bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigations on the relation of dysgnathias and S‐sound pronunciation
Authors: MEHNERT T.
Published: June 2007

A registration‐form phonetic test has been developed which incorporates an established method for checking fine motor skills. Using an objective measuring and computing technique (electro‐acoustic sound analysis according to the sound‐seeking method), the author studied the pronunciation of the S‐sound of one group of eugnathic and three groups of dysgnathic test persons. There were significant differences in sound characteristics between the normal group and all groups with dysgnathia (P=0.001). Therefore it is considered that not every patient with an anomaly of the tooth position must have a disturbance of the S‐sound. In contrast to the relatively narrow variations in the normal group, in all groups with dysgnathia considerable dispersions were registered. The anterior open bite occupies first place with regard to its susceptibility to disturbances of the S‐sound. The statistical analysis of the partial energy values of all the S‐sound spectra revealed typical normal behaviour on the one hand, and characteristic differences between the groups with dysgnathia and the group with eugnathia on the other. The information which is most important for the valuation of the S‐sound are contained in the frequency area up to 9 kHz.
Periodontal disease in partial denture wearers—a biological index
Authors: WILDING R. J. C. , REDDY J.
Published: June 2007

Studies on the adverse effects of partial dentures on the remaining tissues require both a yardstick of measurement to record the level of oral disease, and the use of controls, preferably within the same patient. A method was devised for pooling the individual values related to the level of periodontal disease on abutment and control teeth in partial dentitions. The difference in these combined values was expressed as the Biological Price. This value provided a useful means of evaluating partial denture designs and patient features, in attempting to assess the major contributing factors responsible for the Biological Price levied by the denture.

Whilst wearing an acrylic partial denture at night adds to the price paid by the remaining tissues, the mechanical features of the partial denture, and the overall features of the patient and his remaining dentition appear to be insignificant in determining the Biological Price.
The prevalence of temporomandibular joint dysfunction in edentulous non‐denture wearing individuals
Authors: WILDING R. J. C. , OWEN C. P.
Published: June 2007

This study reports on the prevalence of temporomandibular joint dysfunction in a sample of fifty‐one edentulous non‐denture wearing individuals. In comparison with other studies using similar criteria, and considering the anomalous mandibular postures observed, this sample of patients appears to have a low prevalence of dysfunction. Loss of vertical occlusal height on its own may not be responsible for the temporomandibular joint dysfunction occasionally seen in denture wearers with reduced vertical height. The possibility that posterior occlusal wear producing incisal interference is an aetiological factor, is discussed.
Radiological findings in 1135 edentulous patients
Authors: KEUR J. J. , CAMPBELL J. P. S. , McCARTHY J. F. , RALPH W. J.
Published: June 2007

A sample consisting of 1135 edentulous patients with clinically healthy denture bearing areas, was examined radiologically. It appears that the diagnostic yield is high whereas the expected radiation induced risk is low. Patients should therefore be examined radiologically prior to full denture construction.
The accelerative component of EMG in bite force development in man
Authors: WASTELL D. G. , DEVLIN H.
Published: June 2007

Masseter EMG and bite force recordings were made from six subjects. Multiple regression analysis was performed and an equation produced relating EMG and bite force in SI units. Evidence is presented for a component of masseter EMG which can be related to the acceleration of bite force during onset of a clench.
Effect of clasp design on gingival health
Authors: BAZIRGAN M. K. , BATES J. F.
Published: June 2007

A comparison has been made of the effects on the gingivae of occlusally and gingivally approaching clasps. The effect on the gingivae has been assessed by measuring plaque accumulation, crevicular temperature and microbial distribution in patients and students wearing appliances. Habitual and nil oral hygiene regimes have been used to demonstrate changes. It was concluded that the gingivally approaching clasp is potentially damaging.
Migration of teeth in shortened dental arches
Authors: WITTER D. J. , VAN ELTEREN P. , KÄYSER A. F.
Published: June 2007

In shortened dental arches (SDA) the remaining premolars tend to migrate distally. This may lead to a decrease of the vertical dimension, resulting in an increased load on the anterior teeth. Consequently the number and intensity of the occlusal contacts between the front teeth increase. This may result in interdental spacing in the upper front region. In this study the pattern of migration of the teeth in subjects with SDA (n=60) is described. The SDA group is compared with subjects having complete dental arches (n=72). Although a systemic effect of SDA has been found on interdental spacing for subjects under 40 years of age, it is concluded that this migration is within acceptable levels.
The influence of sleep duration on headache pain and frontalis EMG
Authors: MOSS R. A. , McCLURE J. T. , JACKSON M. C. , LOMBARDO T. W.
Published: June 2007

Recent evidence has been presented suggesting that ‘depression’ headaches and classic migraines may be related to extended sleep duration. This analogue study was designed to evaluate the possibility that mild to moderate headaches induced by excessive sleep might be related to increased muscle activity. Eight subjects who experienced headaches as a function of increasing sleep duration by 2 h were evaluated in headache (i.e., extended sleep) and a non‐headache (i.e., normal sleep) conditions. Sex‐ and sleep‐duration matched controls were evaluated under the same sleep conditions, although none experienced headaches. Frontalis electromyographic (EMG) data were evaluated in a 2 × 2 analysis of variance. The results indicated no EMG differences between groups or across sleep conditions, even though all experimental subjects experienced headaches on the extended sleep night. Discussion focuses on the implication of these results for future headache research.
Follow‐up study of silent periods in complete denture wearers
Authors: TALLGREN A. , McCALL W. D. , MANSOUR N. N. , ASH M. M.
Published: June 2007

Electromyographic silent periods in response to chin taps during clench were recorded from the anterior temporalis and masseter muscles. Ten complete denture wearers were observed up to the 1‐year stage of denture wear and eight patients up to the 2‐year stage. Silent periods were also recorded from patients clenching on paper rolls in place of the dentures.

