bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer‐analysed movements in three dimensions recorded by light‐emitting diodes
Authors: JEMT TORSTEN , LSSON STIGKAR
Published: June 2007

Mandibular movements recorded by means of intraorally placed light‐emitting diodes (LEDs) were described and tested. By using a reference system attached to the test subject, the influence of head movements on the registration of the mandibular movements could be avoided. The errors of the method were tested. The stability of the reference system during function was found to be greater when the light impulses did not have to penetrate the lip.

A limited clinical test was performed and the following observations were made: the mean cycle duration was, after the first cycles, stable through the whole chewing phase, 0.52 s when chewing crispbread; the duration of the occlusion phase appeared to be shorter than that of the opening and closing phases; the velocity of the mandible was greater in the opening phase than in the closing phase, with a mean velocity of 84 and 70 mm/s respectively; the clinical test showed that the method was easy to handle in the clinical situation, thereby creating an instrument for studies in larger groups of patients. By adding a simple computer program, the manual analysis could be reduced considerably and a number of variables could be measured with a high degree of precision.
EDTA enhancement of strontium uptake by intact human enamel
Authors: FRIEDMAN MICHAEL , HIRSCHFELD Z.
Published: June 2007

The aim of this research was to study the effect of EDTA on the strontium uptake by intact tooth enamel.

EDTA did not significantly affect the strontium uptake in an acid medium of pH 4.5. However, it caused a sharp rise in strontium uptake at pH 6.0. At such a pH, the stability constants of the Ca‐EDTA complex are approaching a maximal value, and as a result of it a significant dissolution of the surface enamel, accompanied by a highly effective increase of the contact area for strontium uptake, is taking place. In all the experiments, treatment with strontium solution resulted in a decrease of the solubility and dissolution rate of enamel in an acidic environment.

The resistance of enamel to acid attack was proportional to the quantity of absorbed strontium, reaching maximal values after treatment with strontium solutions in 10−2 M EDTA at pH 6.0.
Staining of composite resins by cigarette smoke
Authors: RAPTIS C. N. , POWERS J. M. , FAN P. L. , YU R.
Published: June 2007

Two conventional composites and one microfilled composite were exposed to cigarette smoke in vitro in a smoking chamber. Colour parameters were measured using reflectance spectrophotometry. The conventional composites showed more extensive staining than the microfilled composite. The stains were effectively removed by extensive cleaning.
Prevention of microleakage into experimental cavities in teeth: an in vitro study
Authors: THE G. S. T. , VAN MULLEM P. J. , PLASSCHAERT A. M.
Published: June 2007

Dye penetration into cylindrical, 1 mm diameter cavities in forty‐nine extracted human teeth was studied. Twenty‐eight teeth were filled with Cavit‐W or gutta percha and the remainder were left unfilled. The enamel surrounding all cavities was etched and the cavities sealed with three types of sealants. After 8 weeks, during which the temperature of the teeth was changed twice daily, Estilux appeared to have prevented the dye from penetrating into the cavities.
Correlations between EMG jaw muscle activity and facial morphology in complete denture wearers
Authors: TALLGREN A. , HOLDEN S. , LANG B. R. , ASH M. M.
Published: June 2007

In a sample of fifteen partially edentulous subjects assigned for immediate complete denture treatment, a correlation analysis was performed between pre‐extraction facial morphology determined from lateral cephalograms, and EMG activity of the anterior temporal and masseter muscles in maximal clench and tapping of teeth. Marked correlations observed between vertical and sagittal jaw relations and mean voltages of the jaw‐closing muscles indicated strong biting activity in subjects with a square facial type. No significant associations were observed between biting strength and the age of the subjects.

Correlations between facial morphological changes and changes in EMG biting activity after denture insertion and during 1 year of denture wear indicated that the anterior temporal muscles were extremely sensitive to sagittal changes in anterior occlusion. The masseter muscles were less sensitive, but responded in some instances to changes in vertical jaw relationship.
The use of biofeedback to obtain jaw‐muscle relaxation in denture‐wearing subjects
Authors: YEMM R.
Published: June 2007

A group of ten edentulous patients, who had experienced persistent soreness of the mucous membrane underlying their lower dentures, have been shown to exhibit a tendency towards greater activity of the temporal muscle while ostensibly at rest, compared with a number of normal subjects. A biofeedback technique, based on electromyography, proved effective in teaching the patients to relax during an experiment of approximately 20 min duration. In contrast relatively little change could be achieved by the normal subjects. It is concluded that the results support the hypothesis that muscle tension may contribute to lower denture discomfort, and suggest that biofeedback muscle relaxation training may be a useful method of treatment in such cases.
An investigation of the process of casting cores on to preformed wrought dental posts
Authors: TURNER C. H. , WILLOUGHBY A. F. W.
Published: June 2007

The casting of gold on to wrought ‘Wiptam’ and ‘G.T.’ posts has been investigated. Notching of ‘Wiptanm’ posts gave rise to grain structure rearrangement; carbon deposits from the wax burn were retained in the notches and prevented complete filling by the gold. Serious cracks developed from these notches when the core was cast on centrifugally but only slightly when Solbrig's method was used. These cracks explain why ‘Wiptam’ posts occasionally fracture.

