bluuebunny/crossref_metadata_2025 huggingface dataset:
An electromyographic and cephalometric study on facial pains and facial morphology in children
Authors: CHRISTENSEN L. V.
Published: June 2007

Twelve children, five girls and seven boys with a mean age of 12 years, exercised maximal voluntary tooth clenching until intolerable pains and total subjective exhaustion of at least the right masseter muscle forced the children to stop the isometric muscle exercise; that is, the pain tolerance, or the isometric endurance time, of at least the right masseter muscle was determined in seconds, and it amounted to an average of 100 s. Concomitantly, the electrical activity in the right masseter muscle was recorded by bipolar surface electrodes and integrated, and it showed a significant decrease of 32 % during the endurance test, probably as an expression of progressive physiological muscle fatigue. A large ANB angle was associated with relatively little decline of the contractile activity and a trend not to endure pains, possibly because isometric tension was generated predominantly by muscle fibres with a high anaerobic capacity.
Oral awareness and oral motor proficiency in retchers
Authors: WRIGHT SUSAN M.
Published: June 2007

It has been suggested that hypersensitivity and awareness of dentures are causes of retching associated with dentures and dental treatment. Oral form recognition (OFR) and oral motor (OM) ability were examined in fifty‐three pairs of retchers and controls. The retchers had all had problems with retching when wearing dentures or during dental procedures. The controls were the same sex as the retchers and were matched with them as closely as possible for age, remaining teeth and edentulous spaces.

No difference in OFR and OM ability was found between the paired subjects which might indicate that increased oral awareness contributed to the retchers' symptoms.
Structural changes in composite surface material after dry polishing
Authors: DAVIDSON C. L. , DUYSTERS P. P. E. , De LANGE C. , BAUSCH J. R.
Published: June 2007

The purpose of this study was to investigate the properties of composite materials that had been heated to temperatures which may occur during dry polishing. Bulk composite material was submitted to thermal analysis from R.T. to 200°C. Two distinct stages of thermal reaction in this range could be identified. One at approximately 70°C, which could be related to a further initiating of unreacted groups, and one above 100°C, which could be related to the glass transition. The glass transition was also observed microscopically. Hardness measurements were carried out on the warm material at different temperatures as well as on the material being cooled down to R.T. With temperature rise, a continuous increase in hardness and abrasion resistance could be demonstrated. The observed phenomena for bulk material are related to the properties measured on dry polished surfaces.
The role in masseter muscle activities of functionally elicited periodontal afferents from abutment teeth under overdentures
Authors: MUSHIMOTO EIKO
Published: June 2007

Five overdenture wearers with a small number of remaining natural teeth were selected to evaluate the effect of the afferent input from periodontal mechanoreceptors on masseter activity in man. As a control, a full denture wearer was included. The subjects were instructed to chew a piece of gum, and/or tap their teeth. Surface EMG from the bilateral masseter muscles were recorded and analysed.

When functional pressure was applied, during chewing, to the abutment teeth as well as to mucosa through the denture base, masseter activities were encouraged. Following application of anaesthesia to the periodontal membrane of the abutments, masseter activities were reduced.

The duration of the silent period (SP) appearing in the EMG burst following tooth tapping was significantly increased with root support compared to mucosal support only. With topical anaesthesia of the periodontal tissues, SP duration decreased significantly.

In conclusion, it has become apparent that the pressure sensibility of abutment teeth bearing functional pressure under an overdenture base is capable of facilitating masseter activity, as one of the sources of oral sensory input during mastication.
Recent results concerning physiological tooth movement and anterior guidance
Authors: SIEBERT G. , Siebert Götz
Published: June 2007

Physiological tooth movements during mandibular excursions with and without occlusion have been considered. Using electronic and pantographic techniques, anterior guidance and tooth movements during simulated mastication (without a bolus) were investigated.

Investigations in the absence of occlusion showed that elastic deformation of the mandible gave rise to tooth movements. During occlusion three‐dimensional tooth movements of up to 60 μm in each direction occurred.

Pantographic measurements of anterior guidance showed that each type of occlusion (balanced occlusion, group function and canine protected occlusion) has its own characteristic. Only canine protected occlusion gave values which corresponded to physiological data.
The Dentatus screw: comparative stress analysis with other endodontic dowel designs
Authors: STANDLEE J. P. , CAPUTO A. A. , HOLCOMB J. P.
Published: June 2007

Using photoelastic stress analysis, this study shows that the tapered, self‐threading, Dentatus endodontic screw causes severe wedging forces on installation. These stresses are magnified by increases in dowel diameter and the application of occlusal loads. The Dentatus screw produces more severe stress concentrations than the Unitek, Whaledent, Radix, and Kurer dowel designs; this is true both during installation and under load.
Masticatory muscle activity before and after elimination of balancing side occlusal interference
Authors: INGERVALL BENGT , CARLSSON GUNNAR E.
Published: June 2007

The activity of the masseter and anterior and posterior temporal muscles was studied by electromyography (EMG) in thirteen subjects with unilateral balancing side interferences and in twelve control subjects without such interferences. In both groups the EMG recordings were made during postural activity and various functions of the masticatory system and in the interference group they were repeated on two occasions following occlusal adjustment.

