bluuebunny/crossref_metadata_2025 huggingface dataset:
Tensile strength of the bond between resin to enamel etched with phosphoric acid containing fluoride
Authors: GRAJOWER R. , GLICK A. , GEDALIA I. , KOCHAVI D.
Published: June 2007

The tensile bond strength of Epoxylite 9075 and Enamelite to enamel treated with NaF and SnF2, at two concentrations, in the etching acid (H3PO4) was determined. The average fracture stress of those samples in which fracture occurred in the resin only, may be considered as the tensile strength of the resin, 69·8 + 5·6 kg/cm2. The mean fracture stresses of the Epoxy 9075 systems etched with pure phosphoric acid or with acid solutions containing 0.5 % F salts were significantly higher than those treated with acid solutions containing 2 % F salts. Incorporation of NaE or SnF2 in the etching solutions highly increased the fluoride concentration of enamel. The fluoride increase depended on the fluoride concentration of the etching solution and was greater for NaF than SnF2.
Effect of toothbrush stimulation on temperature of gingival and alveolar mucosae
Authors: KROONE H. , MAEDA T. , STOLTZE K. , BRILL N. , Tryde Gerd
Published: June 2007

Thermometry was used to study the effect of applying a toothbrush to three types of oral mucosae, in forty dental students. Brushing with an electric tooth brush resulted in an immediate fall in temperature, but 3 min later the temperature was significantly higher than before stimulation. The temperature changes were greater in gingival crevice and attached gingiva compared with alveolar mucosa. Moreover, it was found that a static application of the toothbrush produced temperature changes which were equal to those following a dynamic application.
The use of differential scanning calorimetry for the evaluation of dental materials
Authors: McCABE J. F. , WILSON H. J.
Published: June 2007

summary
Thermal changes occurring during the setting of restorative materials have been measured accurately using a differential scanning calorimeter. The results were used to evaluate setting characteristics. The heat of reaction and rate of heat output may be significant in determining thermal damage to the pulp. The heat capacity is related to thermal insulation properties. These properties have been determined and their effect on the efficacy of restorative materials discussed.
Fluoride uptake by cavity walls following application of Duraphat® around amalgam restorations
Authors: BJØRGTVEIT ANNE
Published: June 2007

This study aimed to assess possible fluoride uptake by cavity walls following a single application of Duraphat® around class V or I amalgam restorations which were inserted in seventeen human premolars in vitro and in vivo. Six cavities were lined with one layer of Copalite® insertion of the restorations.

After a week in vivo and 12–24 h in vitro, 200–300 μm thick longitudinal sections passing through the cavities were prepared. By electron probe microanalysis F concentrations ranging from 2000 to 6000 ppm were measured near the surface of the cavity walls. Copalite seemed to inhibit F uptake. The study indicates that F ions released from the Duraphat varnish have been taken up by the cavity walls. Such uptake may influence development of secondary caries (wall lesions) in connection with amalgam restorations.
Concatenation of variations in plaque formation with variations in crevicular temperature
Authors: MAEDA T. , KROONE H. , STOLTZE K. , RUNOV J. , El GHAMRAWY E. , BRILL N. , Tryde Gerd
Published: June 2007

The hypothesis was tested that variations in the temperature of gingival crevices are linked to variations in plaque formation. Fifty‐nine abutment teeth to removable partial dentures were studied during four experiments, under various conditions of plaque formation, i.e. not brushing the teeth whilst wearing and not wearing dentures, and performing ordinary and then specialized tooth brushing whilst wearing dentures. The collation of temperature curves with plaque curves revealed a proportional relationship between the rate and magnitude of plaque formation and the rate and magnitude of the recorded temperature changes. Furthermore, the removal of plaque resulted in a reversal of induced temperature rises. The lowest crevicular temperatures were obtained with the practice of the specialized tooth brushing.
Some subjective‐experiential parameters of experimental tooth clenching in children
Authors: CHRISTENSEN L. V.
Published: June 2007