The above problems were not encountered with the ‘G.T.’ post, which has inbuilt retention channels, and allows a more complete burn out of the wax pattern.
The wearing of complete dentures: guidance to patients
Authors: POLYZOIS GREGORY L.
Published: June 2007

The effect of continuous wear of complete dentures in relation to the health of the oral mucosa is discussed. The results of a questionnaire on denture wearing advice among 120 dental schools, revealed divergence of opinions on the subject.
Influence of auriculotemporal nerve anaesthesia on the masseteric silent period
Authors: SMITH D. M. , ZITER W. D. , MOHL N. D. , McCALL W. D.
Published: June 2007

Silent periods were evoked from the masseter muscles bilaterally in response to chin taps during a clench. Injection of 0.75 ml of 3% Mepivicaine posteromedial to each condyle led to a distribution of skin anaesthesia consistent with the distribution of the auriculotemporal nerve. Silent periods were evoked prior to and during anaesthesia in ten subjects.

The silent period latencies (mean ± standard deviation) prior to anaesthesia were 12.5 ± 1.8 ms and 11.9 ± 2.5ms in the right and left masseters. During anaesthesia the latency decreased by 0.3 ± 1.3 ms in the right masseter and by 0.3 ± 2.1 ms on the left masseter. Neither change was statistically significant (P > 0.05).

The silent period durations prior to anaesthesia were 20.3 ± 4.0 ms and 22.8 ± 7.1 ms in the right and left masseters. During anaesthesia, these decreased by 2.74 ± 5.8 ms on the right and 2.15 ± 4.4 ms on the left. These decreases were not statistically significant (P > 0.05).

These results failed to demonstrate an influence of the predominant nerve supply of the TMJ on either the latency or the duration of the masseteric silent period.
Surface treatment studies aimed at streamlining fissure sealant application
Authors: MAIN C. , THOMSON J. L. , CUMMINGS A. , FIELD D. , STEPHEN K. W. , GILLESPIE F. C.
Published: June 2007

Three laboratory studies were carried out with the aim of improving or streamlining enamel surface treatment procedures in fissure sealing.

In Study 1, the effect of reducing acid etch time from 60 s to 10 s was assessed by SEM and tensile bond strength measurements. Reduction in etch time produced a finer etch pattern, gave a reduced but still high, bond‐strength, albeit with slightly poorer long‐term adhesion.

Study 2 showed that a conventional acid etch treatment could completely remove acquired pellicle, without prior prophylaxis. SEM studies and bond‐strength measurements corroborated this view.

In Study 3, compressed air and chemical drying agents were compared for drying speed and efficiency. Compressed air gave more rapid, thorough drying, and greater resultant bond strengths.
Long‐term dimensional stability of three current elastomers
Authors: CLANCY JAMES M. S. , SCANDRETT FORREST R. , ETTINGER RONALD L.
Published: June 2007

The long‐term dimensional stability of three non‐aqueous elastomeric impression materials, a silicone, a polyether and a polysiloxane, were investigated. The testing apparatus was an A.D.A. specification No. 19 test block and mould. The impressions were measured by the use of a travelling stage reflecting microscope and a Quantimet 720 Image Analyzing computer at time zero and again at 4, 24 and 48 h, and at 1, 2, 3 and 4 weeks.

Impressions poured immediately had the greatest accuracy for all the materials. The polysiloxane (0.025 mm) and polyether (0.033 mm) showed very little change in dimension after 4 weeks when compared to the test block. However, the silicone showed significant change at 4 h (0–14 mm) and 0–2 mm after 4 weeks. After 4 weeks the polysiloxane maintained the best surface detail, the polyether was adequate but the silicone lost much of its detail in as little as 24 h. The reasons for these findings are discussed.
Variations in the particles produced at the end of mastication in subjects with different types of dentition
Authors: JIFFRY M. T. M.
Published: June 2007

The final composition of the size of particles of food or the swallowable composition (SC) has been investigated in subjects with different types of dentition. A convenient mouthful of hard‐baked soya beans was masticated and thereafter the bolus was dried, sieved and weighed. Full denture wearers prepared a SC with a mode value around 4000 μm whereas subjects with mixed dentition prepared a SC with a mode value around 2000 μm. Subjects with partial dentition produced wide variations in the SC. To produce a SC which is usually swallowed by a particular subject the quantity of masticated food should bear an optimum ratio to the area of the healthy oral tissues.
The relationship of occlusal wear to occlusal contact area
Authors: RUSSELL M. D. , GRANT A. A.
Published: June 2007

It has been suggested that masticatory efficiency is directly related to the area of the occlusal surfaces that make contact. However, little work has been carried out to determine if occlusal wear increases the area of contact, and controversy exists as to whether this would be an advantage. Using a wax registration method, occlusal contact area was measured in a group of individuals with either local or generalized wear, before and after treatment. The changes in occlusal contact area were statistically significant for the group exhibiting generalized wear but not for the group exhibiting localized wear.
Denture aesthetics: an evaluation of laymen's preferences
Authors: MARUNICK M. T. , CHAMBERLAIN B. B. , ROBINSON C. A.
Published: June 2007

The purpose of this study was to evaluate whether the lay public perceives anterior teeth selected by Williams's typal matching method as aesthetically pleasing. The theory was tested by laymen responding to questions about photographs of three edentulous male and three edentulous female patients. These patients were selected as representatives of square, tapering, and ovoid facial forms. The photographs were portrait views of the patients wearing different dentures displaying square, tapering, and ovoid teeth.