Regarding the patterns of the silent periods, similar observations of double silent periods were made as in our previous study up to the half‐year stage of denture wear (McCall, Tallgren & Ash, 1979). The frequency of the double silent periods was 13.8% at the 1‐year stage and 7.3% at the 2‐year stage.

The mean duration of the silent periods did not differ significantly at the 1‐year and 2‐year stages. The mean silent period duration when clenching on paper rolls without dentures in the mouth was significantly shorter than when clenching with the dentures.
Digital phonoarthrometry of temporomandibular joint sounds: a preliminary report
Authors: CIANCAGLINI R. , SORINI M. , DE CICCO L. , BRODOLONI F.
Published: June 2007

A new technique is presented for recording and evaluating the dysfunctional TMJ sounds on an objective basis. The physical implications related to TMJ phonoarthrometry (PAM) are discussed and three cases are presented. The phonoarthrography and the digital phonoarthrometry presented in this paper can be a useful harmless diagnostic tool. Differential diagnosis of TMJ pathology is possible on the basis of an acoustical analysis and it is hoped that future investigation will confirm these observations.
The orthopantomogram, an aid in diagnosis of temporomandibular joint problems. I. The factor of vertical magnification
Authors: HABETS L. L. M. H. , BEZUUR J. N. , VAN OOIJ C. P. , HANSSON T. L.
Published: June 2007

As an orthopantomogram provides bilateral information, it seems to be an efficient tool for screening for arthropathy of craniomandibular disorders. An experimental model was designed and constructed to resemble a human mandible. By changing the position of the model in the horizontal plane of the orthopantomograph, nine different images were analysed for changes of vertical magnifications. Emphasis was put on large parts of the mandible like the condyle. In positions that had been altered less than 10 mm from the originally centred position of the mandible in the orthopantomograph, vertical differences between the left and right sides were less than 6%. Observed condylar asymmetries within a 6% difference might, therefore, be due to technical failures.
Patient satisfaction after insertion of an osseointegrated implant bridge
Authors: HOOGSTRATEN J. , LAMERS L. M.
Published: June 2007

The general and specific satisfaction of patients treated with a jawbone‐anchored bridge was compared with their pretreatment satisfaction with dentures (condition 1, n=31). Patients who asked for information on the osseointegration method but did not apply for treatment (condition 2, n=32), and a group of patients that did not ask for information (condition 3, n=10) were also questioned on their satisfaction with dentures. The results indicated that condition 1 subjects were both socially and physically substantially more satisfied with their bridge than with their earlier dentures. On all satisfaction measures condition 3 subjects indicated more satisfaction with dentures than either condition 1 or condition 2 subjects. There were no significant differences between the three groups on several personality characteristics (neuroticism, test‐taking attitudes, internal/external control). Condition 3 subjects were less extrovert (socially oriented) than the other subjects. Condition 1 subjects made several suggestions towards improvement of the pre‐ and post‐operation phase, concerning the amount of pain involved and the cleaning of the bridge, etc.
Force transmission and retentive capabilities utilizing labial and palatal I‐bar partial dentures
Authors: HIGHTON R. , CAPUTO A. , MATYAS J.
Published: June 2007

A maxillary photoelastic model was constructed to determine the retention and force transmission characteristics of a bilateral distal extension base partial denture. Comparisons were made using palatal and labial I‐bars. It was shown that there were no significant differences in retention and force transmission between palatal and labial I‐bars. From a stress and retention standpoint, it may be concluded that the use of palatal I‐bars is a viable alternative to the labial I‐bars, especially where aesthetics is of primary concern.
The amplitude distribution of electromyographic activity in painful masseter muscles during unilateral chewing
Authors: HAGBERG C.
Published: June 2007

The aim of this study was to investigate whether the amplitude distribution of electromyographic activity (EMG) in terms of muscular load revealed any differences between patients with painful masseter muscles and referents* during the chewing of an almond and of gum. The relative masticatory forces of the masseter muscle and the anterior temporal muscle during chewing were calculated by a transformation of the muscular load levels of EMG activity (μV) to load levels of relative masticatory force (%RVC). This was done by regression in reverse of an isometric reference voluntary contraction (RVC) for EMG versus bite force biting on a bite‐force sensor. The maximal bite‐force values for patients and referents were similar. The relative masticatory force for chewing an almond was higher than that for gum‐chewing. The peaks of the relative masticatory forces were similar for both patients and referents. During the chewing of an almond the relative masticatory forces of the masseter muscle below the peak load were higher for patients than referents. During gum‐chewing the patients used higher forces than referents for 70% of the total chewing time analysed. This also applied to the anterior temporal muscle when chewing an almond. Estimates of the peak masticatory forces were calculated in newtons.
Partial edentulism, prosthetic treatment and oral function in a Dutch population
Authors: BATTISTUZZI P. , KÄYSER A. , KANTERS N.
Published: June 2007

