bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methodological Considerations Concerning the Use of Bruxcore Plates to Evaluate Nocturnal Bruxism
Authors: Pierce C.J. , Gale E.N. 
Published: November 2010

The purpose of this study was to evaluate the Bruxcore Plate (BP) as a dependent measure of nocturnal bruxing activity. As part of a bruxism treatment study, we evaluated 100 nocturnal bruxers for bruxing activity before, during, and immediately after treatment and again at a six-month recall. The first 40 subjects wore both a BP and an EMG (electromyographic) unit for every night of each 14-night evaluation period (bcrseline; post-treatment; six-month recall). During the treatment period, these subjects wore the EMG unit but no Bruxcore Plates. Another 40 subjects wore the EMG unit and never used Bruxcore Plates. We evaluated a 20-subject no-treatment control group by two methods. Ten control subjects were evaluated with the EMG unit and the BP and another ten with the EMG unit alone. We hypothesized that the BP would not measure the same construct as an accepted EMG measure of bruxing activity, and that the BP would effect changes in EMG measured nocturnal bruxing activity. The results supported the conclusions that the BP did not measure the same construct as the EMG measure, and that the BP did effect changes in nocturnal bruxing activity. Correlations of BP scores with EMG data for equivalent measurement periods were low or non-existent. For the control group and the massed practice (negative practice) treatment group, there were significant interaction effects for EMG-measured bruxing episodes per hour for BP vs. no-BP Groups, with respect to measurement periods (time). Interpretation of these results indicated that BP evaluation of nocturnal bruxing activity was confounded with measurable treatment effects.
Effect of an Acute Maternal Fluoride Dose on Fetal Plasma Fluoride Levels and Enamel Fluoride Uptake in Guinea Pigs
Authors: Bawden J.W. , Deaton T.G. , Koch G.G. , Crawford B.P. 
Published: November 2010

We conducted this study to measure maternal plasma, fetal plasma, and fetal enamel fluoride concentrations for four hours following an oral F dose to near-term pregnant guinea pigs. We placed female guinea pigs on de-ionized (Group I) or 3-ppm-F (Group II) drinking water prior to breeding and during gestation. On the 57th day of gestation, we administered a maternal dose of NaF solution (0.6 mg Flkg) by stomach tube. We collected samples of maternal plasma, fetal plasma, and fetal enamel at baseline, at 15 and 30 min, and at one, two, and four h after administration of the dose. We assayed samples for F using a modification of the micro-diffusion and ion-specific electrode method. Group I mean baseline F values were: maternal plasma, 0.016; fetal plasma, 0.002 ; and fetal enamel, 7. 0 ppm. Group II mean values were: 0.055, 0.004, and 19.0 ppm. After the maternal fluoride dose, the mean maternal plasma [F] rose sharply for 30 to 60 min and declined to about 50% of peak values by four h. Fetal plasma [F] changed less in absolute values, but similarly to maternal changes relative to baseline. Fetal enamel mean [F] rose more in Group II than in Group I. Baseline F status had an important effect on F uptake in fetal enamel following an actue maternal fluoride dose.
The Effect of Thermal History on Porcelain Expansion Behavior
Authors: Fairhurst C.W. , Hashinger D.T. , Twiggs S.W. 
Published: November 2010

Porcelain-fused-to-metal restorations are fired several hundred degrees above the glass-transition temperature and cooled rapidly through the glass-transition temperature range. Thermal expansion data from room temperature to above the glass-transition temperature range are important for the thermal expansion of the porcelain to be matched to the alloy. The effect of heating rate during measurement of thermal expansion was determined for NBS SRM 710 glass and four commercial opaque and body porcelain products. Thermal expansion data were obtained at heating rates of from 3 to 30°C/min after the porcelain was cooled at the same rate. By use of the Moynihan equation (where Tg systematically increases in temperature with an increase in cooling/heating rate), the glass-transition temperatures (Tg) derived from these data were shown to be related to the heating rate.
Output from Visible-light Activation Units and Depth of Cure of Light-activated Composites
Authors: McCabe J.F. , Carrick T.E. 
Published: November 2010

