bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of an occlusal splint on integrated electromyography of masseter muscle in experimental tooth clenching in man
Authors: CHRISTENSEN L. V. 
Published: June 2007

SummarySix male subjects exercised maximal voluntary tooth clenching until fatigue appeared in the masseter muscle and until pains and exhaustion of this muscle could no longer be endured; that is, the fatigue threshold and the pain tolerance of the muscle were determined in seconds. An occlusal splint was inserted and the clenching exercises were repeated. During these exercises, and also during 10s of clenching, the electrical activity in the masseter muscle was recorded by bipolar surface electrodes and linearly integrated. Use of the splint did not result in significant changes in the subjective sensations of onset of fatigue and endurance of pain. As the periods of clenching increased, after insertion of the splint, the electrical activity decreased consistently, and use of the splint caused a significant decrease in the electrical activity of the pain tolerance test. As induced by the splint, there was no orderly pattern in changes of the fatigue thresholds and pain tolerances in relation to changes in the electrical activities of these parameters. The mode of action of the splint, in reducing the muscle activity, might have been that of stretching the elevator jaw muscles beyond their resting length.
The effect of maximal mouth opening on dimension discrimination
Authors: MORIMOTO TOSHIFUMI , CHRISTENSEN JOHN 
Published: June 2007

SummaryThe ability of twenty‐five young persons to discriminate dimensions was tested. A reference stick of 10 mm was placed between the teeth, alternating with test sticks of different heights. After application of the reference stick the subjects were asked to open the mouth maximally. A test stick was placed on the lower incisors and the subjects closed the mouth slowly, until their upper incisors contacted the test stick. The subjects were then asked to assess whether a test stick felt higher or lower than the reference stick.Using this experimental method, it was found that incorrect assessments were symmetrically distributed around the 10 mm reference stick.A receptor mechanism is proposed, and applied to explain the results of the present and a previous experiment.
Studies on the setting behaviour of sealants using a new acoustic method of determining set
Authors: YOUNG K.C. , MAIN C. , GILLESPIE F.C. , STEPHEN K. W. 
Published: June 2007

SummaryAn acoustic method has been used to compare the setting behaviours of three chemical and three u.v. activated sealants. The setting rates of the u.v. sealants were found to have similar sub‐linear dependences on the applied u.v. intensity. However, considerable differences in the rates of set of these materials were noted when the same u.v. intensities were applied. Adjusting the composition of one of the sealants (Alphaseal) increased the penetration of the u.v. radiation, resulting in a ten‐fold improvement in the setting rate. Suitable exposure times and the intensities of radiation necessary to satisfactorily set these u.v. sealants are recommended.
The delay time of tooth vibration signal recorded at facial skin surface
Authors: MITANI H. , INUBUSHI Y. , FUJII H. , MUSHIMOTO E. 
Published: June 2007

SummaryThe onset of a tooth vibration signal with a mini acceleration pickup attached to the skin on the forehead was delayed by 0.1788 ms on average after the actual tooth impact. When the signal was recorded at the zygomatic arch, the delay time was 0.1008 ms on average, which was significantly shorter than that obtained from the forehead (P < 0.001). The difference due to a transposition of the vibrated tooth was also smaller (0.025 < P < 0.05) and had almost no effect on the intensities of the tooth flipping force. The delay time was even more prolonged when a poor frequency specification pickup and/or low pass filter were applied.
The reliability of clinical evaluation of some characteristics in complete prosthetics
Authors: RAMSTAD TORE , NORHEIM PER W. , ECKERSBERG THOMAS 
Published: June 2007

SummaryThe aim of this investigation was to study intra‐assessor reliability and the relationship between individual and simultaneous evaluations when retention and stability of complete prostheses and the condition of the residual ridges were clinically assessed according to defined criteria. Further, inter‐assessor reliability and the reliability of simultaneous evaluations were studied by evaluating the condition of the residual ridge on two occasions. Nine patients and three prosthodontists participated.Generally, the reliability levels were low and individual deviations from the simultaneous evaluations were common.
An apparatus for the preparation of cavities in the canine teeth of ferrets
Authors: TYAS MARTIN J. , TOBIAS ROSALIND S. , BOVIS S. C. 
Published: June 2007