Substantiation for typal match was found in the square female, square male, and the ovoid female patients. Responses to the photographs demonstrated a preference for square tooth forms over ovoid, and then tapering. Overall, ovoid teeth were preferred for females and square teeth were preferred for males.
Investigation of hydrostatic pressure changes during cementation of screw‐retained posts, and posts with integral cement release channels
Authors: TURNER C. H. , GROSS M. J.
Published: June 2007

Intra‐radicular pressures during the cementation of screw‐retained posts have been found to reach 1.5 × 104 KN/m2 when cement is inserted into the prepared post hole or no pressure, indicating that an incomplete cement lute had developed, when the post was coated with cement. The effectiveness of cement channels was investigated and for the traditional single channel, using the cement ‘insertion’ method, there was an intra‐radicular pressure of 8.5 × 104 KN/m2, compared with 1.1 × 104 KN/m2 for the corresponding round post. Multiple cement release channels* gave an enhanced pressure reduction to 2.0 × 103 KN/m2.
Relationship between creep, γ2, and marginal fracture of dental amalgams
Authors: SARKAR N. K. , EYER C. S. , NORLING B. K.
Published: June 2007

The effect of γ1 and γ2 on the creep deformation of dental amalgams has been investigated. It has been shown that the creep of a conventional amalgam is not dependent on γ1 as was previously reported. Rather it is strongly influenced by γ2 and its volume fraction. It has been speculated that Sn‐rich grain boundaries also enhance creep by facilitating grain boundary sliding. The reported correlation between creep and marginal fracture has been explained in terms of this dependence of creep on corrosionprone Sn‐rich microstructural constituents of amalgams.
Serum creatine kinase studies in mandibular pain dysfunction
Authors: COX P. J. , ROTHWELL P. S.
Published: June 2007

A biochemical test for muscle damaghe (serum creatine kinase estimation) was used to investigate twenty‐six normal subjects, nine normal subjects following experimental bruxism and twenty‐seven patients suffering from mandibular pain dysfunction. No significant differences in serum creatine kinase levels were detected between any of the groups.
Antiplaque properties of sustained release SnF2: pilot studies
Authors: SWANSON T. D. , TINANOFF N.
Published: June 2007

Pilot studies examining the physical and clinical properties of an intracoronal sustained release fluoride delivery system were performed. After testing various percentages of SnF2 incorporated into polycarboxylate, zinc phosphate, and zinc oxide cements, 70% SnF2 polycarboxylate cement was found to have adequate compressive strength while releasing the greatest amount of fluoride in vitro.

A 30‐day in vivo trial, in which this fluoride cement was used as a temporary intracoronal restoration, produced elevated salivary fluoride levels with only transient elevation in urinary fluoride levels. Plaque scores decreased during the experimental period, suggesting that the released SnF2 affected bacterial growth or attachment. The SnF2‐polycarboxylate cement was an adequate temporary restorative material without significant side effects.
Influence of chin tap force and bite force parameters on the duration of the electromyographic silent period
Authors: McCARROLL R. S. , NAEIJE M. , ZORN H.
Published: June 2007

Controversy exists as to whether chin tap force and bite force affect the duration of the electromyographic silent period following the jaw jerk reflex during isometric contraction of the elevator muscles of the mandible.

This study demonstrates that statistical trends exist showing increased silent period duration for increased tap forces and decreased silent period duration with increased bite forces.
Quantitative cement solubility experiments in vivo
Authors: PLUIM L. J. , ARENDS J. , HAVINGA P. , JONGEBLOED W. L. , STOKROOS I.
Published: June 2007

The dissolution and dissolution rate of dental luting cements was measured longitudinally. Cement samples in enamel were placed in a full prosthesis and worn in the mouth for up to 6 months. At given intervals, replicas of the cement surfaces were made and quantified by means of SEM stereographic photographs. With a stereometer the distance between cement surface and original enamel surface can be determined quantitatively. The results show in vivo solubility rates for zinc‐phosphate and glass‐ionomer cement of about 80μ week−1 and 2μm week−1 respectively.
An investigation into the type of union achieved between cast cores and Wiptam wire posts
Authors: AHMAD M. , JONES J. C. GLYN
Published: June 2007

The type of union formed between Wiptam wire posts and cast cores has been investigated.

Scanning electron microscopy of sectioned ‘as cast’ specimens showed that the union between Wiptam posts and cast cores was predominantly mechanical in nature.

