dissolution rates (IDRs) were measured in 0.1 mol/L acetate buffer, pH = 4.5, both with and without calcium and/or phosphate common ion, by means of a rotating disk assembly. The effects of (1-hydroxyethylidene) bisphosphonic acid (EHDP), fluoride (F), and dodecylamine HCI (DAC) at various levels upon the IDR were also determined. All of the findings were consistent with the hypothesis that CO2 laser irradiation converts dental enamel to hydroxyapatite (HAP) possessing site #2 character (Yamamoto et al., 1986). The dissolution driving force function, KHAP = aca10apO46aOH2, was found to have a value of 10-129.9 after being lased, as compared with 10-121.4 before being lased. The IDR values for EHDP (3 mmol/L) and DAC (3 mmol/L) were essentially zero as expected for site #2 HAP. For solution F, the deduced dissolution driving force function, K FAP = aca10aPO46aF2 was 10-128.6 after being lased as compared with 10-116.3 before being lased. These results all support the hypotheses (1) that laser irradiation may convert the surface of human dental enamel to an apatite of significantly lower effective solubility (i.e., site #2 HAP) than that of unlased enamel; and (2) that there is significant synergism between laser treatment and these chemical dissolution rate inhibitors (again consistent with site #2 HAP). Simple model calculations indicate that, in both the presence and absence of fluoride, these laser-induced changes in the driving force for dissolution should dramatically lessen the susceptibility of enamel to the types of acid challenge that might be encountered in the mouth
Effects of Chlorhexidine-containing Gel and Varnish on Abutment Teeth in Patients with Overdentures
Authors: Keltjens H.M.A.M. , Creugers T.J. , Schaeken M.J.M. , Van Der Hoeven J.S. 
Published: November 2010

Previous experiments have shown that daily use of 1% chlorhexidine gel strongly reduced caries development in the abutment teeth under overdentures. The present experiment was designed to determine whether intermittent application of chlorhexidine, either in a varnish or in a gel, might be used as an alternative preventive method, less demanding for the patient. To this end, 31 patients were distributed among four treatment groups, with the number of mutans streptococci in plaque and saliva used as a balancing criterion. The treatments consisted of a single application of 40% chlorhexidine varnish, daily application of 1% chlorhexidine gel for one week, or the corresponding placebo treatments with varnish or gel without chlorhexidine. Patients were re-called for bacteriological and clinical examination at various intervals during an eight-week period following treatment. Chlorhexidine varnish and chlorhexidine gel applications significantly suppressed mutans streptococci on the abutment teeth for four and eight weeks, respectively. In agreement with earlier findings, the numbers of Actinomyces viscosus/naeslundii in plaque were significantly increased after chlorhexidine varnish treatment. The chlorhexidine gel reduced plaque accumulation and gingival bleeding for one week but had no long-lasting effect. The results seem to justify a long-term clinical test of intermittent chlorhexidine applications as an alternative for daily use in patients with overdentures.
An Assessment of Survival Rates and Within-patient Clustering of Failures for Endosseous Oral Implants
Authors: Weyant R.J. , Burt B.A. 
Published: November 2010

This study examined endosseous cylinder implant survival, defined as the unqualified presence of the implant in the mouth at the end of the observation period, in 598 consecutive VA patients, with a total of 2098 implants. Data were taken from the Department of Veterans Affairs (VA) Dental Implant Registry, which has maintained longitudinal data on the survival of individual dental implants in VA patients since 1987. The maximum time of observation in any one patient was 2040 days (5.6 yr). Survival analysis by use of life-table methods was carried out on both an implant- and a patient-specific basis. Implant cases were accrued randomly, and therefore a random censoring model was used. A correlated binomial model was used for assessment of the degree of within-patient clustering of implant removals. Results showed that the implant-specific survival rate during the longest time interval (5.6 yr) was 89.9%; the patient-specific implant survival rate during the same time was 78.2%. Among implants which were removed, the mean time to removal was 292 days. The hazard function, which describes the probability of implant loss as a function of time, decreased steadily throughout the observation period. The correlated binomial model suggested a clustering of removals within patients with multiple implants (p = 0.11, p = 0.0001). The odds of having a second implant removed were 1.3 times greater if the patient had already had one implant removed. This study suggests that when implants fail, they do so soon after placement, and the likelihood of failure decreases steadily from implantation through the first five years post-surgery. These findings also suggest the existence of systemic factors which affect the survival of all implants within a given patient and may lead to multiple implant failures. Identification of these systemic factors may lead to improvements in patient selection and increases in the success rates for oral implants. Finally, results show that pure titanium implants had better short-term survival rates, but worse long-term survival rates, when compared with implants that had some other form of surface coating.
Differences Two Years after Tooth Extraction in Mandibular Bone Reduction in Patients Treated with Immediate Overdentures or with Immediate Complete Dentures
Authors: Van Waas M.A.J. , Jonkman R.E.G. , Kalk W. , Van 't Hof M.A. , Plooij J. , Van Os J.H. 
Published: November 2010

