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At least 1,585 records · Page 88Linked to original sources
PubMed1991

[The treatment of condyle neck fracture: statistics gathered by multi centric study and the related prognosis].

There are two different treatments for condyle neck fracture. One is non-surgical treatment involving intermaxillary fixation, and the other is radical surgical treatment through various techniques, but it is difficult to discuss the relative merits. The purpose of this report is to decide whether surgical treatment is necessary, by comparing the two types of treatment. In the period between April 1981 to December 1987, we treated 136 cases of condyle neck fracture at the Second Department of Oral and Maxillofacial Surgery School of Dentistry Aichigakuin University, and in 18 nearby hospitals. Of the 136 cases, 58 cases had fracture only at the condyle neck, while 78 cases had some concomittant fracture. As regards treatment, of the 136 cases, 49 (36%) were treated surgically, while 87 (64%) were treated non-surgically for condyle neck fracture. The surgically treated cases were divided into three groups: 24 cases were treated by pinning, 16 cases were treated by inter osseous wiring, and there were 9 other cases. In the treatment of concomittant fracture, 38 cases involved inter osseous wiring, 22 cases involved metal plate fixations, and there were 4 other cases. Non-surgical treatment accounted for 15 cases. The rate of surgical treatment for concomittant fracture was 82.1% of the cases treated. In surgically treated cases of condyle neck fracture, the mouth opening prognosis was generally poor. However, in these cases the deviation of mouth opening was generally better than in non-surgically treated cases. There were no differences in mastication, occlusion and pain in the TMJ region.

Bone Wires↗
PubMed1991

The path of chewing movement before and after experimental occlusal interference.

To understand functions of the masticatory system accurate recording and analysis of mandibular movement are indispensable. The purpose of this experiment was to find functional differences in the path of masticatory movement due to experimental occlusal interference. Occlusal interference was placed on the mandibular first molar or cuspid of the habitual chewing side in seven normal subjects. While subjects were asked to masticate gum on one side at a time, jaw movements were recorded and analyzed using an automatic masticatory movement analysis system previously developed. Standard deviations (SD) of the vertical and lateral elements in the opening and closing phases were calculated and compared before and after the occlusal interference. In the opening phase the SDs increased significantly with either the interference placed on the cuspid or molar tooth. In the closing phase it generally increased with either the interference. The effect was significantly more with the cuspid interference than that of the molar tooth. The SD of the vertical element is also generally increased with either interference. However, in contrast to the lateral element, the effect of the molar interference on the vertical element was significantly more than that of the cuspid.

Adult↗
PubMed1990

[Electromyographic and computerized magnetic gnathokinesiographic studies of normal subjects].

The authors used electromyographic and computerised magnetic gnathokinesiographic equipment to examine habitual mastication and electromyographic activity of the masseter and anterior temporal muscles in two subjects with complete dentition, physiological functional occlusion and with no history or clinical records of cranio-mandibular disorders (CMD). The results obtained show the presence of common models of masticatory movement and electromyographic activity which conform to previously published data.

Dental Equipment↗
PubMed1990

Age changes of mandibular condyles and glenoid fossae in mice fed a liquid diet.

The effects of the masticatory function on age changes of the temporomandibular joint were studied in 163 C3H/He strain male mice, separated into solid and liquid diet groups from 2 weeks of age. The sizes and shapes of the mandibular condyles and glenoid fossae of the two groups were compared up to 60 weeks. The sizes and shapes of the condyles in the solid diet group increased and developed with age, but there was almost no change after 3 weeks of age in the liquid diet group. The sizes and shapes of the fossae increased and developed with age until 20 weeks in both groups, and there was no differences between the two groups. The poor functional stimulus of mastication has distinct effects on the underdevelopment of the condyle. Since the effects on the fossae were less than those on the condyles, not only the amount of mandibular movement, but also its pattern may have affected the liquid diet group.

Age Factors↗
PubMed1990

Some considerations about maintenance of the mandibular position for adult patient with TMJ disorder.

The patient was twenty-three year old female with TMJ disorder and crowding. She had often had a clicking sound caused probably by malocclusion since she was eighteen years of age. Limitation of mouth opening with TMJ locking has been occurring since she had an impacted right lower third molar extracted at nineteen. A stabilization splint was applied for better mandibular position to rectify the TMJ disorder. The clinical symptom was relieved one month later, so the malocclusion was treated with a multi-bracket appliance. Since cross bite in [formula: see text] was corrected in a year and three months, symptoms of the TMJ disorder disappeared and this condition has remained stable for the past year. A stabilization retainer worn at night was considered necessary to prevent a relapse of the dentition and mandibular position, and to keep the masticatory muscles relaxed. For the purpose of stabilizing the TMJ condition and occlusion, the patient was taught unilateral mastication in order to diminish the difference between sides in chewing force, because only one side had been habitually used for a long time. It is suggested that such an alternative chewing habit will improve functional stability following the structural correction.

