bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bisphosphonate Effects on Alveolar Bone During Rat Molar Drifting
Authors: Hardt A.B. 
Published: November 2010

The remodeling of bone during molar drifting and cortical growth in the rat maxilla and the effects of dichloromethylene bisphosphonate (Cl2MBP) on these processes were investigated in 30 age-matched rats. A control group of six rats was killed at 10 weeks of age. Beginning at 10 weeks of age, 12 rats were treated with daily subcutaneous injections of Cl2MBP (10 mg/kg), and 12 control rats were injected daily with normal saline. Six rats of each group were killed at 12 and at 20 weeks of age. All rats were injected with fluorescent bone labels eight and one days before termination. Calcified and decalcified vertical sections through the lingual roots of maxillary molars were prepared for histomorphometry. Bone apposition rates, remodeling activity, and bone cell populations were quantified by image analysis on depository and resorptive surfaces of alveolar bone and on cortical bone surfaces. The drift rates of the first and second molars were calculated. Results showed that in control animals the drift rate of the first molar exceeded that of the second molar (p < 0.05), supporting a previously proposed mechanism for age-dependent narrowing of interdental bone. Cl2MBP treatment decreased remodeling activity on resorptive surfaces of alveolar bone, despite a transient increase in osteoclasts. Cl2MBP also decreased the osteoblast number and bone apposition rate on depository surfaces of alveolar bone, and reduced the rate of molar drifting (p < 0.05). However, Cl2MBP treatment had no detectable effect on osteoblast number or bone apposition on cortical bone surfaces. These results support the concept that bisphosphonates influence bone formation indirectly through a coupling mechanism which links formation with resorption.
The Effects of 1% Pyrophosphate and 0.02% Sodium Fluoride on Artificial Caries Lesions in vivo
Authors: Mellberg J.R. , Petrou I.D. , Deutchman M. , Grote N. 
Published: November 2010

We evaluated the potential of a pyrophosphate-fluoride solution to affect the remineralizing-demineralizing equilibrium, i.e., caries-inhibitingl-promoting effects on enamel in vivo. Fifteen subjects carried dentin blocks and enamel thin sections with artificial caries lesions in removable partial dentures for periods of two weeks, during which time they rinsed twice daily in a double-blind, randomized cross-over design with solutions containing (a) 90 ppm F, (b) 90 ppm F and 1% pyrophosphate, or (c) no active agents (placebo). A severe cariogenic challenge provided to the lesions by plaque under a stainless steel mesh cover resulted in the placebo-treated lesions losing 70.2% ± 72.1% mineral. The pyrophosphate rinse with fluoride held the mineral loss to only 28.1 ± 52.8%, while the fluoride rinse without pyrophosphate held the loss to 24.2 ± 50.1%. The differences between the fluoride and placebo results were significant (p < 0.01), but the difference between the two fluoride groups was not. A large amount of fluoride was deposited in the dentin lesions. In the surface layer, the concentration was increased from 1000 ppm F to more than 2300 ppm F by both fluoride treatments. The concentration of fluoride in both groups of fluoride-treated lesions further increased to more than 3500 ppm F in the approximate center of the lesion before declining in deeper layers toward the level found in the placebo-treated group. The findings from both mineral change and fluoride uptake phases of this study show that in the presence of 90 ppm F, 1% pyrophosphate did not promote demineralization of artificial caries lesions.
Effects of Sustained-release Chlorhexidine Acetate on the Human Dental Plaque Flora
Authors: Schaeken M.J.M. , De Haan P. 
Published: November 2010

