bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro chloride corrosion behaviour of Dispersalloy
Authors: SARKAR N. K. , GREENER E. H. 
Published: June 2007

SummaryThe in vitro chloride corrosion behaviour of Dispersalloy has been investigated by anodic polarization as a function of time after trituration (ageing) and compared with conventional dental amalgam. Dispersalloy is a commercial alloy containing a mechanical mixture of Ag3Sn and Ag–Cu eutectic in the ratio 2:1. From measurement of 1 h corrosion potentials it was observed that over a time period of 1 year Dispersalloy became appreciably more noble (potential shift from –500mV to – 350 mV Vs. SCE), whereas the corrosion potential of conventional amalgam remains unchanged.Initial anodic polarization profiles for Dispersalloy indicated presence of y2 and Cu6Sn5 phases as evidenced by presence of the –250 mV peak. However, the current density associated with this peak was about three times less than that of conventional amalgam. As a function of ageing time the polarization profile is shifted in the direction of decreasing current density and after 1 year the –250 mV peak is absent. The anodic polarization profile of conventional amalgam is unchanged after 1 year. The improved corrosion resistance of Dispersalloy is attributed to the formation of Cu3Sn as a function of time due to solid state reaction between Ag–Cu eutectic and y2.
Changes of cheek pressure during swallowing following expansion of the maxillary dental arch in repaired cleft palates
Authors: SAKUDA M. , YOSH1DA K. , WADA K. , KURODA Y. , HAYASHI I. 
Published: June 2007

SummaryCheek pressure during swallowing was measured on six operated complete cleft lip and palate cases (4–8 years of age) before and after expansion of buccal segments of maxillary arch, As control, seven non‐cleft subjects with acceptable occlusion of the same age level were used. Before expansion, the pressures in the cleft cases were much higher than the controls. Immediately after expansion, increase in pressure was observed in cases which received rapid expansion. However, a few months after expansion, most cases showed a decrease in pressure. This is explained as being due to the adaptation of the perioral musculature to the expanded dental arch and/or the disappearance of hyperactivity of the perioral musculature during swallowing.
Bite force in patients with functional disturbances of the masticatory system
Authors: HELKIMO EVA , CARLSSON GUNNAR E. , CARMELI YEHUDA 
Published: June 2007

SummaryIn thirty patients (24 women and 6 men) treated because of dysfunction of the masticatory system at the department of Stomatognathic Physiology, University of Gothenburg, bite force was registered before, during and after treatment had been completed. In the controls, thirty‐six dental students and trainee dental nurses, with no dysfunction of the masticatory system, bite force was registered on two occasions.Bite force was measured between the first molars on each side and between the central incisors. Also finger force was registered. The force measurements were made at five different levels, increasing from very weak to maximum force. Repeated tests of bite force in the control group, made at intervals of about 1 week, gave almost identical results. Bite force in the patient group was lower than in the control group at the first registration but increased with palliation of the symptoms during treatment. There was no significant difference in bite force between the affected and the unaffected side.
Reflex activity in the masseter muscle of young individuals
Authors: WIDMALM SVEN‐ERIK , HEDEGÅRD BJÖRN 
Published: June 2007

SummaryThe monosynaptic, myotatic (jaw jerk) potential (MSP) evoked in the relaxed masseter by a tap on the chin and recorded electromyographically in this muscle (latency 6·3 ms, duration 5·9 ms) was similar in subjects with, or without, TMJ clicking. The latency of the myotatic potential was significantly shorter (5·8 ms) when evoked during isometric contraction. The duration was 5·2 ms. A potential with similar characteristics as the MSP was evoked by TMJ clicking, as we believe by excitation of muscle spindles from tissue transmitted vibrations (latency 5·5 ms, duration 5·6 ms). The TMJ click evoked MSP could in the contracting masseter be followed by silent periods (SPs) both of the early (latency about 10 ms) and the late type (latency about 50 ms). A tap on the chin during isometric contraction of the jaw elevators, was followed by an SP of the early type (latency 12·2 ms, duration 17·5 ms) and sometimes by an SP of the late type (latency 58 ms, duration 18 ms). The late SP occurred significantly more often in patients with TMJ‐dysfunction. The period of lower activity following an MSP can be divided into two phases: a first phase with a complete electrical silence, denoted SP, and a second phase during which the activity is slowly increasing to reach the control level. This latter phase will be called‘depressed activity’(DA) and is introduced as a new parameter. The SP with tooth tapping (latency 10·5 ms, duration 9·4 ms) was similar in groups with or without TMJ clicking. The superimposed MSP (SMSP) preceding the SP at tooth tapping is supposed to be a manifestation of the‘load‐compensation reflex'.
Characterization of porosity of isostatically pressed and sintered nickel‐base powdered metal*
Authors: FUYS R. A. , CRAIG R. G. , ASGAR K. 
Published: June 2007