Twelve children, aged 9–14 years, exercised maximal voluntary tooth clenching until facial pains were experienced and could no longer be endured. The pains were localized in the masseter and temporalis muscles and, occasionally, in the supra‐orbital region. After onset of clenching pains appeared, on average, in 49 s (pain threshold) and they could, on average, be endured for 118 s (pain tolerance). The pain threshold varied significantly between individuals, but not within individuals. The number of pain sites, and the number of teeth in contact during clenching, did not determine the moment of onset of pains, nor the ability to endure pains. The pain tolerance did not seem to be influenced by the pain threshold.
Continuing changes in the contour of the maxillary residual alveolar ridge
Authors: JACKSON R. A. , RALPH W. J.
Published: June 2007

Using a cast measuring technique, the change in contour of the residual maxillary alveolar ridge of patients who have worn dentures for a number of years and are then fitted with new dentures, has been investigated. The study confirmed that even after 30 years of denture wearing, further bone resorption may occur beneath new dentures.
Effects of an occlusal splint on integrated electromyography of masseter muscle in experimental tooth clenching in man
Authors: CHRISTENSEN L. V.
Published: June 2007

Six 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

The 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.
Cultural, clinical and physiological aspects of pain: a review
Authors: CHRISTENSEN L. V.
Published: June 2007

A review is given of selected cultural, clinical and physiological issues pertaining to: is human experience of pain. Special attention is devoted to the modern gate control theory of pain as it applies to the sensory pathways of the fifth cranial nerve; that is, facial pains and some of their associated symptoms and signs.
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

An 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

The 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

The 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

An 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

In 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

A 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

The 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

The 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

The 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

The 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

A 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

A 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

A 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

A 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

Functional 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

It 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

Even 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

To 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

A 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

Eight 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

Four 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

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

The 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

The 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

The 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.
Effect of occlusal splints on the EMG activity of masseter and temporal muscles in bruxism with clinical symptoms
Authors: HAMADA T. , KOTANI H. , KAWAZOE Y. , YAMADA S.
Published: June 2007

An electromyographic study of the masseter and anterior temporal muscles was performed on fifteen bruxism patients with clinical symptoms such as muscle pain, fatigue and tenderness. The slopes of the voltage tension (V/T) curves (calculated as the value of the relative inclination between the integrated electromyogram and the biting force) were compared before and after treatment with an occlusal splint. Following use of the splint, the steep slopes of the V/T curves, common in bruxism, became gentle and similar to those of healthy subjects. The differences found in the slopes of different types of bruxism (grinding, clenching, grinding and clenching) might be useful as a diagnostic tool. Follow‐up recording of the slopes was considered to be a useful indicator of treatment effectiveness.
Muscles involved in voluntary mandibular retrusion in man
Authors: DUTHIE N. , YEMM R.
Published: June 2007

It is generally accepted that voluntary mandibular retrusion, with the mouth closed, is brought about by contraction of the posterior fibres of the temporal muscle. The present experiments have shown that, in each of a small series of subjects, activity of some submandibular muscles, normally associated with jaw‐opening, was involved. It is suggested that a retruded posture is the effect of balanced activity of both temporal and submandibular muscles. This finding can be confirmed by palpation.
Analysis of the mandibular relationship of TMJ dysfunction patients using the Mandibular Kinesiograph
Authors: MARUYAMA TAKAO , MIYAUCHI SHUHEI , UMEKOJI EISHUN
Published: June 2007

Analyses of the relationship between centric relation and centric occlusion were performed using the Mandibular Kinesiograph to show the abnormality of mandibular positions of the TMJ dysfunction patients.

The distance between centric relation and centric occlusion in antero‐posterior, left, and linear direction showed significant differences between the normal subjects and the TMJ dysfunction patients. In the TMJ dysfunction patients, the number of the subjects who showed larger deviation between centric relation and centric occlusion increased remarkably when compared with normal subjects.

It is suggested that the slide between centric relation and centric occlusion can be one of the causes of the TMJ dysfunction.
Evaluation of the bonding of cervical restorative materials
Authors: VOUGIOUKLAKIS G. , SMITH D. C. , LIPTON S.
Published: June 2007

Variable results have been reported for the bonding of cervical lesion restorative materials to enamel and dentine. The effect of surface condition on bond strength was studied for two glass ionomer and one polycarboxylate cements and one composite resin material.