The postural muscle activity was significantly lower in the interference than in the control group while there was no difference during maximal bite. The number of chewing cycles was greater and the act of chewing was somewhat longer in the interference than in the control group. During swallowing of water the maximal mean voltage amplitude was smaller in the interference than in the control group.

The findings are discussed in relation to previous results and the conflicting ideas concerning occlusal factors in the aetiology of mandibular dysfunction.
Comparison of intra‐oral long‐cone paralleling radiographic surveys and orthopantomographs with special reference to the bone height
Authors: ADRIAENS P. A. , DE BOEVERW J. , VAN DE VELDE F.
Published: June 2007

A comparison between bone height scores from long‐cone paralleling radiographic surveys and orthopantomographs (Panex‐EC) of forty‐one patients was made. Intra‐examiner reliability and inter‐examiner objectivity of the measuring method (Schei ruler) proved to be very good (r = 0.954 and r = 0.923 respectively for the intra‐oral surveys; r = 0.928 and r = 0.916 respectively for the orthopantomographs). Distribution and frequency of the non‐measurable surfaces were evaluated. In each technique an attempt was made to discern the main cause of non‐measurability: overlapping of adjacent structures, absence of the surface and absence of the apical region on the image.

For twenty of the thirty‐six surfaces significant differences were found between bone height scores for corresponding surfaces in the long‐cone survey and in the orthopantomograph. In periodontal, prosthetic and conservative dentistry the long‐cone paralleling technique should be considered as the best radiographic technique.
A clinical study of the number of occlusal tooth contacts in the intercuspal position at light and hard pressure in adults
Authors: RIISE CLAES
Published: June 2007

Young adults and Adults were investigated with respect to the number of occlusal tooth contacts. In the habitual intercuspal position (centric occlusion) there was, on a highly significant level, a smaller number of tooth contacts at light pressure than at hard pressure.

When Young adults were compared with Adults there was a significantly smaller number of contacts at light pressure in the Adults. During hard pressure, there was no significant difference between the groups. There was no significant difference in the number of tooth contacts at light and hard pressure between patients referred for orthodontic treatment and others.

In the group of Young adults, approximately 5% of the contacts appeared on a restoration at light pressure, while approximately 10% did so at hard pressure. There was no significant difference between those with and without contacts on a restoration with respect to the number of contacts at light and hard pressure. If the number of contacts on study casts of 106 adults (Adults‐A), after occlusal adjustment in an articulator, was compared with the number of hard pressure contacts found clinically in thirty‐five of them, no significant difference was found.
Residual monomer (Bis‐GMA) of composite resins
Authors: INOUE K. , HAYASHI I.
Published: June 2007

A method of measuring residual monomer (Bis‐GMA) is described. In addition, the percentage of residual monomer eluted into water from composite resins after setting was compared for several commercial products.
Incisal angle adhesive resins: a 5‐year clinical survey of two materials
Authors: SMALES ROGER J.
Published: June 2007

Two hundred and seventy‐eight restoration examinations were made of Concise and Nuva‐fil resins used to restore fractured incisors, over periods of up to 5 years. Following the placement of wide bevels along the fracture margins, retention was achieved by using acid‐etching with bonding resins and by pins in some instances. Although the short‐term results were usually reasonable, provided that the materials had been placed and finished correctly, longer‐term findings revealed problems of resin darkening and corrosion staining of dentine from exposed pins. The Nuva‐Fil restorations were generally superior to the Concise restorations.
The influence of eye closure on muscle activity in the anterior temporal region
Authors: WIDMALM SVEN‐ERIK , ERICSSON SVEN GOTTMAR
Published: June 2007

In the experiments reported here the influence of eye closure upon the muscle tone in the region of the anterior temporal muscles was studied during mandibular rest in four patients with TMJ dysfunction and in four healthy subjects. The muscle activity as well as the cortical activity (EEG) of the patients was influenced by changes in visual stimulation. EMG (the anterior temporal region) and EEG (parieto‐occipital region) were recorded with needle electrodes. Ongoing EMG activity was present in all patients when their eyes were open. Closure of both eyes reduced the muscle activity by 50–100%. Closure of one eye could also abolish all activity but the degree of this influence was variable. Opening of the eyes blocked the alpha rhythm in the EEG. Simultaneously, increased activity was observed in the region of the temporal muscle. The activity level in the temporal region of the healthy subjects was very low and could easily be reduced to noise level using ordinary relaxation manoeuvres without eye closure.