A simple and reproducible method for monitoring the intensity of radiation from composite light-activation units has been developed. The method depends upon the use of a cadmium sulfide photo-conductive cell, the electrical resistance of which varies with the amount of light falling upon its surface. Filters were used for selection of the wavelength of light that is thought to be most effective in activating polymerization. The use of broad-band wavelength filters failed to give results for light intensity that correlated with depth of cure. Narrow-band interference filters, having a band width of only 10 nm and being selective within the wavelength range of from 460 to 480 nm, produced results for light intensity that correlated with depth of cure. The depths of cure for various types of composite material were measured with use of a penetrometer that enabled the thickness of unpolymerized material at the base of the test mould to be determined. The depth of cure was inversely proportional to the attenuation of light caused by the composite resin at 470 nm. The relationship between depth of cure and light intensity at 470 nm was not a simple linear one over all intensity values. Above a certain critical value of intensity (about 550 lux for a 3.5-mm aperture in these experiments), the depth of cure appeared to be almost independent of intensity. Below this critical value, depth of cure fell markedly with decreasing intensity.
Maximum Bond Strength of Dental Luting Cement to Amalgam Alloy
Authors: Mojon P. , Hawbolt E.B. , MacEntee M.I. , Belser U.C. 
Published: November 2010

Although dental amalgam is used frequently under artificial crowns for restoration of severely damaged teeth, there is little information available on the bond between luting cements and this alloy. This study was designed for determination of the strength of the bond between a dental amalgam alloy and three crown-luting cements. Cylinders of dental amalgam were joined in pairs, with use of a zinc-phosphate, a glass-ionomer, and an acrylic-adhesive resin cement. The tensile-fracture stress of 45 samples of each cement was measured with a universal testing machine, and subjected to a Weibull analysis. The fractured surfaces were examined under low magnification with use of a light microscope, and at low and high magnifications with use of a scanning electron microscope, for evaluation of the appearance of the fractured joints. The Weibull analysis demonstrated that the adhesive resin cement provided a stronger and more predictable bond than either the zinc-phosphate or the glass-ionomer cement. The appearance of the fractured surfaces gave no indication of the strength of the joints, a feature that is common to brittle materials. The results suggest that crowns placed on teeth offering a large amalgam-alloy surface could be retained more predictably with an adhesive resin cement.
Comparison of Jaw-muscle Bite-force Cross-sections Obtained by Means of Magnetic Resonance Imaging and High-resolution CT Scanning
Authors: van Spronsen P.H. , Weijs W.A. , Valk J. , Prahl-Andersen B. , van Ginkel F.C. 
Published: November 2010

Cross-sectional areas of the jaw muscles were determined by means of magnetic resonance imaging (MRI) in 12 healthy adult male subjects. These findings were compared with the cross-sectional areas of the jaw muscles of the same subjects, obtained by means of computer tomography (CT) in a previous study (Weijs and Hillen, 1985). Significant correlations (r>0.7) were found between the CT and MRI cross-sections of the masseter, medial pterygoid, and temporalis muscles. The low correlation between the CT and MRI cross-sections of the lateral pterygoid muscle could be explained by the different imaging techniques (slice thickness) of MRI and CT scanning. CT and MRI cross-sectional areas of the masseter and medial pterygoid muscle (but not the temporalis muscle) showed highly positive and significant correlations with the maximal voluntary bite force. In living subjects, the cross-sections of the masseter and medial pterygoid muscles can be visualized with CT and MRI. Compared with CT, MRI has some advantages, such as the absence of adverse effects (no radiation) and the excellent soft-tissue imaging. Furthermore, a series of frontal, horizontal, sagittal, and angulated MRI scans can be made without modification of the patient's position, facilitating reconstruction of the jaw muscles.
Fracture-mechanics Parameters of the Composite-Enamel Bond
Authors: De Groot R. , Van Elst H.C. , Peters M.C.R.B. 
Published: November 2010