Diffusion studies, however, using an X‐ray Microanalysis Unit, revealed that there was evidence of diffusion of silver atoms into the post from the core. This suggests that the bonding between the two components is not merely a simple mechanical lock.
Influence of experimental interfering occlusal contacts on the activity of the anterior temporal and masseter muscles during mastication
Authors: RIISE C. , SHEIKHOLESLAM A.
Published: June 2007

Quantitative electromyography (EMG) was used to study, in eleven volunteers with complete, natural dentitions, the effects of an experimental intercuspal occlusal interference on the pattern of activity of the anterior temporal and masseter muscles during mastication.

The results show that a small occlusal interference (about 0‐5 mm) in the intercuspal position can change the co‐ordination of muscular activity during mastication. In general, there was a prolonged contraction time as well as a reduction of the activity in all the investigated elevators, especially on the side of the interference. Furthermore, after 48 h several subjects preferred to chew unilaterally. After removal of the interference, the pattern of co‐ordination of muscular activity returned almost to the pre‐experimental pattern within 2 weeks.
Cumulative electromyography of the human masseter muscle during fatiguing isometric contractions
Authors: CHRISTENSEN L. V.
Published: June 2007

Six adult males performed maximum voluntary tooth clenching (MVC) for 10, 20, 30, 40 s and, after 15 min, for 40, 30, 20, 10 s. During the isometric exercises the electrical currents of the masseter muscle were sampled by integrated and cumulative surface electromyography. Subjective masseter fatigue was present after 30 and 40 s of MVC clenching, accompanied by changes in myoelectrical activity. Strength testing of the masseter muscle, before and after endurance testing, showed that the strength increased by a significant 16% following two endurance tests. This observation was explained by a post‐tetanic potentiation and/or a differentiated use of motor units in the fatigued muscle. It is concluded that brief MVC isometric activity, or strength testing, is not a reliable measure of fatigue in the masseter muscle when cumulative electromyography is used. Prolonged MVC isometric activity, or progressive endurance testing, monitors reliably the onset and progression of masseter fatigue.
The fracture toughness of dental composites
Authors: LLOYD C. H.
Published: June 2007

Three composite products were subjected to prolonged storage in four different environments. The fracture toughness parameter KIC was obtained for these by the fracture of SEN specimens. For each composite no significant differences were found between samples of material held in these conditions.
The minimal width of the periodontal space
Authors: RALPH W. J. , JEFFERIES J. R.
Published: June 2007

Radiographs of horizontal serial sections of dentate human mandible disclose a picture of the periodontal space, the bony margin of which is highly irregular. The minimal width of this space was measured at four points roughly 90° apart and the average minimal width obtained.

It is suggested that the usual clinical radiographic picture of the periodontal space of a particular tooth or teeth is such that a judgment of the width of the space cannot be made with any certainty.
Visco‐lelastic properties of four currently used tissue conditioners
Authors: DE MOT B. , DE CLERCQ M. , ROUSSEEUW P.
Published: June 2007

About 60% of complete denture wearers experience a mostly painless inflammation of the palatal mucosal membrane. Especially prosthetic trauma and Candida albicans infection are assumed as aetiological factors. The treatment can be prosthetic or medicamentous, dependent on the cause. In this connection tissue conditioners could be very effective by their visco‐elastic properties.

Four tissue conditioners have been examined (Coe Comfort, FITT, Ivoseal, Visco Gel) for their impression softness and elastic recovery. All tests have been done on 20 mm specimens. The length of the specimens was measured during a 10 min compression and a 60 min relaxation. Eight ageing times have been taken into consideration.

From the results large differences appear between the various tissue conditioners. Two main groups can be distinguished. FITT and Ivoseal are harder materials, whereas Coe Comfort and Visco Gel are softer. The ageing time has a clear hardening influence especially on Visco Gel. Visco Gel appears to be the best tissue conditioner by its relative plasticity during the first hours and its elastic behaviour during a longer ageing period. The clinical relevance of these materials is certainly not proved by this study. Further research will show this.
Relationship of electromyographic parameters in jaw dysfunction patients classified according to Helkimo's index
Authors: McCARROLL R. S. , HONEE G. L. J. M. , NAEIJE M.
Published: June 2007

Forty‐two jaw pain‐dysfunction syndrome patients (PDS) were divided into three groups depending on the severity of their condition using the Helkimo clinical dysfunction index. For both the left and right masseter and anterior temporal muscles three parameters of their electromyographic activity were measured, the silent period (SP), the root mean square value (RMS) and the mean power frequency (MPF). During the experiments the patients were instructed to clench as hard as possible in the intercuspal position.