SummaryCharacterization of the pore structure of compacted and sintered parts made from a nickel‐base powder was accomplished using the mercury porosimetry method. The theoretical density values for the sintered specimens varied from 56.3 to 96.7% which corresponds to a porosity of 43.7 to 3.3%. A maximum interconnecting median pore diameter of 21 μm resulted from a −80/+ 200 mesh powder compacted at 138 MN/ m2 and sintered for 2 h at 1250°C. Photomicrographs of the same sample showed that it had a maximum pore diameter of 200 μm. The interconnected pore volume decreased with decreasing particle size of the powder, increasing compaction pressure, and increasing sintering temperature. Mechanical properties of tensile strength, yield strength, elastic modulus and percentage elongation were correlated with the pore structure. Proper selection of particle size, compaction pressure, sintering times and sintering temperatures should permit parts with controlled porosity characteristics to be produced that possess adequate mechanical properties for application as implants.
Late results of treatment with partial dentures
Authors: CARLSSON GUNNAR E. , HEDEGÅRD BJÖRN , KOIVUMAA KALERVO K. 
Published: June 2007

SummaryNinety‐nine people who were fitted with partial dentures in 1959 were invited to take part in an investigation 13 years later. A questionnaire was answered by fifty‐eight, which means a frequency of 81% if allowance is made for an explainable loss. Of the sixty‐eight partial dentures in these fifty‐eight patients, twenty‐three were still being used, fourteen patients had had their original partial dentures replaced by new ones and three by a fixed bridge, while seven had been replaced by complete dentures. Twenty‐one were no longer used and had not been replaced. Of the fifty‐four patients who originally had a complete upper denture and a partial lower denture, thirty were still available. Following an invitation to take part in a clinical review, twenty‐seven (90%) co‐operated. Most of the patients were in need of treatment (for caries, periodontitis and/or prosthetic treatment). The periodontal injuries were rarely serious. A correlation was found between good oral hygiene and good results of treatment.
Relation between functional disturbances of the masticatory system and some anthropometric, physiological and psychological variables in young Swedish men
Authors: CARLSSON GUNNAR E. , INGERVALL BENGT , LEWIN THORD , MOLIN CARL 
Published: June 2007

SummaryThe relation between functional disturbances of the masticatory system and anthropometric, physiological and psychological variables was studied in 248 Swedish men, aged 18–25 years.No physiological variables and only a few anthropometric variables were found to be correlated with symptoms of functional disorders or to the state of the dentition. Thus, for example, face height was greater in the presence than in the absence of disturbances of the occlusion (mainly occlusal interferences).The psychological variables were found to be most closely correlated with symptoms of functional disorders and the state of the dentition. Men with clinical dysfunction had a lower general level of intelligence than men without. Social adaptation at school was poor in those who reported parafunctions. Men with parafunctions, frequent headache, general muscle and joint symptoms and balancing side interferences had low emotional stability compared with those without such symptoms. Individuals completely free from symptoms of functional disturbances had high emotional stability.
Marginal leakage with different composite restorative materials in vitro
Authors: ERIKSEN HARALD M. , BUONOCORE MICHAEL G. 
Published: June 2007