The results reported here indicate that visual stimulation may increase muscle tone in the temporal region probably as part of an arousal reaction. It is, however, possible that the activity might stem not from the temporalis muscle but from the temporoparietalis.
The effects of cyclic stress on dental polymethylmethacrylate
Authors: HARGREAVES A. S.
Published: June 2007

Alternative resins to traditional denture base acrylic need to be assessed for both short‐and long‐term performance before their potential can be evaluated. Much dental materials testing is carried out on fresh material and a baseline of knowledge about the properties of aged material is incomplete. Studies have been carried out to examine the effects of thermal and environmental fluctuation on dental acrylic, with testing procedures reconsidered so as to resemble service conditions as closely as possible. Thermal cycling proved detrimental to the resin only when superimposed on intermittent partial drying out and resaturation.
Movement of abutment teeth in spring cantilever bridges: a laboratory study
Authors: GRAY H. S. , MYERS G. E.
Published: June 2007

The extent and directions of movements of spring bridge abutments were studied on acrylic casts with resilient steep and shallow palates and containing human molar and premolar abutments with compressible ‘periodontal ligaments’. Bridges with rigid bars and ‘flexible’ standard, long and short lengths were cast in Type IV gold, and soldered to Type III gold retainers which were pinned to the abutments. The pontic on each bar was depressed a standard 0.2 mm, and the movement of the abutments registered on a dial gauge resting against the mesio‐buccal corner of each retainer. The combination of bar length and palatal contour causing least movement of an abutment was the shortest bar to the molar abutment in the shallow palate model; indeed all bars on this model deflected the molar abutment less than similar bars on the steep palate model. Differences in palatal contours did not affect the extent of movements of the premolar abutments which were comparable to molar movements in the steep palate model. Abutment teeth moved mesio‐buccally when the pontic was depressed, and the elbow of the bar usually moved off the palate indicating the fulcrum was positioned along the anterior section of the bar.
The effects of cyclic stress on dental polymethylmethacrylate
Authors: HARGREAVES A. S.
Published: June 2007

Mechanisms of fatigue failure in polymers and the aims of fatigue testing have been examined, and factors affecting testing summarized. In the light of available work in several fields, parameters have been suggested for realistic flexural fatigue testing of denture base resins. A testing machine has been developed, with which the changes in properties of acrylic resin after fatigue in different environments can be studied. These changes developed gradually after 104 cycles and were related to the development of bulk crazing rather than to thermal effects. The amount of decay in the elastic modulus was not such that the material could have been said to have ‘failed’.
Assessment and treatment of stress in myofascial pain‐dysfunction syndrome: a model for analysis
Authors: HABER JOEL D. , MOSS ROBERT A. , KUCZMIERCZYK ANDREW R. , GARRETT JAMES C.
Published: June 2007

Myofascial pain dysfunction (MPD) syndrome has received widespread attention in the dental and psychological literature. The present paper considers issues concerning a stress‐related muscular hyperactivity theory of MPD syndrome. A review of the empirical evidence as well as methodological problems evident in these studies has been noted. In addition, definition aspects of stress and a conceptual model of stress in clinical use is presented. A functional analysis of the problem components will help determine a proper treatment protocol for patients suffering from stress‐related myofascial pain. A discussion of the conceptual model for assessment and treatment purposes is presented and its implications for future research noted.
An assessment of new dental ultraviolet sources and u.v.‐polymerized fissure sealants
Authors: MAIN C. , CUMMINGS A. , MOSELEY H. , STEPHEN K. W. , GILLESPIE F.C.
Published: June 2007

The performance of six dental ultraviolet (u.v.) sources was assessed to establish minimum output requirements and possible u.v. hazards. Exposure criteria for u.v.‐cured materials (Nuva‐seal P.A., Nuva‐cote P.A., Nuva‐fil P.A., Lee‐seal, u.v.‐Dentoseal, Uviobond, Visiobond) were assessed by determining setting time‐intensity characteristics, u.v. transmission and microhardness as a function of u.v. intensity and depth. A minimum intensity of 10 mW cm−2 was required for adequate curing and both Nuva‐seal P.A. and Nuva‐cote P.A. set well in depth with realistic exposures. Total u.v. outputs, average intensities and spatial distributions were assessed for the u.v. sources, most of which were well above minimum requirements. Ultraviolet spectra and maximum permissible exposure measurements indicated that all of the sources were safe in normal use.
Optical properties of composites of selected shades in white light
Authors: POWERS J. M. , YEH C. L. , MIYAGAWA Y.
Published: June 2007

Light reflectivity, scattering coefficient, absorption coefficient, infinite optical thickness, and contrast ratio were determined in white light, for seven shades of a conventional composite and five shades of a microfilled composite, from reflection spectrophotometric data using Kubelka's equations. Significant differences among shades were observed for each property. Values of infinite optical thickness ranged from 2–97 to 5–90 mm among the shades studied.
Diagnosis of the aesthetic components of the mandibular anterior prosthesis
Authors: LORTON LEWIS , WHITBECK PETER
Published: June 2007

This paper explores seven different factors which should be considered when prescribing the lower anterior prosthesis: alignment as seen from the incisal; height of the incisal edges; degree of irregularity of the teeth; character of the incisal edge; height of the cuspid; mesio‐incisal angle of the cuspid; and ridge coverage. The weights and variations of these different factors are discussed and suggestions made for a complete work authorization.
Antibacterial and mechanical properties of restorative materials combined with chlorhexidines
Authors: JEDRYCHOWSKI JOSEPH R. , CAPUTO ANGELO A. , KERPER STEVEN
Published: June 2007

Chorhexidine gluconate or chlorhexidine dihydrochloride were added to a composite resin and a glass ionomer restorative material in concentrations of 0,1,2,3,5, and 10% by weight. Antibacterial activity was measured by inhibition of growth of S. viridans, S. pyogenes, S. mutans, L. acidophilus, and E. coli. for 4 days.