No statistically significant differences could be found between the values for any of the muscles measured between the different Helkimo clinical dysfunction groups. However, when the affected side was compared with the unaffected side in this patient material, statistically significant longer silent period durations and greater RMS values were found in the masseter muscles of the affected side group.
A cantilevered swinglock removable partial denture design for the treatment of the partial mandibulectomy patient
Authors: ADAMS D.
Published: June 2007

The use of the swinglock denture concept in the treatment of patients who have undergone mandibulectomy is discussed. The rationale for its use in cases with and without reconstruction is also discussed by reference to three treated cases.
Effect of oxygen on the corrosion of dental amalgam
Authors: GREENER E. H. , MATSUDA K.
Published: June 2007

The anodic and cathodic polarization of five dental amalgams were determined as a function of oxygen concentration in Ringer's solution and artificial saliva. The results indicate an anodic polarization behaviour dependent on Cl ion concentration and a corrosion potential determined primarily by oxygen concentration. At high oxygen concentrations the corrosion rates of traditional and copper enriched amalgams were equivalent.
A long‐term prognosis for the free‐end saddle‐bridge
Authors: IZIKOWITZ LENNART
Published: June 2007

A consecutive series of eighty‐seven saddle‐bridges with free‐end saddles, executed by the author during the years 1958‐72, was investigated in 1982. The aim was to assess the long‐term prognosis.

Five years after application 98% of the bridges were still functioning. The corresponding percentage after 10, 15 and 20 years was 82, 69 and 49%, respectively. The risk that saddle‐bridges cease to function is very low during the first 5‐year period but significantly higher thereafter.

Soldering fractures constitute an important cause of the removal of appliances during the first 8 years following application. After this time the most frequent causes are caries and loosening of the teeth.

Factors such as sex, time of application, patient's age, length of saddle and whether the bridges were fitted in the mandible or maxilla, have not had a significant influence on the prognosis. Furthermore, no statistically significant difference has been found between the long‐term prognosis for full and partial saddle‐bridges. On the other hand, patients with a removable full denture in the opposing jaw show a significantly worse prognosis (P<0.05) than patients without a denture in this jaw.

The results of the present study indicate that the short‐term prognosis for saddle‐bridges is very favourable and that the long‐term prognosis is so good that saddle‐bridges can constitute an alternative therapy even in jaws with as few as three remaining teeth.
An experimental comparison of vertical tooth movement of 33† and 0† teeth after denture processing procedures
Authors: CARR L. , CLEATON‐JONES P. , FATTI P. , WOLFAARDT J.
Published: June 2007

Movement of teeth during denture processing is an unsolved problem. This study investigates the amount of vertical tooth movement during controlled processing of acrylic, using 33° and 0° teeth invested in specific mixes of plaster of Paris or dental stone.

Forty sample set‐ups each containing four posterior teeth were processed under strictly controlled laboratory conditions. Twenty of these samples carried 33° teeth and the other twenty carried 0° teeth. Each group of twenty samples was randomly divided on a factorial design into batches of ten for investment in plaster of Paris or stone. The vertical movements were measured with a greater degree of accuracy than is required for clinical application. All results were analysed statistically.

Significantly greater movement occurred with teeth invested in stone than those invested in plaster of Paris. Whereas, for teeth invested in stone, significantly greater movement occurred with 33° than with 0° teeth, no such effect was found with teeth invested in plaster of Paris.
Automated thermatic condensation of gutta‐percha root fillings in teeth with open (immature) apices
Authors: DUMMER P. M. H. , DAVIES J. , HARRIS M.
Published: June 2007

Forty upper human premolar teeth with open (immature) apices were root filled by one of three methods, namely lateral condensation with sealer, automated thermatic condensation with sealer, and automated thermatic condensation without sealer. The completed root fillings were then assessed for apical defects, apical extrusions, radiographic voids, apical seal and surface adaptation. The majority of the results indicate that the automated thermatic technique without sealer produces marginally better root fillings in teeth with open apices than the other two methods. However, it is impossible to say whether this would confer any clinical advantage on the technique.

The authors recommend that clinicians who wish to use the automated thermatic technique for condensing gutta‐percha become highly proficient before its use on patients.
Temporomandibular joint abnormalities and bite force in a group of adults with rheumatoid arthritis
Authors: LARHEIM T. A. , FLÖYSTRAND F.
Published: June 2007

Maximal mouth opening, translatory condylar motion (radiographically assessed) and bite force in sixteen adults with rheumatoid arthritis and radiographic temporomandibular joint abnormalities were compared with data from sixteen individuals without joint disease. Mean mouth opening in the arthritis group was reduced, but not statistically significant. Condylar translation and bite force showed significantly lower values than in the healthy individuals. Maximal mouth opening seemed to be the most uncertain parameter for the estimation of jaw function. In seven patients with a normal mouth opening (40–46 mm), both the condylar translation and the bite force were significantly impaired.
An evaluation of crowns and bridges in a general dental practice
Authors: LEEMPOEL P. J. B. , ESCHEN S. , DE HAAN A. F. J. , VAN'T HOF M. A.
Published: June 2007

In this article the results are presented of an evaluation of crowns and bridges in a general practice. The study includes 601 solitary crowns, 213 crowns on bridge abutments and 103 crowns on RPD abutments. In total eighty‐four bridges were examined. All these restorations were constructed during a period of 11.5 years. By means of the Kaplan‐Meier method a prognosis is given of the life span of the different solitary crown‐types over periods between 1 and 11 years. The total amount of failures and follow‐up treatments on bridge and RPD abutments was very small. The authors also examined whether the bridges were constructed according Ante's law. A follow‐up of this study in other Dutch general practices in combination with experimental clinical trials is under way.
Lateral preference in mastication: a feasibility study
Authors: CHRISTENSEN L. V. , RADUE J. T.
Published: June 2007