The aim of this study was to determine the effect on the human dental plaque flora of a varnish containing chlorhexidine diacetate. The in vitro release of chlorhexidine acetate from the varnish preparation was relatively fast on the first day, followed by a substantial decline in the subsequent three days. In a clinical experiment, 26 volunteers were randomly distributed over four experimental groups. After a dental prophylaxis, the subjects were treated with a single application of a placebo varnish (group I), a fluoride varnish (group II), a chlorhexidine varnish (group III), or a fluoride-plus-chlorhexidine varnish (group IV). Saliva and pooled plaque samples from approximal surfaces were taken before (baseline) and one, two, three, four, and six weeks after the treatments. No suppression was found of total cultivable flora or S. sanguis after the experimental treatments. Application of the fluoride varnish did not suppress the A. viscosus/naeslundii or S. mutans levels in the dental plaque. Chlorhexidine suppressed A. viscosus/naeslundii until two weeks after the treatment. S. mutans was significantly suppressed until four weeks after a single chlorhexidine application. While in some subjects S. mutans was effectively suppressed over the whole experimental period, in others S. mutans recovered quickly. In five subjects in whom S. mutans recovered quickly, the dentition was treated twice with chlorhexidine varnish, with an interval of one week between the treatments. After two chlorhexidine treatments, S. mutans in saliva and on the teeth was suppressed more strongly than after a single treatment. However, the second chlorhexidine treatment could not prevent the return of S. mutans in the approximal areas to its original level.
Changes in the Tartrate-resistant Acid Phosphatase Cell Population in Dental Follicles and Bony Crypts of Rat Molars during Tooth Eruption
Authors: Wise G.E. , Fan W. 
Published: November 2010

It was the aim of this study to determine the cellular changes that occur in the enamel organ, dental follicle, and surrounding bony crypt of the rat molar prior to and during tooth eruption. By use of light microscope histochemistry to detect cells containing tartrate-resistant acid phosphatase (TRAP), it was seen that TRAP-positive mononuclear cells were present in the dental follicle prior to the onset of eruption (e.g., three days postnatal age) and then declined in number during eruption. Concurrently, TRAP-positive osteoclasts were initially present in large numbers on the surface of the bony crypt surrounding the molars (three days postnatal age) and then declined in number as eruption progressed. Electron microscopy confirmed that these were mononuclear cells and osteoclasts. The results suggest that the mononuclear cells are either precursors of the osteoclasts or perhaps release cytokines that affect osteoclast formation or activity. Staining for alkaline phosphatase (ALP) activity indicated that at an early postnatal age (secretory stage of amelogenesis), ALP was detected only in the stratum intermedium of the enamel organ, whereas at a later age (maturation phase of amelogenesis), it was present only in the ameloblasts. These results, combined with a survey of the literature, strongly suggest that ALP moves from the base of the enamel organ to the enamel itself over a period of time ranging from pre- to post-eruption. Rat molars are teeth of limited eruption, and the cellular events that occur in eruption appear comparable with what is seen in dog and human dentition, especially in terms of the cellular events seen in the dental follicle prior to and during eruption. Thus, because rat molars are often more amenable to experimental protocol, they may be a suitable choice for answering questions pertaining to tooth eruption in the dog and in humans.
Measurement in vivo of Masticatory Mucosal Thickness with 20 MHz B-Mode Ultrasonic Diagnostic Equipment
Authors: Uchida H. , Kobayashi K. , Nagao M. 
Published: November 2010

Analysis of the movement of the denture foundation under function is very important for construction of a denture. For this analysis, the thickness of the masticatory mucosa gives the required quantitative information. The thickness measurements were taken from 21 oral sites in 100 edentulous patients, by means of 20 MHz B-mode ultrasonic equipment. The average thickness of the masticatory mucosa ranged from 1. 92 mm to 2.38 mm at the upper edentulous ridge and from 1.45 mm to 1. 58 mm at the lower edentulous ridge. The center of the palate had the thinnest mucosa and the lateral area of the palate had the thickest among all the measuring points. Contrary to what is often believed, a decrease in mucosal thickness with age was not observed by one-way analysis of variance. Furthermore, as the degree of ridge reduction increased, a decrease in the mucosal thickness was found by one-way analysis of variance at only two of the 14 measuring sites on the ridges. At four of the 21 measuring sites, male patients had significantly thicker mucosa than did females, and the correlation coefficients of the thickness of mucosa between right and left sides in the palate were higher than those in residual ridges.
Mechanical Properties of Poly(alkyl a-fluoroacrylate)s as Denture-base Materials
Authors: Kurata S. , Yamazaki N. 
Published: November 2010