Compressive, tensile, and restorative material‐enamel adhesive shear strength tests were performed. The addition of chlorhexidine gluconate or chlorhexidine dihydrochloride increased the antibacterial activity of the composite resin and the glass ionomer restorative material and changed the mechanical properties of the restorative materials. The addition of chlorhexidine dihydrochloride resulted in mechanical properties closest to controls.
Laser techniques for the evaluation of wear in Class II restorations
Authors: WILLIAMS D. F. , CUNNINGHAM J. , LALOR M. J. , GROVES D. , ATKINSON J. T.
Published: June 2007

A technique for the quantitative determination of the changes in surface topography of restorations during wear has been developed. This involves the optical contouring of the surface using a laser, and the generation of contour maps. Several different methods for interpreting these maps are discussed. A computer‐aided method is the most consistently accurate and measures wear volume to an accuracy of 2–5%.
Solubility of enamel powder following treatment with a sodium‐n‐lauroyl sarcosinate containing toothpaste in the presence and absence of fluoride
Authors: RAJSTEIN J. , FUKS M. , MARKITZIU A. , GEDALIA I.
Published: June 2007

Toothpaste solution exerts an inhibitory effect on dissolution of enamel in acidic solution. The presence of a detergent will not predispose enamel to acid dissolution or affect the inhibitory effect of fluoride on dissolution.
A clinical study of the distribution of occlusal tooth contacts in the intercuspal position at light and hard pressure in adults
Authors: RIISE CLAES , ERICSSON SVEN GOTTMAR
Published: June 2007

Young adults (Md 24) and Adults (Md 41) were examined with respect to the distribution of occlusal contacts in molars, premolars and anterior teeth when exerting light and hard pressure respectively in the habitual intercuspal position.

There was no difference between the right and left side and the number of contacts per tooth was low. In all groups of teeth there was a smaller number of contacts at light pressure. The lower number of contacts at light pressure in Adults when comparing with Young adults was related only to the anterior teeth. The increase of the number of contacts at hard pressure was greater for the anterior teeth than for the molars. In cases where there was a greater number of contacts present on one side, the distribution did not alter significantly when changing from light to hard pressure. Neither did the articulator‐adjusted intercuspal position differ significantly in this respect from the clinically recorded intercuspal position at hard pressure. A further result was that about 50% of the individuals had 60% or more contacts on one side at light pressure.

These findings stress the importance of meticulous care when performing occlusal adjustment, as the number of contacts per tooth is low and indicates the need for observing the difference between light and hard pressure.
The possible activity of large and small jaw muscle units in experimental tooth clenching in man
Authors: CHRISTENSEN L. V. , MOHAMED S. E.
Published: June 2007

Eight human subjects exercised maximum voluntary tooth clenching until there was complete exhaustion of the contracting jaw muscles (isometric endurance time). During the isometric muscle contractions the myoelectrical currents of the masseter and anterior temporalis muscle were sampled by bipolar surface electrodes, integrated, and cumulatively stored. The myoelectrical activity was studied at recording thresholds of 1 μV and 40 μV, i.e. all action potentials below threshold level were ignored. The observations suggested that the number of fast glycolytic and fast oxidative glycolytic motor units in the masseter muscle might have exceeded that in the anterior temporalis muscle; and/or the size of the masseter muscle units might have been larger than that of the anterior temporalis muscle units.
Temporomandibular joint dysfunction syndrome and myofascial pain dysfunction syndrome: a critical review
Authors: MOSS ROBERT A. , GARRETT JAMES C.
Published: June 2007

Temporomandibular joint (TMJ) dysfunction syndrome and myofascial pain dysfunction (MPD) syndrome have been primarily viewed as dental problems and have only recently received close attention by psychologists. The literature reviewed in the present paper reveals that a substantial portion of the population is affected by these disorders. There is, however, a great deal of confusion that exists in relation to the aetiology and treatment of these syndromes. In an attempt to clarify the current understanding of these disorders, the present review first presents a discussion of the symptoms which comprise each of these syndromes and the proposed physiological mechanisms associated with each symptom. Next, the aetiological theories for each of these syndromes are reviewed and critically evaluated. Treatments which have been derived from the theoretical models are then discussed. Finally, methodological considerations involving classification, assessment and treatment issues are presented and future research needs are outlined.
Occlusal forces in prosthetically restored dentitions: a methodological study
Authors: LUNDGREN DAN , LAURELL LARS
Published: June 2007

The present paper describes a method developed to study occlusal forces in prosthetically restored dentitions. Using this method the magnitude, duration and frequency of the forces can be measured in various parts of the dentition simultaneously. The measurements are based on the use of strain gauge transducers of such dimensions that they can be mounted into artificial crowns, bridge‐pontics or removable dentures, without interfering with the occlusion. The output signal of each transducer is linear for forces up to 300 N which corresponds to an amplitude (elastic deformation) of 20 μm.