Adult↗
PubMedDate not supplied

Evaluation of eccentric occlusal contacts in complete dentures.

Three edentulous patients were evaluated using the kinesiograph and a specially designed computer program to identify the length of eccentric contacts between their dentures when masticating test foods. Three different interchangeable occlusal arrangements were constructed and tested. Results of the evaluation of more than 1,400 chewing cycles showed that while 25% of masticatory contacts were eccentric, the great majority of contacts were within a distance of 1 mm from centric occlusion. More eccentric contacts occurred in the opening phase than might be expected. Posterior tooth form did not appear to affect the range of eccentric contacts.

Aged↗
PubMed1990

[A study on the relationships between imbalance of stomatognathic function and asymmetry of craniofacial morphology, and the center of gravity of the upright posture].

Mastication is one of the most important functions of the stomatognathic system and it can be performed either on the left side or right side. However, some people have each habitual chewing side, so imbalance of stomatognathic function between left and right is observed. This imbalance is supposed to reflect the relationship between the left and right elements of the stomatognathic system. Therefore, the analysis of this imbalance is very useful for assessing the stomatognathic system. The purpose of this study was to reveal the relationship between imbalance of stomatognathic function between left and right and asymmetry of craniofacial morphology, and the relationship between imbalance of stomatognathic function between left and right and center of gravity of upright posture. Eighty subjects without stomatognathic dysfunction were selected for this study. Electromyograms of the left and right masseter, anterior temporal, posterior temporal and anterior belly of digastric muscles during clenching were recorded, and mandibular movements during chewing were recorded. Analysis of imbalance between left and right was performed using functional parameters. Cephalograms (P-A) were taken for an analysis of craniofacial symmetry. The center of gravity of the upright posture was recorded using stabilograph. Analyses were performed to study the relationships between the parameters of stomatognathic function and craniofacial asymmetry, and the center of gravity of the upright posture. The results were as follows: 1. The analysis of functional parameters revealed some subjects showed imbalance between left and right sides. 2. On the side with wider craniofacial morphology as determined by some parameters, the activity of the masseter muscle during clenching showed tendency to be higher than that of the opposite, while the activity of the anterior temporal muscle showed tendency to be lower. On the side with longer craniofacial morphology, the activity of the anterior temporal muscle showed tendency to be higher than that of the opposite. 3. On the side where the center of gravity was shifted during clenching, the activities of the masseter, anterior temporal and posterior temporal muscles showed tendency to be higher than those of the opposite, and the durations of chewing cycle and opening phase showed tendency to be shorter. These results suggest that there are close relationships between imbalance of stomatognathic function and craniofacial asymmetry, and between imbalance of stomatognathic function and the center of gravity of the upright posture.

Cephalometry↗
PubMed1990

[In vivo wear test for posterior composites. 1. Development of wear test predicting composite wear in vivo].

A wear test method based on a new concept was developed for predicting the wear rate of posterior composite restorations in vivo. The concept based on the conclusions derived from our clinical tests on posterior composites that composite restorations would be deteriorated chemically and by repeated compressive stress as well as by abrasion by food passing during mastication. New wear tests were performed on several posterior restorative materials under various conditions to compare the effect of abrasion using the tooth-brush. The results of wear rate using the present test on specimens stored in a 0.1 N-NaOH solution (37 degrees C) for 6 days were parallel to those measured in clinical tests. However, the abrasion test results obtained using a tooth-brush on deteriorated specimens did not match the clinical data. These findings suggested that degradation or aging of specimens and repeated compressive stress are necessary for the wear test to simulate the wear of posterior composites in vivo.

Composite Resins↗
PubMedDate not supplied

[Stability of complete dentures. 2].

There is a necessary correlation between the Monson's curve, due to the mandibular kinematics, and the interalveolar axis' inclination in the different occlusal areas with unitary function. In the triturating area the verticality of the interalveolar axis is necessary for the stability of the cusp-fossa relationship in centric occlusion and for the stability of the prothesis during mastication. The Author shows the occlusal morphology and the arrangement of the prosthetic teeth in the different skeletal classes in relation to functional interalveolar strength's direction.

Dental Occlusion, Centric↗
PubMed1990

[Clinical and instrumental examination of tongue motor function].

The examination of tongue motor functions requires a clinical examination of voluntary movements as well an objective evaluation of the intraoral movements during speech, deglutition, mastication and during rest. For a comparison with the simple visual assessment of voluntary movements with the mouth opened, intraoral tongue movements have been studied using various techniques. The use of lateral x-ray palatography and electromagnetic articulography (EMA) for objective intraoral measurement of tongue motor activitiesis described. Case examples are given for simultaneous recording of midsagittal movements of the tongue, the mandible and the velum during swallowing and speaking.