SummaryIn this preliminary study the degree of marginal leakage was assessed for different cavity designs using both ultra violet‐curing and self‐curing composite restorative materials and sealants. Butt joint restorations placed in etched and sealant primed cavities failed to prevent leakage. Both saucer‐shaped and funnel‐shaped cavities and cavities with rounded margins were able to prevent leakage when the restorations were bonded to etched and sealant primed peripheral enamel. Further, less than 1 mm of gingival enamel available for bonding seemed to be sufficient in most instances to prevent leakage.
Power spectral distribution of the masseter electromyogram from surface electrodes
Authors: DUXBURY A. J. , HUGHES D. F. , CLARK D. E. 
Published: June 2007

SummaryThe power spectral distribution of an electromyogram offers a useful presentation of the myoelectric signal at any level of muscle activity. Various factors which may affect this distribution are considered. A computerized method for obtaining the power spectral distribution for masseter and a study of the effect of bite force and electrode position on this is described.
The influence of percussion, occlusion and mastication on the occurrence of silent periods in masseter muscle activity
Authors: WATT DAVID M. , TURNBULL JAMES R. , SABERI MOZAFFAR , BEYLI MEHMET S. , AGUILAR EDUARDO 
Published: June 2007

SummaryThe occurrence of silent periods in masseter muscle activity was investigated during percussion of the bony structures of the head and neck, during occlusion of the teeth on surfaces of varying hardness, and during chewing of different food‐stuffs. Silent periods were demonstrated on percussion during isometric and isotonic contraction of the masseter muscles and the occurrence of silent periods was influenced by the force of occlusion and by the nature of the surface contacted. Mandibular velocity was investigated during tapping and chewing sequences by ultra‐high‐speed cinematography, but it was not found possible to identify a critical change in mandibular velocity associated with the occurrence of silent periods. More silent periods were observed during the chewing of hard foods than of soft foods and there were more silent periods near the beginning of chewing sequences than towards the end. Differences in latency and duration of silent periods were observed in relation to artificial changes in the occlusion.
Stress distribution within circumferential clasp arms
Authors: MORRIS H. , FARAH J. W. , CRAIG R. G. , HOOD J. A. A. 
Published: June 2007

SummaryAn analysis of stress distributions within circumferential clasp arms with various tapers, was undertaken in an effort to (1) determine the area of maximum stress concentration in both tapered and non‐tapered clasps, and (2) to compare this point of maximum stress concentration with the area of frequent clasp breakage. The non‐tapered clasp showed better distribution of stresses than the tapered clasps. The less favourable stress concentrations could result in eventual failure of the clasp when coupled with other factors such as porosities. The maximum shear stresses in the non‐tapered clasp also were lower than those in the tapered clasps. As the taper of the clasp became more accentuated, the magnitude of the stresses increased and shifted towards the tip of the clasp. The maximum tensile stress calculated in a replica of a chromium–cobalt–nickel clasp was in the order of 34 MN/m2 which is well below the ultimate tensile strength of the alloy. This observation leads to the proposal that failure of clasps is a function not only of design but also of other variables, such as porosities, surface irregularities, and fatigue.
Oral rehabilitation of adult class II, division 1 malocclusion complicated by collapse of posterior occlusion
Authors: STERN NOAH , MICHMAN JULIUS 
Published: June 2007

SummaryThe complications and limitations in rehabilitating an adult woman with class II, division 1 malocclusion and posterior occlusal collapse is described with special consideration given to the aspects of time, the patient's personality and socio‐economic situation. Fixed restorations were chosen for optimum function, comfort and to enhance the patient's emotional security. The importance of an individual treatment approach is stressed.
Quantitative evidence for the helicoid relationship between the maxillary and mandibular occlusal surfaces
Authors: BROWN W. A. B. , WHITTAKER D. K. , FENWICK J. , JONES D. S. 
Published: June 2007

SummaryA method for measuring the transverse inclination of molar teeth is described which enabled significant differences (P < 0·001) between the three molars to be demonstrated for a sample of English Modern (n 24) and Romano‐British (n 20) skulls.No significant differences between the transverse molar inclinations were found for the Bronze Age (n 10) or the Neanderthal (n 8) sample.
A new intra‐oral screw jack
Authors: McMILLAN D. R. , TRYDE GERD , STOLTZE K. , FUJII H. , KATO H. , BRILL N. 
Published: June 2007