To study lateral bolus placement during mastication, referred to as masticatory lateral preference, fifteen males and ten females chewed sugarless gum for 15, 20 and 25 s, and visual inspections were done of either right or left side bolus placements. In each of three series of observations, there were no significant differences between right or left side bolus placements. Three consecutive spot checks, in single subjects, showed that lateral preference occurred at random. However, information on a favoured chewing side predicted fairly reliably the side of observed masticatory lateral preference. Observed lateral preference could not be predicted from hand laterality. Consistent and predominant right or left lateral preference was, presumably, an expression of mainly motivational chewing behaviour.
A photogrammetric method for monitoring changes in the residual alveolar ridge form
Authors: ADAMS L. P. , WILDING R. J. C.
Published: June 2007

Resorption of the residual alveolar ridge calls for regular attention to the fitting surface of a denture. In the case of distal extension partial dentures, changes which occur in less than a year may require attention. These changes are apparent, though difficult to measure using radiographic techniques. Stereopho‐togrammetry is a means of recording and measuring contours of land masses. A short focus non‐metric camera was used in this study to produce stereoscopic paired pictures of four casts of the same partial dentition. Additional casts were made 2 and 12 months after a partial denture had been made. A stereophoto‐grammetric plotting instrument was used to map the alveolar ridge area of each cast. A prescribed area for each map was traced out and the volume above a reference height was calculated. The percentage error between the four columns for the pretreatment casts was _t2%. A 10% loss of ridge volume was observed after wearing a partial denture for.2 months. The same area observed 12 months later revealed an 18% volume reduction. Short range stereophotogrammetry may be applied to study changes in alveolar ridge morphology which may result from wearing a partial denture.
Prediction of the shape and size of the maxillary anterior arch in edentulous patients
Authors: PRETI G. , PERA P. , BASSI F.
Published: June 2007

The aims of the study were to examine the morphometric and angular relationships between the interincisive papilla and the maxillary anterior teeth, and to describe a clinical method derived from this analysis useful in siting the upper front teeth.

Plaster casts of upper jaws of adult patients with complete dentition, were selected. Two measurements were taken: (i) the distance from the centre of the papilla to the most vestibular part of the labial surface of the anterior teeth; and (ii) the angles between the perpendicular to the median line and the line from the centre of the papilla to the most vestibular part of each tooth.

The equation of the resulting parabola, corresponding to the upper frontal arch, can be applied to every maxillary dimension. Parabolas were divided into small, medium, and large, using the mean and standard deviations. Each curve was traced on a transparent base‐plate shaped for intra‐oral placement. In individuals with complete dentition the closest parabola to the maxillary frontal arch was selected and the distance between the lateral frenula measured.

Statistical study demonstrated a correspondence between the interfrenulum distance and the parabolas. In edentulous patients the interfrenulum distance thus provides a curve useful in siting the maxillary anterior arch.
An assessment of visible‐light polymerizing sources
Authors: MOSELEY H. , STRANG R. , STEPHEN K. W.
Published: June 2007

Measurements were made of the spectral distribution of light emitted from five commercially available visible‐light polymerization units. All emissions peaked between 400 and 500 nm but the ‘functional’ irradiance varied by a factor of 20 for the sources investigated. Timer checks revealed errors of up to 20%. Light output was plotted as a function of time and, after 60 s, varied from −15% to +38% of the initial level. The decrease in irradiance with distance from the end of the guide was such that irradiance at 20 mm was between 20% and 40% of that at 2 mm. The light distribution across the face of each light guide was investigated and significant inhomogeneities discovered. An ultraviolet light (UV) hazard assessment was performed and it was concluded that none of the light sources presented a hazard to the operator in normal use.
An examination of the surface corrosion state of dental fillings and constructions
Authors: HÅKANSSON B. , YONTCHEV E. , VANNERBERG N.‐G. , HEDEGÅRD B.
Published: June 2007

Electrochemical measurements on amalgams and gold alloys in natural saliva and saline solutions have been performed.

The results show strong inhibiting effects of some components in natural saliva on the surface corrosion behaviour of amalgams.

For the gold alloys the cathodic reduction of oxygen was notably lower in natural saliva than in saline solutions.