a-Fluoro-substituted acryl polymers, poly(methyl a-fluoroacrylate) (PMFA) and poly(2,2,2,-trifluoroethyl α-fluoroacrylate) (P3FFA) were investigated for extension to denture-base resins. PMFA, in which fluorine attaches to the polymer chain, had excellent mechanical properties: For instance, compressive and bending strength and bending modulus were 50% higher than those of PMMA. P3FFA, in which fluorines are substituted at the end of the pendant alkyl ester, showed poor mechanical properties. Contrary to expectations, the amount of water sorption of PMFA was about twice that of PMMA, while that of P3FFA was almost zero. Copolymers of MFA and 3FFA were prepared in an attempt to optimize the mechanical properties and the water sorption. The copolymer with 40% of 3FFA showed higher compressive, diametral tensile, and bending strength; in particular, the bending modulus and water resistance were about 35% and 20% higher, respectively, than those of PMMA. Improvement of the mechanical properties and increase of the water sorption of PMFA may be due to intermolecular forces induced by polarizability of the fluorine and carboxy group along the polymer chain. Decrease of the water sorption by fluorine substituted on the alkylester group as in P3FFA may be due to higher hydrophobicity and steric ejj"ect of the fluoroalkyl substitute.
The Influence of Surface Free-energy on Planimetric Plaque Growth in Man
Authors: Quirynen M. , Marechal M. , Busscher H.J. , Weerkamp A.H. , Arends J. , Darius P.L. , van Steenberghe D. 
Published: November 2010

The purpose of this study was to examine the change in plaque area over nine days in vivo on four materials with different surface free-energies (s.f.e.). Twelve healthy dental students participated in a crossover, split-mouth, double-blind study. Supragingival plaque formation was recorded over a nine-day period, on four different materials: fluorethylenepropylene (Teflon) (FEP), parafilm (PAR), cellulose acetate (CA), and enamel (E) with s.fe. of 20, 26, 57, and 88 erg/cm2, respectively. Strips made from the first three materials were stuck to the buccal surface of an upper incisor. The remaining incisor was carefully polished and served as an enamel surface. The increase in plaque was evaluated after three, six, and nine days. A planimetrical analysis was used so that the plaque area could be expressed as a percentage of the total buccal tooth surface. This procedure was repeated on each subject, so that at the end, each pair of central or lateral incisors received the four tested materials. The results indicated that the adherence of micro-organisms on pellicle-coated substrata was influenced by the material's s.f.e.; there was an association between the s.f.e. of the substrata and the supragingival plaque extension in vivo. High surface free-energy substrata in the oral cavity attracted more micro-organisms than did low energetic materials. Additionally, the bacterial adhesion seemed very weak on surfaces with a low s.f.e.
Changes in Plasma Epinephrine Concentration after Dental Infiltration Anesthesia with Different Doses of Epinephrine
Authors: Knoll-Kohler E. , Frie A. , Becker J. , Ohlendorf D. 
Published: November 2010

To define the cardiovascular risk as a result of epinephrine in local anesthetic solutions used in dental anesthesia, we measured the plasma epinephrine levels, the mean arterial brachial pressure (MAP), and heart rate for 15 min, after infiltration anesthesia in the area buccal to the upper permanent left lateral incisor and canine. For this purpose, 12 dental student volunteers received 2.0 mL 2% lidocaine with and without 20 or 80 μg epinephrine, in a double-blind cross-over trial. - Plain lidocaine solution caused no significant changes in the parameters under study when compared with the baseline values. - Lidocaine with 20 μg epinephrine caused a sustained doubling of the plasma epinephrine concentration two min after injection, and at the same time, a slight but significant (p<0.05) decrease in MAP. Two min and 45 s after injection, the heart rate increased by four beats/min when compared with the baseline rate. - Lidocaine with 80 μg epinephrine caused a doubling of the basal plasma epinephrine value as early as one min and 25 s after injection, and a ten-fold increase above the basal value at the end of the observation period (15 min). The heart rate increased significantly (p<0.01) by five beats/min above the baseline value starting two min after injection, and rose to a maximum of 13 beats/min until the end of the observation period. The time-point of the decrease in MAP was earlier, but the amount of the decrease equaled that measured after submucosal injection of 20 μg epinephrine with 40 mg lidocaine.
Maxillary Arch Dimensions after Palatal Surgery at Different Ages on Beagle Dogs
Authors: Wijdeveld M.G.M.M. , Grupping E.M. , Kuijpers-Jagtman A.M. , Maltha J.C. 
Published: November 2010

