bluuebunny/crossref_metadata_2025 huggingface dataset:
An analysis of tooth position on initial tooth contact
Authors: FAULKNER K. D. B. , ATKINSON H. F.
Published: June 2007

A closed circuit television movement detector was used to study mandibular movement in the form of tooth tapping, in subjects with no apparent dental disease or malocclusion. The velocity and form of various phases of movement was studied, in the transverse, sagittal and coronal planes, from measurements made on u.v. charts and X‐Y recordings. It was shown that closing movements were more direct and faster than opening movements; that initial contact on closing is in a well‐defined contact area, followed by a sliding of cusps over each other to a final centric position and that the closing path of the mandible in tapping movements is in the form of a smooth curve showing simple axis rotation through distances normally greater than those accepted clinically. It was also shown that microphone signals can be detected at times other than when normally expected, indicating displacement with tooth contact, at times other than at the fully intercuspated position.
Development of the swallowable composition of food in normal dentate subjects
Authors: JIFFRY M. T. M. , MOLLIGODA A.
Published: June 2007

This study aimed to find out the changes which occur in the frequency distribution of the size of particles produced during mastication of a convenient mouthful of hard‐baked soya beans to its swallowable composition (SC), and to identify the particles which undergo rapid pulverization.

In this group the total number of masticatory strokes utilized to prepare food for the SC varied between forty and eighty masticatory strokes. All the subjects produced a similar pattern of the frequency distribution of particles produced at the end of mastication and when mastication was interrupted at a particular phase. Particles larger than 1180 μm were pulverized to form particles smaller than 1180 μm. Most rapid pulverization was seen in particles of 2400 μm whereas particles of average size 655 μm, formed rapidly.
Magnetic retention units for overdentures
Authors: SMITH G. A. , LAIRD W. R. E. , GRANT A. A.
Published: June 2007

Mechanical attachments used to improve retention of overdentures have their limitations. With the recent development of the cobalt‐samarium magnet an alternative method of achieving increased overdenture retention is offered. The most suitable form of magnet appears to be of a reverse split pole design with a ferromagnetic disc or keeper which will ensure a closed magnetic field. Clinical techniques involve conventional endodontic therapy, and the basic method of overdenture construction can be followed with only minor modification.
A standardized programme for studying the occlusal force pattern during chewing and biting in prosthetically restored dentitions
Authors: LAURELL LARS , LUNDGREN DAN
Published: June 2007

A recently described method for studying occlusal forces in prosthetically restored dentitions (Lundgren & Laurell, 1984) was applied in a standardized programme to elucidate the occlusal force pattern and the functional capability of a dentition during chewing and biting. The method is based on the use of strain gauge transducers mounted into preformed matrices evenly distributed over the tooth‐arch. The programme was tested in a subject prosthetically restored with a fixed bridge of crossarch design in the upper jaw, and with unsplinted teeth in the lower jaw. It involved chewing of (a) peanuts, (b) roast beef with potato salad, biting with maximal strength in habitual occlusion and biting over one limited contact area at a time.

The magnitude of the occlusal forces developed during chewing and swallowing was well below all biting forces.

The magnitude of the total force acting over the entire dentition when biting at maximal strength in habitual occlusion did not seem to be limited by reactions from the teeth or the periodontal tissues but, seemingly, by the capability of the jaw‐closing muscles themselves. The magnitude of the local bite force over one limited contact area at a time was much smaller than that which the jaw‐closing muscles were able to develop. This indicated that feedback mechanisms in the periodontal tissues and/or the temporo‐mandibular joints were limiting factors for these forces.

The programme will be applied to studies of dentitions supplied with prosthetic constructions of various design and with different distribution of periodontal support.
Fluoride enhancement of chlorhexidine uptake by hydroxyapatite and enamel powders
Authors: BEN‐YAAKOV D. , FRIEDMAN M. , HIRSCHFELD Z. , GEDALIA I.
Published: June 2007

The purpose of the present study was to examine the in vitro adsorption of Chlorhexidine and fluoride to hydroxyapatite and tooth enamel powders. Samples of hydroxyapatite or enamel powder were suspended in aqueous solutions of chlorhexidine gluconate 2.0; chlorhexidine acetate 1.5%; sodium fluoride of various concentrations (0.2%, 1%, 2%) and mixtures of sodium fluoride and chlorhexidine. The data obtained in the study show that chlorhexidine and fluoride adsorb to hydroxyapatite and tooth enamel in vitro. Furthermore, the amount of fluoride adsorbed to hydroxyapatite is reduced in the presence of chlorhexidine in the solution. A probable explanation for this effect may be that there is a competitive adsorption of fluoride and chlorhexidine on to the same binding sites on the hydroxyapatite. Additionally, the presence of fluoride dramatically increases the affinity of chlorhexidine for hydroxyapatite. The fact that fluoride strongly enhanced the adsorption of chlorhexidine to hydroxyapatite and enamel, indicates that fluoride may be of clinical interest beyond the prevention of caries.
Three year follow‐up TMJ patients: success rates and silent periods
Authors: STRYCHALSKI IRENE D. , MOHL N. D. , McCALL W. D. , UTHMAN A. A.
Published: June 2007

