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Biomedical subjects

S Kiliaridis

Publications and source records attributed to S Kiliaridis.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effects of masticatory muscle function on bone mass in the mandible of the growing rat.

The effect of altered masticatory muscle function on bone mass at different sites in the rat mandible was studied using aluminium as a reference substance in computer-assisted image analysis. Forty-two growing male rats were divided into three groups, of which one group was killed at the beginning of the experiment to provide baseline values. Of the remaining two, one received a hard diet (control group) and the other a soft diet. After 28 days the rats were killed and the mandibles were excised. Lateral radiographs were taken of the mandible halves together with an aluminium stepwedge and then analysed by an image analysis system. Radiographic bone mass was measured in the transverse plane as "aluminium-equivalent thickness' in millimetres. Standardized areas were chosen to investigate regions with different functional demands. Significant differences were found between the groups in the alveolar bone of the molars and the incisor, as well as in the condylar costa and the condylar process. Significant differences were also found in some areas related to muscle insertion, such as the anterior lower border of the ramus, whereas no statistically significant differences could be found in others, such as the posterior lower border of the angular process. In conclusion, altered masticatory function influences the amount of bone mass in certain parts of mandible, where changes in applied bending forces have possibly altered the bone strain.

Animals↗
PubMed1996

Craniofacial bone remodeling in growing rats fed a low-calcium and vitamin-D-deficient diet and the influence of masticatory muscle function.

Fifty-two male growing rats were randomly divided into three groups. The first group (n = 18) received a hard deficient diet, and the second (n = 18) a soft deficient diet. The control group (n = 16) was fed the normal hard diet. At the beginning and in the middle of the 28-day experimental period oxytetracycline was injected. Two representative coronal sections of the snout and the corresponding contact microradiographs were analyzed. The bone mass of the premaxillary and nasal bones seemed to be less in the two deficient diet groups than in the normal one, due to an increased endosteal bone resorption and decreased bone formation. No difference in the bone apposition rate and pattern could be seen between the deficient hard and soft diet groups, except in the dorsal part of the premaxilla, where the bone formed in the first half of the experiment was markedly more resorbed in the deficient soft diet group during the remaining period than in the deficient hard diet group. The morphology of the sutures was influenced by the altered function, since the sutural space became narrower, and premature obliterations of the internasal suture were observed in the deficient soft diet group. In conclusion, poor bone quality was observed in the skull of rats fed a low-calcium and vitamin-D-deficient diet, with less bone mass than in normal conditions. Masticatory function was a significant factor influencing bone remodeling and sutural growth even in situations in which a metabolic bone disturbance exists.

Animals↗
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

Craniofacial morphology, occlusal traits, and bite force in persons with advanced occlusal tooth wear.

The aim of this study was to investigate the dentofacial structure, the occlusal traits, and the bite force in subjects with advanced occlusal wear. The material comprised 54 adults, 30 men (mean = 40 years, range 16 to 61) and 24 women (mean = 28 years, range 18 to 47), most of whom had a full or near-full complement of natural teeth, and the presence of occlusal wear. Craniofacial structure was studied on lateral cephalograms. Occlusal traits were examined on study casts, these serving also for an evaluation of occlusal wear to be carried out by using an ordinal scale. Bite forces were recorded at differing force levels (maximum biting, "biting as when chewing" and "light biting") and occlusal positions. Although maximum bite force and endurance time did not differ significantly between men and women, the level of bite force was high compared with other samples. The craniofacial structure of the sample was characterized by a deviation in the vertical direction, a small angle between the mandibular-palatal planes and a small gonial angle, as compared with Swedish adult norms. No significant differences were found in anteroposterior relationships between persons with advanced wear and normal standards. The results support the hypothesis that functional hyperactivity of the masticatory system imposed increased stress on the bony structures of the craniofacial complex with possible influences on its structure.

Adolescent↗
PubMed1995

Craniofacial structure in children with juvenile chronic arthritis (JCA) compared with healthy children with ideal or postnormal occlusion.