At least four transducers are used distributed over the tooth‐arch to create bilateral and simultaneous contacts. They are mounted in a supraoccluding position of 20 μm in relation to non‐transducer areas. This means that on jaw closure each transducer registers all the force transmitted to that part of the prosthetic construction represented by the transducer, provided there is no force leakage to non‐transducer areas. The sum of these local forces constitutes the total force acting on the entire dentition at any given moment.
Mastication after surgical reconstruction of the mandibular residual ridge
Authors: RENAUD MAGDELEINE , MERCIER PAUL , VINET ALAIN
Published: June 2007

A group of thirty‐one female denture patients who underwent surgical reconstruction of their deficient residual ridges with ridge extension and skin graft or ridge augmentation with bone graft were evaluated with regard to their masticatory function before surgery, then at 8 months and 12 months post‐operative with their new dentures. Two objectives tests of masticatory efficiency were used. The masticatory efficiency index (MEI), based on the size of chewed almond particles, determined the potential capacity of patients to masticate while the masticatory performance (MP) based on the time required to masticate food before swallowing assessed the individual ability of each patient to chew food. A subjective index of difficulty (SD) provided information on the patient's own assessment of chewing difficulty of certain foods selected for their hard texture. The evolution of each index and their interrelationship were statistically evaluated. It was shown that the masticatory performance (MP) and the subjective index of difficulty (SD) both improved significantly during the rehabilitation period and even more rapidly than the masticatory efficiency index (MEI).

The discrepancy between the objective and the subjective tests and the overestimation from the patients indicate that the real benefit of the rehabilitation is not limited to improved chewing, but also to an acquired self‐confidence in mastication.
Bruxing patterns in man during sleep
Authors: CLARKE N. G. , TOWNSEND G. C. , CAREY S. E.
Published: June 2007

Nocturnal clenching was monitored using a dedicated microprocessor, appropriate EMG amplification and digitisation. The hardware was located at the subject's bedside and the software provided for the real time recording of clenching bruxism, duration of the episode and the severity in electronic values. Forced clenches before retiring and on arousing provided maximal baseline data against which to compare the severity of sleeping clenches. All ten subjects tested were found to brux and two used intensities of effort while asleep that exceeded their maximal conscious clenches.
Contractile activity of the masseter muscle in experimental clenching and grinding of the teeth in man
Authors: CHRISTENSEN L. V. , MOHAMED S. E.
Published: June 2007

Six human subjects exercised maximum voluntary tooth clenching and right‐sided tooth grinding to determine the onset of fatigue in the right and left masseter muscle. Static and dynamic contractile activity of the two muscles was determined by surface electromyography. Muscle fatigue appeared after about 30s of isometric contractions (clenching), while 30s of combined concentric and eccentric contractions (grinding) induced no fatigue. In the right muscle the contractile activity of negative work (eccentric contractions of mandibular laterotrusion) was about 50% of that of positive work (concentric contractions of mandibular mediotrusion). During clenching an increased number of contacting teeth might have facilitated the contractile activity of the two muscles. During grinding the height of the cusps of the working side teeth might have contributed to a decrease of tension production by the right masseter muscle. Non‐working side tooth contacts and peripheral receptors might have facilitated the contractile activity of the left masseter muscle during tooth grinding. Static contractile activity of the mandibular elevator muscles produced high levels of isometric tension and led to masseter muscle fatigue in about 30s. The same duration of dynamic contractile activity, resulting in low levels of tension during positive and negative work, did not induce fatigue.
The effect of body posture on the preferred vertical dimension of occlusion
Authors: WRIGHT SUSAN M.
Published: June 2007

Thirteen edentulous adults were investigated to see whether their preferred vertical dimension of occlusion (PVDO) was affected by vertical and horizontal body posture. The PVDO was found by the forced choice method using a graduated series of sticks in random sequence. The subjects were tested in both postures on two separate occasions. No significant difference was found between the PVDO's when the subjects were sitting upright and when they were supine. Nor was there any significant difference in the PVDO of the first and second sessions for either position.
Surface roughness and marginal behaviour of experimental and commercial composites: an in vitro study
Authors: ROULET J.‐F. , HIRT T. , LUTZ F.
Published: June 2007