A telephone survey to assess treatment success was conducted 2–3 years after treatment of patients suffering from TMJ syndrome. Pre‐treatment silent period durations were compared among groups of patients determined by their response to the telephone survey. The short‐term (immediately post‐treatment) improvement rate was 81 %. Some 35 % of patients were completely cured. There was no statistically significant difference in mean silent period duration among the groups of patients that achieved complete, partial or no relief of symptoms. The long‐term (2–3 years after treatment) persistence of improvement rate was 72%. There was also no statistical difference in the mean silent period duration between those patients who had experienced persistence of success and those who reported either no relief or relapse of symptoms.
Mandibular movement in lateral excursions
Authors: FAULKNER K. D. B. , ATKINSON H. F.
Published: June 2007

Mandibular movement during lateral articulatory movements was studied in young subjects with no apparent dental disease or malocclusion. A closed circuit television movement detector was used. Signals of each vector of movement were combined in pairs to provide envelopes of movement in three planes, mutually at right angles. Symmetry of movement was not as common as expected and sudden small changes in direction were frequently observed. Maximum displacement in each vector of movement was not always coincident.

It is postulated that treatment factors, such as simple restoration of teeth, are initiating factors which cause variation in mandibular movement from the normal.
Quantification of marginal leakage of amalgam restorations in vitro
Authors: Veen H. v. d. , Scholtanus H. , Arends J.
Published: June 2007

A method is described to quantify marginal leakage of amalgam restorations in vitro as a function of time. The method consists of the determination of the amount of nitrogen gas passing through the margins of the restoration at 2atm. pressure in 30min.

The method described needs about sixteen specimen per experiment. The standard error is 20‐30% of the mean leakage value and is independent of the type of condensation and the amalgam type.

Two amalgams, the non‐γ2‐Dispersalloy and the conventional, Amalcap was compared longitudinally over a period of 4 months. The results showed:

The marginal leakage of Dispersalloy decreased strongly with time; the time dependency of Amalcap was less pronounced.

That carefully condensed Amalcap showed significantly less marginal leakage than Dispersalloy.

Whereas the marginal leakage of Amalcap was dependant on the condensation procedure, the leakage of Dispersalloy did not depend strongly on it.
The difficulties of prosthetic management of endentulous cases with hemi‐mandibulectomy following cancer treatment
Authors: WATSON R. M. , WELFARE R. D. , ISLAMI A.
Published: June 2007

The presenting features of edentulous subjects who have undergone hemimandibulectomy for the removal of squamous cell carcinoma of the mouth are described. Suggested methods of prosthetic treatment are discussed and the means of assessing problems of speech and swallowing with sequential radiography are reported.
The fracture toughness of tooth coloured restorative materials
Authors: LLOYD C. H. , MITCHELL L.
Published: June 2007

A fracture mechanics approach has been used to quantify the failure of tooth coloured restorative materials which are subjected to tensile forces. The materials examined included silicates, glass ionomers, composites (both chemically and photo‐initiated) and bonding resins for composites. The parameter chosen was the plane strain critical stress intensification factor, KIC. Silicate and glass ionomer are both brittle and have values for KIC inferior to those of composites. Composites have fracture toughnesses in a range from marginally higher than that of the bonding resin to almost three times that figure. The reason for this is discussed in terms of the dispersion toughening theories.
Effects of biofeedback training on tonic masticatory neck reflex: a case report
Authors: FUNAKOSHI MASAYA , NAKASHIMA MASATO , NODA KAZUHIRO , GALE ELLIOT N.
Published: June 2007

Biofeedback training to reduce muscle tension lowered not only the spontaneous activity but also the tonic neck reflex in the jaw closing muscles. Tolperisone‐HCL, which may inhibit the gamma system, inhibited the tonic masticatory neck reflex, but did not reduce the patient's spontaneous activity of the jaw closing muscles in this case. Biofeedback training may be considered to reduce the gamma as well as alpha motor systems.
Treatment of mandibular dysfunction: the clinical usefulness of biofeedback in relation to splint therapy
Authors: DAHLSTRÖM LARS , CARLSSON SVEN G.
Published: June 2007

The long‐term treatment effects of biofeedback and occlusal splints on mandibular dysfunction were compared. Thirty female patients were randomly divided into two treatment groups. One group had full coverage splints, the other group received biofeedback training. At the re‐examinations 1 and 12 months after completion of therapy, the subjective and clinical symptoms were significantly reduced in both groups. No significant differences between the groups were found. A stepwise analysis of regression indicated that biofeedback training may be a useful alternative to splint therapy in cases where night time bruxing is not the dominating feature.
Thermal diffusion in some polyelectrolyte dental cements: the effect of powder/liquid ratio
Authors: WATTS DAVID C. , SMITH RAYMOND
Published: June 2007

Thermal diffusivity values for glass ionomer and polycarboxylate cements have been determined for varying proportions of cement powder and liquid. Diffusivity is observed to be an increasing function of powder/liquid ratio. This is discussed in relation to the application of these cements as cavity bases.
Prevalence of mandibular dysfunction in 10–18 year old Israeli schoolchildren
Authors: GAZIT E. , LIEBERMAN M. , EINI R. , HIRSCH N. , SERFATY V. , FUCHS C. , LILOS P.
Published: June 2007

The prevalence of mandibular dysfunction in a sample of 369 Israeli schoolchildren was found to be 56.4%, indicating that one or more of the cardinal symptoms were present. It increased with age from about 51% in the 10–13 year old group to 67.8% in the 16–18 year olds.