The aim of this study was to gain a better insight into the location and frequency of prosthetic replacements and the consequences of tooth loss on oral function. The sample, stratified according to socio‐economic class and age, consisted of 750 subjects. The investigation was done by questionnaire and clinical examination. In the lower social levels the percentage of removable prostheses was lower than in the higher levels. An average of 60% of all open tooth spaces were not prosthetically restored. In the lower jaw 1 to 3 free‐end spaces were completed with removable partial dentures (RPD). The present study did not support a relationship between missing teeth or number of contacting pairs and the functioning of the dentition. The distribution of antagonistic contacts in the dental arch seems to be of more importance.
Limited mandibular mobility and potential jaw dysfunction
Authors: BALTHAZAR Y. , ZIEBERT G. , DONEGAN S.
Published: June 2007

This investigation studied relationships between signs and symptoms of potential mandibular dysfunction and limitations of maximum active depression and maximum active lateral excursion of the mandible in young adult males. Mouth opening capacity was not associated with symptoms and signs thought to be clinically indicative of the status of the mandibular locomotor system. Limitations of mandibular lateral excursions, on the other hand, were associated with signs and symptoms of potential mandibular dysfunction, but not with signs and symptoms from the tem‐poromandibular joints.
Properties of a modified cross‐linked silicone for maxillofacial prostheses
Authors: FARAH J. W. , ROBINSON J. C. , KORAN A. , CRAIG R. G. , HOOD J. A. A.
Published: June 2007

A dimethyl siloxane‐triacetoxy terminated silane, Type A adhesive, can be modified with the base component of a medium grade polydimethyl siloxane with vinyl groups, MDX 4‐4210, to produce more pliable maxillofacial prostheses. The mechanical properties of samples with various Type A adhesive/MDX 4‐4210 ratios were determined. Addition of the MDX 4‐4210 base decreased the hardness, modulus, and ultimate tensile strength, while the percentage elongation increased. The initial tear strength was relatively constant for the various ratios except for the 50/50 mix, where a 50% decrease was observed. The ability to obtain different mechanical properties by using various ratios of Type A adhesive and MDX 4‐4210 could result in the production of maxillofacial prostheses which will more closely stimulate the properties of facial tissues.
The silent period in the masseter and anterior temporalis muscles in young adult subjects unaware of mandibular dysfunction symptoms
Authors: FURUYA R. , ZULQARNAIN B. J. , HEDEGÅRD B.
Published: June 2007

In fourteen individuals unaware of mandibular dysfunction symptoms, latency and duration of the silent period in the masseter and anterior temporalis muscles at tooth tapping and jaw jerk were reasonably reproducible after 5 weeks and 5 months. Although the subjects felt no discomfort in the stomatognathic system, in some of them mild to moderate muscle tenderness, TMJ sound and occlusal disharmony were found at clinical examination. The relationship between these symptoms and the silent period was analysed. Muscle tenderness was the only factor to affect the silent period. The subjects with muscle soreness had a shorter duration of the silent period than the subjects without such symptoms.
Glass ionomer cement: 10 years of clinical use
Authors: KNIBBS P. J.
Published: June 2007

Glass ionomer cements have been commercially available for 10 years. Research has led to the production of improved formulations and the material is now advocated for use in a number of clinical situations. The aim of this review is to bring together the findings of published studies that provide information on the clinical uses and performance of this material.

The opening section looks at the biocompatibility of the glass ionomer cements. Their clinical handling and techniques for use are then discussed. Finally, specific clinical uses are considered in the light of published clinical data.

The glass ionomer cements appear to offer the profession many benefits and they are proving to be successful in a variety of clinical situations. Improvements in strength, abrasion resistance and colour matching will widen the scope of their application still further.
A comparative study between two randomly selected samples from which to derive standards for craniofacial measurements
Authors: SARHAN O. A. , NASHASHIBI I. A.
Published: June 2007

The present study was performed to derive cephalometric standards for Saudi Arabian boys aged from 9–12 years. The sample was then compared with a British sample aged 9–12 years to detect statistical differences. The differences between both samples demonstrated a slightly prognathic Saudi face, more protrusive upper and lower incisors, and low Gonial and saddle angles.
The amalgam margin angle, marginal breakdown and adjacent caries in occlusal enamel, a pilot study on extracted teeth
Authors: GRAJOWER R. , NOVICKAS D.
Published: June 2007

