Fossa Relationship Research Articles

Cone-beam tomography assessment of condylar position discrepancy between centric relation and maximal intercuspation

The magnitude of occasional discrepancies between the centric relation and maximal intercuspation positions remains a controversial subject. This study quantitatively evaluated the possible discrepancies in the condyle/mandibular fossa relationship between these positions using cone-beam computed tomography. Twenty young and asymptomatic volunteers were distributed equally into normal occlusion and Angle Class I, II and III malocclusion groups. They were submitted to one tomographic scan in maximal intercuspation and one in centric relation. Measurements were performed on lateral and frontal cuts of the patients' temporomandibular joints, and the data collected were compared using Student's t test at a significance level of 5%. The results showed that there were no statistically significant differences between the centric relation and maximal intercuspation positions in young and asymptomatic patients with practically intact dentitions using cone-beam computed tomography.

Assessment of condyle fossa relationship and disc position in class II Div 1 subdivision cases - A CT scan and MRI study

Assessment of condyle fossa relationship and disc position in class II Div 1 subdivision cases - A CT scan and MRI study

Effects of fixed functional appliance treatment on the temporomandibular joint

In this study, we tested the hypothesis that fixed functional appliance treatment in a group of Class II Division 1 patients with mandibular retrusion changes the condyle position in the glenoid fossa. Transverse computed tomography images were taken of the temporomandibular joint region in 60 children with Class II Division 1 malocclusion. Thirty randomly selected patients were treated with a fixed functional orthodontic appliance (Forsus nitinol flat-spring, 3M Unitek Corp, Monrovia, Calif) for 7 months; another 30 patients without treatment were used as controls. Computed tomography images taken at the beginning and end of fixed functional appliance treatment were used for estimating the condyle-glenoid fossa relationship, including the volumes of condyle, glenoid fossa, and anterior and posterior joint spaces. Although the volumes of the condyle and glenoid fossa increased more in the study group than in the control group, the differences were not statistically significant. However, statistically significant differences were found between the groups in the volumes of the anterior and posterior joint spaces (P < 0.05). When the volumes of the anterior and posterior joint spaces changed, the condyle was more posteriorly positioned in the glenoid fossa in the study group than in the control group.

The Effect of Condyle Fossa Relationships on Head Posture

Although it is commonly accepted that there is an interrelationship between the temporomandibular joint (TMJ) and head posture, few, if any, previous studies have quantified this effect. The purpose of this study is to quantify the effect of a change in the condyle fossa relationship of symptomatic temporomandibular joints on head posture. Charts of 51 patients (N=10 men and N=41 women) with symptomatic TMJ pathology were reviewed. The condyle fossa relationships were measured pre- and posttreatment using sagittal corrected hypocycloidal tomography. The amount of slant between the shoulder and external auditory meatus (EAM) was measured in pre- and posttreatment photographs as an indicator of forward head posture; less slant indicates better posture. Subjects ranged in age from 13-74 years (mean=43.1) and had been treated for an average of 5 months. Comparisons with pre-treatment measures showed that after treatment, the amount of retrodiskal space was significantly increased by an average of 1.67 mm on the left side (t=-10.11, p<0.0001) and 1.92 mm on the right (t=-9.62, p<0.0001). Comparisons also showed that after treatment, the amount of slant between the shoulder and EAM decreased by 4.43 inches on average which was also significant (t=13.08, p<0.0001). Improvement in the condyle fossa relationship was related to decreased forward head posture. This suggests that optimizing mandibular condyle position should be considered in the management of forward head posture (adaptive posture).

CONDY-RAY & ACCURAD 200 SEBAGAI SARANA PENCITRAAN UNTUK MENGATASI KELAINAN SENDI TEMPORO MANDIBULA

Since the temporomandibular joints are components of the stoamtognathic system that dentist is most familiar with, problems relating to this joints must be recognized, understood and treated by dentists. A comprehensive evaluation of this joint problems must include the radiographic examination. Transcranio lateral is the most commonly used of all conventional TMJ radiographic projection from the lateral aspect that shown the condyle, fossa and eminence as well as the condylar fossa relationship in selected functional movements, but which is not free from superimposed of the adjacent structures. A modified positioning device has been developed over this past years, to overcome these superimposition problems. The use of 'Condy ray and Accurad 200 apparatus that have some advantages over the standard transcraniolateral radiographic projection will be discussed in this paper.