The most common cardinal sign of dysfunction was joint sounds (35.8%), which increased with age from 28% in the youngest group to 44.3% in the oldest group. The second most common sign was joint sensitivity to palpation (30.4%), which showed a slight increase in the oldest group. Sensitivity of the superficial muscles was recorded third, with 20%. Joint pain and restriction of mandibular movement appeared infrequently.

Two of the more common cardinal symptoms, namely joint sounds and muscle sensitivity, were statistically related to several possible aetiological factors and to age and sex.

Analysis of association showed that the probability of muscle sensitivity increased in the presence of malocclusion and/or joint sensitivity to palpation. It also showed that age, occlusal wear, locking of the jaw and joint sensitivity to palpation increased the probability of joint sounds.
The heats of reaction and temperature rises associated with the setting of bonding resins
Authors: LLOYD C. H. , BROWN E. A.
Published: June 2007

DTA has been used to obtain the heats of reaction and temperature rises occurring during the setting of bonding resins. Four products have been examined. There was little difference between these. Setting reactions were highly exothermic and produced substantial temperature rises. Both factors are linearly related to resin volume, thus it is fortunate that this material is employed in small volumes, but problems may arise from spillage or the careless application of excessive quantities.
The effect of sustained submaximal clenching on maximum bite force in myofascial pain dysfunction patients
Authors: CLARK G. T. , BEEMSTERBOER P. L. , JACOBSON R.
Published: June 2007

The effect of a sustained (30% maximum) isometric clenching task on the maximum voluntary bite force level was evaluated on normal jaw function subjects as well as on abnormal jaw function subjects (MPD patients). The results indicate that the MPD subjects had a lower maximum voluntary bite force level and a shorter endurance time when compared to normal subjects. Neither the control subjects nor the MPD subjects demonstrated a change in their brief MVBF after a ‘fatigue inducing’ task. These results suggest a lack of contractile element failure in the jaw closing muscles following sustained submaximal isometric clenching on a force transducer.
The effect of changing the maxillomandibular relationship by a bite plane on the habitual mandibular opening and closing movement
Authors: MARUYAMA T. , NISHIO K. , KOTANI M. , MIYAUCHI S. , KURODA T.
Published: June 2007

The relationship between the change of afferent information from occlusal contacts and its influence on the jaw muscles was investigated. For this purpose, the following questions were posed and experimental studies designed. If the subject was given habitual occlusal contacts in centric relations with a bite plane, were the habitual mandibular closing and opening movements influenced? Second, was it easier for the subjects to accomplish regular habitual mandibular opening and closing movements, when the bite plane was inserted and removed?

From the results it could be concluded that the centric occlusal contacts in centric relation were more physiological for the jaw muscles. In addition, when the new occlusal position was coincident or close to the centric relation, it was easier for the subject to study and acquire the new habitual mandibular opening and closing movement.
The role of the free‐way space in the generation of muscle pain among denture‐wearers
Authors: MONTEITH BRIAN
Published: June 2007

Although the myofascial pain dysfunction syndrome has a multiple aetiology, faulty vertical dimension is a frequent cause of muscular pain among wearers of full dentures. Furthermore, it has been found that the restoration of a physiological free‐way space in such cases, using a method which is based upon cephalometric analysis of the gonial angle, often leads to a dramatic remission of pain.

The present investigation was prompted by curiosity as to what the underlying algogenic mechanisms in these cases might be; and how a change in the vertical dimension should so modify them as to result in the disappearance of the pain symptoms. The study is necessarily of a speculative nature, and makes use of two representative cases, one of which was adjudged to have too little free‐way, and the other too much. Principles of neuromuscular physiology are applied in attempting to explain the clinical phenomena involved, as well as to find a reason for certain electro‐myographic artefacts noted in one of the cases, which would appear to call into question the notion that muscular hyperactivity, per se, is responsible for muscular pain.

Potgieter, Monteith & Kemp (1983) have presented an hypothesis that the amount of free‐way space present in an individual is an expression of the contractile power of the masseter and medial pterygoid muscles. They have also devised a method whereby, through cephalometric analysis, the optimal amount of free‐way may be determined for an edentulous patient during denture construction.

Furthermore, they have stated that their method has proved particularly effective in the treatment of denture‐wearers presenting with symptoms of the myofascial pain dysfunction syndrome. However, in the light of this syndrome's multifactorial aetiology one must assume that only those symptoms which are related to a faulty free‐way space are at issue.