SummaryA new pattern of screwjack for assessing the vertical dimension for occulusion utilizing an edentulous patient's proprioceptive sensation is described. It provides a greater range of movement than other, giving infinitely variable heights between 9 and 21 mm. The elements being captive, it cannot come to pieces in use.Laboratory experiments were contrived to define the magnitude of reading errors and the play in the screw threads. It was found that, only in instances where a graduation related closely to the datum mark, did errors of interpretation arise. These were found to exceed the height set for test purposes by 0·1 mm consistently. An error of this order is of no practical significance clinically and is no impediment to such an application of the device. Mean play in the new pattern jacks was 0·01 mm compared to 0·05 mm in the Timmer versions.In a clinical experiment the performance of the screw was compared to that of Timmer. Statistical evidence was found which suggested a functional difference between the two, the new pattern being significantly more accurate.
Musculo‐articular disorders of the stomatoganthic system in school children examined according to clinical criteria
Authors: GROSFELD OLGA , CZARNECKA BARBARA 
Published: June 2007

SummaryThe present investigations were undertaken for establishing the frequency of musculoarticular disorders of the stomatognathic system in healthy children as well as determining their features and degree. The study covered 500 children from Warsaw's primary schools—250 children aged 6–8 years and 250 aged 13–15 years. An incidence of disorder of 56·4 and 67·6% was found in the groups of younger and older children, respectively; their numnber and severity being significantly higher among the latter. The chi‐square test showed no relation between the disorders of the temporomandibular joint and malocclusion or the premature loss of teeth in the group of younger children; in the older group the correlation was significant but of very low degree. The suggestion is made that the correlation between musculo‐articular disorders, malocculusions and loss of teeth, is probably determined by the length of time during which the dysfunction is exerting its effect.
The in vitro measurement of amalgam corrosion rates by the polarization resistance technique
Authors: STAHELI P. J. , von FRAUNHOFER J. A. 
Published: June 2007

SummaryMeasurement of the corrosion rates of three distinctive amalgam alloys (lathe‐cut, spherical and dispersed‐phase) when immersed in three differnt electrolytes, including saliva, is reported. The results indicate that the dispersed phase alloy amalgam exhibits a lower corrosion rate than a conventional lathe‐cut alloy amalgam but is somewhat inferior to a spherical alloy amalgam.
Effect of bevelling on the occurrence of fractures in the enamel surrounding composite resin fillings
Authors: ØILO GUDBRAND , JØRGENSEN KNUD DREYER 
Published: June 2007

SummaryThree different types of cavities: (1) with a 90° cavo‐surface angle, (2) with a bevel at the cavity margin 0·25–0·50mm wide, and (3) with a bevel at the cavity margin 0·5–1·0 mm wide, were prepared in extracted human teeth.Fifteen cavities of all three types were filled with Adaptic®. Fifteen cavities of Type 2 and of Type 3 were filled with Cosmic® and the same number and types of cavities with Prestige®.The fillings were polished 10 min after starting the mix of the composite resins. Fractures in the enamel at the cavity margins were visualized by discoloration with methylene blue.Fractures were observed around all types of cavities, but, for all types of materials, an increased bevel at the margin gave an increased number of fillings without fractures in the enamel.However, great variations in the frequency of fractures were also observed; i.e. Adaptic showing a small frequency, Cosmic a medium and Prestige a great frequency of fillings connected with fractures at the enamel margin.
Influence of different endodontic methods of treatment upon the process of apical closure of immature pulpless human teeth and the structure of the newly formed calcified tissue in apical opening
Authors: VOHINOVIĊ OLIVERA 
Published: June 2007