In a previous study, the critical values of the opening mode stress intensity factor (K1 ), its equivalent, the strain energy-release rate (G1 ), and the J integral (J1 ) (in the elastic case being equal to that of G1 ) were determined for resin composite. In this study, the strength of the composite-tooth interface was investigated. The critical values of K1 and J1 were measured with single-edge notched-bend (SENB) specimens of resin composite bonded to enamel, with the notch at midspan at the bonded interface. Due to enamel's anisotropy, the values of K1c and J1c to be used in a fracture-mechanics application for failure prediction of a structure depend on the enamel prism orientation relative to the adhesive interface. Where interfacial failure is to be expected, the following values for J 1c and K1c can be used: Silux, J1c = 145 ± 35 Jm-2 and K1c = 0.84 ± 0.16 MNm-3/2; P-30, J1c = 163 ± 13 Jm-2 and K1c = 1.02 ± 0.07 MNm-3/2. Where enamel failure is expected or where the failure mode cannot be predicted, the following values can be applied: Silux, J 1c = 89 ± 15 Jm-2 and K1c = 0.84 ± 0.16 MNm-3/2; P-30, J1c = 89 ± 15 Jm-2 and K 1c = 0.75 ± 0.10 MNm-3/2.
Mutans Streptococci in Plaque from Margins of Amalgam, Composite, and Glass-ionomer Restorations
Authors: Svanberg M. , Mjör I.A. , Ørstavik D. 
Published: November 2010

Levels of mutans streptococci in plaque samples from margins of Class II amalgam (Dispersalloy), composite (P-10), and glass-ionomer (Ketac Silver) restorations were compared. Fifty-one children, each having one of the restorations in a permanent first molar, were part of an inter-individual comparison, giving 17 restorations of each material. The age of the children, the age of the restorations, and the salivary levels of mutans streptococci were comparable in the three groups. Another seven children-each having both a composite and a glass-ionomer restoration of the same age placed on contralateral premolar or molar teeth-were part of an intra-individual comparison. The percentage mutans streptococci of total CFU count in plaque was higher on composite (mean 13.7) and amalgam (mean 4.3) than on glass-ionomer (mean 1.1) restorations in the inter-individual comparison, and higher on composite (mean 4.2) than on glass-ionomer (mean 0.4) restorations in the intra-individual comparison. In both comparisons, the differences in values between samples from glass-ionomer restorations and samples from composite or amalgam restorations were statistically significant (p<0.05).
Endocytosis in Odontoclasts and Osteoclasts Using Microperoxidase as a Tracer
Authors: Tanaka T. , Morioka T. , Ayasaka N. , Jima T. , Kondo T. 
Published: November 2010

Microperoxidase (MP, a peptide tracer) was intravenously injected into rats after six days of tooth movement by the Waldo method. Bone resorption was seen along the distal bone surface of the inter-radicular septum of the upper first molar, and tooth root resorption occurred along the mesial and distal surfaces of the distal root of the same molar. Odontoclasts were smaller in size and numbers than osteoclasts, but had the same organelles [multiple nuclei, ruffled borders (RB), clear zones, vacuoles, mitochondria, and specific granules] as osteoclasts. MP was deposited on the resorbed area through the clear zone and was transported into the vacuoles along the channels of the RB. The uptake of MP by odontoclasts was small, compared with that by osteoclasts. Collagen fibrils were found in the channels of the RB but were not detected in the vacuoles. Instead, filament-like structures were seen in the vacuoles and were located very near the collagen fibrils in the channels. Fibroblasts outside the resorbed lacunae had endocytosed collagen. In contrast, some cells close to odontoclasts (osteoclasts) in the dentin (bone)-resorbed lacunae had not endocytosed any collagen fibrils. These findings suggest (1) that odontoclasts resorb the dentin or cementum just as osteoclasts do in bone resorption, (2) that the resorbed area connects with the extracellular spaces of the odontoclasts or osteoclasts, and (3) that the organic components (e.g., collagen ftbrils) of dentin or cementum are endocytosed through the channels of the RB in the same manner as that for MP. However, the endocytotic ability of odontoclasts appears inferior to that of osteoclasts.
A Histological Comparison in the Dog of Porous-coated vs. Threaded Dental Implants
Authors: Deporter D.A. , Watson P.A. , Pilliar R.M. , Chipmani M.L. , Valiquette N. 
Published: November 2010