The object of this study was to determine for amalgam restorations the relationship between marginal breakdown and (i) over‐ or undercarving; (ii) the amalgam margin angle (AMA); and (iii) the incidence of carious occlusal enamel adjacent to the restoration. Fifty‐two extracted human teeth with occlusal amalgam fillings from the Chicago (C) area and forty‐three teeth from the Jerusalem (J) area, were examined with a probe. Employing common clinical criteria, it was found that replacement of the fillings was indicated due to extensive marginal defects, in 45% of the C teeth, and 41% of the J teeth. The occlusal amalgam margins and the incidence of caries adjacent to these margins were studied on facio‐lingual sections. The incidence and the average AMA values for six margin types were measured on random sections and were found to be: all margins (100%, 67°); intact flush margins (31%, 69°); fractured flush margins (21%, 56°); undercarved margins which fractured (22%, 74°), or did not fracture (9%, 80°) near the cavity margin; margins with amalgam deficiencies (12%, 62°); and margins with separation between enamel and amalgam by remnants of linings (5%). Marginal breakdown was found in 42% of the margins and was associated mainly with flush carving at low AM As, and with broken flashes resulting from undercarving. Occlusal carious enamel was detected on 19% of the J teeth and none of the C teeth. Sixty‐three per cent of these lesions were associated with fractured undercarved margins.
The corrosion resistance of a new cobalt‐chromium‐molybdenum‐ceramic alloy
Authors: MEZGER P. R. , VRIJHOEF M. M. A. , NEWMAN S. M. , GREENER E. H.
Published: June 2007

Cobalt‐chromium alloys are extensively used for removable partial dentures and implants. Recently, this type of alloy has been introduced for porcelain‐fused‐to‐metal crown and bridgework. The objective of this in vitro study was to evaluate the corrosion behaviour of such a ceramic alloy (Vicomp) and compare it to a cobalt‐chromium alloy for removable partial dentures (Vitallium). A 0.9% saline solution and an artificial saliva were used as electrolytes. Results indicate a similar, adequate, corrosion resistance.
Composite laminate veneers: a clinical study
Authors: WALLS A. W. G. , MURRAY J. J. , McCABE J. F.
Published: June 2007

A 2‐year clinical trial of a composite laminate veneer system for masking discoloration or hypoplasia on the anterior teeth of patients has been undertaken. Three hundred and twenty restorations were placed in seventy‐nine patients, of these 273 restorations in sixty‐eight patients have been followed over a 2‐year period. The technique produced an acceptable improvement in the aesthetics of the patients in the trial. However, the veneers were susceptible to chipping (52% of lateral incisor veneers and 79% of central incisor and canine veneers showed some evidence of material loss after 2 years) and marginal staining (75% of veneers showed some evidence of marginal staining after 2 years) during function. The veneer restorations had a deleterious affect upon the gingival health of the teeth on which they were placed.
The position of the occlusal plane in dentulous subjects with various skeletal jaw‐relationships
Authors: SINOBAD D.
Published: June 2007

This study was conducted to examine the level and inclination of the occlusal plane in dentulous subjects with various skeletal jaw‐relationships with the purpose of finding more reliable guides for locating the occlusal plane in edentulous patients.

The investigation was carried out on 140 lateral cephalometric radiographs of young people with natural teeth in the intercuspal position. The sample was divided into three groups according to the skeletal relation of the jaws.

The occlusal plane in this study and the two reference planes (maxillary and mandibular plane) were established according to the cephalometric criteria of Schwarz. On each radiograph both the angulation and the perpendicular distance of the occlusal plane to the reference planes were recorded and the values of the obtained data were subject to statistical analysis.

The selected mean values of the angles and linear distances between the occlusal plane and reference planes calculated on the probability level of 95% could be used as cephalometric indicators for the locating or correcting the position of the occlusal plane in the prosthetic treatment of edentulous patients.
Tooth support in the human mandible
Authors: RALPH W. J. , THOMAS C. D. L.
Published: June 2007

Prepared surfaces of anterior portions of dentate human mandibles were serially ground in steps of 0.2 mm and the anatomical features traced. The information was stored in a computer and then reassembled and plotted in colour. The percentage porosity of the bone, together with the width of the periodontal space was calculated. The cortical plates of the mandible appear to provide the major boney support for the anterior teeth, trabecular bone only being present in scant amounts in the periapical areas. The apparently random arrangement of trabeculae does not support the commonly accepted picture of trabeculae aligned to resist the functional loads transmitted by the periodontal ligament.
The measurement of the setting characteristics of rigid autopolymerizing resins for direct use in the oral cavity
Authors: HUGGETT R. , BROOKS S. C. , JONES N. , SWAN G. P.
Published: June 2007

Differential scanning calorimetry has been used with success to determine working and setting times of autopolymerizing denture and orthodontic base resins. The technique is considered to be far more suitable for this task than thermal methods which are influenced by specimen geometry and heat transfer. Since only a few milligrams of material are required the technique would be suitable for other dental materials whose setting characteristics are of interest.
Neutralizing phosphoric acid in the acid etch resin technique
Authors: KELLAR M. , DUKE E. S.
Published: June 2007

The use of an alkaline wetting agent, used to neutralize phosphoric acid in the acid etch technique, was investigated with respect to improving the bond strength and microleakage behaviour of composite resin. The alkaline wetting agent has been shown to prevent the accumulation of calcium biphosphates, as a result of secondary recrystallization of hydroxyapatite, within the depths of etched enamel.

