bluuebunny/crossref_metadata_2025 huggingface dataset:
Bite force in patients with functional disturbances of the masticatory system
Authors: HELKIMO EVA , CARLSSON GUNNAR E. , CARMELI YEHUDA
Published: June 2007

In 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

The 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

Characterization 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

Ninety‐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

The 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

In 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

The 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

The 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

An 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

The 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

A 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

A 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

The 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

Measurement 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

Three 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

A 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

The 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

A 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

Intermaxillary 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

Impressions 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

In 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).
Prosthodontic failures in patients with systemic disorders
Authors: LANGER A.
Published: June 2007

When a patient wishes to be treated for dentures, a careful examination and anamnesis have to be made. In the course of the anamnesis a detailed medical and dental history has to be taken, to diagnose any systemic disease the patient might suffer from, such as metabolic, hormonal, autoimmune, neurological, mental or emotional disorders. It is necessary to assess their possible effects and relationship to complaints about previous dentures. The dentures may of course be the main offending factor or contribute to the patient's oral problems, but only when this is confirmed beyond doubt should the dentures be replaced without referring the patient for supportive treatment. In cases of transition from natural or partly natural dentition to complete dentures, these disorders must be given careful attention, since in this critical situation any present systemic instability may trigger clinical symptoms that thus far were sub‐clinical and unfelt by the patient.

No improvement in patients ability to use his dentures properly can be expected unless the primary causative systemic factors have been relieved by specific therapy.

It is noteworthy that the majority of problem cases are women in the postmenopausal period, because of their special susceptibility to disturbances of the systemic homeostatic equilibrium.
Treatment planning for the management of selected dento‐facial abnormalities
Authors: MURRAY C. G.
Published: June 2007

Existing treatment planning aids for the management of dento‐facial abnormalities do not adequately assess the neuromuscular status of the oro‐facial soft tissues. Where an element of mandibular overclosure exists the patient assessment technique provides a reproducible and clinically acceptable occlusal vertical dimension of occlusion. In the three cases treated a functional impression technique for establishing the upper lip support produced a reproducible profile which was both aesthetically and functionally satisfactory.
Biological testing of dental restorative materials in vitro—a review
Authors: BROWNE R. M. , TYAS MARTIN J.
Published: June 2007

In vitro methods for the biological evaluation of dental restorative materials are discussed, with particular reference to the type of cells used, the physical state of the test material, the method of establishing cell‐material contact, and the criteria of cytotoxicity. It is postulated that in vitro methods should provide a reliable assessment of the toxicity of dental restorative materials, but since the current in vitro methods do not mimic in vivo conditions sufficiently closely, the correlation between in vitro and in vivo results is at present poor. The development of in vitro methods more closely simulating in vivo circumstances is advocated.
Limits of perceptibility of condyle displacements on temporomandibular joint radiographs
Authors: KUNDERT MARTIN
Published: June 2007

The present study investigated to what extent condyle positions have to be different from each other in order to be clearly detectable under clinical conditions on serial radiographs of the temporomandibular joints in identical projection. For that purpose of ten test subjects serial radiographs in optimal lateral oblique and identical projection were made with various positions of the joint. The joint was brought to these positions by displacement of the mandible to an exactly known extent with a special device. Evaluation showed that mean differences between condyle positions of 0.61 ± 0.16 mm can be recognized clearly. It was statistically proved that this value did not depend upon the experience of an examiner in reading radiographs but upon the technical quality and the interpretability of the radiographs as well as upon the radiographic dimension of the posterior joint space.
The effect of time on the marginal fracture behaviour of amalgam
Authors: MAHLER DAVID B. , MARANTZ RICHARD L.
Published: June 2007

