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Results for “MANDIBULAR CONDYLE”

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At least 1,333 records · Page 74Linked to original sources
PubMed1992

A look at ear canal changes with jaw motion.

Two procedures were used with one subject to examine changes in the ear canal with jaw motion. Silicone ear impressions were examined to measure the effect of jaw position. Magnetic resonance imaging was used to define the three-dimensional structure of the canal and visualize key underlying tissue. Results showed that inexpensive impressions can detail changes in the cartilaginous region of the canal. Approximately a 25% change in this subject's ear canal with different jaw positions was observed in the anterior/posterior plane with essentially no change in the superior/inferior plane. This is likely related to asymmetric stress from action of the mandibular condyle on neighboring cartilaginous tissue. Solutions to jaw motion-induced feedback problems are suggested.

Ear Canal↗
PubMed1989

The temporomandibular ligament and the articular eminence as constraints during jaw opening.

It is generally thought that during symmetrical jaw opening the mandible rotates about an axis passing through the centres of the two mandibular condyles, and translates down the articular eminence. The author argues that there are no data to support this assumption. The true combination of movements can only be understood by understanding the constraints that operate during jaw opening and these are the articular eminence and the temporomandibular (TM) ligament. The TM ligament is pulled taut during jaw opening, and so acts like the chains of a swing: the mandible rotates about the lowest attachment of the TM ligament to the condyle and swings about the most posterior attachment to the articular tubercle. The effects of combining the swing and rotation are demonstrated by a simple mechanical model. The functional advantage of the TM ligament is that it keeps the condyle close to the temporal bone during jaw opening, until the condyle passes under the articular eminence. The constraints described in this paper may have important implications related to the diagnosis and treatment of some disorders of the TM joint (to be described in a later paper).

Facial Muscles↗
PubMedDate not supplied

A 5-year follow-up of signs and symptoms of TMD and radiographic findings in the elderly.

PURPOSE: The aim was to clarify the associations among subjective symptoms, clinical signs of temporomandibular disorders (TMD), and radiographic findings in the mandibular condyles of elderly people during a 5-year follow-up. MATERIALS AND METHODS: As part of a comprehensive medical survey of a random sample born in 1904, 1909, and 1914 (Helsinki Aging Study), 364 subjects living in Helsinki participated in the dental part of the examination during 1990 and 1991; after 5 years, 103 of these were reexamined. Comprehensive data on TMD were available for 94 subjects, and radiographic data were available for 88. TMD were assessed by Helkimo's anamnestic and clinical indices, and radiographic status was assessed by panoramic radiographs. RESULTS: During the 5-year follow-up, reported anamnestic symptoms of TMD for men changed little (9%); among women, the change from baseline was 42%. When the unchanged indices were compared, the gender difference was obvious. At baseline, 5% of the women, but no men, had severe signs (clinical index III) of TMD. At the end of follow-up, none showed severe signs. Comparison of radiographic findings between baseline and follow-up showed no differences, nor did differences appear in associations between radiographic findings and anamnestic or clinical indices. CONCLUSION: During the 5-year follow-up, signs and symptoms of TMD in these elderly individuals became milder or vanished. The radiographic status of the condyles remained stable, and no association appeared between radiographic findings and signs and symptoms of TMD.

Aged↗
PubMed1990

[Postankylosis condylectomy of the temporomandibular joint in a 5-year old girl. Report of a case].

A case of post-traumatic temporomandibular joint ankylosis is described, and the technique of the treatment is detailed. Previous review of the literature was made in order to know the advantages of the treatment. There are several reports of children who have suffered facial injuries and fractures of the facial bones that became into ankylosis, characterized by the formation of new temporomandibular joint surfaces. The patient was a five years old girl who presented ankylosis of TMJ due to a car accident six months before. The symptom were: Limitation of motion, persistent close lock of mouth (2 mm) muscle pain that causes the patient to avoid eating foods, and the gradual loose of phonetic function. Condylectomy of the left mandibular condyle was performed to correct the mechanical problems associated to ankylosis. The patient had an uncomplicated postoperative course, and now are waiting the outcome of the treatment by a follow up study.

Ankylosis↗
PubMed1993

Repair of articular defects with autologous mandibular condylar cartilage.