The purpose of the present investigation is to examine the latter assertion; and by the application of the suggested method of cephalometric analysis to two representative cases, attempt to explain the phenomenon in terms of neuromuscular mechanisms. Of the two cases to be examined, one was found to have too much free‐way, while the other had been provided with too little. Both had presented with symptoms of severe muscle pain.
Splinting of teeth with fixed bridges: biological effect
Authors: RENGGLI H. H. , ALLET B. , SPANAUF A. J.
Published: June 2007

Forty abutment teeth with pathological mobility were splinted with telescoped removable bridges. During the first 4 weeks the bridges were fixed. From the beginning of the fifth week they were removed once a day. Mobility was measured prior to placing the bridges and at 4 and 10 weeks intervals. Average mobility of the abutment teeth and the control unsplinted teeth did not change significantly during the experimental period.
Observations on a calcium hydroxide lining in retrieved deciduous teeth, with proximal amalgam fillings
Authors: GRAJOWER RAFAEL , BIELAK SHIMON , EIDELMAN ELIECER
Published: June 2007

The integrity and thickness of Dycal linings were determined on exfoliated deciduous teeth in which proximal fillings had been placed in vivo. The teeth remained in the oral cavity for more than 18 months after placement of the restorations. The average lining thickness was found to be 114 μm. One‐third of the samples showed evidence for the presence of Dycal at the gingival floor, up to the proximal tooth wall. Wash‐out of the lining was observed for most teeth in which Dycal had been present near the proximal tooth wall. Incipient caries formation, associated with wash‐out of the lining, was noted in a few samples. Contact between amalgam and dentine was frequently observed at the line angle, pulpal floor and axial wall.
‘Byte‐ryte’, an apparatus for the determination of the preferred vertical dimension of occlusion required for the construction of complete denture prosthesis
Authors: VAN WILLIGEN J. D. , RASHBASS C. , MELCHIOR H. J.
Published: June 2007

A computer‐controlled apparatus is described for the measurement of the preferred vertical dimension of occlusion (PVDO). The proposed apparatus guides the dentist through the measuring process and calculates the measure of the PVDO from the observations made.
The reaction zone around experimental amalgam alloy particles of Ag‐Cu eutectic composition
Authors: BRYANT R. W.
Published: June 2007

An electron microprobe was used to investigate the composition and microstructure of the reaction zone occurring around experimental particles of approximately Ag‐Cu eutectic composition in two experimental dental amalgams. This study formed the basis for the examination, described in a subsequent paper, of the reaction zones in several commercially available amalgams. Techniques of phase composition analysis were further developed in order to identify and quantify the component phases in the regions of the reaction zone. The clumped, outer, more darkly shaded region of the zone contained predominantly η1 (Cu6Sn5) phase. The inner, more lightly shaded region of the reaction zone was found to contain substantial quantities of η1, γ1, a Cu‐Hg phase and a Ag‐Cu component.
The reaction zone around commercially available amalgam alloy particles of Ag‐Cu eutectic composition
Authors: BRYANT R. W.
Published: June 2007

An electron microprobe was used to investigate the composition and microstructure of regions in the reaction zones around particles of approximately Ag‐Cu eutectic composition in commercially available and experimental dispersion modified amalgams. Two distinct regions were identified. Techniques of phase composition analysis were further developed in order to identify and quantify the component phases present in the two regions. The outer, somewhat clumped region contained principally a network of strands and particles of η1 (Cu6Sn5) composition and some γ1 phase. After phase composition analysis, the inner region was found to contain η1 phase and substantial quantities of γ1 phase, a Cu‐Hg phase (probably Cu4Hg3 formulation) and unreacted Ag‐Cu. The two regions may be best described as η1‐rich and η1‐sparse, respectively.
Speech sound distortions caused by changes in complete denture morphology
Authors: PETROVIĆ A.
Published: June 2007

A numerical method for speech analysis has been developed. The method is based on sounds spectrograms as carriers of information about individual voice characteristics.

The effects on speech sounds caused by alterations of the oral cavity dimensions with complete dentures of different morphology were analysed. Different positions of upper incisors and different thickness of the denture palatal plate were used as changeable factors in the longitudinal and transverse dimensions of the oral cavity. The effects of these changes on the relative duration of separate sounds in a word and the patient adaptation period were also analysed.

From the results some conclusions of pragmatic value were obtained useful in the clinical procedures of denture construction.
The effect of iron on in vitro decalcification of human tooth enamel
Authors: WEISS G. , STABHOLZ A. , MARKITZIU A. , MEYER I. , BRAYER L. , GEDALIA I.
Published: June 2007

The effect of iron chloride on an in vitro acid attack of human enamel was studied.

Slices of teeth were covered with varnish except for a window left on one of the enamel surfaces for exposure. The iron salt was used as a supplement to acid gel, or as pretreatment of the enamel surfaces before exposure to the pure gel.

Differences in light transmission of the experimental and control specimen from the radiographs taken before and after immersion in the decalcifying media were assessed quantitatively.