To examine the influence of the alkaline wetting agent on bond strength, composite cylinders were prepared on enamel surfaces of extracted third molar teeth and tested for shear bond strength. Microleakage behaviour was observed on class V oval preparations in the cervical thirds of extracted third molars using a dye penetration technique.

No significant improvement in shear bond strength was demonstrated with the alkaline wetting agent over conventional acid etching. In addition, the microleakage observed following the use of the alkaline wetting was characteristic of that for conventional acid etching.
Carbon absorption of palladium‐enriched ceramic alloys*
Authors: van der ZEL J. M. , VRIJHOEF M. M. A.
Published: June 2007

Palladium‐enriched alloys are sensitive to carbon absorption. High carbon levels in ceramic alloys negatively influence some mechanical properties and cause porosities in the porcelain during the firing process. The influence of the palladium content on carbon absorption of alloys with a range of palladium content from 5 to 80% approximately was investigated. Carbon content was measured for alloys in the ‘as received’ condition as well as after melting once and three times. Carbon contents up to 200 ppm were measured in the case of a high‐palladium system.
Electromyographic activity of the human masticatory muscles during submaximal clenching in the inter‐cuspal position
Authors: NAEIJE M. , McCARROLL R. S. , WEIJS W.A.
Published: June 2007

The activity patterns of the masseter and the anterior temporal muscles were studied in twenty‐one healthy male subjects while clenching at 10, 20, 30, 40 and 50% of the maximum clenching level. At low clenching levels the temporal muscle activity tended to dominate, at high levels the masseter muscle activity was stronger (P < 0.001). The asymmetry in muscle activity also depended upon the clenching level (P < 0.001), while at each level the masseter muscle asymmetry was greater than the temporal muscle asymmetry (P < 0.05–P < 0.025). By comparing the electromyographic activities of the left and right side within each subject it was found that the masseter muscle with the higher electromyographic activity tended to have the larger cross‐sectional area (P < 0.01) and at the 50% clenching level it tended to be on the side with the greater number of post‐canine tooth contacts (P < 0.001).
Oral habits in common between tension headache and non‐headache populations
Authors: MOSS R. A. , LOMBARDO T. W. , MARLIN HODGSON J. , O'CARROLL K.
Published: June 2007

Previous research has suggested a relationship between migraine pain and oral habits. The present study was designed as a replication of a prior study that found self‐reported higher frequencies of certain oral habits in migraine as opposed to tension headache and non‐headache groups. Three groups of subjects (common migraine, tension headache and non‐headache) were given a single questionnaire in which five oral habits (i.e. teeth clenching, jaw jutting, cupping the chin in the hand, and resting the right and left side of the face on the hand) were rated on a 0 (not at all) to 10 (almost always) scale. Significant main effects were obtained for groups and oral habits in a 3 (groups) ×5 (oral habits) anova. Post hoc Tukey tests revealed the common migraine group reported significantly more frequent oral habits than did the tension headache group. The non‐headache control group did not differ significantly from either headache group. Discussion focuses on the need for continued research in this area.
Some causes of failure of crowns, bridges and dentures
Authors: PICTON D. C. A. , CREASEY S. J.
Published: June 2007

With increasing emphasis being placed on precision in the construction of prostheses the importance of the visco‐elastic characteristics of tooth support should be understood. Since the tooth returns to its resting position quite slowly, especially when repeated or sustained forces have been applied, an impression prepared prior to full recovery will convey erroneous relationships of the tooth with its neighbours to the working model and, eventually, to the prosthesis.

Such an error has been identified in young human subjects when inter‐dental wedges, gingival retraction cord, and rubber dam are placed. The preparation of conventional alginate impressions in special trays can displace abutment teeth to a clinically significant degree as was recorded for seven partially dentate patients. Simple precautions will circumvent these potential sources of error.
The silent period in the masseter and the anterior temporalis muscles in adult patients with mild or moderate mandibular dysfunction symptoms
Authors: ZULQARNAIN B. J. , FURUYA R. , HEDEGÅRD B. , MAGNUSSON T.
Published: June 2007

The electromyographical silent period in the masseter and the anterior temporalis muscles during tooth tapping and jaw jerk were studied in patients with fairly mild temporomandibular joint dysfunction symptoms. The length of the silent periods in the patient group did not differ generally from that in a control group. During tooth tapping, however, patients with distinct muscular disorders had shorter silent period duration (7.7 ms) than patients with other symptoms or when compared with control subjects (10.5 and 11.3 ms, respectively). The duration returned to normal after correction of the muscular disorders. This finding suggests that the duration of the silent period is affected by the muscle condition. Patients with obvious muscular disorders of mild to moderate magnitude, thus, may show a shorter silent period duration during tooth tapping.
The immediate effect of splint‐induced changes in jaw positioning on the asymmetry of submaximal masticatory muscle activity
Authors: McCARROLL R. S. , NAEIJE M. , KIM Y. K. , HANSSON T. L.
Published: June 2007