Three experimental inhomogeneous microfilled composites (IMC) containing spherical prepolymerized particles with an interpenetrating network (IPN) were compared with the reference materials Estic MF, Adaptic and the amalgam Dispersalloy in vitro. With surface roughness tests, different polishing procedures were investigated. In addition an SEM analysis of the margins of Class I fillings using a replica technique was performed. With the same technique the proximal boxes of Class II fillings were analysed to further determine the best method to handle the materials clinically. The experimental materials showed a superior adaptation to the walls of proximal boxes of Class II cavities than the reference materials. This superiority was increased by the use of a filled bonding agent. The influence of viscosity, filler load and glass transition point on adaptation and polymerization shrinkage are discussed. It was concluded that especially designed diamonds with very fine abrasive particle size (40 μm and 15 μm) are the best for finishing and contouring composite fillings. Based on the results of this study it is recommended to use the experimental material for clinical investigations.
In vivo evaluation of occlusal wear of two experimental composites versus amalgam
Authors: HIRT TH. , LUTZ F. , ROULET J.‐F.
Published: June 2007

Two experimental inhomogeneous microfilled composites with spherical prepolymerized particles and an interpenetrating network (IPN), which provides a stable bond between prepolymerized spheres and the matrix (B‐21 and B‐51), and amalgam were used for Class II MOD fillings in mandibular molars. After 3 and 6 months of clinical use, wear of the material was measured with a replica technique and a modified surface roughness test. The failure mode was analysed with SEM photographs also using a replica technique. After 6 months the wear of the composites in the occlusal contact area was more than twice as high as the substance loss of amalgam.

It was concluded that the composites were not suitable for fillings bearing occlusal load. However, the failure mode seen in the SEM for B‐21 indicated that the IPM leads to a stable incorporation of the spherical prepolymerized particles into the matrix. Due to its good surface characteristics B‐21 should be further investigated for its use as an anterior composite. B‐51 was especially designed as a posterior composite. Beside the construction elements of B‐21 it contained also barium glass spheres to obtain radiopacity. This hybrid construction failed due its wear mode.
Distribution of nocturnal bruxing patterns in man
Authors: CLARKE N. G. , TOWNSEND G. C.
Published: June 2007

The distribution of nocturnal bruxing patterns in nine subjects was recorded and interpreted in accordance with current concepts of sleep physiology. Few bruxing events were seen in the first 2 h of sleep but peak periods were identified during the night. The findings suggested that bruxism and REM sleep were closely associated and pointed towards a central aetiology for bruxing activity.
Repeatability of the mandibular retruded position
Authors: HELLSING G. , McWILLIAM J. S.
Published: June 2007

Repeatability of the centric jaw relation recorded with the one‐handed push‐back technique was tested on six subjects. Condylar positions were radiographically recorded using cold cure acrylic indices to lock the jaws in centric. This was done on two occasions with an interval of 1 week between recordings. Utilizing the subtraction technique, the radiographs of these condylar positions were compared. Intra‐individual differences were not found to be significant and it may be concluded that centric relation registered with the push‐back technique results in accurate and consistant repositioning of the condyles in the glenoid fossa.
The pattern of adsorption of cationic antiseptics to polymethylmethacrylate
Authors: MORAN J. , ADDY M.
Published: June 2007

Few studies have reported the maximum potential of surfaces to adsorb the cationic antiseptics and few comparisons between antiseptics have been carried out. The purpose of this investigation was to measure the maximum uptake of alexidine, cetyl pyridinium chloride, chlorhexidine gluconate and chlorhexidine acetate to polymethylmethacrylate and by the construction of adsorption isotherms determine the pattern of molecular attachment to the recipient surface. The mean maximum adsorption findings for these antiseptics demonstrated significantly greater uptake of cetyl pyridinium chloride than the other antiseptics and significantly less uptake of alexidine compared with the other antiseptics. All four antiseptics showed a Langmuir type adsorption isotherm consistent with the formation of a monolayer of molecules on the recipient surface. For chlorhexidine preliminary studies demonstrated that the pattern of adsorption was not altered by saliva pre‐treatment of surfaces. No evidence of molecular multilayering was observed even at higher concentrations of the antiseptics. However, the maximum uptake on to the surface was significantly increased when no post‐treatment washings were carried out. It was concluded that this increased uptake would be unlikely to play an important role in antiplaque activity because of its relative instability. The pH dependency for the adsorption of these antiseptics was demonstrated such that as previously observed for chlorhexidine gluconate at low pH adsorption is almost completely, or completely, prevented.
Gnathosonic monitoring of occlusion of complete and partial dentures
Authors: WATT D. M. , McPHEE P. M.
Published: June 2007

The durations of occlusal sounds of edentulous patients wearing complete dentures and of partially endentulous patients with and without partial dentures were measured. In general the durations of the sounds decreased after adjustment of occlusion and after periods of wearing the dentures, but in a cross‐section study of sound duration of old complete dentures (mode 16 years) an increased sound duration was observed.
The effective minimum cement thickness of zinc phosphate cement for luted non‐precious crowns
Authors: GRAJOWER R. , LEWINSTEIN I. , ZELTSER C.
Published: June 2007