In this study the effect of time on the marginal fracture behaviour of amalgam was determined. Six alloys in clinical service for up to 6 years were used as a data base and occlusal photographs were categorized according to a standard set of photographs depicting varying degrees of marginal fracture. The standard set of photographs was assigned a linear numerical scale, and the index of extent of fracture was considered to be an arithmetic mean based on this linear scale. An observed patient effect and unequal sample sizes were considered in the determination of both the mean and variance. The results of applying these procedures to the data of this study showed that marginal fracture increased with time for all alloys; that the relative ranking of alloys did not change with time; and that, with certain limitations, early time evaluations can predict long‐term behaviour.
The prosthodontic rehabilitation of selected adults class III malocclusions
Authors: MURRAY C. G.
Published: June 2007

In a previous paper (Murray, 1978) some of the problems associated with currently employed preoperative assessment aids were discussed. Techniques were described for establishing the occlusal vertical dimension of occlusion, and support for the upper lip. The incorporation of these treatment planning aids in the prosthodontic rehabilitation of two adult cases, with class III malocclusions, is reported.
Change in the gonial angle
Authors: FISH S. FRANCIS
Published: June 2007

Cross‐sectional studies have promoted the view that the gonial angle is increased by age and by the edentulous state. Longitudinal studies do not support this view. It is proposed that the data support the concept that the gonial angle may show enlargement or reduction, as may be expected of any bony angular relationship, and that ageing and loss of teeth are not, and should not be expected to be, the sole determinants of such change.
Crevicular temperature rises stimulated by plaque formation
Authors: MAEDA T. , EL GHAMRAWY E. , KROONE H. , RUNOV J. , STOLTZE K. , BRILL N. , Tryde G.
Published: June 2007

In nineteen subjects, temperatures were recorded thermo‐electrically in the vestibular and proximal crevices of fifty‐nine teeth. It was found that the formation of a new plaque was followed by a rise in crevicular temperature. In addition, it was found that the normal as well as the abnormal crevicular temperatures were higher in the mandible than in the maxillae.
Oral recognition of forms and oral muscular coordination ability. A longitudinal study in young adults
Authors: LANDT HORST , FRANSSON BO , ALIN LARS
Published: June 2007

A study has been carried out to investigate the constancy of results in oral recognition of forms (RF‐test) and in tests which demand a fine coordination of the oral muscular apparatus (MA‐test). Twenty examinees with a mean age of 22–5 years were tested with both test forms in 1972 and retested 4 years later in 1976. The performances in the RF as well as in the MA‐test improved considerably.

As to the learning (training) effect in both test forms, the test results acquired by training during the previous period have largely been preserved until the next test period 4 years later.

Individuals with a given capacity to perform either the RF‐ or MA‐test, showed about the same grade of ability 4 years later. The RF‐ as well as the MA‐test seem to reflect a given ability, which, at least in this age‐group, remained constant during a period of 4 years.

These results may be explained by reference to the notion of schema in which some motor‐sensory feed‐back will be stored. The specificity of the perceptual and motor patterns used, may have produced schemata with good resistance against forgetting.
Evaluation of alternative alloys to precious ceramic alloys
Authors: MEYER J.‐M. , PAYAN J. , NALLY J.‐N.
Published: June 2007

In the first part of this study, the microstructures and the mechanical properties of precious, semi‐precious, and nonprecious dental casting alloys for the porcelainbaked‐ to‐metal technique have been determined. The semi‐precious alloys contained only 50 % gold, and palladium, silver, and some base metals. The nonprecious alloys were of the nickel‐chromium type. Discs and miniaturized tensile bars have been cast and tested either in the as cast condition, or after a simulation of the various porcelain bakes. Proof stress, ultimate tensile strength, elongation, and plastic stiffness have been measured and results compared by use of analyses of variance. The microstructure examination shows that the simulation of the porcelain bakes improves the homogeneity of the precious and semi‐precious alloys. Simultaneously, the mechanical properties of the same alloys are also improved. One semi‐precious alloy, still under development at the time of these tests, has its mechanical characteristics markedly dovv'ngraded by the thermal treatments. The nickel‐chromium alloys exhibit the best range of mechanical properties for the porcelain‐baked‐to‐metal technique, when considering the three most relevant properties: proof stress, plastic stiffness, and modulus of elasticity.
Some electromyographic parameters of experimental tooth clenching in adult human subjects
Authors: CHRISTENSEN L. V.
Published: June 2007