Maxillary full‐arch splints in the retruded position (RP) and in a right lateral occlusion (1.0‐ 1.5 mm to the right of the retruded contact position) were fabricated for ten subjects. Surface electromyography of the masseter and anterior temporal muscles was performed during submaximal clenching in order to investigate the immediate effects of the splints on the activity patterns of these muscles relative to the patterns found with the subjects occlusion in the inter‐cuspal position. The splints in the RP were found to have no effect on the asymmetry of the activity of the masseter and the anterior temporal muscles, while the splints in a right lateral occlusion resulted in relative increases in right anterior temporal muscle activity (P<0.005).
Effects of texture of food on chewing patterns in the human subject
Authors: HORIO T. , KAWAMURA Y.
Published: June 2007

To elucidate the effects of food character on chewing patterns in humans, the electromyographic activity (EMG) of the chewing muscles and also the jaw movements were recorded in twenty‐nine young subjects during ordinary chewing of five different foods.

The results obtained were as follows. (a) The harder food materials showed a higher amplitude of the masseter EMG than the softer ones. (b) Concerning the number of chewing strokes and the elapse of time until the last swallowing action, subjects could be divided into two groups. (i) In the first major group, the number of chewing strokes and chewing time until the last swallowing action increased following increase of hardness of the food. This suggests that chewing force and chewing movements may be strongly influenced by the texture of food, especially its hardness. Further, the degree of pulverization of eating materials appears to be the major factor in controlling the swallowing action. (ii) In the second minor group, the chewing strokes and the chewing time were less influenced by the hardness of food. Here, a certain number of chewing strokes could be stimulating the swallowing centre in the brain and so induce swallowing, regardless of the degree of pulverization of the food.
Assessment of occlusal interferences
Authors: VALLON D. , NILNER M. , KOPP S.
Published: June 2007

The variability in the assessment of occlusal variables was investigated in eight subjects by the repeated registrations of four observers. The following variables were investigated in three different ways: sliding between the RCP (retruded contact position) and the ICP (inter‐cuspal contact position) in the sagittal, vertical and lateral plane. Interferences during lateral movements on the working and balancing sides as well as interferences causing deviation of the mandible during protrusive movements were recorded.

The intra‐ and inter‐observer error for the measurement of sagittal and vertical distance RCP‐ICP was within acceptable limits. There was no significant difference between the three methods used. The intra‐ and inter‐observer agreement between duplicate recordings of the lateral distance RCP‐ICP was high and there were no differences between the different measurement modalities.

The inter‐observer agreement was lower than the intra‐observer agreement concerning presence/absence of balancing side interferences, and positive interobserver agreement was only found on lateral movement more than 3 mm from the RCP or the ICP.

The observer error for the variable working side interferences should be acceptable for future research, while the observer error for measurement of lateral deviation of the mandible upon protrusion was somewhat larger.
A comparative in vitro study of visible light‐cured sealants
Authors: LEKKA M. P. , PAPAGIANNOULIS L. , ELIADES G. C. , CAPUTO A. A.
Published: June 2007

The introduction of visible light polymerization in dentistry led to the development of a new generation of pit and fissure sealants. The purpose of this study was an overall evaluation of some in vitro characteristics of four new sealants (Delton LC, Helioseal, Pentra‐Seal and Visioseal) in comparison with a chemically cured control (Delton). The results indicate that the monomer systems utilized in the new materials have already been used in dental polymer technology. The relatively new monomers TCDDMA/TCDMA were identified in one product. Camphoroquinone is used as a photoinitiator in all the light‐cured systems which, after 40 s exposure, present better conversion than the control. The extent of oxygen inhibition was considerably reduced in the new sealants and the surface hardness was enhanced. Great differences were obtained in the penetration coefficient values; these, however, did not affect the enamel retention capacity of the materials tested. Consequently, light‐cured sealants should be considered to be strongly compatible with the conventional chemically cured sealants from a laboratory aspect until more clinical evidence is available for their effectiveness in the prevention of pit and fissure decay.
Preliminary studies of mandibular movement at initial tooth contact
Authors: FAULKNER K. D. B.
Published: June 2007

Mandibular movement that occurred after initial tooth contact in a rhythmical tooth‐tapping task was investigated using a closed‐circuit television movement detector. Tooth contact was monitored by the placement of a small microphone on the subjects' foreheads. Movement was traced on ultraviolet‐sensitive chart and a statistical method of analysis was developed to determine movement patterns at the commencement and cessation of each cycle. Results showed that a regular pattern of movement could be observed as a cycle of movement commenced, but that this was not so apparent on cessation.
Joint strength between two layers of different amalgam types condensed successively
Authors: GORDON M. , LIBERMAN R. , BEN‐AMAR A. , ELDAR S.
Published: June 2007

The flexure strength of the joint between layers of different types of amalgam condensed consecutively one on to the other was evaluated in vitro. The data indicated no statistical differences in flexure strength between the combined samples (single composition spherical and lathe‐cut eutectic amalgams) and the control (homogeneous lathe‐cut eutectic amalgam).
Investigation of the surface texture of hydroxylapatite‐coated dental implants by means of SEM
Authors: VAN ROSSEN I. P. , DE PUTTER C. , DE GROOT K.
Published: June 2007