SummaryAn apparatus is described for the preparation of standardized cavities in the canine teeth of ferrets. One hundred cavities were cut, and there was highly significant correlation between the distance the bur was advanced (machine depth) and the cavity depth in dentine. It was possible to cut cavities predictively with small and large residual dentine thicknesses. The method described was not damaging to the pulp.
The temporomandibular joint in children after breech delivery
Authors: GROSFELD OLGA , KRETOWICZ JANUSZ , BROKOWSKI JAN 
Published: June 2007

SummaryIn an effort to explain the aetiology of early temporomandibular joint (TMJ) injuries, their incidence in children born by vaginal breech delivery and possible correlation with such deliveries were investigated.The study covered 156 children aged from 4 to 6 years, eighty‐three of them born by vaginal breech delivery under application of the classical Mauriceau manoeuvre in seventeen cases and the Bracht manoeuvre in sixty‐six. Seventy‐three children delivered spontaneously in vertex presentation served as the control group.Signs of TMJ injury were found in 59.6% of the total group, the by‐birth percentages being 67.5 in those after breech delivery and 50.7 in those after spontaneous delivery—the difference is statistically significant.The difference was even more significant for the more severe TMJ disorders, their percentages being in two groups respectively 48.2 and 29.7. In the children born by breech delivery the TMJ disorders were invariably attended by severe forms of distocclusion, among which the unilateral form deserves particular attention.The authors conclude that vaginal breech delivery is probably among the factors responsible for early TMJ abnormalities. They call the attention of paediatricians and obstetricians to this fact and urge examination of this joint as a very important part of oral examination in children born by vaginal breech delivery.
Occlusal dysfunction and stress
Authors: BUDTZ‐JØRGENSEN EJVIND 
Published: June 2007

SummaryA dysfunctional occlusal relationship was produced in six Macaca irus monkeys by insertion of occlusal splints which raised the vertical dimension of occlusion by 3–4 mm and incorporated interferences into the occlusion. Cortisol levels of plasma and 24 h urine samples were measured by competitive protein‐binding analysis. After insertion of the splints there was an immediate, approximately two‐fold rise of the mean 24 h urinary cortisol excretion rate and a significant decrease of urinary volume and body weight. The plasma cortisol level did not rise significantly. During the 3 weeks experimental period the teeth showed increasing mobility and occlusal wear facets developed on the splints. Urinary cortisol excretion rates were significantly elevated throughout the experimental period. Urinary cortisol levels declined to basal values when the splints were removed. This animal model produces experimental evidence in support of the hypothesis that a dysfunctional occlusal relationship may result in bruxism associated with emotional stress.
Addition of fluoride compounds to acrylic resin plates: bending strength and fluoride release
Authors: ZITZ A. , GEDALIA I. , GRAJOWER R. 
Published: June 2007

SummaryThe effect of incorporated CaF2 (2.04%), NaF (2.27%) and amine fluoride (0.71%) in acrylic resin plates, on bending strength and fluoride release by rinsing and immersion in synthetic saliva, was determined. Bending strength was reduced by 6.7, 9.5 and 20% respectively. The most elevated release of fluoride from the NaF containing—and the most protracted from the CaF2 containing—plates may be related to the solubilities of the compounds.It appears that the organic molecule of the AmF compound affects the strength of the acrylic plates most significantly.The F‐ concentrations released in the in vitro rinsing experiment may be presumed to occur in vivo at some higher level due to the larger size of dental appliances.
X‐ray diffraction and SEM/EDS analyses of phases in new dental amalgams*
Authors: MARSHALL GRAYSON W. , MARSHALL SALLY J. 
Published: June 2007