Unlike hyaline cartilage, mandibular condylar cartilage can respond to injury by complete healing. We have used the reparative potential of mandibular cartilage to promote repair of defects in a hyaline cartilage joint surface. In 12 adult marmosets, articular fibrocartilage from the mandibular condyles was transplanted into full-thickness defects created in the femoral condyles. Additional defects acted as an ungrafted control group. The grafted defects showed good incorporation of the transplant with restoration of the articular surface within six months. Repair was by proliferation of the fibrocartilaginous graft and chondrogenesis of hyaline cartilage. The repopulating cells were distributed in a matrix of maturing collagen and sulphated glycosaminoglycans. Ungrafted control defects were only partly repaired with fibrous tissue, leaving articular deficiencies. We conclude that transplanted mandibular fibrocartilage can promote reconstitution of wounded hyaline cartilage joint surfaces in primates.

Animals↗
PubMed2005

Surgical treatment of temporal bone chondroblastoma.

BACKGROUND: Temporal bone chondroblastoma is a rare primary bone tumor that affects the floor of the middle cranial fossa. This tumor is known to have high recurrence rate after curettage, and wide resection is therefore recommended. However, the literature provides little information regarding long-term results after wide resection of temporal bone chondroblastoma. METHODS: Four cases of surgically treated temporal bone chondroblastoma underwent long-term follow-up. RESULTS: Four patients, 3 males and 1 female, with mean age of 34, were surgically treated at the neurosurgery department of Keio University Hospital. Two patients were treated for recurrent tumor and the other two for new disease. In all cases the tumor mainly involved the mandibular fossa with variable degree of infiltration into tympanic and petrous parts. The tumor was totally removed via zygomatic approach in all patients. In 3 patients, the mandibular condyle was removed to expose the tumor. These patients had temporary malocclusion and restricted motion postoperatively, which resolved within 3 to 12 months with conservative treatment. All patients have no recurrence to date with a mean follow-up period of 9 years. CONCLUSION: Temporal bone chondroblastoma was removed totally with skull base surgical technique and no recurrence has occurred for 6 to 13 years postoperatively. We found that removal of the mandibular head does not cause permanent problems of mastication in patients with normal dentures.

Adult↗
PubMed1979

Development of the squamosomandibular articulation in the Mongolian gerbil (Meriones unguiculatus). II. Succinate dehydrogenase activity.

Succinate dehydrogenase activity has been studied, according to the method of Nachlas et al. (1957), in the developing tissues forming the squamosomandibular articulation in the Mongolian gerbil from its inception through the sixty postnatal day. Increased activity was observed in the chondroblasts, osteoblasts and mesenchymal tissues of the developing articulation. The chondroclasts of the developing mandibular condyle displayed intense reaction as did the osteoclasts of the developing bony articulation. Succinate dehydrogenase activity appeared to be related to the functional maturity of the cellular elements of the developing joint.

Animals↗
PubMed1999

Effect of low masticatory function on condylar growth: a morphometric study in the rat.

The aim of this study was to estimate the influence of functional alterations on the size of the mandibular condyle and to elucidate in detail, by means of histomorphometric analysis, the effect of changing the consistency of the diet on different portions of the condylar cartilage in growing rats. Forty growing rats were randomly divided into 2 groups. One group received the normal hard diet for rats; the other group received a standardized soft diet. The experimental period was 28 days. Ten animals from each group were used for gross morphometric analysis; the other 10 animals were used for histologic analysis of the condyle. The morphometric analysis of the condylar cartilage was based on the 25th, 50th, and 75th percentiles of the mediolateral sections of the condyles. The sections were divided into 3 parts: the anterior, intermediate, and posterior part; 4 measurements were performed in each. Significant differences were found in the condylar length and width between the groups, the soft diet group having a smaller condyle. The histomorphometric analysis of cartilage thickness showed significant differences between the 2 groups, being thinner in the anterior part and thicker in the posterior part of the condyle in the soft diet group. These routine histologic findings cannot explain the gross morphologic differences in the condylar size between the groups; this means that increased condylar cartilage thickness is not necessarily evidence of increased condylar growth. The results from this study indicate that a low masticatory function leads to decreased growth of the condyle and changes in the thickness of the cartilage. This may be the effect of an alteration in the stress distribution in the temporomandibular joint area, because of the absence of large masticatory forces.

Animals↗
PubMed1994

Histological and immunohistochemical studies on the articular cartilage after experimental discectomy of the temporomandibular joint in rabbits.

Total discectomy was performed experimentally in the rabbit temporomandibular joint (TMJ). In order to evaluate the injury and repair of the articular cartilage of the mandibular condyle after discectomy, both histologic and immunohistochemical observations were made. Immunohistochemical observation by using bromodeoxyuridine (BrdU) and its monoclonal antibody in vivo labelling method was used. The present study demonstrated that the cartilage on the articular surface of the condyle disappeared at 1 week post-operatively. This defect in the injured articular cartilage was not repaired by the cartilage, but was covered by a fibrous connective tissue at 6 weeks post-operatively, where the condylar recontouring by the adjacent articular cartilage, and flattening and hyperplasia of the condyle were observed. Thus, the cartilaginous repair following discectomy was characterized by the proliferation of the adjacent cartilage to the injured site and osteoblastic formation in the bone marrow at the exposed subchondral bone.