The increase in radio‐opacity of the enamel sections incubated in the iron‐containing acid media was attributed to a lower degree of enamel decalcification.
Evaluation of the effect of anxiety on the masseteric silent period duration
Authors: NOWLIN T. P. , BAILEY J. O.
Published: June 2007

The duration of the masseteric silent period (SPD) and environmental stress are parameters which have been associated with the symptoms of masticatory dysfunction. In this study, the relationship between differing levels of anxiety and the masseteric silent period duration, for nineteen subjects reporting a history of symptoms of mandibular dysfunction, was evaluated by a stress model based on the Sta X‐l anxiety test. The results suggest that the durations of masseteric silent periods were not significantly affected by differing levels of anxiety.
Long‐term observations of an increased occlusal face height obtained by a combined orthodontic/prosthetic approach
Authors: DAHL B. L. , KROGSTAD O.
Published: June 2007

Twenty individuals received an increased occlusal face height by orthodontic means (a partial bite‐raising splint). After splint treatment some of the anterior teeth were capped at the new occlusal face height. The average increase from start of splint treatment till after crown cementation was 1.9 mm. The stability of the vertical relations of the face after this treatment was studied. The average observation time was 67 months, i.e. 5.5 years. The modes of reaction were highly individual. A certain average relapse of the occlusal face height did occur, mostly in the course of the first 6 months after crown cementation. However, in no case did the increased face height revert to basis. In the period from 6 to 67 months after crown cementation twelve out of nineteen patients showed practically completely stable vertical relations.
The pulpal response to dilute citric acid smear removers
Authors: McINNES‐LEDOUX P. , CLEATON‐JONES P. E. , AUSTIN J. C.
Published: June 2007

The aim of this study was to determine the pulpal response to three dilute citric acid smear removers. Forty‐eight vervet monkeys (Cercopithecus aethiops pygerythrus), in three groups of sixteen animals provided 384 tooth specimens for the histological evaluation of the pulpal response at 3, 31, and 59 days post‐operatively. Labial Class V cavities were prepared in the maxillary and mandibular incisor teeth. The pulpal responses elicited by 1% aqueous citric acid, 1% citric acid in 30% ethanol and 0.1% citric acid in 30% ethanol solutions, in unlined cavities and in cavities lined with Dycal after acid application, were compared with those elicited by a negative control material—(Nobetec), and a positive control material—(Syntrex). Using Stanley's criteria the most severe pulpal responses were seen in teeth treated with 1% aqueous citric acid and 1% citric acid in 30% ethanol without a subsequent liner, and by Syntrex at all three time intervals. The use of Dycal as a liner after smear removal markedly reduced the pulpal responses.
Quantified marginal leakage of composites in vitro
Authors: ARENDS J. , VEEN H. v. d. , GROENINGEN G. v. , SCHUTHOF J.
Published: June 2007

In this in vitro study the marginal leakage of three composite systems—Sevriton, Consize and Isocap—has been quantified as a function of time.

The method used (v.d. Veen et al., 1984) consists of the determination of the amount of nitrogen gas passing through restoration margins at 2 atm.

The results show that the marginal leakage of all composites decreased strongly with time and became negligible after about 1 month. If we rank the three systems investigated according to their marginal leakage we have Consize>Isocap>Sevriton. The data suggest that water uptake and subsequent expansion of the polymers account for the leakage decrease.
The refractory period of the masseteric cutaneous silent period
Authors: SVEN‐ERIK WIDMALM , ASH M. M.
Published: June 2007

Silent periods were elicited in the electromyographic activity of the masseter and temporalis muscles from six normal subjects, by electrical stimulation of the skin over the contralateral masseter during clenching. Pairs of suprathreshold square pulses with varied time intervals were delivered using surface electrodes. It was found that the silent periods, which were mostly of the long latency (about 53 ms) type, had a refractory period, during which a new silent period could be evoked only by increasing the strength of the second stimulus. This refractory period could last for up to 1.5 s. During the first 200 ms after the first stimulus a second silent period was almost impossible to evoke with the moderately painful stimuli used in the present experiments. It is suggested that the refractory period should be considered as significant for the methodology when recording the silent period duration. It is also suggested that the long latency silent period should be recorded as a separate parameter and differentiated from the short latency (10–12 ms) silent period. This may be of special importance to recognize when a short latency silent period and a long latency silent period merge.
Mandibular reference positions
Authors: MOHAMED S. E. , CHRISTENSEN L. V.
Published: June 2007

An overview is presented of the mandibular reference positions of centric occlusion, centric relation and centric relation occlusion, and the position of rest. Clinical applications of the different positions are discussed on the basis of the physiology of the mandibular locomotor system.
Jaw morphology in edentulous individuals: a radiographic cephalometric study
Authors: ENGSTRÖM C. , HOLLENDER L. , LINDOVIST S.
Published: June 2007

The jaw morphology in the mandible and maxilla was studied by cephalometric analysis in two groups of edentulous subjects and in two groups of individuals in possession of all teeth. The predominating facial type in these groups was the orthognathic type. The alveolar bone height differed significantly between men and women in the edentulous groups but not in the subjects in possession of all teeth. Thus, there seemed to be a sex difference in alveolar bone diminution after extraction of all teeth. The gonial angle was significantly greater in both men and women in the edentulous groups than in either sex in the groups in possession of all teeth. Thus, the basal bone morphology in the mandible seemed to be changed in the same manner in both sexes in the edentulous groups after extraction of all teeth, in contrast to the alveolar bone diminution. Indications were found that the gonial angle might be age related.