Non‐precious metal crowns were prepared for natural teeth which were ground to a taper angle of 5°. The movement of the crowns on teeth during repeated try‐on seating was measured with a micrometer. Increasing the applied load from 2 to 10 kg resulted in an average crown movement of 63 μm. For most samples this movement continued when try‐on was repeated. Casting irregularities were found to create furrows on some regions of the axial tooth surface during try‐on seating. The diameter of the ADA specification consistency disk for zinc phosphate cement was found to depend strongly on the P: L ratio and the ambient temperature. The castings were cemented with zinc phosphate cement of controlled consistency. Cementation with a load of 10 kg gave rise to an average crown elevation of 54 μm and a range of measurements between −8 and 113 μm. The effective minimum cement thickness corresponding to this average was calculated to be 4.7 μm. Small negative values of elevation were attributed to deepening of tooth furrows during cementation. An analysis is given of data from the literature, relevant to the cement flow and irregularities in cement thickness.
Effects of various agents in cleaning cut dentine
Authors: DUKE E. S. , PHILLIPS R. W. , BLUMERSHINE R.
Published: June 2007

The effectiveness of various agents in cleaning cut dentine surfaces was investigated. Attempts to remove the smeared layer of dentine after the preparation of a cavity showed that a polyacrylic acid (Durelon liquid) gave the best result, flour of pumice or a prophylaxis paste (Prevodontic) used with a rubber cup were effective, but 3% hydrogen peroxide and a cavity cleaner (Cavilax) were not. The only effective agents following the use of a zinc oxide eugenol temporary cement were the flour of pumice and prophy paste.
The temporomandibular joint in young adults at autopsy: a morphologic classification and evaluation
Authors: SOLBERG W. K. , HANSSON T. L. , NORDSTRÖM B.
Published: June 2007

Macroscopic features of temporomandibular joints (TMJs) were studied in young adults who comprise the largest portion of individuals seeking TMJ treatment. Deviation in form (DIF), arthrosis, size, shape and disc displacement were evaluated on ninety‐five autopsied TMJs. Few TMJs (13%, 12/95) showed no intracapsular changes. Thirty‐nine per cent (37/95) of the TMJs displayed mild‐to‐marked DIF in all three TMJ components. Smaller changes were more prevalent and tended to appear in the younger TMJs. Condylar changes were more exuberant and extensive compared to the other components. Minor arthrotic lesions were visible in 3% (3/95), and all displayed DIF. Disc displacement was found in 12% (11/95) and was more common in women (P > 0.05). Folding and deformation of the articular disc was associated with disc displacement (P < 0.01), the direction of which was mostly anteromedial. Most of the unchanged condyles' components had curved, slightly rounded, convex, and elliptical shapes when viewed from different planes (P < 0.01). Applied in diagnosis, the presence of DIF can be inferred from features which deviate from the above shapes. The concept that the above macroscopic changes might be a precursor to TMJ arthropathy in susceptible individuals is compatible with the results of this study, but the most apt characterization is that TMJ changes in this age group are adaptive phenomena occurring in order to cope with the details of articular fit and function.
Lateral preference in mastication: relation to pain
Authors: CHRISTENSEN L. V. , RADUE J. T.
Published: June 2007

Ten subjects performed deliberate right and left‐sided chewing of gum, each exercise with a duration of 60 s, followed by maximum voluntary teeth clenching (MVC) until onset of pains in the masseter muscles (pain threshold). Contractile activities of the right and left masseter muscles were assessed by integrated and cumulative surface electromyography (EMG). When the right and left muscles functioned as chewing side muscles only, they generated practically identical levels of chewing force; the same applied when they functioned as non‐chewing side muscles only. During identical functions, EMGs suggested identical motor unit recruitment and firing patterns in the two paired muscles; i.e., units producing relatively high tensions for chewing side activity, and other units producing relatively low tensions for non‐chewing side activity. During isometric MVC activity, until onset of pains, the right and left muscles generated practically identical levels of bite force, but right and left motor unit activity patterns seemed to differ. Right and left motor units might have fired at different rates or begun to drop out at different times. In the latter case, rapidly before slowly fatigued units. There was a tendency for a low pain threshold with high chewing side activity in both masseter muscles. Motor units producing high levels of tension, but easily fatigued, might have caused early onset of muscle pains. No relationships could be established between preferred chewing side and side of initial muscle pains, nor between MVC activity and side of pain onset and preferred chewing side.
Distribution of stresses in the human skull
Authors: ALEXANDRIDIS C. , CAPUTO A. A. , THANOS C. E.
Published: June 2007

A three‐dimensional photoelastic model was reproduced from a human skull. The insertions of the superficial and deep portions of the masseter muscle, the temporalis muscle, the medial pterygoid muscle and the temporalis fascia were simulated with leather bonded to the appropriate areas. The following loading conditions were employed: (i) all three muscles were bilaterally loaded without occlusal loads; (ii) all three muscles were bilaterally loaded while occlusal loads were simultaneously applied on the maxillary teeth. The stress freezing technique was used to lock the resulting stress patterns into the model skull. The stress trajectories were observed and photographed in a circular polariscope.