For galvanic combinations of gold and amalgams substantially lower currents than those calculated from thermodynamic data can be expected in natural saliva.
Creep versus marginal fracture of amalgam restorations
Authors: VRIJHOEF M. M. A. , LETZEL H.
Published: June 2007

In the literature there is controversy over the existence of a correlation between creep and marginal deterioration of amalgam restorations. It was the aim of this study to re‐investigate this correlation. In five clinical trials, 2068 amalgam restorations were made of six conventional alloys and ten high copper systems. The results show a correlation between creep and marginal fracture in the conventional, low copper amalgams. No correlation could be found for the group of high copper, non‐gamma‐2, amalgams. It is emphasized that dental practitioners should not buy their amalgam alloy on the basis of creep data, because wrong decisions might be taken. Evidence from a controlled clinical study is a more reliable criterion.
Particle and pore size distributions of investments
Authors: MUELLER H. J.
Published: June 2007

The particle‐size distributions of investment powders and the pore‐size distributions of set‐fired investments were investigated by electrozone size analysis, and by mercury intrusion scanning porosimetry, respectively, for a number of different investments, representing all three types available, namely: the gypsum‐, phosphate‐ and silicate‐bonded. The pore volume (V), the pore surface area (S), and their first derivatives with respect to radius, r, dV/dr and dS/dr, were obtained with pressures up to 414 MPa corresponding to spherical pores of 0.0018 μm radius if the Washburn equation is to apply. Results distinguished pores with a range of different sizes. Besides the porosity due to the matrix binder, porosity was also attributable to the refractory components. This latter type of porosity occurred with pore radii below about 0.03 μm, whereas matrix porosity occurred above this pore size. Matrix porosity for the phosphate materials was smallest at about 0.03 to 0.5 μm in radius, followed by the gypsum materials at about 0.3 to 0.6 μm, and by the silicate materials at about 1 to 10 μm. The particle‐size distribution of the investment powders may affect both types of porosities, whereas the setting chemistries of the particular investment types may affect matrix porosity, by the generation of gaseous by‐products. No major distinctions in pore size and distributions occurred between air‐set and hygroscopic‐set materials. This study emphasizes that at present, knowledge of the total pore volume only is inadequate for characterizing porosity distribution and hence investment permeability.
The mechanical advantage of biting with the posterior teeth
Authors: DEVLIN H. , WASTELL D. G.
Published: June 2007

The greater forces generated between posterior teeth compared with between anteriors, may be explained by interpreting the behaviour of the mandible as a lever system, with the condyle as a fulcrum. This study used a semi‐conductor strain gauge transducer to measure load, and EMG activity to index muscular effort. A posterior and an anterior load position were compared by using parallel metal platforms which maintained the occlusal vertical dimension for different biting positions. Reductions in muscular effort were observed for the posterior position of a magnitude that was consistent with the greater mechanical advantage predicted by the lever model.
Occlusal interferences analysed in patients treated with fixed prosthesis four years earlier
Authors: ETTALA‐YLITALO U.‐M. , MARKKANEN H. , YLI‐URPO A.
Published: June 2007

This study consists of 147 subjects treated with fixed prostheses 4 years previously. Occlusal analyses were made, and the fillings, crowns, and pontics on the occlusal surfaces were recorded. Occlusal interferences were found in 42.6% of the fillings, in 34.9% of the crowns, in 27.0% of the pontics, and in 24.6% of the intact surfaces. The most common interference types were intercuspidation, retrusion and mediotrusion in the fillings, as well as intercuspidation, retrusion, and laterotrusion interferences in the crowns. In pontics interferences appeared mostly in intercuspidation and retrusion. When adjustment was made for preprosthetic occlusion, the number of interferences on all types of occlusal surfaces considerably decreased.
Composite versus amalgam restorations
Authors: HENDRIKS F. H. J. , LETZEL H. , VRIJHOEF M. M. A.
Published: June 2007

In a clinical study the behaviour of posterior composite restorations was evaluated. For the study, 232 Class I or II restorations in premolars and molars were made by three operators in a group of forty‐nine adult patients. Each patient underwent one or two series of four restorations. The materials within a series were a strontium glass filled composite (Profile), a microfilled composite (Estic MF), a macrofilled composite (Adaptic Radiopaque) and a high copper amalgam (Dispersalloy). The last two materials served as a negative and positive controls respectively. For a period of 3 years the clinical behaviour was evaluated yearly with the USPHS criteria (anatomic form, marginal adaptation, colour match, marginal staining and caries). Differences in the ratings of the criteria between materials, tooth type and evaluation year were tested statistically for significance. The number of restorations replaced after 3 years in clinical service was eight (=3.6%). The results showed that the material, tooth type and evaluation year all have an influence on the anatomic form and the colour match of the restoration. The behaviour of the three composites with respect to colour match, marginal adaptation and marginal staining was acceptable. For anatomic form, however, only the behaviour of the microfilled composite Estic MF was still acceptable after 3 years.
Retentive and stress characteristics for a magnetically retained partial overdenture
Authors: HIGHTON R. , CAPUTO A. A. , MATYAS J.
Published: June 2007

The retentive and stress characteristics of a magnetically retained partial overdenture were studied. The retentive properties were compared to those of an I‐bar and Zest Anchor retained overdenture.