Eight adult human subjects exercised maximal voluntary tooth clenching until fatigue and pains were experienced, and could no longer be endured, in the right masseter muscle. The integrated electrical activity in the right masseter muscle was determined as a ratio of the different isometric exercises, and it showed a consistent decrease from onset of fatigue, via onset of pains, to the endurance of pains, possibly because of progressive muscle fatigue. The relative muscle activity might have determined the perception of the moment of onset of fatigue in the masseter muscle, and the perception of the moment of muscle exhaustion, but not the perception of the moment of onset of muscle pains.
Prevalence of symptoms of functional disturbances of the masticatory system in Swedish men
Authors: INGERVALL BENGT , MOHLIN BENGT , THILANDER BIRGIT
Published: June 2007

Subjective and clinical symptoms of mandibular dysfunction and cuspal interferences were studied in 389 Swedish men (median age 32 years).

Impaired chewing function was noted in about 10%, different types of parafunction in 26%, frequent headaches in 5 %, TMJ or muscle pain in 3 % and difficulties in mouth opening in 10% of the men.

Locking or luxation of the mandible was the most prevalent clinical symptom (24%), followed by reduced movement capacity and deviation on opening of the mandible, TMJ‐sounds and muscle tenderness. Sixty per cent of the men had one or more clinical symptoms of dysfunction.

Subjective symptoms of dysfunction were positively correlated with reduced movement capacity of the mandible and tenderness of the masticatory muscles and temporomandibular joints upon palpation.

Positive correlations were found between subjective symptoms of dysfunction and non‐working side interference as well as single tooth contact on the working side. Locking or luxation of the mandible and TMJ‐sounds were positively correlated with single tooth contact on the working side and TMJ‐sounds and muscle tenderness with interferences in the retruded position of the mandible.
A theoretical and clinical investigation into the taper achieved on crown and inlay preparations
Authors: MACK PETER J.
Published: June 2007

The minimum angles of taper that can in theory be formed to various preparations were established for representative dental preparations and operating distances.

These values were compared with the taper of dental preparations formed both under laboratory conditions and in clinical practice, the latter by measurement of taper on the dies of clinically successful crowns and inlays.

A possible explanation for the discrepancy noted between recommended degrees of taper and the tapers produced under clinical conditions was considered to be due to the requirement by a dental surgeon to avoid forming undercuts to the line of withdrawal of a cast intracoronal or extracoronal retainer.
The distribution of nickel in mice.
Authors: BERGMAN B. , BERGMAN M. , MAGNUSSON B. , SöREMARK R. , TODA Y.
Published: June 2007

Metallic restorations are corroded in the oral environment. Corrosion products penetrate into the tissues and are distributed thssroughout the body seeking certain organs and tissues as targets.

The distribution patterns of nickel in albino mice were studied autoradiographically at various periods after an intravenous injection of 63Ni in order to locate the target organs and tissues of nickel.

Wth short survival periods the highest uptake of 63Ni was found in the blood, kidney, urinary bladder, lung, eye and hair follicles. With long survival periods, 3 weeks, the distribution pattern was dominated by high uptake in the lung tissues, central nervous system, kidneys, hard tissues and skin.

The distribution pattern in brown mice was similar to that in albino mice. However, the concentration in the eye and the skin was more pronounced. The importance of release of nickel from nickel containing dental alloys in nickel allergic patients is discussed.
The prevalence of temporomandibular joint disturbances in complete denture patients
Authors: CHOY EUGENE , SMITH DALE E.
Published: June 2007

‘Complete denture patients do not suffer from TMJ disturbances’ is a statement commonly accepted by many dentists and clinicians. This statement is not valid since few dentists include a TMJ examination among routine clinical procedures for complete denture patients. Identification of an edentulous patient with TMJ disturbances is not possible with just a visual examination or the use of a TMJ questionnaire.