Flat surfaces of human enamel and dentine, prepared by wet grinding on 600 grit silicon carbide paper, were treated respectively with water, phosphoric acid, citric acid, EDTA and/or remineralizing solution. Using an improved bonding device the cements and the composite resin were bonded to the prepared enamel and dentine surfaces. After 24 h in water at 37°C a tensile bond strength was determined. The bond fracture surfaces were examined in the scanning electron microscope. The results showed good bonding of the materials to enamel after the recommended surface treatments with cohesive failure and values 60–120 kg/cm2

Bonding to dentine was more variable and was critically dependent on surface preparation.

Caulk‐ASPA bond strengths that were obtained after various treatments ranged from 34 kg/cm2 (untreated dentine) to 54 kg/cm2 (citric acid treatment).

Fuji ionomer bond strengths that were obtained after various treatments ranged from 42 kg/cm2 (citric acid treated dentine) to 56 kg/cm2 (EDTA treated).

Durelon bond strengths that were obtained after various treatments ranged from 24 kg/cm2 (citric acid treated dentine), to 69 kg/cm2 (remineralizing solution treated dentine).

The bond strengths that were obtained with Cervident after various treatments ranged from 0 kg/cm2 (untreated dentine) to 30 kg/cm2 (phosphoric acid treated dentine plus the adhesion promoter).

SEM examination showed micromechanical bonding through penetration into dentinal tubules for all materials.
Identifying the denture space
Authors: NEILL D. J. , GLAYSHER J. K. L.
Published: June 2007

In the absence of pre‐extraction records, the positioning of teeth on complete dentures is a somewhat arbitrary procedure. The present study was designed to evaluate a number of different criteria for tooth placement.

Miniature foil strain gauges were used to measure the forces brought to bear on complete dentures by the lingual and peri‐oral musculature.

Previous studies of the pattern of post‐extraction resorption found that the vestige of the lingual gingival margins of the maxillary teeth could be identified on the cast and it was suggested that these biometric guides are reliable for the correct placement of the upper artificial teeth. The results reported confirmed the use of biometric guides to tooth placement as a reliable method of positioning the teeth in Class I edentulous cases.
Rheological aspects of non‐eugenol periodontal dressing materials
Authors: WATTS T. L. P. , COMBE E. C.
Published: June 2007

Three dressing materials were studied using two different methods of viscometry. The rheological characterizations are discussed with reference to clinical needs, and limitations of the experimental method are also considered. Suggestions are made for desirable rheological properties of future materials.
Perception of vertical dimension
Authors: GAMON JOHN A. , WRIGHT SUSAN M.
Published: June 2007

Ten edentulous adults were investigated to learn more about the preferred vertical dimension of occlusion (PVDO) and the comfortable zone. A screw jack device was employed, using the forced‐choice and external approach methods. The dimensional discrimination ability of each subject was assessed at the mean PVDO, and at points 3 mm above and below it.

For each subject, both the forced‐choice and external approach methods gave a mean PVDO value which was reasonably constant. The comfortable zone widths were less consistent. In all but two of the subjects the mean PVDO values appeared consistent with a clinically acceptable occlusal vertical dimension.

No relationship was found between the dimensional discrimination ability of the subjects and their definition of PVDO and comfortable zone.
Lip morphology and area changes associated with surgical correction of mandibular prognathism
Authors: WEINSTEIN S. , HARRIS E. F. , ARCHER S. Y.
Published: June 2007

Changes in lip morphology and area, measured in two dimensions from standardized lateral head films, were assessed in a series of twenty adults at three times: pre‐surgically, 8–14 months post‐surgically, and a long‐term follow‐up at 5–7 years. All individuals received the same, single surgical procedure (Obwegeser sagittal split for correcting mandibular prognathism. Upper and lower lip changes were quantified as millimetres displacement of the lip centroid vertically and horizontally, plus changes in cross‐sectional area. Direction and amount of change, its dependency on the amount and kind of surgically induced symphyseal changes, and the intercorrelations among lips and among lip and symphysis variables were statistically evaluated, both univariately and multivariately. Three measures are made of symphysis change: horizontal and vertical repositioning and amount and direction of rotation. Horizontal repositioning primarily affected the lengthening and areal increase of the upper lip. Vertical repositioning had its major influence in the height and cross‐sectional area of the lower lip: a superior shift of the mandible made the lower lip shorter, more protrusive and smaller in area; an inferior shift produced an increase in lower lip height with increased area. The third variable, symphyseal rotation, had its greatest influence on the labial‐lingual shift of the upper lip's centroid. The long‐term follow‐up showed little change from the 1 year post‐operative conditions; equilibrium of the soft tissue components was then achieved fairly soon after surgery.
A laboratory and clinical study of Trevalon® denture base material
Authors: MURPHY W. M. , HUGGETT R. , HANDLEY R. W.
Published: June 2007