The magnetically retained partial denture uniformly distributed stress to the supporting structures and exhibited significantly greater retention than that of the I‐bar, but less than that of the Zest Anchor. Based on these observations, the magnetically retained denture should be considered as an option to be used instead of or in conjunction with other types of partial overdentures.
An application of impedance techniques to corrosion research on dental amalgam
Authors: LEMAITRE L. , MOORS M. , VAN PETEGHEM A.P.
Published: June 2007

AC impedance techniques are finding increasing application in corrosion research. It was our aim to introduce them as a method for the evaluation of the electrochemical behaviour of dental amalgam. The complex plane plots are large depressed semicircles representing the frequency dependence of the impedance and measured at the corrosion potential. Conventional dental amalgams, in a chloride medium, exhibit a current peak in the proximity of –250 mV (vs. SCE). The corresponding impedance spectra are rather complex and difficult to interpret. The high frequency part, however, can be fitted to a semicircle with its centre lying below the real axis. An evaluation of the corresponding ‘charge transfer resistance’ shows that it is inversely proportional to the corrosion current density.
Comparison of the strengths of aluminous porcelain fired on to platinum and palladium foils
Authors: PIDDOCK V. , MARQUIS P. M. , WILSON H. J.
Published: June 2007

The disc strengths of aluminous porcelain fired on to both platinum and palladium foil matrices have been determined. Also, the effect on strength of removing the matrices has been measured. The appearance of the separated metal and porcelain surfaces has been studied using scanning electron microscopy, and energy dispersive X‐ray analysis has been used to evaluate the chemical composition of these surfaces. Reasons for the increase in strength observed when the matrix is left intact are discussed. Practical suggestions for obtaining stronger jacket crowns are presented.
The role of personality in the management of partial dentures
Authors: WATSON C. L. , REEVE P. E. , BARNES E. , LANE A. E. , BATES J. F.
Published: June 2007

A sample of fifty‐three partially dentate subjects who had had partial dentures provided in the last 3 years completed a personality questionnaire (Cattell's 16 PFQ). At the same time they completed a clinical questionnaire and were examined by two of the authors. The purpose of this was to assess the patients' satisfaction with their partial dentures.

The results of the personality questionnaire showed that this group of partial denture wearers differed from the general population on only two factors. They were less intelligent and more self‐sufficient. Interestingly they differed from a similar group of complete denture wearers on a further three factors. The partial denture group were more self‐assured, self‐sufficient and more relaxed. On the basis of the clinical questionnaire and examination, five partially dentate patients were found to be dissatisfied. Their personality scores were significantly more unstable than the satisfied group of partial denture wearers.

Although based on a relatively small group, the results do suggest that personality may have a marked effect on the patients' adaption to partial dentures. When compared to a similar group of edentulous patients, marked differences were found, suggesting that the loss of the natural teeth in some individuals affects behaviour.
The metal post and composite core combination
Authors: KÄYSER A. F. , LEEMPOEL P. J. B. , SNOEK P. A.
Published: June 2007

Restoring broken down non‐vital teeth implies in general the provision of a post and core foundation. Many materials and techniques have been introduced for this purpose in recent years. In this article the advantages and disadvantages of the cast and the non‐cast post and core are discussed. The problems involved with the application of the post and core are reviewed. An efficient procedure for restoring a broken down tooth with a prefabricated post in combination with a composite core is presented.
The air‐powder dental abrasive unit—an evaluation using a model system
Authors: WALMSLEY A. D. , WILLIAMS A. R. , LAIRD W. R. E.
Published: June 2007

Air‐powder abrasive systems are used in dentistry to remove dental plaque, calculus and stain from the surfaces of teeth. A model system consisting of a thin layer (14 μm) of vacuum‐deposited aluminium was used to demonstrate the effectiveness of such a system. Photomicrographic analysis showed two distinct areas of removal: an inner area where removal of aluminium was complete, surrounded by an area where removal was incomplete.

With the aid of a relocation pin attached to the nozzle of the instrument it was demonstrated that nozzle–target distance, the air pressure input, the flow of water and the time of operation were all factors which affected the clinical efficiency of the instrument.
Adaptation of dental amalgam to the cavosurface margin of Class I cavity preparations
Authors: SYMONS A. L. , WING G. , HEWITT G. H.
Published: June 2007

The adaptation of a range of amalgam alloys to the cavosurface margin of Class I cavity preparations was examined for two condensation techniques. The marginal contour of amalgam condensed into the cavity preparation and packed approximately 1 mm past the cavosurface margin was compared with amalgam margins of restorations which were packed to final contour with minimal carving. The effect of burnishing and/or polishing the cavosurface margin was compared with carving the amalgam to the cavosurface margin. Specimens were sectioned, metallographically polished and examined using a light microscope.

The technique of overpacking amalgam produced a greater number of acceptable amalgam margins at the cavosurface margin than the condensation technique of packing to final contour, the best cavosurface margin was produced when specimens were burnished and polished, the carved margin being the least desirable. The cuspal incline also influenced the quality of the marginal finish with the difficulty of marginal finishing increasing with the steepness in cuspal incline.
Evaluation of proximal contacts with shim stock
Authors: BOICE P. A. , NILES S. M. , DUBOIS L. M.
Published: June 2007

A total of 969 proximal contacts in forty volunteer subjects was examined for proximal contact integrity with shim stock. It passed uninhibited through 88% of the contacts. Neither sex nor age affected the evaluation; however, shim stock was more likely to pass through contacts with enamel surfaces than those which were restored.