Animals↗
PubMed1995

Experimental occlusal interferences. Part V. Mandibular rotations versus hemimandibular translations.

Frontal plane mandibular rotations and corresponding hemimandibular translations were studied in vitro by using direct observations of a human cadaver mandible and in vivo by using the indirect observations of rotational electrognathography. A comparison between the two methods showed that rotational electrognathography erred in measuring the clinically relevant hemimandibular translations resulting from mandibular rotations having a unilateral molar point (simulated occlusal interference) as the pivot of frontal plane torque. In vitro frontal plane rotations about a unilateral mandibular molar tooth (simulated occlusal interference) suggested that the resulting hemimandibular upward translations of the lateral portion of the mandibular condyle, contralateral to the molar tooth, would cause considerable compressive loading of the temporomandibular joint disc.

Adult↗
PubMed1982

Condylar development and mandibular rotation and displacement during activator treatment. An implant study.

An analysis of the effects of activator treatment on the spatial development of the mandible over 11 months was performed via the metal implant method for a group of nineteen patients. A series of centers of rotation were derived, the position and effect of which are described and related to observed changes in basal and dentoalveolar structures and the development of the mandibular condyle. A posteriorly directed condylar development, in conjunction with an anterior rotational pattern, was found to be optimal if a basal Class II malocclusion is to be treated by means of a forward developmental displacement of the mandible.

Activator Appliances↗
PubMed1995

The extraction-nonextraction dilemma as it relates to TMD.

Extraction has been a controversial subject for as long as the specialty of orthodontics has existed. Some authors believe that the extraction of premolars leads to temporomandibular disorders. This occurs, they say, because the vertical dimension collapses. Concomitantly, over-retraction and retroclination of the incisors cause the facial profile to flatten, bring about premature anterior contacts, and distally displace the mandible and mandibular condyle. Numerous correlation studies in the dental literature do not support this contention. There appears to be no higher incidence of temporomandibular disorders in patients treated with the extraction of premolars than in nontreated patients or those treated without extractions. Analysis of premolar extraction cases reveals that there is no collapse of the vertical dimension; on the contrary, the vertical dimension is either maintained or slightly opened. Similarly, there is no evidence that premolar extraction causes undesirable flattening of the facial profile. The facial profile established during treatment is primarily the result of diagnosis and treatment mechanics. Excessive anterior interferences resulting in possible posterior condyle displacement are the result of treatment mechanics. When arches are leveled properly and space closure and overjet reduction are adequately controlled, there is no reason that such interferences should occur.

Bicuspid↗
PubMed1998

[Induction of insulin-like growth factor I expression to mandibular advancement in growing rat condylar cartilage].

It was studied effects of functional mandibular advancement on IGF-I peptide of condylar cartilage of 60 5-week-old male rats. Animals were randomly divided into the experimental and control groups, and the mimic functional appliances were used in experimental group. The rats were killed after 1, 3, 7, 14, 21 and 28 days. The results showed that the condylar cartilage of growing rats expressed IGF-I the strongest in the germinal layer, medial in the transitional layer, and the least in the maturational layer. IGF-I positive cells and their immunoreactive levels increased after 1 week of functional mandibular advancement, and reached the peak level at 2 weeks. The results suggest IGF-I in mandibular condyle of rat is related to its growth and differentiation activity, and changes of condylar IGF-I after functional protrusion are relevant to the histologic changes and cellular functions which indicate their involvement with active bone growth and remodeling.

Animals↗
PubMed1995

[The recognition of mandibular asymmetries in the panoramic tomogram. An example of the need for judging the value of a diagnostic procedure].

According to Habets et al. (1988), dental rotational panoramic radiographs can be used to diagnose vertical asymmetries between the right (R) and left (L) mandibular condyle and/or ramus. The difference in vertical height between the two sides is expressed by an asymmetry index which is calculated with the formula (R - L)/(R + L) x 100%. The aim of this paper is to investigate the accuracy of this diagnostic method with the help of the parameters sensitivity and specificity. For each of 25 fully preserved and macerated skulls with a stable occlusion. Two dental rotational panoramic radiographs were made. The values obtained for condylar and rami heights as well as for the asymmetry indices as proposed by Habets and al. (1988) were compared with the values received from the corresponding measurements on the skulls. For the determination of sensitivity and specificity, the five highest asymmetry values found on the skulls were classified as "high asymmetry present". In order to achieve an acceptable sensitivity (.8), an insufficient specificity must be accepted (for ramus height .25, condyle height .2), resulting in a very high rate of false positive diagnoses. The study emphasizes the necessity of a critical evaluation of the utility of diagnostic tests and procedures.