Deglutition↗
PubMed1990

[The biomechanics of the base of the skull and face].

The biomechanics-, engineering- and anatomy-oriented authors studied the craniofacial structures emphasizing their perfect adaptation to stresses developing during mastication or related to head statics and motions. For a better understanding of the biomechanics of the basis of the skull and face, attention is consistently drawn to solutions used in state-of-the-art engineering, such as aeronautics, in consideration that such solutions as are chosen by engineers are often--consciously or not--copied from nature.

Adaptation, Physiological↗
PubMed1990

Hypoglossia congenita.

Hypoglossia and aglossia are rare congenital malformations, especially when found as isolated abnormalities. In view of their usual association with other anomalies of the face, oral cavity, and distal extremities, an accurate investigation is required. We describe a 2-year-old girl with isolated hypoglossia and severe dental disease. Clinical understanding of the changes in the mechanisms of oral suction, mastication, swallowing, and speech, as well as the existing dental occlusion, requires a multidisciplinary team approach so that a more effective treatment can be administered.

Child, Preschool↗
PubMed1989

[Enamel wear from ceramic and stainless steel orthodontic brackets].

The purpose of this investigation was to examine the potential enamel wear upon contact with ceramic and stainless steel orthodontic brackets of the same company into an artificial mouth, which is a simulated oral environment. Two groups of ten lower premolars were bonded with ceramic and stainless steel brackets. The same number of upper premolars were used and each upper premolar was brought in contact with the opposing bracket and subjected to a lateral type of movement, like a mastication movement, by the artificial mouth. A constant load of approximately two pounds was used for the masticatory force, the rate of chewing was one cycle per second and the teeth were subjected to 2.5 and 10 masticatory cycles. The before and after occlusal surfaces of the upper premolars were compared using a computerized profiling system and the enamel volume loss was calculated. Qualitative changes, such as rate of enamel wear, were examined visually using SEM and computer graphics. Abrasion scores (mean +/- SD) in mm3 were 0.0142 +/- 0.020 for the metal and 0.2433 +/- 0.150 for the ceramic brackets and were significantly different at p less than 0.05. Ceramic brackets caused significantly greater enamel abrasion than stainless steel brackets.

Bicuspid↗
PubMed1989

[Electromyographic study of masticatory dysfunction in patients with unilateral cleft lip and palate and reversed occlusion].

UNLABELLED: Masticatory dysfunction in patients with unilateral cleft lip and palate was studied on the basis of electromyograms of the masticatory muscles. The purpose of the study was to elucidate the origin of the dysfunction by means of comparisons among electromyograms of masticatory muscles in cases of normal occlusion, reversed occlusion and reversed occlusion caused by unilateral cleft lip and palate. Subjects were 10 cases of normal occlusion (10y2m-11y10m), 10 cases of reversed occlusion (7y2m-11y2m) and 20 cases of unilateral cleft lip and palate (8y0m-14y3m). In each subject, electromyograms of the masseter and anterior venters of the temporal muscles at the isometric-contraction phase were recorded by means of the surface-electrode method with mandible loads of 1-5 kg. The electromyograms were analyzed quantitatively by means of an electromyographic device called a Turn Counter. Relations between loads and amplitude as well as numbers of turns were examined. At the same time maximum masticatory pressure and occlusal contact points were measured and then examined in comparison with electromyographic findings. RESULTS: 1. Correlation coefficients between loads and amplitudes as well as numbers of turns decreased among the groups in this order: normal occlusion, reversed occlusion and cleft-caused reversed occlusion. Significant differences were observed between the normal-occlusive group and the reversed and cleft-caused reversed-occlusive groups. 2. No. difference was observed between the normal-occlusive and reversed-occlusive groups in terms of correlation coefficients between total sums of amplitudes and turns of the 4 masseter muscles (right and left masseters and anterior venters of the temporal muscles) and loads. Correlation coefficients in the cleft group were significantly smaller than those in the other 2 groups. 3. Because of great differences in regression coefficient among individuals, no synergic contraction pattern of the 4 mastication muscles (right and left masseter and temporal muscles) could be specified. 4. The A/T ratio of masseters in the cleft group was significantly smaller than those in the normal- and reversed-occlusive groups. 5. Under maximum load, the activity ratio of the 4 masseter and temporal muscles was 1:1 in the normal- and reversed-occlusive groups, whereas temporal-muscle activity predominated over masseter-muscle activity in the cleft group. 6. Maximum masticatory pressure decreased in the order: normal-occlusive, reversed-occlusive, and cleft caused occlusive. No correlation with electromyographic findings was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Child↗
PubMed1989

[Study of objective assessment for pathways in areas of intercuspal position during masticatory movements].