Trevalon is a denture base material which can be cured by three basic alternative curing cycles, thus providing a choice of processing technique which can be selected to suit laboratory or clinical needs. The flexibility of working properties is probably due to the interaction between on the one hand, the high molecular weight of the powder and on the other hand, the particle size distribution which are important factors influencing the doughing time (14 min), working time (40 min) and the exothermic reaction. The effect of each curing cycle upon the following properties of the material was investigated; dimensional accuracy, Young's modulus, modulus of rupture, impact resistance, water sorption, indentation resistance, creep and transverse bend behaviour. The particle size and molecular weight distribution of the powder were also evaluated. A clinical investigation of Trevalon was carried out by constructing complete dentures for a sample of patients, divided into three groups, each group having dentures processed by one of the three alternative curing cycles. Although some laboratory tests demonstrated that there were statistically significant differences between specimen bases, no clinical differences were recorded between dentures 1 year after construction.
In vitro plaque formation on commonly used dental materials
Authors: DUMMER P. M. H. , HARRISON K. A.
Published: June 2007

An in vitro method has been developed for the study of microbial plaque formation on commonly used dental restorative materials. Standard samples of the materials to be studied are suspended in a complex culture medium inoculated with a bacterial suspension. The samples are transferred daily into freshly inoculated medium for a total of 4 days. The resultant microbial plaques are then graded, weighed and assessed for a number of colony forming units (viable count).

In this preliminary experiment samples of amalgam, composite cement, gold and porcelain were examined. Significantly less plaque was formed on amalgam than on any of the other materials.
A retrospective study of the fit of jacket crowns placed around gold posts and cores, and the associated gingival health
Authors: TURNER CHRISTOPHER H.
Published: June 2007

A retrospective study has been carried out of the marginal fit and associated gingival health of jacket crowns placed around gold posts 5 years previously. Crown fit was classified as either visibly or palpably satisfactory, overhanging or deficient. 67.2% of crowns showed one or more discrepancies of marginal fit, and this varied with the position around the tooth. Palatal margins of maxillary porcelain jacket crowns fitted poorly and there was frequent caries at this site. Periodontal pocketing developed mesially and distally, and little gingival recession. In contrast gingival recession, exposing the crown margins, occurred frequently labially and palatally, but the mean periodontal pocket depth remained within normal limits.
Maximal bite force with centric and eccentric load
Authors: WIDMALM SVEN ‐ ERIK , ERICSSON SVEN GOTTMAR
Published: June 2007

Premolar bite force was measured conventionally with a pressure transducer. During biting the tips of the buccal cusps made contact with the transducer. It was shown that the maximal bite force increased significantly if the eccentric load on the upper premolar was made centric and axial with respect to the transducer by covering the whole occlusal surface of the tooth with a plastic filling. Possible neurophysiological explanations of the difference in bite force are discussed. It is concluded that biting on a pressure transducer with an eccentric load cannot give a fair estimation of the true value of the maximal bite force during clenching in the position of intercuspidation.
The measurement of masseteric silent periods after experimental tooth grinding
Authors: COX P. J. , AL‐KHATEEB T. L. , ROTHWELL P. S. , DUXBURY A. J.
Published: June 2007

Masseteric silent periods were recorded in normal subjects who performed experimental bruxism. All subjects showed a significant increase in silent period duration immediately following and 3 h after a session of experimental bruxism. The silent period had returned to presessional levels by 3 weeks.
Contacts in maximal occlusion
Authors: BATTISTUZZI P. G. F. C. M. , ESCHEN S. , PEER P. G. M.
Published: June 2007

Occlusion, defined as the presence of contact of antagonistic teeth, has been measured. This has been done by measuring the amount and magnitude of holes in bite registration materials taken from nine persons with complete natural dentitions.