SummaryThe superior clinical performance of several dental amalgams which contain high Cu concentrations and little or no γ2 has stimulated the introduction of a number of new amalgam alloys. This investigation sought to study the nature of the phases present in eight commercial systems after trituration. Samples were powdered for X‐ray diffraction phase analysis or were polished for SEM/EDS analysis. These methods were complementary since they permitted positive identification of the phases and their distribution and composition, respectively.The matrix phase of all systems was γ1 (Ag‐Hg). Cu6Sn5 was found as the major Sn‐rich amalgamation product. The Cu6Sn5 phase forms reaction zones around the Cu‐rich particles with morphological variations from system to system. All amalgams contained the γ (Ag3Sn) phase, but it was microstructurally distinct only in two particle systems. Small amounts of the γ2 (Sn‐Hg) phase were found in three systems. These results suggest that there are important microstructural variations in the new Cu‐rich systems which could eventually result in variations in clinical performance.
The variability of EMG silent periods in TMJ patients
Authors: McCALL W. D. , GALE E. N. , UTHMAN A. A. 
Published: June 2007

SummaryThe variability of the EMG silent period in jaw closing muscles of TMJ dysfunction patients was examined. Considerable within‐subject variability was found in the duration of the silent period. This variability increased with symptom severity. The authors recommend that multiple measurements be averaged to obtain a more accurate estimate of the silent period duration.
Stresses in a cantilever metal‐ceramic bridge in model experiments
Authors: DÉRAND TORE 
Published: June 2007

SummaryThe stresses in the porcelain part of the last anchor crown in a cantilever bridge was analysed when loaded. The experiments were made with a model bridge. The load directions were vertical and horizontal. The critical load at the end of a four unit bridge was calculated to about 200 N. When the load direction was perpendicular to the axis of the pontic the critical load was estimated to 50 N.
Analysis of particles produced at the end of mastication in subjects with normal dentition
Authors: JIFFRY M. T. M. 
Published: June 2007

SummaryA study was made to establish a norm for the frequency distribution of the size of particles produced by masticating a certain food item to its swallowable composition by normal dentate subjects. Only about 80% of the initial weight of food taken into the mouth could be recovered after mastication for particle size analysis. The particles ranged from 53 μm to 4750 μm, showing a positively skewed distribution with a mode value between 600 μm and 1200 μm.
A technique for the production of standard test specimens of aluminous dental porcelain
Authors: HUSSAIN M. A. , BRADFORD E. W. , CHARLTON G. 
Published: June 2007

SummaryA technique has been developed for the preparation of test bars of the different types of aluminous porcelains using the standard laboratory procedures for the preparation of aluminous porcelain jacket crowns. Up to now the investigation of the properties of dental porcelain has been conducted using test specimens produced either by vibration of a slurry of porcelain powder without platinum foil or by grinding from the solid block. These techniques are far removed from the methods used for the production of porcelain restorations in the laboratory. This might lead to a variation in the results achieved by testing porcelain jacket crowns on the one hand and test specimens on the other.
Determination of the usual physiological occlusal position by radiotelemetry—A preliminary report
Authors: JONIOT BERNARD , RICARD‐TOURNIER G. , VIGNEAU C. 
Published: June 2007

SummaryA method is described which allows the tridimensional determination of the occlusal position. The device comprises an intra‐buccal transducer and a remote recorder where the signals received by microwaves are decoded, translated and recorded.The transducer is miniaturized and small enough to be placed within the wax rims of the bite plate of an endetulous patient. As the bite plate is comparable in size to the patient's future denture and the latter is not inconvenienced by wire coming out of his mouth, the experiment takes place in what are normal physiological conditions.The results achieved so far through preliminary clinical experience are encouraging. Further work is in progress.
An excitatory response preceding the silent period in masseter electromyographs
Authors: FUJII HIROYUKI , INUBUSHI YOSHITOMI , MUSHIMOTO EIKO , MITANI HARUYASU 
Published: June 2007

SummaryA masseteric excitatory reflex response preceding the silent period which appears following tapping movement of the jaw, was investigated in order to evaluate its origin. In the pre‐anaesthetic state, the latency of response did not change with the intensity of tapping. However, its amplitude increased depending on the intensity of tapping. The response did not disappear even after the anaesthesia. After the anaesthesia the lighter the intensity of tapping was, the longer the latency of the response, coming up to that of the jaw‐jerk reflex. The pre‐anaesthetic response had an intricate wave form comparing with the post‐anaesthetic one. From the above findings it was concluded that the response must be a complex one in nature originating in the muscle spindle of jaw closing muscles and in a certain receptor of the structures surrounding the tooth.
Oral rehabilitation of functional mesio‐occlusion
Authors: MARUYAMA T. 
Published: June 2007

