bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

SummaryYoung 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

SummaryEight 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

SummaryTemporomandibular 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

SummaryThe 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

SummaryA 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

SummaryNocturnal 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

SummarySix 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

SummaryThirteen 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

SummaryThree 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

SummaryTwo 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

SummaryThe 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

SummaryRepeatability 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

SummaryFew 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

SummaryThe 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

SummaryNon‐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

SummaryThe 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

SummaryMacroscopic 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

SummaryTen 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

SummaryA 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

SummaryFrom 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.