In this experiment hydroxylapatite‐coated dental implants were submitted to a wear test in order to study their resistance to toothbrushing. After 20,000 double brush strokes the coating had disappeared in some places. It was concluded that the wear resistance of the coating was not good enough to withstand longer brushing periods.
The gothic arch tracing and the upper canine teeth as guides in the positioning of upper posterior teeth
Authors: EL‐GHERIANI A. S. , DAVIES A. L. , WINSTANLEY R. B.
Published: June 2007

The relationship between the position of the buccal cusps of the natural upper posterior teeth and the distance between the lateral arms of the Gothic arch tracing or the distance between the upper canine teeth has been found to be constant to within ±2mm. This may be of value when setting up artificial teeth for denture patients, enabling them to be positioned close to the natural predecessors.
Cyclic fatigue of composite restorative materials*
Authors: DRUMMOND JAMES L.
Published: June 2007

The purpose of this project was to investigate and evaluate dental composite restorative materials classified according to filler particle size (microfill, small particle, hybrid) regarding fracture characteristics and susceptibility to stress corrosion. The composite materials were tested by cyclic fatigue in distilled water at 37°C. No trend was observed between the number of cycles to fracture and the cycling load as a percentage of the modulus of rupture. Linear regression analysis correlation was weak for most of the composites used to determine the stress corrosion resistance constant, which ranged from 0.80 to 12.05.

Observation of the fracture interface revealed inter‐ and intraparticle fracture for the small particle and hybrid composites. The microfills fractured between and through the prepolymerized particles.
A mechanistic study of the electrochemical corrosion of the γ2 phase in dental amalgams. I. Evaluation of the measurements
Authors: LEMAITRE L. , MOORS M. , VAN PETEGHEM A. P.
Published: June 2007

Conventional dental amalgams are prone to corrosion of the γ2 phase. In an anodic polarization experiment the presence of γ2 causes a current peak in the proximity of −250mV vs. SCE. Electrochemical impedance measurements carried out at this potential indicate the occurrence of an impedance curve in two parts. The high frequency part is a semi‐circle with its centre below the real axis. Apart from the faradaic impedance and the double layer capacitance, the high frequency part is dominated by the behaviour of the corrosion products layer on the amalgam surface. The low frequency part has the form of a diffusion‐like curve. However, since the phase angle is smaller for the above‐mentioned case than for a free diffusion, this phenomenon is ascribed to diffusion in a porous layer at the interface between amalgam solution.
A mechanistic study of the electrochemical corrosion of the γ2 phase in dental amalgams. II. Introduction of a model
Authors: LEMAITRE L. , MOORS M. , VAN PETEGHEM A. P.
Published: June 2007

Electrochemical impedance measurements on conventional dental amalgams at an anodic polarization potential of −250 mV vs. SCE were performed. An initial evaluation was given in part I of this study; in the second part the results are interpreted in terms of a model. The latter, characterized by an equivalent circuit, is a parallel combination of a flat surface and a pore. The selection of appropriate values for the elements of the equivalent circuit leads to a better insight into the corrosion process. Although no simple relationship exists between the circuit elements and the impedance curves, an explanation was found for some typical features of these curves. As an application, the influence of the anodic polarization potential on the impedance curves was studied. Evaluation by means of the model demonstrated the importance of the characteristics of the corrosion products.
In vitro acid decalcification of human surface enamel pretreated with toothpaste slurries
Authors: TADMOR E. , POITOU P. , GEDALIA I.
Published: June 2007

An in vitro caries‐like challenge of human tooth enamel treated with inorganic fluoride (NaF) and organic fluoride (aliphatic and aromatic amine fluorides) toothpaste slurries has been investigated. The results revealed that the organic fluoridecontaining toothpastes affected positively the resistance of tooth enamel to demineralization.
The anatomical effects of surgically repositioning the disc in the temporomandibular joint of rats. An experimental study.
Authors: LEKKAS C. , HONEE G.L.J.M.
Published: June 2007

A sample of 16 rats was used as experimental material to evaluate the effect of surgical repositioning of the disc of the temporomandibular joint according to the technique described by McCarty and Farrar (1979) and its variation according to Leopard (1984). The animals were killed 6 weeks postoperatively. Macroscopic and microscopic examination revealed that in all rats treated according to the procedure of McCarty and Farrar (1979) the disc had completely disappeared. The underlying condyle was deformed to a mushroom shape and the cartilage of the condyle was thickened. In seven of eight rats operated on according to the technique of Leopard, the same results were observed. It is concluded that surgical repositioning of the disc according to these techniques represents a method of disc removal.
Mucosal reactions to amalgam restorations
Authors: JAMESON M.W. , KARDOS T.B. , KIRK E.E.J. , FERGUSON M.M.
Published: June 2007