In a randomized controlled clinical trial, 74 patients who required immediate dentures were randomly treated with immediate overdentures on two lower canines or with immediate complete dentures. Mandibular bone reduction was measured by use of oblique lateral cephalometric radiographs made at baseline and the results compared with those of one year and two years after denture treatment. Analysis of the data showed that the average bone reduction in the lower canine regions in the first year was 0.9 mm in the immediate-overdenture group and 1.8 mm in the immediate complete-denture group. In the posterior parts of the mandible, the bone reductions were, respectively, 0.7 mm and 1.9 mm. The differences were statistically significant in all measured regions. During the second year, no significant differences in bone reduction were found. The sums of differences in the first two years were significant in all regions except the molar region, preserving the initial difference. Retention of roots of canines beneath a mandibular denture in immediate denture patients, even when they were in poor condition, reduced the collapse of the alveolar processes in all regions of the mandible.
Transport of Sugars, Including Sucrose, by the msm Transport System of Streptococcus mutans
Authors: Tao L. , Sutcliffe I.C. , Russell R.R.B. , Ferretti J.J. 
Published: November 2010

The range of substrates transported by the sugar-binding protein-dependent msm (multiple sugar metabolism) system of S. mutans was investigated. By determining the ability of unlabeled sugar to compete with radiolabeled melibiose transport, we have demonstrated that the transported sugars included a number of carbohydrates structurally related to raffinose. A model accommodating these results has been devised which accounts for the sugars transported by the msm transport system. Competition with radiolabeled melibiose transport indicated sucrose to be an msm substrate. This was confirmed by examination of uptake of radiolabeled sucrose in scrAB mutants lacking the sucrose-specific phosphotransferase system.
The role of pramipexole in a severe Parkinson’s disease model in mice
Authors: ElHak Seham Gad , Ghanem Abdel Aziz , Abdelghaffar Hasan , ElDakroury Sahar , ElTantawy Dina , ElDosouky Sara , Salama Mohamed 
Published: November 2010

Background: Pramipexole is one of a new generation of dopamine agonists. Recently there have been questions regarding its neuroprotective effects. These effects have been tested against various insults, which have yielded conflicting results. Methods: In this study, we introduced a combination of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)/paraquat to induce a severe Parkinson’s disease model. The mice, after receiving the combination of toxins, were evaluated using mortality rates and immunohistochemistry for degenerating tyrosine hydroxylase-positive neurons. Results and conclusions: Pramipexole was tested for its capacity to offer protection against neurotoxic the effects of MPTP/paraquat in this model; however, the results showed no improvement with pramipexole therapy.
Oxidation States of Unsymmetrically Substituted Quaterthiophenes with Two Terminal Ferrocenyl Groups
Authors: Sato Masa-aki , Kamine Hirokazu , Kato Takumi 
Published: November 2010

Abstract
Unsymmetrically substituted quaterthiophenes with two terminal ferrocenyl groups were prepared as long π-conjugated systems. Anisotropy of the chemical structures of the π-conjugated systems was introduced by substitution of methoxy and hexyl groups. Electrochemical and spectroscopic studies were carried out to evaluate the oxidation states of the diferrocenylquaterthiophenes and the interaction between the two terminals. The one-electron oxidation of one diferrocenylquaterthiophene adequately substituted with two methoxy and one hexyl group occurs at one ferrocene moiety specified due to the unsymmetry of the quaterthiophene moiety. The one-electron oxidizing species extends into the quaterthiophene moiety and apparently interacts with the other terminal ferrocene moiety.