SummaryFunctional mesio‐occlusion is thought to be uncommon, but, as observed in dental clinics, it may be sometimes mistaken for a true anterior cross‐bite, and unfortunately patients are left without any treatment or they are treated improperly. This may result in mandibular dysfunction and unattractive appearance. There are some clinical methods for the diagnosis of functional malocclusion. They include occlusal analysis on an articulator, radiographic cephalometry, temporomandibular joint radiography, mandibular kinesiography, electromyography and so on. In this article, functional mesio‐occlusion is illustrated using these scientific methods and based on clinical cases to complete oral rehabilitation.
On the early‐stage diametral tensile strength of dental amalgam
Authors: VRIJHOEF MATTHIJS M. A. , SPANAUF ADAM J. 
Published: June 2007

SummaryIt was investigated whether theoretical doubts against the diametral tensile strength test applied to a material such as dental amalgam in the early stage of hardening have practical consequences. The diametral tensile strength values were compared with compressive strengths. The same conclusions may be drawn independent of whether a compressive or a diametral test is used.
The condyle as a stress‐distributing component of the temporomandibular joint
Authors: STANDLEE J. P. , CAPUTO A. A. , RALPH J. P. 
Published: June 2007

SummaryEven though the temporomandibular joint is loaded in function, it often arthroses under heavy use. The effects of stress to the joint are not well understood. This study utilizes three‐dimensional photo‐elastic stress analysis to visualize the intensity and direction of stresses within the mandibular condyle generated by various occlusal forces.Functional stresses were shown to concentrate in the condylar neck, but were reduced within the condylar head due to its elliptical shape. Stress directions within the condyle were found to be non‐preferential, varying with different mandibular positions. This supports the idea that the condyle is designed to receive light varied forces rather than heavy, cyclical unidirectional forces.
Progressive jaw muscle fatigue of experimental tooth clenching in man
Authors: CHRISTENSEN L. V. 
Published: June 2007

SummaryTo determine the onset of subjective fatigue and the subjective endurance of fatigue and pains in the masseter muscle, ten adult male subjects exercised maximal voluntary tooth clenching. Concomitantly, the electrical activity in the masseter muscle was recorded by bipolar surface electrodes and integrated. Onset of subjective fatigue occurred on average 21 s after onset of muscle hyperactivity and the isometric endurance time of the masseter muscle, during which period severe muscle pains were present, was on average 82 s. The electrical muscle activity of the threshold and endurance tests showed a curvilinear configuration (y = a+b logx), and it is suggested that progressive physiological, or peripheral, muscle fatigue accompanied the psychological, or central, endurance of tooth clenching.
Clinical evaluation of high copper amalgam restorations
Authors: RYDINGE E. , GOLDBERG J. , SANCHEZ L. , LAMBERT K. , MUNSTER E. 
Published: June 2007

SummaryA comprehensive clinical investigation of amalgam restorations was undertaken to evaluate the performance of ‘high copper’ amalgams and the methods used to examine the marginal integrity of restorations.Six alloys, Aristaloy CR (A), Dispersalloy (D), Indiloy (I), an experimental ‘high copper’ amalgam (E), Tytin (T), and New True Dentalloy (N) as a control, were randomly placed by four operators in 435 Class 1 and Class II restorations. Black and white 1 x photographs were taken at baseline, 6, 12 and 18 months and evaluated using the method described by Mahler & Marantz (1979). In addition, the U.S. Public Health Service system (Cvar & Ryge, 1971) was used at each recall.An analysis of variance based on photographic scoring indicated significant differences (P < 0.05) among alloys at each recall. The use of Duncan's multiple range test resulted in two homogeneous subsets at 18 months: D, I, E and T, N, A. Six and 12 months recall data showed a close similarity in the rank order of the six alloys. The U.S.P.H.S. system showed no statistically significant differences between the alloys using the chi‐square test, however, at each recall the rank order was comparable to that obtained with the photographic method.
Isometric endurance of masseter muscle in children
Authors: CHRISTENSEN L. V. 
Published: June 2007