SummaryA description is given of the pathohistological structure of the calcified tissue in the apical opening of four extracted immature pulpless human teeth treated by various endodontic methods. It is concluded that in the tooth treated by mortal extirpation there was neither histological healing nor any tendency for further apex formation. In both the tooth where vital extirpation was performed and in one of the teeth treated as apical periodontitis, the apices were formed from conglomerates of different calcified tissues, identical to the tissue which was formed under comparable conditions in experimental dogs. In the fourth human tooth also treated as apical periodontitis after treatment the apical opening closed with irregular dentine tissue. In this study consideration was given to the problem of the origin of the odontoblasts which co‐exist with the hard destructive process present in some pulpless teeth. It is concluded that in the case presented in this study the irregular dentine was formed by the same odontoblasts which took part in the process of normal odontogenesis. This fact, should be respected in the course of endodontic treatment of immature pulpless teeth.
Some self‐reported symptoms of temporomandibular joint dysfunction in a population in Northern Norway
Authors: NORHEIM PER W. , DAHL BJØRN L. 
Published: June 2007

SummaryThe distribution of a number of self‐reported symptoms of temporomandibular joint (TMJ) dysfunction, parafunctions and treatment behaviour was studied by means of a questionnaire answered by 94% of a population group of 358 persons aged 20–69 years in Northern Norway.Nine subjects reported pain from the temporomandibular joint (TMJ) when opening their mouth and/or when chewing, while twenty‐one subjects had clicking sounds in the TMJ. Seventeen persons had been grinding their teeth during the previous week. Only seven individuals had ever sought medical or dental advice because of TMJ disorder. Tooth grinding and symptoms of TMJ dysfunction were most common in young people, in people with twenty teeth of more and/or in people from high social classes, whereas differences according to sex and income were small.The low frequency of subjective symptoms of TMJ dysfunction and parafunctions in this population was related to demographical, social, dental and methodological influences.
A study of temperature changes occurring in setting dental cements
Authors: CRISP STEPHEN , JENNINGS MICHAEL A. , WILSON ALAN D. 
Published: June 2007

SummaryA study has been made of the rise in temperature associated with the setting of dental cements. Results are discussed in terms of the chemistry of the cement systems and are related to specification testing and clinical usage. Zinc oxide cements evolve more heat than those based on ion‐leachable glasses, and phosphate bonded cements evolve more heat than polycarboxylate cements.
Effects of intermaxillary elastic traction on orthodontic tooth movement
Authors: STEWART CANDICE M. , CHACONAS S. J. , CAPUTO A. A. 
Published: June 2007

SummaryIntermaxillary elastics are commonly used in orthodontic treatment, yet the exact mechanism by which they effect tooth movement has been unclear. A photoelastic model was produced to simulate this type of therapy in examples of Class II and III malocclusions.In the open situation, inter‐arch activity precipitated occlusal plane rotation; counter clockwise in Class II malocclusion and clockwise in Class III.Comment is made on the force vectors involved when using intermaxillary elastics.
Undercut reproducibility of functional impression materials (tissue conditioners)
Authors: MCCARTHY J. A. , MOSER J. B. 
Published: June 2007

SummaryImpressions of, a laboratory model of an edentulous ridge were made with three commercial tissue conditioners (FITT, Hydro‐Cast and Coe‐Comfort). Combinations of undercut dimensions and tray relief were tested by using three different sized trays with each tissue conditioner. Greater tray relief increased the accuracy of all materials tested; increasing ageing time from 7 to 24 h resulted in little change of accuracy of the stone models poured from the impressions taken.
Condylar displacements related to dynamic and static recordings of the comfortable zone
Authors: KATO H. , FUJII H. , STOLTZE K. , BRILL N. , TRYDE G. 
Published: June 2007

SummaryIn a previous study it was found that the distance between the borders of the comfortable zone was considerably wider when the zone was recorded statically rather than dynamically. However, it was not reported how condylar displacements may be related to the zonal borders. Therefore, an attempt is made in the present study to translate zonal border recordings into the equivalent amount of condylar rotation. Using a dental articulator, it was found that the condyles rotated 4.96°, when the comfortable zone was recorded statically, and 2.50°, when the zone was recorded dynamically. The difference, 2.46°, was statistically significant (P < 0.001).