The mandibular closing muscles and the occlusal loads produced stresses which progressed through the maxilla, following a nasal, a zygomatic and a pterygoid route, while stress concentrations were seen in the frontonasal, zygomaticomaxillary and the pterygopalatine sutures. In the malar bone area the stresses were seen to branch superiorly to the frontozygomatic suture and posteriorly along the zygomatic arch to the zygomaticotemporal suture and the temporal bone. Generally, the stresses were concentrated in those areas of the skull where architectural reinforcement had been demonstrated by other methods.
A four‐year follow‐up, by means of a questionnaire, of patients with functional disturbances of the masticatory system
Authors: WEDEL A. , CARLSSON G. E.
Published: June 2007

From a group of consecutive patients referred for diagnosis and treatment of functional disturbances of the masticatory system, two groups, a young group (16–30 years, 113 subjects) and an older group (55–80 years, sixty‐three subjects) were selected for a follow‐up study. A self‐administered questionnaire was mailed to them 4 years after the start of treatment. They had answered a similar questionnaire at the first visit. Of the selected patients, 148 (84%) participated. If explainable losses are excluded, the response rate was 89%.

Most of the pain and dysfunction symptoms had diminished significantly in frequency while ‘peripheral’ symptoms such as tinnitus, vertigo, tongue pain and swallowing difficulties had the same prevalence on both occasions. Two‐thirds of the patients reported a positive effect of treatment, without any significant difference between the younger and the older group. The remaining symptoms differed, however. The older group reported pain in the face and jaws, vertigo, tinnitus, tongue pain and TMJ crepitation more often than the younger group, while the opposite was found for TMJ clicking and tooth grinding.

Only one variable from the original questionnaire (duration of initial symptoms), with none from the first clinical examination, was significantly correlated to the retrospective assessment of treatment outcome. This shows that it is difficult to predict the long‐term outcome of treatment from data collected at the first examination of a patient with TMJ pain and dysfunction, but that a long duration of symptoms may have a negative influence on the prognosis.
A clinical and electromyographic study of the long‐term effects of an occlusal splint on the temporal and masseter muscles in patients with functional disorders and nocturnal bruxism
Authors: SHEIKHOLESLAM A. , HOLMGREN K. , RIISE C.
Published: June 2007

The postural activity of the temporal and masseter muscles in thirty‐one patients with signs and symptoms of functional disorders were studied: before, during and after 3–6 months of occlusal splint therapy. The fluctuating signs and symptoms, as well as the postural activity of the temporal and masseter muscles were significantly reduced after treatment. Further, the coefficients of correlation within pairs of postural activity of the right and left muscles increased significantly. After cessation of the splint therapy the signs and symptoms recurred to the pre‐treatment level within 1–4 weeks in about 80% of the patients. The results indicate that an occlusal splint can eliminate or diminish signs and symptoms of functional disorders and re‐establish symmetric and reduced postural activity in the temporal and masseter muscles, which can facilitate procedures, such as functional analysis and occlusal adjustment.
Excitatory response of jaw elevators associated with sudden discomfort during chewing
Authors: STOHLER C. S. , ASH M. M.
Published: June 2007

Abnormalities associated with the chewing contraction of the masseteric and anterior temporal muscles were evaluated in patients who sensed pain in the area of the temporomandibular joint during mandibular movement. The patients were instructed in the use of an electronic switch to mark any event of discomfort/pain during natural chewing. Individual stimulus to response reaction‐times were determined. The electromyographic pattern of the jaw elevators was quantified by root mean square (r.m.s.) peak voltage and contraction time. The statistical analysis of group data showed significantly prolonged contraction times and greater r.m.s. amplitudes for chewing cycles with, compared to cycles without, indication of pain. Also, individual data showed statistically significant differences between painful and non‐painful cycles in some cases. It is concluded, that the conscious perception of nociception during the closing phase of chewing is associated with an excitatory response of jaw elevators.
Analysis of salivary proteins by thin layer sodium dodecylsulphate polyacrylamide gel electrophoresis
Authors: SHIBA A. , SHIBA K. S. , SUZUKI K.
Published: June 2007

Samples of the whole, parotid, submandibular and palatine salivas and serum, all collected from the same human subject, were developed by simultaneous electrophoresis on a single SDS thin layer gel plate, and simple proteins, glycoproteins and sialoglycoproteins in the samples were isolated and analysed.

Simultaneous electrophoresis of the salivas and serum showed the presence of thirty‐four protein bands in serum, twenty‐two bands in whole saliva, sixteen bands in parotid saliva, nineteen bands in submandibular saliva and ten bands in palatine saliva. Glycoprotein bands in the isolating gel zone presented five bands in whole saliva, four bands in submandibular saliva, three bands in parotid saliva and no band in palatine saliva. Palatine saliva, however, showed a single clear band in the concentrating gel zone. Palatine saliva showed only one sialoglycoprotein band in the concentrating gel zone.