Tomographic stability of condyle fossa relationships in 40 treated temporomandibular disorder patients

Condylar position and stability after treatment of 40 temporomandibular disorder patients was studied. This study determined pretreatment position and posttreatment condylar stability. Forty temporomandibular disorder patients with symptoms of muscles of mastication pain, temporomandibular joint sounds, attrition, interceptive occlusal contacts, and restricted range of motion were used. Axial corrected midcut sagittal tomograms were made of the 80 temporomandibular joints before treatment. Tracings from the tomograms were used to measure and analyze pretreatment position and posttreatment stability. Pretreatment condyle fossa position was not concentric in 26 of 80 patients (32.5%). Posttreatment condylar position showed no change and was statistically stable. In this study of 40 temporomandibular disorder patients, no statistical change in condylar position was detected. Variable condylar positions were found in the 80 pretreatment axial corrected midcut sagittal tomograms. All patients were asymptomatic after 1 year.

Comparison of four different methods of evaluation on axially corrected tomograms of the condyle/fossa relationship

One hundred temporomandibular joints of 50 dry skulls were used to determine whether there was a statistically significantly difference among four different techniques that were employed to assess the condyle/fossa relationship on axially corrected tomograms. A two-way analysis of variance was performed and the results indicated that: (1) a highly significant difference in the condyle/fossa relationship existed (p = 0.002) among the various skulls and (2) no significant difference existed between the four techniques employed to assess the condyle/fossa relationship (p = 1).

The Temporomandibular Joint

MRI is the procedure of choice for diagnosing most internal derangements. MRI provides images that not only demonstrate bony detail but show excellent representation of soft tissues in both anatomic and semifunctional relationships. MRI does not use ionizing radiation and has no known adverse effects. Multiplanar imaging allows a three-dimensional analysis of the TMJ, providing a more complete assessment of the condyle, articular disc, fossa relationships. Whenever capsular adhesions or disc perforations are suspected and are not demonstrated with MRI, then arthrography should be performed.

An electromyographic study of mandibular position in response to changes in body position

lrotrusion of the mandible, with the attached muscular mass of the tongue, aids in maintaining a patent upper airway. In contrast, passive retrusion of the mandible and tongue, when the body is in the semireclined or reclined position, could compromise the airway. For example, it has been postulated that one factor increasing the risk of sudden infant death syndrome is allowing an infant to sleep lying on its back.’ Posterior displacement of the mandible, tongue, and soft palate with possible airway obstruction is more likely with the infant in this position. Previous electromyographic studies indicate a substantial increase in the baseline myoelectric activity of the genioglossus muscle, the main protruder of the tongue, when a subject’s head is tilted from the anatomic position to the supine position.2 Sauerland and Mitchell2 have referred to the “tongue-safety” feature of the genioglossus muscle in precluding airway obstruction. Mandible-maxillae and condyle-mandibular fossa relationships are necessary for airway patency and important for the management of the dental patient in the semireclined to reclined position. These relationships are dependent on associated muscle response to altered body position. The primary protruders of the mandible that might accompany the genioglossus muscle in counteracting passive retrusion of this bony tissue complex are the medial and lateral pterygoid and the masseter muscles. Therefore, it was of interest to investigate whether or not these muscles also demonstrate fluctuations in levels of myoelectric activity due to positional head changes. Numerous investigators have documented the electromyographic activity patterns of masticatory muscles in response to various movements of the head and to changes in the position of the mandible.3-6 These studies, however, did not use the more specialized

Failures in Orthodontics

There are several dogmatic rules for the prevention of orthodontic failure and to aid in the philosophical approach to orthodontic problems: 1. No occlusion is so stable as a malocclusion once established and in equilibrium. 2. Stability of the anterior teeth can more easily be maintained when upright over basal bone and closest to the position of the original malocclusion. 3. The intercuspal widths and intermolar widths of the mandibular teeth are most stable when contained within the arch form and muscular balance of the original malocclusion. 4. Growth of the jaws is largely a product of genetics, endocrine balance, and nutrition. 5. Proper skeletal relationships may be more important than dental relationships in evaluating the severity of a malocclusion. 6. Relapse is more likely to occur in the mandibular arch first than in the maxillary arch. 7. Most well-treated malocclusions will lose about 10 to 15 per cent of the treatment result after retention. Disregard of the following factors, singly or in combination, probably leads to most failures in orthodontic treatment: 1. Tooth-to-bone discrepancies. 2. Bone-to-bone discrepancies. 3. Tooth-to-tooth discrepancies. 4. Aberrant neuromuscular patterns. 5. Changing growth patterns. 6. The limitations of treatment goals. 7. The limitations of appliance therapy. 8. The effects of orthodontic therapy on the psyche of the patient, his self image, his goals, and his cooperation. Today, it is naive to anticipate that a good dental cusp–fossa relationship, a good centric occlusion and centric relation, proper contact points, and reasonable alignment of the anterior teeth with good cuspid rise, and other mechanistic parameters, will suffice as the sole criteria for tissue health, dental stability, and facial esthetics. Most orthodontic failures cannot be laid to one single factor. Failures usually are the cumulative effect of several factors, one leading to another like a series of fallen dominoes. The important factors in successful treatment can be linked to a chain of events with each link having importance, and the omission of a link causing a break in the successful outcome of treatment. The orthodontist strives, along with his dental colleagues, for perfection in occlusion, stability, function, and dental and facial esthetics, but it is simpler to move a tooth into a given position with known mechanical forces than to maintain the tooth in a new position subject to the unknown forces of occlusal stress and a new muscular environment. Fortunately, the oral mechanism is forgiving of ignorance and abuse, will tolerate many minor errors, and will adjust and compensate to establish harmony and homeostasis within its functional limits.