Diagnostic Errors↗
PubMed1993

Determination of the existence of hinge movements of the temporomandibular joint during normal opening by Cine-MRI and computer digital addition.

PURPOSE: The purpose of the first phase of this two-part investigation was to determine if the opening motion of the mandible could be illustrated and described using a dynamic imaging method. The purpose of the second phase of the investigation was to determine if a center of rotation would be discovered. MATERIALS AND METHODS: Five volunteer subjects, 2 female and 3 male, whose temporomandibular joints had previously been determined to be asymptomatic, were examined by magnetic resonance imaging (MRI) during opening from a standardized position. The serial static images were reconstructed by the MRI's computer in "cine mode" to simulate dynamic motion, similar to a motion picture. For the second phase, each patient's series of static images were digitally added and manipulated by a computer graphics program to locate the center of hinge motion. RESULTS: After reviewing the animated images recorded on videotape, three independent dentist observers confirmed that the opening movement of the mandible was initially rotational, followed by translation within the glenoid fossa. A center of rotation was calculated to be in the anatomic center of the condylar head of all of the subjects in this study. CONCLUSIONS: This study showed that opening dynamics of the mandibular condyle could be studied by cine-MRI and that an opening hinge axis appears to be located in the anatomic center of the condylar head.

Biomechanical Phenomena↗
PubMed1986

Studies on hormonal regulation of the growth of the craniofacial skeleton: IV. Specific binding sites for glucocorticoids in condylar cartilage and their involvement in the biological effects of glucocorticoids on cartilage cell growth.

Using a whole-tissue binding assay and cell-free binding measurements indicated the presence of a specific steroid receptor for triamcinolone in cartilage cells of neonatal mouse mandibular condyle. Analysis of receptor levels showed that whole-tissue preparations bound 1360 fmol triamcinolone/mg protein. Affinity measurements revealed a dissociation constant of 7.6 X 10(-9) M. There was a close correlation between triamcinolone inhibition of DNA synthesis and steroid occupancy of whole-tissue receptors. The inhibitory effect of triamcinolone upon DNA synthesis could be significantly reduced by "blocking" the respective receptors with cortexolone. All the cartilage cells in the condyle revealed distinct intracellular labeling using [3H] dexamethasone autoradiography. Hence, neonatal condylar cartilage, an active site of endochondral bone formation in the craniofacial skeleton, can be regarded as a genuine target tissue for the biological effects of glucocorticoids.

Animals↗
PubMed1996

Variations in costochondral grafting of the mandibular ramus.

This paper reviews the indications for, and the biological basis of, costochondral grafting for mandibular condyle replacement in adults and children. Our approach to costochondral grafting is described and illustrated, and known variations in techniques are reviewed and discussed. Data from our clinical series of 28 grafts is summarized.

Adolescent↗
PubMed1989

Discomalleolar and anterior malleolar ligaments: possible causes of middle ear damage during temporomandibular joint surgery.

Damage to structures within the middle ear during surgical manipulation of the temporomandibular joint (TMJ) has been reported. Two structures are proposed as possible intermediaries in this trauma: the discomalleolar ligament (DML), which passes from the malleus to the medial retrodiscal tissue of the TMJ, and the anterior malleolar ligament (AML), which connects the malleus with the lingula of the mandible via the sphenomandibular ligament (SML). It has been hypothesized that when tension is applied to the DML and/or AML, the resulting movement of the malleus could cause damage to the tympanic membrane and associated structures. The objective of this study was to determine whether tension applied to the DML and/or the AML could cause movement of the malleus. With the use of a superior medial approach through the middle cranial fossa, the ligaments connecting the malleus with the mandible were examined in 52 adult/human cadaveric half-heads. Tension applied directly to the SML resulted in movement of the malleus in three specimens. Similar tension applied to the DML did not cause movement of the malleus. Histologic evidence showed a continuity of fibers between the SML and AML. When the mandibular condyle was distracted inferiorly, tension was demonstrated in the SML. The results indicate that the AML via the SML has the potential to cause middle ear damage and is more likely to do so than the DML.

Adult↗