The histological findings of an 18-month trial, in the dog, of a partially porous-coated endosseous dental implant made of Ti-6Al-4V, with a truncated conical shape, are described and compared with those for a cylindrical, threaded, endosseous implant made of commercially pure Ti. Six beagle dogs each received two porous-coated implants on one side of the mandible and two threaded implants on the contralateral side. Each set of two implants supported a two-unit fixed bridge for an 18-month functional period. Methylmethacrylate sections of both the buccolingual and mesiodistal aspects of each implant were examined qualitatively and by computer-assisted morphometry. The morphometric measurements were used for determination of the length of implant surface in direct contact with bone on each aspect of each implant. The data were expressed both as an absolute length and as a fraction of the maximum length available for contact (contact length fraction or CLF). On the buccal and lingual aspects of the implants, both the absolute lengths and CLF were significantly smaller for the porous-coated design. For the mesial and distal aspects, the absolute lengths and CLF were less for the porous-coated design, but the differences were not significant. However, when the absolute contact length was related to the corresponding vertical bone height, significant differences were observed, the absolute contact length being greater for any given bone height for the porous-coated design. Taken together, the data suggest that shorter implants may be used with the porous-coated design.
The Possible Role of Oral Epithelial Cells in Tissue-type Plasminogen Activator-related Fibrinolysis in Human Saliva
Authors: Sindet-Pedersen S. , Gram J. , Jespersen J. 
Published: November 2010

We studied the fibrinolytic activities of the following subfractions of unstimulated human whole saliva on plasminogen-rich fibrin plates: (1) submandibular saliva, (2) parotid saliva, and (3) smears of buccal epithelial cells from ten healthy males. A cell-bound plasminogen activator could be demonstrated in the sediments of all three subfractions of whole saliva. The incorporation of antibodies (goat IgG) against human two-chain tissue-type plasminogen activator (t-PA) could quench the assessed fibrinolytic activities, whereas additional experiments suggested the absence of urokinase-like and F XII-dependent activators of fibrinolysis. The determinations in growth medium from buccal-epithelial cell culture of t-PA antigen by means of enzyme-linked immunosorbent assay showed the presence of t-PA. These clinical and experimental findings suggest that buccal-epithelial cells produce t-PA, while the activity of t-PA in parotid and submandibular saliva is very low.
Transverse Development of the Human Jaws Between the Ages of 8.5 and 15.5 Years, Studied Longitudinally With Use of Implants
Authors: Korn E.L. , Baumrind S. 
Published: November 2010

We report longitudinal data on the transverse widening of the maxilla and mandible from a sample of normal subjects (11 males and 20 females) with metallic implants of the Bjork type. Data were from measurements on lateral and frontal (posterior-anterior) cephalograms generated at annual intervals between the ages of 8.5 and 15.5 years (although data were not available for all subjects at all time points). The maxillary data were, in general, similar to those reported by Bjork and Skieller (1974, 1977) for a smaller sample of slightly younger boys. During the age interval studied, transverse widening was greater in the more posterior part of the palate. [The mean annual rate of change in the posterior-most (zygomatic) region was 0.43 mm, sd = 0.18 mm; p < 0.001.] Although the rate of palatal widening was not large in absolute terms, widening appeared to continue throughout the age interval under study, and there was no evidence to support the conventionally accepted idea that palatal growth in the transverse dimension tapers off substantially or even ceases during the age interval under observation. Evidence of statistically significant widening of the mandibular arch by means of transverse rotation of the osseous matrix was noted in nine of the 29 subjects for whom three-dimensional mandibular information was available. For these nine subjects, the estimated annual increase in mandibular arch angle ranged from 0.52 degrees to 1.40 degrees. As far as we are aware, this is the first report of mandibular matrix rotation in the transverse direction from a sample of subjects with metallic implants. The finding that spontaneous changes in this dimension are relatively common raises the possibility that classical attitudes concerning the immutability of osseous relationships in the symphyseal region during growth may be inappropriate.
The Effects of Sucralose on Coronal and Root-surface Caries
Authors: Bowen W.H. , Young D.A. , Pearson S.K. 
Published: November 2010