The chin angle as such was found to be less than 60° in the majority of edentulous individuals which makes this value seem to be of minor importance when selecting edentulous individuals for surgical deepening of the vestibular sulcus.
The electrochemical activity of the oral cavity—a new approach
Authors: EWERS G. J. , GREENER E. H.
Published: June 2007

In order to develop model systems for studying and understanding corrosion phenomena in the oral cavity the electrochemical nature of the oral cavity must be known.

Accordingly, the PH and oxidation potential Eh (SCE) were measured in vivo in nine patients utilizing microelectrode techniques. Three of the patients had periodontal therapy and three had received minimal dental care. Sampling was always performed at five specific sites and in periodontal pockets greater than 4 mm when available. In the five sites common to all subjects the oxidation potential ranged from −58 to +212 mV (SCE) and the pH ranged from 6.1 to 7.9. For patients undergoing periodontal therapy the pH/potential clustered around acidic pH (6.6) and an oxidation potential range of 270 mV, whereas minimal dental care revealed a pH range from 6.3 to 7.9 and a small range (57 mV) of oxidation potential. Differences in pH and oxidation potential are related to site of measurement, periodontal health of patient and nature and quantity of restorations present.
An electromyographic study of the immediate effect of an occlusal splint on the postural activity of the anterior temporal and masseter muscles in different body positions with and without visual input
Authors: HOLMGREN K. , SHEIKHOLESLAM A. , RIISE C.
Published: June 2007

With the mandible at rest, the clinical postural position was measured and electromyographic recordings (in seated and supine position, eyes open and eyes closed, before as well as 15 min after insertion of an occlusal splint) were from the anterior temporal and masseter muscles in thirty‐one patients with signs and symptoms of mandibular dysfunction and nocturnal bruxism. The results indicated that when the patients were seated upright, there was a distinct postural activity in the anterior temporal and in some patients also in the masseter muscles. This postural activity decreased significantly with closure of the eyes and in supine position. Fifteen minutes after insertion of an occlusal splint, the postural activity in the temporal muscles decreased in 52%, increased in 22% and remained unchanged in 26% of the patients. Moreover, the postural activity reached its lowest level in supine position. The results indicate that the supine position is the body position to be preferred for centric relation recording as well as for occlusal and splint adjustment.
Isometric endurance of the human masseter muscle during consecutive bouts of tooth clenching
Authors: CHRISTENSEN L. V. , MOHAMED S. E. , RUGH J. D.
Published: June 2007

Three human subjects performed teeth clenching at maximum voluntary contraction strength (MVC) of the mandibular elevator muscles. At intervals of 10 s, ten successive bouts of MVC clenching were exercised until total exhaustion of the contracting muscles (isometric endurance). Isometric endurance time decreased exponentially from 59 to 12 s. The curve of the decrease showed a monotone power function (y=x−1). Electromyographic recordings from masseter muscles suggested that fatigable motor units, possibly fast glycolytic units, dropped out during the initial stages of maintained MVC isometric activity. The silent period of the monosynaptic jaw jerk reflex was increased by about 35% following exhaustion of the masseter muscle.
Periodontal problems associated with use of distal extension removable partial dentures—a matter of construction?
Authors: BERG E.
Published: June 2007

It is commonly assumed that a distal extension partial removable dentures rotates around the supporting rests when the saddle is occlusally loaded and that this rotation may expose the abutment teeth to a distal torque believed to be potentially harmful to their periodontal tissues. Attempts are therefore often made to counteract this effect through the denture construction. However, a review of relevant literature does not appear to substantiate an unqualified acceptance of the above mentioned assumptions, nor of the beneficial effect of special denture constructions designed to reduce the abutment loading. On the other hand, well controlled longitudinal studies seem to indicate that a favourable periodontal prognosis may be expected in such cases provided the following conditions are satisfied:

(1) Periodontal problems should be treated and an adequate oral hygiene established prior to the insertion of the denture;

(2) The periodontal health and oral hygiene should be maintained through regular recalls. During these recalls possible prosthodontic defects should be diagnosed and necessary measures implemented.
Tooth loss, attrition and temporomandibular joint changes in a Romano‐British population
Authors: WHITTAKER D. K. , DAVIES G. , BROWN M.
Published: June 2007

Mandibular condyles and temporal fossae were studied in a large Romano‐British collection of skulls.