Changes of maxillary arch dimensions were studied longitudinally until maturity, after palatal surgery was performed on 37 beagle dogs at different ages. The dogs were divided into three experimental groups, a sham group, and a control group. At the age of 6, 16, or 25 weeks in the experimental groups, we created a soft-tissue cleft in the medial region of the palate, made relaxation incisions, and elevated and closed the mucoperiosteum in the midline, thus leaving two areas of denuded bone adjacent to the dentition. We made dental casts regularly until the age of 37 weeks, and studied maxillary arch dimensions. Surgery performed before or during the transition of teeth did not change maxillary arch dimensions in the deciduous dentition, but after the transition, the increase in arch width in the pre-molar region was reduced. Surgery performed after completion of the permanent dentition did not change maxillary arch dimensions. Delay of palatal surgery until the transition of teeth was completed favored normal development of the maxillary dental arch.
Effect of Visco-elastic Behavior on Stress Development in a Metal-Ceramic System
Authors: Dehoff P.H. , Anusavice K.J. 
Published: November 2010

We developed an analytical model to calculate transient stress and gap displacement during cooling of a porcelainized semicircular arch with a gapped diametral segment. Constant cooling rates were assumed after the specimens were slowly cooled (with power terminated to the furnace) from the porcelain firing temperature. The analytical model incorporates linear visco-elasticity and structural relaxation effects. We calculated transient and residual gap displacements and stresses for a semicircular arch specimen (composed of an experimental opaque porcelain and a Ni-Cr-Be alloy) for six thickness ratios at a cooling rate of 3°C/min. Residual gap displacements were measured for metal-porcelain arch specimens of six thickness ratios. Compared with measured values, calculations based on the visco-elastic theory overestimated gap closure for porcelain/metal thickness ratios below 1.5, and underestimated gap closure at thickness ratios above 1.5.
A Three-dimensional Evaluation of the Effects of Functional Occlusal Forces on the Morphology of Dental and Periodontal Tissues of the Rat Incisor
Authors: Steigman S. , Michaeli Y. , Yitzhaki M. , Weinreb M. 
Published: November 2010

We examined the effect of function on tooth and periodontal ligament (PDL) morphology in 40 lower incisors of adult female rats. Ten teeth were exposed to occlusal hyperfunction for three months, ten to hypofunction for three weeks, ten to hypofunction for three months, while ten teeth in normal occlusion served as control. Transverse ground sections were cut at various levels perpendicular to the tooth long axis, and their distances from the apex were calculated. The outlines of the tissues were traced and fed into a computer. We plotted the measurements according to their location and fitted them by second-order polynomials. We calculated tissue volume for the proximal 18 mm of bone-embedded tooth. Hyperfunction affected tooth shape, in that it became more rounded. The volumes of the dental tissues remained unchanged, while width and volume of the cementum-bordering PDL increased. Hypofunction did not alter tooth shape, but influenced its size: After three weeks, tooth circumference decreased, and after three months, it expanded. Dentin width was reduced, with concomitant increase of pulp size. The amount of enamel diminished initially, but after three months returned to normal values. The PDL bordering enamel expanded proportionally to the duration of hypofunction. The changes in socket size reflected the total dimensional variations in the tooth and its PDL. The results demonstrate that the shape and size of growing teeth and their periodontium are influenced by functional occlusal forces.
An Analysis of Factors Influencing Diffusion from Dental Plaque into a Moving Film of Saliva and the Implications for Caries
Authors: Dawes C. 
Published: November 2010