Sucralose is an intensely sweet, chlorinated carbohydrate structurally similar to sucrose; thus, its cariogenic potential is of great interest. Four groups of 12 Sprague-Dawley rats were infected with Streptococcus mutans (sobrinus), caged in a Konig-Höfer programmed feeding machine, and fed diet 2000 or modified diet to contain sucralose at various concentrations instead of sucrose. Rats fed sucralose diet developed significantly fewer lesions than did the rats fed regular diet 2000. Animals fed diet 2000 also harbored more S. mutans (sobrinus) than did the other groups of animals. In a concurrent study, desalivated rats were inoculated with S. mutans (sobrinus) and Actinomyces viscosus. They were fed (ad libitum) either diet 2000 (contains 56% sucrose) or diet 2000 minus sucrose plus 93 mg% sucralose. The severity of caries lesions in the sucralose-fed rats after 35 days was significantly less than those in the sucrose-fed rats. The amount of root exposure was the same in both groups. However, root-surface caries did not develop in the sucralose-fed rats. These results show that sucralose is non-cariogenic in rats.
Development of Horizontal Tooth Wear in Maxillary Anterior Teeth from Five to 18 Years of Age
Authors: Nystrom M. , Könönen M. , Alaluusua S. , Evalahti M. , Vartiovaara J. 
Published: November 2010

Sizes of horizontal wear facets of maxillary anterior teeth were studied longitudinally from the primary dentition at age five to the young adult dentition at the age of 18 years. By a planimetric method, we calculated the wear areas on dental casts taken at the ages of five, ten, 14, and 18 years from the dentition of 39 healthy, orthodontically untreated subjects with good morphological occlusion. For young adults, we also studied the association between the amount of wear and reported parafunctions, maximal bite force, salivary buffer capacity, salivary flow rate, and some cephalometric variables. Size of wear facets on all anterior teeth increased with age. Significant correlations were found between the total wear areas of the six anterior primary teeth at five years of age and those of their permanent successors at age 14 (r = 0.44) and 18 (r = 0.39). For an individual, tooth wear at five years of age was, however, of low predictive value for tooth wear in young adulthood, whereas tooth wear at 14 years of age predicted it well (r = 0.89). Highest correlations between tooth wear and background factors at 18 years of age were found for maximal anterior bite force (r = 0.44) and for the size of the gonial angle (r = -0.31). Wear of anterior teeth was not associated with reported parafunctions in young adulthood.
Fluoride Intake of Infants in New Zealand
Authors: Chowdhury N.G. , Brown R.H. , Shepherd M.G. 
Published: November 2010

Since the fluoride (F-) intake of New Zealand infants and young children is not known, a study was designed to determine and compare the F- intake of infants, aged 11 to 13 months, residing in fluoridated (F) and non-fluoridated (NF) areas. Parents of 60 infants duplicated quantitatively and qualitatively all food and drink that the infants ingested during a three-day period. The acid-diffusible F- content in the liquid homogenate was isolated by the HMDS-HCl diffusion technique (Taves, 1968) and measured by a fluoride electrode. The ionic F- in samples of breast milk was measured directly by the electrode. In the F area, the F- content of the food and drinks of 31 subjects ranged from 0.130 to 0.679 mg/kg (mean, 0.320; SD, 0.168); in the NF areas, the F- content of the food and drinks of 29 subjects ranged from 0.036 to 0.281 mg/kg (mean, 0.095; SD, 0.053). The dietary intake ranged from 0.089 to 0.549 mg F/day (0.009-0.056 mg F/kg bw) in the F area, and from 0.038 to 0.314 mg F/day (0.004-0.038 mg F/kg bw) in the NF area. Including F- from tablets and toothpastes, total intake ranged from 0.093 to 1.299 mg F/day (0.009-0.150 mg F/kg bw) and from 0.039 to 0.720 mg F/day (0.004-0.061 mg F/kg bw) in F and NF areas, respectively. The mean dietary intake of infants in the F area was about half the recommended "optimal" range; in the NF areas, the dietary intake was five to seven times less than the optimal. Sources of high fluoride intake such as soy-milk formulae and tea, however, raised the fluoride content of the diet to near optimal levels. The use of F toothpastes and tablets raised the intake to near optimal levels. The optimal intake was exceeded by one child in the F area as a result of excessive toothpaste use. It was calculated that, if a child on soy formula in the non-fluoridated areas were to ingest fluoride supplements and large amounts of toothpaste as well, the total fluoride intake of this infant could exceed optimal levels. This finding stresses the need for identification of potential sources of high fluoride intake in a child's diet before any form of fluoride supplementation is recommended.