The aim of the present study was to evaluate the influence of condylar destruction on the craniofacial growth of children with juvenile chronic arthritis (JCA) and to compare their craniofacial structure with that of healthy children with ideal or postnormal occlusion. Thirty-five children (7 to 16 years) affected by JCA were compared with 136 children (7 to 16 years) with normal facial structure and occlusion (ideal group) and 62 children (7 to 12 years) with postnormal occlusion (postnormal group). Panoramic radiographs and lateral cephalograms were taken to detect condylar lesions and analyze facial structure. Multiple regression analysis was applied to test the possible relationships between the groups. The present study largely confirms earlier findings that the JCA group has a characteristic craniofacial structure. Their structure differed not only from the facial characteristics of children with ideal, but also to some extent, from children with postnormal occlusion. Furthermore, the craniofacial structure of children with JCA varied greatly, and radiographs showed that the most extreme craniofacial changes, particularly the mandibular structure, were associated with condylar lesions. In conclusion, the arthritic condylar lesions seem to be the main etiologic reason for the altered facial structure and changes in the occlusion in children with JCA. Influences of other factors, such as masticatory muscular function, are also discussed.

Adolescent↗
PubMed1995

Dentofacial growth in orthodontically treated and untreated children with juvenile chronic arthritis (JCA). A comparison with Angle Class II division 1 subjects.

The changes in craniofacial growth and development of dental occlusion were studied in children with juvenile chronic arthritis (JCA), and treatment with functional orthodontic appliances (activators) was tested in both JCA and healthy children with distal occlusion. Fifteen JCA children with Angle Class I occlusion and 15 JCA children with Angle Class II malocclusion were followed longitudinally and compared with 23 healthy children with Angle Class II malocclusion. The facial growth of the JCA children without need of orthodontic treatment mainly followed the normal pattern while the JCA children with Angle Class II malocclusion had a deviating facial morphology, which became more abnormal during growth. During the orthodontic treatment period a slight improvement was seen in mandibular positions in the sagittal and vertical planes in both treated groups, but the changes were more marked in the healthy children. None of the treated groups attained completely normal facial morphology, but in most children the occlusion improved and could be classified as normal. The morphology achieved by treatment largely remained the same during the follow-up period and relapse was seen only in a few children. JCA children with minor skeletal discrepancies can be satisfactorily treated during growth with functional orthodontic appliances, possibly in combination with fixed appliances. Even if skeletal changes in response to orthodontic treatment are rather limited, these changes combined with the improvement in dental occlusion obtained through treatment may result in better dentofacial aesthetics. Furthermore, jaw functions are likely to improve which also might benefit the patient from a psychosocial point of view.

Activator Appliances↗
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↗
PubMed1995

Bite force and temporomandibular disorder in juvenile chronic arthritis.

The aim of this study was to investigate the functional condition of the stomatognathic system in children suffering from juvenile chronic arthritis, with respect to bite force and temporomandibular disorder in relation to radiographic abnormalities of the mandibular condyle, occlusal factors and systemic disease parameters. Thirty-five children with juvenile chronic arthritis were compared to 89 healthy children with an Angle Class I occlusion and 62 children with an Angle Class II malocclusion. Subjective symptoms and clinical signs of temporomandibular disorder and radiographic mandibular condylar changes were more common in children with juvenile chronic arthritis than in the two comparison groups. Maximal molar and incisal bite forces and maximal molar bite force endurance times were also significantly reduced in children with juvenile chronic arthritis. It is concluded that the differences between the groups are caused mainly by the systemic inflammatory disease itself, but a functional influence of weakened masticatory muscles cannot be excluded.

Adolescent↗
PubMed1995

Effect of masticatory muscle fatigue on cranio-vertical head posture and rest position of the mandible.

The aim of this study was to investigate whether induced fatigue of the masticatory muscles had any influence on the head posture, and whether this influence is related to the rest position and the movement characteristics of the mandible. The sample consisted of 13 female individuals, aged 23-34 yr. For the evaluation of possible changes in the natural cranio-vertical head posture, standardized facial profile photographs were used. Photographs were also used for the study of the facial characteristics. The freeway space and the opening and closing velocity of the mandibular displacement, as well as the duration of the masticatory cycles, were monitored with an optoelectronic method. A controlled dynamic fatigue was induced by a specially constructed spring-loaded device placed in the premolar region. No significant changes in the mean cranio-vertical postural position of the head were found during the various recording stages, while the freeway space was found to increase significantly after the fatigue test. No significant differences were observed concerning the average values of the mandibular movement characteristics. The analysis of the association between the individual changes showed an increase in the freeway space after the fatigue test in the subjects which exhibited an increase in the duration of the masticatory cycle in that period. No significant associations could be found between the changes in the head posture and the mandibular movement characteristics. Also, no significant correlation could be found between the facial type of the subjects and the variables studied.