The size and shape of the condyles differed from those in previous populations studied. Changes in form or shape of the condyles were age‐related and could be correlated to the number of teeth lost on the same side and on the contralateral side. No statistically significant correlations were seen between attrition and condylar form and surface change.
An investigation into the compatibility of some irreversible hydrocolloid impression materials and dental gypsum products
Authors: OWEN C.P.
Published: June 2007

Part I of this study considered the ability of alginate and gypsum combinations to reproduce a line on a test block. Part II describes a refined discriminatory procedure in the evaluation of the compatible combinations. Statistical analysis showed this procedure to be consistent, and that it could be expected to be repeatable. On the basis of this analysis, it was found that one alginate was clearly superior to all others, and that it was possible to distinguish a further group of combinations within the group that reproduced the 0.050mm line. Surface treatment of the alginates by fixing solutions showed that none of the treated materials could be improved to the extent of equating them with the best of the naturally compatible combinations.

It is recommended that manufacturers pay more strict adherence to the requirements of the ISO Standard with regard to the availability and recommendation of suitable compatible gypsum products, and also that perhaps the actual Standard should be modified to be more realistic in its demands, and more discriminatory in its evaluation procedure.
Contact allergy to dental materials in patients with orofacial complaints
Authors: YONTCHEV E. , MEDING B. , HEDEGÅRD B.
Published: June 2007

Two groups of individuals were patch tested for frequencies of contact allergy to dental materials. The patient group with orofacial and distant symptoms and complaints referred to the Department of Prosthetic Dentistry were compared with an age–sex matched control group of individuals referred to the Department of Dermatology. The results did not show any differences in patch test reactions between the patient and control groups. The study did not prove any obvious associations between the patients' symptoms or objective findings and the patch test results.
Food breakdown patterns produced by human subjects possessing artificial and natural teeth
Authors: LUCAS P. W. , LUKE D. A. , VOON F. C. T. , CHEW C. L. , OW R.
Published: June 2007

The abilities of thirty‐two complete denture wearers and thirty‐two dentate subjects to break down raw carrot particles were compared. The particle size distributions produced were broader in those subjects that broke down food rapidly per chew and, conversely, narrower in those that were slower. This did not appear to depend on dental status.

An analysis of mastication as composed of two separable processes, one describing the means by which particles come to be broken (selection) and the other, the size distributions of a particle upon fracturing (breakage), indicated that both processes were variable. It is concluded that no qualitative differences in the manner by which the two groups reduce food is apparent. To support this, a small study on dentate subjects suggests the covering of the palatal mucosa with an acrylic plate does not affect masticatory performance.
Further abrasion resistance and bond strength studies of fissure sealants
Authors: STRANG R. , CUMMINGS A. , STEPHEN K. W. , McMENEMY P.
Published: June 2007

As part of a laboratory evaluation, measurements of abrasion loss and tensile enamel–sealant bond strengths have been made on three visible light cured sealants (two filled, one unfilled), two chemically cured sealants (one filled and one unfilled) and an experimental sealant with alumina filler particles. A UV‐cured filled sealant was used as a control. The unfilled sealants had abrasion loss approximately twice that of the filled commercial sealants. The experimental sealant, with filler content above 50%, had an abrasion loss approximately half that of the filled commercial sealants. The chemical cured sealants had bond strengths lower than the UV‐cured control, while the bond strengths of the two visible light‐cured filled sealants and the experimental sealant were not statistically different from either the unfilled visible light‐cured sealant or from the UV‐cured filled sealant.
Criteria leading to patient loss from dental school clinics
Authors: XHONGA‐OJA F. A. , SONNABEND E. , KRAPP H.
Published: June 2007

The study was conducted at two different dental school clinics. The summary of the questionnaires revealed that patients in both cities are similar in their dental needs and expectations of treatment.

In order to solve the problem of losing patients from dental school clinics, several recommendations have been made.
Inaccuracies and defects in frameworks for removable partial dentures
Authors: EERIKÄINEN E. , RANTANEN T.
Published: June 2007

We studied the accuracy of 167 removable partial denture frameworks made in five commercial dental laboratories according to detailed instructions given by dental students, under the supervision of experienced teachers. Fewer than one half of the frameworks proved to be perfect. Some of the faults were accepted in the clinic, but 42% had to be corrected: 26% in the clinic, and 16% in the laboratory. Laboratory problems could be blamed for two‐thirds of the faults, and one‐third seemed to be attributable to the clinic. The advantages of, for example, new impression materials seemed to disappear under other factors.
Common migraine: a review and proposal for a non‐vascular aetiology
Authors: RUFF G. A. , MOSS R. A. , LOMBARDO T. W.
Published: June 2007

A brief review of the literature related to migraine headaches is presented. Information is presented on the epidemiology and diagnostic criteria of migraine headaches and is followed by a discussion on the problems inherent in the current classification system. Previously proposed vascular mechanisms of common migraine are discussed in the light of recent non‐supporting data and a possible link between common migraine and orofacial pain dysfunction syndromes is proposed. The role of oral behavioural patterns and related muscular/ temporomandibular joint problems are advanced as probable factors related to common migraine. The discussion focuses on the need to distinguish classic from common migraine headache sufferers in assessment and treatment outcome studies, as well as suggesting future avenues of research.
Solid soliubility of tin in silver–mercury γ1 in dental amalgams
Authors: SARKAR N. K. , EYER C. S.
Published: June 2007