Range of condylar movement during mandibular opening

Summary The range of condylar movement upon opening 35 mm. or maximally and upon incising of a large bolus of food was studied on 288 subjects with and without the temporomandibular pain-dysfunction syndrome by means of still and motion roentgenography. The condyles of most asymptomatic subjects were located at the eminentiae when a moderately wide incisal opening of 35 mm. was observed. Most of the remaining condyles were found to be anterior to the eminences rather than posterior to them. Maximal incisal opening studies indicate that the anterior range of condylar movement is considerable and not confined to the fossae. Incision, mastication of large boluses, and yawning can involve a condyle position outside the fossae for short periods of time. The incisal opening position commonly employed during dental treatment also involves an out of the fossa relationship, but for longer periods of time. The maintenance of this position, the malleting of the mandible with the anterior condylar positioning, the influence of maxillomandibular elastics upon the range of the condylar movement appear to have hazards. Restricted condylar movement upon opening, particularly condylar rotation or near rotation within the fossae, was found to be associated with disease. The use of such movement as a criterion for the development of occlusion and the anterior position of the condyle during dental treatment may be etiologic factors in the temporomandibular pain-dysfunction syndrome.

Facial and denture changes during orthodontic treatment as analyzed from the temporomandibular joint

Some of the most recent trends of thought on the biology and mechanics of orthodontic therapy have been presented. The importance of the knowledge of behavior of the temporomandibular joint has been stressed, beginning with variation and differences in malocclusion and continuing to its range of change during treatment. Attempts were made to show that within the temporomandibular complex lies the key to knowledge of growth and physiologic changes in the face during treatment. The findings described herein suggest certain restrictions on the application of the mandibular rest position concept. Rest position changes during treatment because it is abnormal at the start of treatment in Class II cases. In order to understand these changes, attention is directed to muscular accommodations in mastication, speech, deglutition, and respiration. Further research is suggested in the growth of musculature and its relation to growth of the face and the neurophysical adjustments necessary during these concomitant growth changes. Changes in condyle position often explained spontaneous correction of Class II malocclusions. Adjustments of the condyle posteriorly also were found to be responsible for delayed arch correction in the presence of continued elastics or cervical traction. Changes in the condyle fossa relationship, therefore, were vitally important during treatment, but only intermittently effected the over-all growth pattern. The observed changes in the face during treatment are the same as those described by Downs 7 and Donovan. 6 An evaluation of the joint offers certain possibilities of explanation for this behavior. Facial changes appeared to be influenced by the amount of condyle growth and by its direction of growth. Changes in the cranial base appeared to produce regional changes of the fossa and caused significant effects on the behavior of the face. Local alterations of the fossa were found to be important to a lesser degree. Condyle growth usually was expressed up the long axis of the neck of the condyle, but the direction varied considerably. A correlation of headplate and joint roentgenographic findings revealed that condyle growth in a backward direction contributed to vertical increase in the face. A more vertical direction of condyle growth actually produced forward movement of the chin. These changes are understood when it is realized that mandibular growth effects are dependent on the stabilization of musculature. Through this action of musculature, the chin is dropped or pulled forward in the variety of growing faces. Facial growth was found to be important to anchorage of the teeth, correction of overbite, and positioning of the lower incisors. Movement of the lower molar correlated with growth of the condyle. Anchorage values thus were related to the growth pattern. Treatment of overbite in patients not expressing vertical growth was accomplished by the depression of incisors, A normal forward swing of the face carried the lower incisors forward as correct relationships were established. Intermaxillary elastics accomplished only a holding action of the upper arch in such instances. Gentle elastic forces were thus indicated. Rapid treatment was contraindicated when growth was employed for advantage. Growth was demonstrated to be of advantage, even to the extent of providing distal positioning of lower arch in spite of Class II elastics in expressing liberal growth (Fig. 13). It appears that the method of laminagraphy has filled that important blind spot of cephalometrics and therefore serves as a valuable adjunct to it and other methods of analysis of malocclusion. At the present time the costly equipment is impractical. However, the information derived from the studies of laminagraphy, when applied to cephalometrics, will provide a clear understanding and a precise application of the cephalometric head films to clinical problems.