Adult↗
PubMed1995

Masticatory muscle influence on craniofacial growth.

The influence of the masticatory muscle function on craniofacial growth has been recorded in a series of animal experimental and clinical studies. The common characteristic of these investigations is that the elevator muscles of the mandible influence the transversal and the vertical dimensions of the face. The increased loading of the jaws due to masticatory muscle hyperfunction may lead to increased sutural growth and bone apposition, resulting in turn in an increased transversal growth of the maxilla and broader bone bases for the dental arches. Furthermore, an increase in the function of the masticatory muscles is associated with anterior growth rotation pattern of the mandible and with well-developed angular, coronoid, and condylar processes.

Animals↗
PubMed1995

Characteristics of masticatory movements and velocity in children with juvenile chronic arthritis.

Oral motor function (mandibular displacement and velocity) in individuals with juvenile chronic arthritis was studied by using an optoelectronic method. The children were compared with two asymptomatic groups: one group with Class I occlusion and the other with Class II malocclusion. The results showed that children with juvenile chronic arthritis and condylar lesions had reduced lateral mandibular masticatory movements. In children with Class II malocclusion, a longer three-dimensional closing distance and a slower closing velocity were found. In children with both juvenile chronic arthritis and Class II malocclusion, an interaction between juvenile chronic arthritis and malocclusion resulted in a longer occlusal time, a shorter amplitude, and a slower velocity. It can be concluded that juvenile chronic arthritis and Class II malocclusion, per se, might have minor influences on the chewing characteristics, but the two factors seem to interact, resulting in an altered masticatory pattern. A possible explanation is that children with juvenile chronic arthritis have an increased risk of developing a Class II malocclusion because of the growth disturbances sequelae of condylar lesions. The alteration in occlusion, together with restricted movements in the arthritic condyle, may be the underlying reasons for the findings.

Adolescent↗
PubMed1994

A comparison of human masseter muscle thickness measured by ultrasonography and magnetic resonance imaging.

Non-invasive imaging techniques such as computerized tomography, magnetic resonance imaging (MRI), and ultrasonography enable measurements of the cross-section and thickness of human jaw muscles in vivo, providing an indication of the maximal force a muscle can exert. In 15 adult Caucasian men the thickness of the masseter muscle was registered bilaterally on three different levels by ultrasonography. Scans were made on the contracted and relaxed muscle. A comparison was then made with measurements from serial MRI scans, using univariate analysis of variance for repeated measurements and Pearson's correlation coefficients. Variances of the repeated measurements were calculated for the different scanning levels and the different muscle conditions and tested for homogeneity. For both the ultrasound and MRI measurements there was no difference in thickness between the left and right muscle. The registration level with highest reproducibility was halfway between the origin and insertion. Measurements from the contracted muscle were more reproducible than those from the relaxed muscle. The relaxed muscle thickness measured by ultrasonography was smaller than that measured by MRI. The correlation between ultrasound and MRI was significant for the upper and middle level of scanning (p < 0.001). The highest correlation was found between MRI (relaxed) and ultrasound (contracted) at the middle level (R = 0.83, p < 10(-6)). The conclusion is that ultrasonography is an accurate and reproducible method for measuring the thickness of the masseter in vivo. It allows for large-scale longitudinal study of changes in jaw-muscle thickness during growth in relation to change in biomechanical properties of masticatory muscles.

Adult↗
PubMed1994

Functional influence on sutural growth. A morphometric study in the anterior facial skeleton of the growing rat.