The purpose of this investigation was to examine a group of 160 complete denture patients and determine the prevalence of TMJ disturbances among this sample of former and current patients at the University of Washington. The study included a TMJ questionnaire of eighteen questions to test its usefulness in identifying TMJ patients among the sample. All data from the clinical examination were programmed, punched, and processed on a CDC 6400 computer and correlated to selected dependent variables of the questionnaire.

The conclusions from this investigation revealed:

(1) Approximately 15% of the complete denture patients in this sample had TMJ disturbances.

(2) The use of this questionnaire was not very reliable as a primary method of identifying TMJ patients, but it could be useful in screening potential TMJ patients.

(3) Routine examination of complete denture patients should include palpation of the head and neck, and TMJ.

(4) Complete denture patients have TMJ disturbances characterized by muscle tenderness, joint sounds, or restricted movements. They may not necessarily be associated with pain.

(5) The lateral pterygoid muscle is the most common muscle involved with TMJ disturbances in complete denture patients.
Forced eruption: biological and clinical considerations
Authors: STERN NOAH , BECKER ADRIAN
Published: June 2007

The biologic width and its importance in the restoration of teeth that have been fractured down to the level of the osseous crest are discussed. Orthodontic principles and clinical considerations in carrying out forced eruption are outlined. A case report demonstrating the practical aspects of treatment is presented.
On the regulation of interincisor bite force in man
Authors: HELLSING GUSTAF
Published: June 2007

The maximum bite force and the ability to perform a requested interincisor bite force was tested on eight healthy subjects with normal dentition and on five full denture wearers under various conditions.

Anaesthesia of temporomandibular joint (TMJ) capsular and/or periodontal receptors, with or without simultaneous vibration‐induced increase of muscle receptor discharge, did not lead to noticeable changes in these capacities.

It is concluded that in maximal voluntary efforts, as well as in trained and pre‐patterned motor acts, the motor activity may function without significant involvement of peripheral feedback mechanisms. However, all subjects significantly underestimated their bite force in the test series.

Another conclusion from the present study is that neither jaw open nor jaw elevator vibration is of any influence upon the maximum bite force. On the other hand, the maximum bite force significantly increased after the performance of the test series.
The effect of some components on the rigidity of mandibular bilateral free end saddle dentures
Authors: GLANTZ P.‐O. , STAFFORD G. D.
Published: June 2007

One partially dentate person, his remaining teeth being 44, 43, 42, 41, 31, 32 and 33, was simultaneously provided with one maxillary complete denture and three mandibular free end saddle dentures having cobalt chromium alloy skeletons of different design. One denture was constructed with a lingual plate, another with a sublingual and a secondary bar, while on a third denture the major connector consisted of an enlarged secondary bar. On all the dentures occlusal rests were placed on teeth nos 44 and 33.

Rosette strain gauges were placed in the midlines of all the major connectors. The gauges were calibrated on the master cast placed in a universal testing machine.

The clinical recordings were taken from the gauges during one session under repeated loading conditions. Readings were repeated on one denture after removal of (1) the secondary bar and (2) the secondary bar and the occlusal rests. The recordings were used to calculate (I) the principal maximum and minimum strains and (2) the direction of the strains at the points of the bases beneath the centre of the gauges.

The results show that studies of relevant functional deformation patterns of dentures can only be made in clinical experiments. Further, they show that the base with an enlarged secondary bar exhibits more deformation than the other two types of base. Removal of the secondary bar did not significantly increase the deformation of the denture also equipped with a sublingual bar, neither did the removal of the occlusal rests. Both these changes, however, caused changes of the deformation patterns.
Flow rate, sodium and potassium concentration in mixed saliva of complete denture‐wearers
Authors: GABAY EVA LANTZMAN
Published: June 2007

Flow rate, sodium and potassium concentrations in stimulated mixed saliva obtained from eleven elderly (mean age 63) inexperienced denture‐wearers, were determined. Salivary samples were collected at four different dental stages:

1. Before tooth extraction. 2. After tooth extraction.

3. Three weeks after wearing newly constructed complete dentures.

4. Following one year of denture wearing.

Plasma electrolytes were included for comparison. The salivary sodium and potassium concentrations varied from stage to stage without showing corresponding variations in sodium and potassium in the blood. This points to selective action and an active transport system in the salivary cells. The mean flow rate and salivary electrolyte concentration showed a definite significant rise following the wearing of new complete dentures as compared with the previous dentulous and edentulous stages (Period A, non‐denture‐wearers). The mean flow rate was 2 ml/min after denture‐wearing compared to 0‐75 ml/min at the dentulous and edentulous stage (Period A). The stimulant effect represented by the dentures was found to be even more pronounced after one year. Mean sodium and potassium concentration at Period A were at levels of 5.50 and 13.67 mequiv /I respectively, as compared to levels of 23.72 and 19.40 mquiv./l respectively, after insertion of dentures. The difference was significant at a level of P<0.005. Although sodium concentration correlated well with flow rate, potassium concentration did not show any correlation with variations during secretion, following the wearing of dentures.
Capillary rheology of two composite resin systems
Authors: WATTS D. C. , COMBE E. C. , GREENER E. H.
Published: June 2007

The rheological properties of two commercial resin systems, Isopast and Cosmic, were studied in the shear rate range 0.65‐65 s−1 by capillary techniques. Isopast represents a low inorganic filled composite, whereas Cosmic is a conventionally filled system whose resin matrix resembles that of Isopast. All components of both systems obeyed power law dependence of shear stress as a function of shear rate according to the relation In τ= In K + n In γ; values of n for Cosmic catalyst and paste and Isopast paste were of the order of 0.6 whereas Isopast catalyst was of the order of 0.3. Setting systems obeyed a power law relationship during the working time with an exponent n≃0.7‐1.0. Accordingly the systems appear pseudoplastic in component form and slightly pseudoplastic to near Newtonian after mixing.
A simplified technique for determining the occlusal plane in full denture construction
Authors: SPRATLEY MARTYN H.
Published: June 2007

Because of difficulties encountered by students in determining the occlusal plane at the registration stage of full denture treatment, a simple technique which can be easily taught has been devised. Review of literature revealed a wide variety of landmarks and techniques advocated by various authorities and these are discussed. A technique using direct vision is described and a review of a series of patients showed it to be valid for the majority of cases.
The in vitro effect of a glass ionomer cement on dentine and enamel walls
Authors: WESENBERG GRO , HALS EINAR
Published: June 2007

Glass ionomer cement (ASPA®) was inserted in unconditioned class V cavities or in contact with polished ground surfaces of enamel and dentine in twelve teeth. Ground sections of all teeth were examined by microradiography, and four of the sections submitted to electron probe microanalysis. A narrow outer zone of increased radiopacity in the dentine walls was explained by a 5−10% increase of Ca and P. In some sections this zone covered a partly demineralized subsurface zone. The concentrations of F and Al in enamel and dentine were ∼0.3% and 1.5%, respectively, decreasing to <0.1 % at a distance of 16–80 μm (F) and 8–24 μm (A) from the surface. Both F and Al penetrated deeper into the dentine than into the enamel. Decreased Zn values, sometimes concomitant with increased Ca, P and Mg values, were in some instances observed in an outer narrow zone of the dentine walls. It is assumed that like silicate cement, glass ionomer cement must have anticariogenic properties, due to uptake of F and Al in cavity walls.
The energy requirement of the dental cutting process
Authors: WESTLAND IR A. N.
Published: June 2007

The results are presented of research into the efficiency of various forms of dental burs. This research was carried out at the Delft University of Technology in collaboration with the Subfaculty of Dentistry of the Free University of Amsterdam. The process efficiency was measured during burring of both human teeth and amalgam plugs, with diamond burs and tungsten carbide burs at different speeds and diameters of the bur. Only the efficiency of the cutting process was evaluated, disregarding a number of other essential aspects of the burring process, such as the remaining surface quality after burring and the vibrations generated during burring.
The effect of salivary contamination on fissure sealant—enamel bond strength
Authors: THOMSON J. L. , MAIN C. , GILLESPIE F. C. , STEPHEN K. W.
Published: June 2007