Recent studies have indicated that saliva in the mouth is present as a film only about 0.1 mm thick, and that this film moves at different rates (about 0.8 to 7.6 mm/min) in different regions of the oral cavity. The clearance rates of KCI, as a model diffusant, from agarose gels at different sites in the mouth have also been found to vary markedly, and it has been proposed that these variations are related to differences in the velocity of the salivary film. A computer model has been developed for prediction of clearance half-times for substances diffusing from plaque of variable dimensions into a film of fluid 0.1 mm thick, moving at different velocities. The results show that over the range of velocities calculated to occur in the mouth, the clearance half-times are directly related to the length of plaque over which the fluid passes, and inversely related to the salivary film velocity. The predictions of the model are in good agreement with experimental results from a physical model. Tests were made of the predicted effect of salivary film velocity on the shape of the pH curve initiated by exposure of plaque to a saturated sucrose solution, followed by normal salivary clearance. With a low salivary film velocity, the fall in pH was greater and more prolonged. These results are relevant to the site-specificity of caries, since they imply that, given two plaque samples of identical area, depth, and microbial composition, the sample located in a region of the mouth where the salivary film velocity is lower will show a more extensive and prolonged pH fall after exposure to fermentable carbohydrate.
Performance Assessment of Colorimetric Devices on Dental Porcelains
Authors: Seghi R.R. , Johnston W.M. , O'Brien W.J. 
Published: November 2010

The selection of an appropriate material that duplicates the appearance of natural tooth structure is very important in restorative dentistry. Photometric and colorimetric analysis techniques offer great potential as a tool for aiding in the duplication process. The degree to which these techniques will be useful depends on the accuracy and precision with which they can be applied to translucent as well as opaque surfaces. The purpose of this investigation was to evaluate the performance of three currently-available photometric devices. The performance capabilities of the instruments were tested on various shades of opaque and translucent dental porcelain surfaces. The performance tests were designed for evaluation of the accuracy and precision of the instrument relative to a well-studied reference instrument. CIELAB color difference metrics were used for the performance analysis. The results revealed that each of the photometric instruments evaluated was capable of producing color measurements with precision. However, the degree of accuracy with which the color measurements were made varied depending on the instrument used and the type of material surface being measured. A photo-electric tristimulus colorimeter showed the best overall performance on the porcelain surfaces, supporting its use as a valuable tool for evaluating color in dentistry.
Facts and Artefacts in Research on Human Dental Plaque Fluid
Authors: Tatevossian A. 
Published: November 2010

In 1966, Jenkins suggested that the plaque fluid environment was likely to have higher concentrations of extracellular solutes than was apparent from analyses of total plaque concentrations. Early work on plaque fluid confirmed this contention, but some artefact was also generated by the prolonged centrifugation used for separation. The solute concentrations in plaque fluid mostly exceed those in saliva or crevicular fluid. Thus, the environmental conditions are distinctly different from those based on the assumption that saliva readily permeates films of dental plaque. In contrast, the presence of serum proteins suggests a crevicular input to plaque fluid. These data suggest that exchange between dental plaque and its environment is apparently restricted. Diffusion rates measured in dental plaque by different methods do not agree on how restricted it is. However, measuring diffusion in plaque introduces artefacts in packing density, a major determinant of the diffusion rate. The conditions used for collection and analysis have been reported to produce artefactual changes in plaque fluid potassium, a predominantly intracellular ion. Measurements of predominantly extracellular ions, such as calcium, are no less prone to artefact, whether based on ion-selective electrodes or on total calcium. We have much to learn about the fluid environment of the teeth and about dynamic changes in plaque fluid composition and properties during perturbations. Such information can give insights into pathological processes such as tooth demineralization and dental caries, calculus formation, and gingival inflammation.