The solid solubility of Sn in γ1 has been studied by examining a series of γ1 samples containing 0.25–2.0 wt% Sn by scanning electron microscopy and energy‐dispersive X‐ray analysis. It has been observed that the addition of Sn to γ1 leads to the formation of mainly an intergranular Sn‐Hg compound. On the basis of this observation it has been concluded that the solubility if Sn in γ1 si virtually nil.
The amplitude distribution of electromyographic activity of masticatory muscles during unilateral chewing
Authors: HAGBERG C.
Published: June 2007

The amplitude probability distribution function (APDF) of electromyographic activity was used to describe the variation in relative masticatory force in the superficial masseter muscle and the anterior temporal muscle during unilateral chewing. The masticatory force, predicted from an isometric reference contraction, increased significantly in both muscles when chewing an almond compared to chewing half a stick of gum. Analysis of the distribution levels of contraction showed that the significant differences in relative masticatory forces were found for high levels of contraction. The individual variations were large when masticatory force between the muscles was compared. Maximal loading of the masseter muscle and the anterior temporal muscle exceeded 100% of the reference voluntary contraction in six females out of nine, mainly during chewing of an almond. The results indicated that APDF can be useful for analysing chewing when estimations of relative masticatory force and a measure of the distribution of different levels of contractions are desirable.
Post‐stimulus EMG complexes in the masseter muscle following gingival electrical stimulation in man
Authors: CARELS C. , VAN STEENBERGHE D.
Published: June 2007

Post‐stimulus EMG complexes (PSECs) were elicited by means of electrical stimulation of the gingiva in six subjects during clenching in three biting positions, namely the maximal occlusion, the incisor edge‐to‐edge and the hyperpropulsive biting position. No interrelationship was found between the mechanically and electrically elicited PSECs. With electrical stimulation the PSEC morphology was not related to the biting position in contrast with the PSECs elicited with mechanical stimulation. Following gingival electrical stimulation, a P wave was not present in the PSEC.
Physiology and pathophysiology of skeletal muscle contractions
Authors: CHRISTENSEN L. V.
Published: June 2007

An overview is presented of the physiology and so‐called pathophysiology of static muscle contractions in the intact living organism. Static muscle activity produces no external mechanophysical work, but is used for fixation. Contingent upon the levels of the generated forces, and the duration of the isometric contractions, static activities give rise to fatigue and pains. The discomforts are viewed as somatic responses that are normally within physiological limits. That is, upon cessation of isometric contractions there is usually rapid recovery from the discomforts, and they do not normally induce chronic lesions.
Changes in masticatory movement parameters within the chewing period in young dentate persons and patients rehabilitated with bridges supported by implants in the mandible
Authors: JEMT T.
Published: June 2007

Experiments were carried out to study changes in masticatory movements in the chewing sequence of young dentate persons and complete denture wearers rehabilitated with bridges on osseo‐integrated implants (OIB) in the lower jaw. Two test foods were used in the dentate group (apple, bread) and bread in the OIB group. A computer‐based opto‐electronic system (Selspot) was employed to record and analyse all single chewing cycles, regarding parameters reflecting, chewing rhythm, mandibular velocity and displacement. The different parameters were tested both intra‐ and inter‐individually versus the series of the single and overall chewing cycles in the masticatory sequences respectively. The results indicated that different subjects performed different patterns of mastication within the chewing period when chewing the same type of food. Different test foods (texture, size) also seemed to affect the chewing pattern in a different way, e.g. mandibular displacement showed an obvious reduction when chewing apple, probably due to the bigger size of the bolus. The inter‐ and intra‐individual analysis showed in some parameters discrepancies implying problems in analysing the chewing pattern within the chewing sequence without using both methods.
Six months clinical evaluation of prefabricated veneer restorations after partial enamel removal
Authors: JENSEN Ø. E. , SOLTYS J.L.
Published: June 2007

Thirty‐three preformed plastic laminate veneers were placed in maxillary anterior teeth of twenty‐one subjects. The indications for veneer placement were intrinsic staining of large conventional composite restorations or discolouration caused by previous endodontic therapy. The veneer restorations were evaluated clinically over a 6‐month period for retention, colour match, surface texture, marginal integrity and gingival response. Twenty‐nine restorations were available for evaluation at 6 months. Three restorations exhibited bonding failure during the study period, giving an overall retention rate of about 91%. Deep brown discolouration in two teeth could not be adequately matched with the opaquer and shader pastes supplied with the kit. Only one patient exhibited any change in veneer surface texture during the study period. Slight, but clinically inconsequential deterioration of marginal integrity was also noted in several restorations. The gingival response to the veneer restorations was uniformly excellent. It was concluded that restoration with preformed veneers, using the enamel reduction and heat adaptation techniques, provided an aesthetic, conservative and functional alternative to fixed prosthodontic therapy in selected cases.