Amalgam restorations have been implicated both in contact sensitivity reactions and in lichenoid reactions. This appears to be related principally to the mercury content, although other metals cannot be discounted. The cases of two patients are reported who showed features of lichenoid reactions of the oral mucosa, in addition to features of a contact hypersensitivity to mercury. The mucosal lesions resolved following replacement of the amalgams with non‐metallic restorations. Consideration is given to the selection of materials and procedures currently available for treatment of these patients. This paper supports the view that sensitivity to heavy metals must be considered as a possible cause of erythematous and lichenoid reactions of the oral mucosa.
Accuracy of impression materials measured with a vertical height gauge
Authors: LEWINSTEIN I. , CRAIG R.G.
Published: June 2007

The objectives of this study were to introduce a different method for evaluating the accuracy of impression materials using a vertical height gauge, and to determine the vertical (axial) and horizontal (transversal) changes of four impression materials. Comparison of means demonstrated the changes for addition and condensation type silicones, and larger changes for the agar/alginate combination and the visible light cured (polyetherurethanedimethacrylate) impression material. The results were in agreement with an earlier study of the agar/alginate combination, and the values for the condensation and addition silicones were about half those reported in previous studies. These small changes might indicate the use of a mandibular stock tray for the upper jaw when a putty/wash technique is employed. The findings suggest that, when the horizontal changes (ΔX) of impressions taken with a mandibular stock tray have a negative sign (contraction), then the vertical changes (ΔL) will have a positive value (expansion), and vice versa. Thus the pattern of distortion can be formulated as δXδL<0.
The effectiveness of dentine adhesives as demonstrated by dye penetration and SEM investigations
Authors: HEGARTY S.M. , PEARSON G.J.
Published: June 2007

A previous investigation identified three types of cuspal movement that occur as a result of polymerization shrinkage when extracted molar teeth are filled with a microfine or hybrid composite used in conjunction with a dentine adhesive. That investigation was extended further by dye penetration and SEM studies of the margin, involving assessment of the degree of dye penetration and marginal integrity around the restoration. These studies indicate that there may be a failure of the adhesive bond between tooth and composite/adhesive complex which correlates with little or no cuspal movement. Failure within the tooth structure itself was also observed in a number of cases.
Viscoelastic properties of tissue conditioners — stress relaxation test using Maxwell model analogy
Authors: MURATA H. , SHIGETO N. , HAMADA T.
Published: June 2007

In order to measure the viscoelastic properties of tissue conditioners, a series of stress relaxation tests was carried out using poly ethyl methacrylate polymer powders and liquids composed of butyl phthalyl butyl glycolate/ethyl alcohol mixtures, respectively. The analysis method using the Maxwell model analogy is discussed. The results may be summarized as follows.

(i) In this study it was feasible to make the stress relaxation curves for 30min analogous to the Maxwell model, using a model with a maximum of 5 elements.

(ii) The elastic modulus E1, the coefficient of viscosity ν, and relaxation time tj, for each element, and the instantaneous modulus Eo, tended to increase with time. These values in the element of the longest relaxation time were most marked in the increase among those in all the elements. Furthermore, in every element the rate of increase of ν was greater than that of E1.

The method described is considered to be one of the most useful techniques available for the study of the viscoelastic properties of tissue conditioners.
The effect of posterior composite restorations on the resistance of cavity walls to vertically applied occlusal loads
Authors: LIBERMAN R. , BEN‐AMAR A. , GONTAR G. , HIRSH A.
Published: June 2007

The resistance of the cavity walls of non‐vital premolars to vertically applied occlusal forces was studied. Standardized MOD cavities were prepared, restored, and vertical forces were applied to each of the cuspal tips by the Instron machine.

Results suggest that bevelled etched‐enamel margins and dentine‐bonded posterior composite resin restorations significantly improved (by 33%) the resistance of the remaining cavity walls compared to amalgam restorations. In a control group, in which no restorations were carried out in the prepared cavities, the resistance of the walls was significantly smaller than in both restored groups.
Radiographic inhomogeneity of posterior composites
Authors: WATTS D.C. , WILSON N.H.F. , OMER O.E.
Published: June 2007

A radiographic technique has been devised for determining the structural inhomogeneity between successive specimens fabricated from any given dental composite. This has been applied to nineteen composites currently recommended for the restoration of Class I and Class II cavities. The inhomogeneity data fell within clearly defined bands, with some light‐cured posterior composites exhibiting an inhomogeneity parameter of zero. Other hands had average inhomogeneities of 1.5%, 2.5%, 3.8% and 6.8%. The level of inhomogeneity exhibited by a composite system may be an important factor in material selection and in long‐term clinical performance.
The temporomandibular joint in rheumatoid arthritis—a comparative clinical and tomographic study pre‐ and post‐prosthesis
Authors: SATO H. , FUJII H. , TAKADA H. , YAMADA N.
Published: June 2007

Six partially or fully edentulous rheumatoid patients participated in the study. By comparing the clinical symptoms and tomograms of the temporomandibular joints (TMJS) pre‐prosthesis with those post‐prosthesis, this report assesses whether dental treatment could provide positive help for TMJS in patients with rheumatoid arthritis (RA).

Among the clinical symptoms of TMJ dysfunction, pain from the TMJ region and limitations of movement were improved in all the patients post‐prosthesis. Tomographic evidence of desirable remodelling of the condylar heads was observed in two cases.