Biomedical subjects

M G Tzakis

Publications and source records attributed to M G Tzakis.

9 recordsLinked to original sources

PubMed1995

Effects of fatigue and chewing training on maximal bite force and endurance.

The purpose of the study was to evaluate the effects of chewing training on the strength and resistance to fatigue of the masticatory muscles. Twenty-five healthy adults were divided into an experimental group (7 men, 10 women) and a control group (4 men, 4 women). The experimental group chewed a special hard chewing gum one hour daily for 28 days. Maximal bite force and endurance were measured. The maximal bite force already showed a significant increase in the experimental group by the middle of the experimental period (p < 0.05), reached the highest values by the end of the training period (p < 0.001), and also remained at high levels 2 weeks after (p < 0.001). Subjects with weak initial maximal bite force values showed the highest increase in their strength after training (r = -0.66, p < 0.01). This type of training did not influence the endurance time during maximal clenching or the reduction in this endurance time after a dynamic fatigue test. No significant differences were found between the maximal bite force before and that after the fatigue test under either untrained or trained conditions. In the control group no significant differences were found between the recording sessions. In conclusion, 4 weeks training with a hard chewing gum seems to influence the functional capacity of the masticatory muscles and increase their strength.

Adult↗

PubMed1995

Ultrasound imaging of the masseter muscle in myotonic dystrophy patients.

Ultrasound technique was applied to measure the thickness and examine the internal structure of the masseter muscle in a group of 16 adult patients (nine women and seven men) with myotonic dystrophy (MyD) and 16 healthy individuals matched in age, sex and number of occluding teeth. The masseter thickness was measured bilaterally under both relaxed conditions and during maximal clenching. The error of measurement was found to be small, not exceeding 0.45 mm. The imaging characteristics of the masseter in most of the MyD patients was an obvious atrophy of the muscle with increased echointensity of the intramuscular tissue and loss of the internal structure concerning tendons and fasciae. The mean masseter thickness (+/- SD) in the MyD group was 10.4 (+/- 2.2) mm under relaxed conditions and 11.1 (+/- 2.4) mm during maximal clenching, compared with 13.3 (+/- 2.2) mm and 14.1 (+/- 2.4) mm, respectively, in the healthy group (P < 0.001). In conclusion, our results indicate that, in most of the myotonic dystrophy patients, the masseter muscle is atrophic with obvious signs of degeneration. Ultrasound is a useful method for both qualitative and quantitative evaluation of the condition of the masseter muscle.

Adult↗

PubMed1994

Effect of a fatigue test and chewing training on masticatory muscles.

The effects of fatigue induced by 30 min of intense chewing before and after 4 weeks of 1 h daily chewing training on masticatory muscles were studied in 15 healthy subjects while eight subjects served as controls. EMG measurements in the postural position and during maximal clenching in the intercuspal position and clinical examination of the stomatognathic system were performed. Marked clinical signs of dysfunction were recorded after the first fatigue test. The severity of dysfunction diminished during the 4-week training period and was back at the baseline level at the end of it. In the second fatigue test, after the training period, the subjects developed less dysfunction. In the control group, a mainly stable pattern was found during the observation period. There was a great variation in EMG activity during the experimental period and there were no statistically significant changes observed between any of the recordings in any of the groups.

Adult↗

PubMed1994

A study of some masticatory functions in 90-year old subjects.

A group of 35 90-year old subjects, randomly selected from the gerontologic population study in Göteborg (H-70), were examined with respect to function and dysfunction of the masticatory system. The methods included a questionnaire, clinical examination and recording of bite force endurance and maximal bite force, measured in the central incisor region. Forty percent were edentulous, 29% were partially edentulous and wore a removable denture, while the others were dentate without removable prostheses. Signs and symptoms of temporomandibular disorders were mostly mild and infrequent, except TMJ crepitation which was recorded in 69% of the subjects. Maximal bite force was in general low (mean 94 N) but showed a great individual variation (range 10 to 410 N). Bite force endurance was also very variable (mean 72 s, range 10 to 205 s). None of the 35 subjects reported poor masticatory ability, but 2 said they could not chew all kinds of food. In spite of a reduced bite force this group of 90-year olds considered their masticatory ability as good and most of them had no severe signs and symptoms of temporomandibular disorders.

Aged↗

PubMed1992

Effects of intense chewing on some parameters of masticatory function.