The aim of this study was to quantify the sutural response in the various parts of the rat's upper frontal viscerocranium and study the possible effects caused by reduced masticatory muscle function. Twenty growing male albino rats were randomly divided into two equal groups: one group (Hard Diet group) received the ordinary diet in a hard pellets form, while the other (Soft Diet group) a soft diet. The experimental period started just before the rats' pubertal growth spurt (28 days old) and its duration was 28 days. After death, the heads of the animals were taken for preparation of undecalcified frontal sections, 100 microns thick. Contact microradiographs of six representative homologous sections, for every animal in both groups, were prepared. The mean width, length, height, and interdigitation ratio of the internasal, naso-premaxillary, and interpremaxillary sutures, as well as the orientation of the bony surfaces of the naso-premaxillary suture were quantified on the contact microradiographs using the IBAS automatic image analysis system. The width of the sutural space was found to be significantly greater in the Hard Diet group than in the Soft Diet group in all the sutures studied (P < 0.01). No differences in the interdigitation of the sutures were found between the two groups, except in the internasal suture in the middle part of the snout, where the Hard Diet group exhibited increased interdigitations. The bony surfaces of the naso-premaxillary suture were significantly more parallelly-orientated in the animals with reduced masticatory muscle function (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
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

Dental injuries, temporomandibular disorders, and caries in wrestlers.

The aim of this study was to examine the prevalence of dental injuries, temporomandibular disorders (TMD), and dental caries in a group of champion wrestlers. Twenty-six male wrestlers, with a mean age of 23 yr, and an age-matched control group participated in the study. A questionnaire was used with questions on trauma, frequency of headache, intensity of practicing sports, use of sugar-containing "sports drinks", use of mouth guards, and previous TMD problems. Four bitewing radiographs were taken in all subjects. In addition, three intraoral apical radiographs of maxillary and mandibular frontal regions were taken in the wrestlers. The number of existing teeth, dental caries, amount and type of restorations, and dental injuries were recorded. Examination of the stomatognathic system comprised bilateral palpation of the masseter and temporal muscles and temporomandibular joints, and evaluation of the mandibular movements. None of the subjects had drunk sports drinks or worn mouth protectors regularly. The wrestlers had more frequent and severe dental injuries localized to the frontal region of the maxilla than the controls. No statistical differences were found in the prevalence of caries or TMD between the groups.

Adolescent↗
PubMed1994

Condylar height on panoramic radiographs. A methodologic study with a clinical application.

The aim of this study was to develop and apply a reliable method of measuring the effects of condylar lesions quantitatively on panoramic radiographs. Three different types of machines were tested. Two dry skulls were exposed in six positions in each machine, and the relative size of the condyle in relation to ramus height was calculated. The results showed good validity for the reference points used. The head position did not contribute to the variation in the measurements, but the type of panoramic machine had some influence. It was concluded that the method may be applied when calculating condylar ratios, provided that the same panoramic machine is used. The relative height of the condyle in relation to ramus height was measured bilaterally in three groups of children, with either normal or postnormal occlusion or with juvenile chronic arthritis (JCA), to detect possible asymmetries and define differences in the relative condylar height. The JCA group had a significantly shorter relative condylar height, and asymmetries were commoner than in the other two groups.

Adolescent↗
PubMed1993

A system for assessing the severity and progression of occlusal tooth wear.

This study represents an attempt to introduce a system for the longitudinal evaluation of the severity and the rate of progression of tooth wear. The material comprised a selected group of 10 males and 10 females, examined twice within an 18-month period. The subjects were predisposed to advanced occlusal wear and had a mean age of 32 years within the range of 16-56 years. Evaluation of occlusal wear was performed on a tooth-by-tooth basis, on study casts, using two ordinal scales, one for assessing the severity, and the other the progression of occlusal wear. The reliability of the scales was assessed by percentage inter-observer concordances. The sample exhibited higher occlusal wear scores in the incisor and canine regions compared to the posterior region. It was found that the overall progression in an 18-month follow-up period was slow. The inter-observer concordance in the evaluation of the severity of wear was 88%, and 91% in the progression of wear. Within the limitations of the described system, the scales may be utilized for determining the severity of occlusal wear and the rate of its deterioration in an individual's dentition. From a clinical standpoint, the need for future treatment may be based on such a evaluation of the progression of wear.

Adolescent↗