SummaryEight children, mean age of 12 years, exercised maximal voluntary tooth clenching to determine the isometric endurance time of the masseter muscle. The endurance time seemed to depend on psychological and/or physiological determinants. The latter might have been Wedensky inhibition, changes in energy metabolism, progressive fatigue and so‐called muscle fitness.
The porosity and roughness of four direct filling resins
Authors: VALCKE C. F. , DUGGAN T. O'D. 
Published: June 2007

SummaryFour direct filling resins were examined in order to compare the roughness and porosity of different materials, mixed by different methods. From each material six specimens were prepared. Each specimen was formed against a Mylar sheet and the Mylar‐formed surface was examined. Subsequently it was trimmed and polished and re‐examined. Each specimen was examined with a microscope using incident light and employing an automatic point‐counting attachment in order to assess the percentage surface (apparent) porosity. Each specimen was also examined with a stylus‐type profile meter. Rt (total roughness height) was recorded for all specimens and Ra (roughness average) was recorded for all polished specimens. The findings support the conclusion that a capsulated resin without an inorganic filler yields a better surface than other resins.
Experimental microleakage around ageing dental amalgam restorations: a review
Authors: JODAIKIN A. 
Published: June 2007

Summary In vitro and in vivo experimental microleakage around ageing dental amalgam restorations has been reviewed. The methodologies, materials and results were examined and discussed. The initial experimental microleakage which occurred around unlined/ unvarnished dental amalgam restorations and the development of leakage around lined/varnished dental amalgam restorations underlines the problem of attaining a permanent effective seal around dental amalgam restorations. The limitations of microleakage studies have been outlined and the importance of an understanding of the chemical changes which occur in the microcrevices stressed. This understanding may facilitate the production of a lifelong successful dental amalgam restoration and perhaps the development of an anticariogenic amalgam type fissure sealant.
The combined application of topical fluoride and fissure sealant—results after 2 years
Authors: LOW T. 
Published: June 2007

SummaryThe effectiveness of combining the application of topical stannous fluoride and fissure sealing using Nuva Seal® was tested in a group of school children over a 2‐year period. The retention rate of the applied sealant was 71.1 %. The caries reduction after 2 years was 76.8% which appears to be slightly better than comparable studies using the sealant alone. Staining of the fissures, which may indicate an uptake of the applied fluoride by the tooth was also observed. Whilst the combined approach theoretically should provide additional protection from dental caries following the loss of the applied sealant, further observations are necessary to substantiate the hypothesis.
Absorption of gas in dental gold alloys during melting
Authors: ENGSTRÖM G. , FREDRIKSSON H. , WICTORIN L. 
Published: June 2007

SummaryThe absorption of gas during heating and melting of pure gold and of two dental gold alloys was studied by gas chromatography. The metals were melted by two methods, i.e. gas‐torch and electric heating. The specimens were analysed regarding the content of hydrogen, oxygen and nitrogen.The amount of nitrogen was not measurable in all specimens. Oxygen gas occurred with rather high values in the two dental gold alloys. The hydrogen content was often larger than the solubility limit. It is proposed that hydrogen often gives pore precipitation. It is also proposed that special caution must be taken during melting to reduce the hydrogen content in the melt before casting. D‐alloy (palladium) demonstrated high H and O values on gas‐torch heating.
The fracture toughness of dental composites
Authors: LLOYD C. H. , IANNETTA R. V. 
Published: June 2007

SummaryThe development of the stress intensification factor (KIC) and the fracture strength (σF) have been determined for a range of composite products. Changes in KIC resulting from storage are equated to the progression of polymerization and the loss or gain of plasticizer. The inherent flaw size, relating toughness to strength, varies in a manner which is more consistent with a matrix dependence than upon any quantifiable filler parameter.