The effect of accidental salivary contamination on the retention of fissure sealants is investigated via in Vitro bond tests and scanning electron microscopy. The strength of the bond between sealant and saliva contaminated and washed enamel (168 ± 14 kg cm−2) is not found to be significantly different from the bond strength to uncontaminated enamel (174 ± 17 kg cm−2). Unwashed contaminated enamel gives significantly reduced bond strength (68 ± 11 kg cm−2).
The treatment of hypersensitive cervical abrasion cavities using ASPA cement
Authors: LOW T.
Published: June 2007

This study evaluated the usefulness of the alumino‐silicate polyacrylate (ASPA) or glass ionomer cement in the treatment of hypersensitive cervical abrasion cavities.

Various methods of treatment of hypersensitive cervical abrasion cavities have been described, and all these methods have their disadvantages. The ASPA cement was used to treat non‐carious hypersensitive cervical abrasion cavities in 189 teeth from fifty‐eight adult patients. The patients were followed‐up for periods ranging from 6–15 months. Of the 189 treated teeth, the ASPA restoration was intact in 163 or 86.2%. Seventeen teeth or 9.0% had partial loss of the restorations and nine or 4.8% had complete loss of restorations. With regard to symptoms, 176 or 93.1% of the treated teeth were no longer sensitive to stimuli from the oral cavity following placement of the ASPA restoration. Of the fifty‐eight patients, fifty‐two or 89.7% were completely relieved of all symptoms. Of the remaining teeth eleven or 5.8% reported a reduction in the severity of the symptoms. Only one patient; with both restorations lost, reported no improvement. No case of pulpal death was recorded, and there was no evidence of caries at the margin of any of the restorations.

The results indicate that the method is effective, and it has some distinct advantages over existing methods of treatment of these cavities.
The effects of the incorporation of chlorhexidine acetate on some physical properties of polymerized and plasticized acrylics
Authors: ADDY M. , HANDLEY R.
Published: June 2007

The effects on the water uptake and weight loss of the incorporation of chlorhexidine acetate in heat cured acrylic and an acrylic gel soft liner was determined. Hardness and transverse bend measurement were similarly made for admixtures to heat and cold cured acrylics. Following soaking in water for 87 days the heat cured test specimens demonstrated an initial weight gain followed by a progressive loss, the soft liner test specimens however all showed weight gains. Drying back specimens to constant weight revealed significantly greater weight losses in test compared to control specimens for both the cured acrylic and gel liner. However these weight losses were less than the chlorhexidine content for 5 and 10% admixtures. Hardness and moduli of elasticity measurements were significantly reduced for heat and cold cured acrylics containing chlorhexidine. The property changes observed in the materials would be consistent with the pattern of incorporation of chlorhexidine into the matrix. However, these do not negate the carriage of medicaments in these materials for prolonged delivery within the oral cavity, if employed as rebase or reline materials in existing prostheses.
Electron microscopy samples: replication using dental inlay wax
Authors: MUELLER H. J.
Published: June 2007

A two‐stage replication technique for electron microscopy is described using indirect dental inlay wax. Its application has particular value in the study of dental polymeric materials.
Mechanical and adhesive properties of a newly developed group of pulp capping and base materials
Authors: NEGM M. M. , COMBE E. C. , GRANT A. A.
Published: June 2007

A new group of dental cements for cavity lining and pulp capping is reported. The mechanical and adhesive properties of the cements, which were designated cement I, II and III, were assessed and compared with a commercially available polycarboxylate cement and calcium hydroxide containing material. The experimental cements were mechanically suitable for use as base materials and proved to be adhesive to dentine, especially cement I which gave adhesive bond values comparable to those of the polycarboxylate cement.