This study recorded the influence of 30 minutes of intense chewing on the masticatory function in 17 healthy subjects. Functional recordings of mandibular movements and velocity, measurements of masticatory efficiency, maximal occlusal force, and occlusal force endurance time were performed before and after functional stimulation and finally in a 2- to 5-day follow-up registration. After intense chewing, a substantially decreased masticatory cycle and occlusal level phase duration were recorded. No major mandibular displacements or changes in velocity were recorded. Masticatory efficiency and maximal occlusal force in the incisal region diminished after 30 minutes of intense chewing. Occlusal force endurance time was also lowered after intense chewing. The measurements were close to their original values at the follow-up. Intense chewing had various short-term effects on masticatory function, including a significant reduction of masticatory efficiency, maximal occlusal force, occlusal force endurance, and masticatory cycle duration.

Adult↗

PubMed1992

Evaluation of masticatory function before and after treatment in patients with craniomandibular disorders.

The masticatory function was evaluated in 12 patients with signs and symptoms of craniomandibular disorders of mainly muscular origin. Palpation of the masticatory muscles and measurements of occlusal force endurance, on a submaximal level with visual feedback, and of masticatory efficiency were performed before and after treatment. Significant changes occurred between the two measurements. Of a total of 10 masticatory muscles, 8 were sensitive to palpation before treatment and 2 after treatment. Occlusal force endurance increased from 92.5 seconds before treatment to 132 seconds after treatment, and masticatory efficiency increased from 54% to 65%, respectively. It is concluded that the masticatory muscle function of these patients is compromised and that treatment had a positive effect on the masticatory function.

Adult↗

PubMed1990

Short-term and long-term effects of chewing training on occlusal perception of thickness.

The aim of this study was to investigate the short-term and long-term effects of functional stimuli, induced by intense chewing and by prolonged systematic chewing training, on the response of occlusal perception of thickness. The material comprised 25 young adults divided into an experimental group (17) and a control group (8). The occlusal perception of thickness was tested by successively placing different thicknesses of aluminum foil between five pairs of occluding teeth, i.e. right and left second premolars and canines and one pair of the central incisors. The experimental group was tested 2 wk before the start of the experiment and at the start and the end of the experiment, i.e., after 4 wk systematic chewing training, and before and after 30 min intense chewing. The control group was tested on the same occasions but without performing any special chewing activity. The discrimination threshold increased in most of the subjects after 30 min of chewing, both before and after the 28-day training period. This threshold increase was found in all groups of teeth tested. No changes were found in the discrimination threshold of the teeth tested after 28 days of chewing training. In the controls no differences were found between the recording occasions. Since no statistically significant differences were observed between the groups of teeth tested, the changes in the threshold of occlusal perception after intense chewing may reflect the influence of receptors other than periodontal, for example those in TMJ and muscles, which are involved in the control of other neuromuscular mechanisms such as those that control the postural position of the mandible.

Adult↗

PubMed1990

Oral function in patients treated with prostheses on Branemark osseointegrated implants in partially edentulous jaws: a pilot study.

To study the oral function of partially edentulous patients treated with fixed prostheses on osseointegrated implants, recordings of the masticatory efficiency and occlusal perception of thickness were performed. The retrievable fixed partial prostheses were used to study the immediate impact of reduced fixed occlusal support on masticatory efficiency. The masticatory efficiency was subjectively satisfactory but objectively lower when compared to naturally complete dentate persons. Furthermore, the immediate impact of reduced fixed occlusal support was compromised masticatory efficiency, which was more pronounced when the occlusal support was removed on either side.

Aged↗

PubMed1989

Effect of chewing training on masticatory efficiency.

A special, hard chewing gum was used to study the effects of chewing training on masticatory efficiency. An experimental group of 17 individuals used this chewing gum 1 h daily for 28 days, while a control group of 8 individuals performed no chewing-gum training. The percentage of masticatory efficiency was measured with a special sieve system, and the time for 10 chewing cycles was taken from EMG recordings. These measurements were made in trained and untrained condition before and after 30 min of intense chewing. The results indicate that intense chewing for 30 min decreased the masticatory efficiency and increased the frequency of the chewing cycles significantly in both trained and untrained individuals, possibly due to fatigue of the masticatory muscles. However, chewing training for 28 days did not influence these factors significantly.

Adult↗