In spite of clear differences between the bites found by inspection, small differences have been found by measurement. Bite‐, day‐ and testee‐effects were controlled. The implications of the findings are discussed in terms of reliability and also of the epidemiological and clinical applicability of the method.
Reproducibility of chewing rhythm and of mandibular displacements during chewing
Authors: JEMT TORSTEN , HEDEGÅRD BJÖRN
Published: June 2007

In a small group of individuals the chewing behaviour was recorded through light‐emitting diodes in the Selspot system repeatedly over a 7‐month period. The test food was crispbread of a standard size. It was shown that a characteristic chewing pattern can be recognized in each test person, and that the pattern was stable during the test period with only insignificant variations in chewing rhythm and magnitude of mandibular displacement.
Subcutaneous tissue response in rats to an aluminoborate cement
Authors: WATTS TREVOR L. P. , BERTENSHAW BARRY W.
Published: June 2007

In the interests of producing an improved periodontal dressing material, adhesive cements are under consideration. A new glass ionomer system—aluminoborates—shows some potential in this respect, and a relatively soluble formulation was chosen for a simple biological test in rats, by means of implantation in polypropylene tubes. As a positive control, the widely used aluminosilicate cement Aspa® was employed, and empty tubes were used as negative controls. A simple scoring system using interval measurements was employed, and showed no difference at the 5% level between the experimental cement and either control, although slight differences were discernible between controls. The study also indicated that the side of a filled tube is not the best control for assessment of reaction at tube ends.
The masseteric silent period following experimental bruxism in subjects wearing acrylic anterior bite planes
Authors: COX P. J. , ROTHWELL P. S. , DUXBURY A. J.
Published: June 2007

Masseteric silent periods were recorded in normal subjects who performed experimental bruxism whilst wearing an acrylic anterior bite plane. No significant increase of the silent period duration occurred. The results are compared with similar studies without the anterior bite plane.
Denture mobility and bolus position during mastication in patients wearing conventional and pelotte‐retained full upper dentures: a cineradiographic study
Authors: KARLSSON STIG
Published: June 2007

With cineradiographic technique an assessment was made of the denture mobility of conventional and pelotte dentures in the upper jaw and of the position of the bolus during chewing of meat and bread. Five randomly selected edentulous patients with moderate alveolar ridge resorption rehabilitated with dentures of conventional design, and another five with dentures furnished with subnasal retentive pelottes, were incorporated in the study. Cineradiographic registrations were made in lateral and frontal projections with a picture frame speed of 38/s.

Analysis of the cineradiographic films revealed only small differences for the denture mobility for the two patient groups. This indicated in the patients with severe ridge resorption, an obvious reduction of denture displacement through the use of the nasal pelotte or prong. The displacement was of similar magnitude as for those dentures where an alveolar ridge creates effective retention and limitation of horizontal movements. The analyses of the bolus position during chewing gave the information that in all individuals wearing pelotte dentures, the bolus was positioned more distally, than for patients with conventional dentures. Presumably this was in order to reduce discomfort in the frontal region, i.e. the region of the pelottes. Patients with conventional dentures showed a more even distribution of the bolus to all regions.
A method for sampling the cavity wall/material interface for microbiological culture
Authors: BROWNE R. M. , SIDAWAY D. A. , TOBIAS R. S. , BOVIS S. C. , BRITTEN A. S.
Published: June 2007

A punch method for sampling the cavity wall/material interface for microbiological culture is described. Good correlation was obtained between the recording of micro‐organisms by this method and from histological sections.
Influence of experimental interfering occlusal contacts on the activity of the anterior temporal and masseter muscles during submaximal and maximal bite in the intercuspal position
Authors: SHEIKHOLESLAM A. , RIISE C.
Published: June 2007

The effects of an intercuspal occlusal interference on the pattern of activity of the anterior temporal and masseter muscles during submaximal and maximal bite, were studied in eleven volunteers with complete, natural dentitions.

The results show that, during maximal and submaximal bite an occlusal interference (about 0.5 mm) in the intercuspal position is able to disturb the almost symmetric pattern of muscular activity in the anterior temporal and masseter muscles. Further, the level of muscular activity during maximal bite decreased significantly in all muscles studied. In some subjects, the decrease of muscular activity could still be observed one week after insertion of the interfering contact. After eliminating the interference, the muscular co‐ordination pattern improved and the level of muscular activity increased significantly.