Masicatory function is the result of a highly complicated neuromuscular activity which coordinates in stomatognathie system. Functional directions of masticatory cycles in areas of intercuspal position (IP) were objectively evaluated on each stroke obtained through the Sirognathography Analyzing System (S. G. G./A. S.; Siemens, W. Germany). Twenty seven dantate subjects were selected at random from students and staff members of Kanagawa Dental College. A piece of chewing gum was given to each subject to masticate it for a minute on one side and on the other side respectively. A total of masticatory cycles were successively recorded into S. G. G./A. S.. A statistical analysis, the equal probability for ellipstical variations, was made on the angular measurements from opening and closing phases of each cycle within 3 mm from onset and terminus in areas of IP during masticatory movements. Four characteristic features of angular measurements are presented, namely, subjects who showed different types in position and forms by plotted angles within 80% of total amounts. The following results were obtained from this study. 1. Functional directions of masticatory cycles are clearly recognized in areas of IP from opening and closing phases during masticatory movements. 2. An application of the equal probability for ellipstical variations seems to be efficient for the functional analysis of masticatory cycles. 3. A classification of different types of plotted angles contributes to become a basis for diagnosis of masticatory function and occlusion.

Dental Occlusion↗
PubMedDate not supplied

[Recording of masticatory cycles by electrognathographic method].

Electrognathographic method of the three-dimensional recording of mandibular movements can be successfully used in the analysis of spatial shifting of interincisal point during mastication. Investigations carried out in the world by a sirognathograph (Sirognathograph, Siemens A.G., Bensheim, W. Germany) resulted in classifications of the masticatory cycles in order to determine types of samples and to establish the basis for comparative studies of patients with or without disorders in the stomatognathic system. Since our preliminary sirognathographic studies also confirmed the existence of the reported types of masticatory cycles, we considered it necessary to present here these classifications and to emphasize the positive results of their use in both scientific research devoted to analysis of function or disfunction of the stomatognathic system, and in estimation of therapeutical effects of prosthetic aids in complete denture wearers, as applied in routine clinical practice.

Denture, Complete↗
PubMed1989

[Clinical study on mandibular condylar fracture. 2. Long-term follow-up study in 48 patients with 66 joints].

Sixty-six joints in 49 patients with mandibular condylar fracture were investigated by means of long-term follow-up observation. The group of patients consisted of 39 males and 10 females with ages from 15 to 75 years. The classification of the fractures was follows: MacLennan type 1; four, type 2; four, type 3; 39, and type 4; 39 joints respectively. Treatment was as follows: 25 joints were by conservative therapy, 31 joints were by surgical fixation, and 10 joints condylectomy. The follow-up period of observation ranged from 18 months to 10 years and one month an average of five years and seven months. Clinical assessment was based upon Nakatomi's dysfunction index on mandibular condylar fracture, of which the criteria are as follows; Excellent (No clinical dysfunction sign on the TMJ), Fair (Slight pain, noise, and limited range of motion of the mandible, but clinically no affected mastication), Poor (Moderate dysfunctioned jaw), and Failure (Severe dysfunctioned jaw). 23 joints in 18 patients were ranked as having excellent results. 31 joints in 22 patients were assessed as fair. Ten joints in seven patients were defined as poor, and the remaining two joints in two patients were failures. The overall success rate was 81.7%. There are no statistical differences between patient's groups based on age, sex, uni/bilateral modality, with/without other concomitant fracture, surgical/conservative procedure, location and form of fractures, and duration of period from injury. These results indicated that the conservative procedure would be the first choice as a reasonable and less invasive procedure for functional repair of mandibular condylar fracture. On the other hand, as most patients had some dysfunction sign on the TMJ after mandibular condylar fracture, a more appropriate treatment, surgical or otherwise, should be found.

Adolescent↗
PubMed1989

[A classification of foods by the amount of masticatory action involved].

With a view to classifying foods on the basis of the amount of masticatory action required, an attempt was made to correlate the properties of different foods as shown by mechanical measurements with the amount of masticatory action involved as determined by means of an electromyogram. We obtained the following results: 1) We found an extremely high correlation (r = 0.924) between the amount of masticatory action involved and the mechanical properties of our samples when these were expressed as values given by the formula: log (firmness x cohesiveness x strainess x 10) We refer to this parameter as toughness. 2) We were then able to estimate the amount of activity necessary in actual mastication of various foods from out toughness values and other values obtained through texturometer readings, a procedure which we carried out for 144 types of foods. 3) We were thus able to classify foods into ten levels according to masticatory action. We further feel justified to add masticatory action to our list of classification criteria as set out in an earlier report by the present author and others entitled "A classification of foods by physical properties."

Food↗