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Results for “Condylar position”

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PubMed1999

Ulnar nerve pressure: influence of arm position and relationship to somatosensory evoked potentials.

BACKGROUND: Although the ulnar nerve is the most frequent site of perioperative neuropathy, the mechanism remains undefined. The ulnar nerve appears particularly susceptible to external pressure as it courses through the superficial condylar groove at the elbow, rendering it vulnerable to direct compression and ischemia However, there is disagreement among major anesthesia textbooks regarding optimal positioning of the arm during anesthesia. METHODS: To determine which arm position (supination, neutral orientation, or pronation) minimizes external pressure applied to the ulnar nerve, we studied 50 awake, normal volunteers using a computerized pressure sensing mat. An additional group of 15 subjects was tested on an operating table with their arm in 30 degrees, 60 degrees, and 90 degrees of abduction, as well as in supination, neutral orientation, and pronation. To determine the onset of clinical paresthesia compared to the onset and severity of somatosensory evoked potential (SSEP) electrophysiologic changes, we studied a separate group of 16 male volunteers while applying intentional pressure directly to the ulnar nerve. Data are presented as mean (median; range). RESULTS: Supination minimizes direct pressure over the ulnar nerve at the elbow (2 mmHg [0; 0-23]; n = 50), compared with both neutral forearm orientation (69 mmHg [22; 0-220]; P < 0.0001), as well as pronation (95 mmHg [61; 0-220]; P < 0.0001). Neutral forearm orientation also results in significantly less pressure over the ulnar nerve compared to pronation (P < or = 0.04). The estimated contact area of the ulnar nerve with the weight-bearing surface was significantly (P < 0.0001) smaller in the supine position (2.2 cm2 [0.5; 0-9]; n = 50) compared with both neutral orientation (5.5 cm2 [5.0; 0-13]) and pronation (5.8 cm2 [6; 0-12]). With the forearm in neutral orientation, ulnar nerve pressure decreased significantly (P < or = 0.01; n = 15) as the arm was abducted at the shoulder from 0 degrees to 90 degrees. In the 16 male subjects tested, notable alterations in ulnar nerve SSEP signals (decrease > or = 20% in N9-N9' amplitude) were detected in 15 of 16 awake males during application of intentional pressure to the ulnar nerve. However, eight of these subjects did not perceive a paresthesia, even as SSEP waveform amplitudes were decreasing 23-72%. Two of these eight subjects manifested severe decreases in SSEP amplitude (> or = 60%). CONCLUSIONS: Extrapolating these results to the clinical setting, the supinated arm position is likely to minimize pressure over the ulnar nerve. With the forearm in neutral orientation, pressure over the ulnar nerve decreases as the arm is abducted between 30 degrees and 90 degrees. In addition, up to one half of male patients may fail to perceive or experience clinical symptoms of ulnar nerve compression sufficient to elicit SSEP changes.

Adult↗

PubMed2000

Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.

The aim of this prospective longitudinal study of 62 consecutively treated Class II malocclusions was to determine whether bite-jumping causes temporomandibular disorders (TMD). The function of the temporomandibular joint (TMJ) was assessed anamnestically, clinically, and by means of magnetic resonance images (MRIs) taken before (T1), after (T2), and 1 year after (T3) Herbst treatment. Average treatment time with the Herbst appliance was 7.2 months. In all subjects, Herbst treatment resulted in a Class I or overcorrected Class I dental arch relationship. Thereafter, treatment was continued with a multibracket appliance. The condyle was positioned significantly forward during treatment but returned to its original position after removal of the Herbst appliance. A temporary capsulitis of the inferior stratum of the posterior attachment was induced during treatment. Over the entire observation period from before treatment to 1 year after treatment, bite-jumping with the Herbst appliance: (1) did not result in any muscular TMD; (2) reduced the prevalence of capsulitis and structural condylar bony changes; (3) did not induce disc displacement in subjects with a physiologic pretreatment disc position; (4) resulted in a stable repositioning of the disc in subjects with a pretreatment partial disc displacement with reduction; and (5) could not recapture the disc in subjects with a pretreatment total disc displacement with or without reduction. A pretreatment total disc displacement with or without reduction did not, however, seem to be a contraindication for Herbst treatment. In conclusion, bite-jumping using the Herbst appliance does not have a deleterious effect on TMJ function and does not induce TMD on a short-term basis.

Adolescent↗

PubMed1991

Corrected TMJ tomography: effectiveness of alternatives to SMV tracing.

An axial (SMV) radiograph has been widely used to determine parasagittal head position in TMJ tomograms. The purpose of this study was to investigate the efficacy of alternative anatomic methods for patient positioning in TMJ tomograms. The positioning methods studied included (1) rotation of the patient's head toward the film plane on the basis of the condylar orientation as determined by an SMV radiograph, (2) arbitrary rotation of the patient's head 20 degrees toward the film plane, (3) placement of the zygomatic arch parallel to the film plane, and (4) positioning of the posterior occlusal plane parallel to the film plane. Statistical analysis of the accuracy of the positioning techniques revealed no differences in the SMV, the zygomatic arch, and the arbitrary 20 degrees positioning. Aligning the posterior occlusal plane did not adequately align the mandible into a favorable radiographic position.

Analysis of Variance↗

PubMed1990

[Comparative study of the movements between condyle and exterior point in lateral movement].

The study was performed on 30 left and right temporomandibular joints of 15 adults with normal occlusion. The exterior point was set on condylar center of each subject. Using cephalometric laminagrams and submental-vertical cephalograms, the movement of condyle and the movement of exterior point were compared on the nonworking side in 3mm lateral movement at incisal region. Also, the relation between the inclination angle of front wall of mandibular fossa and the movement of condylar center was evaluated. The standard of horizontal plane was F-H-L. The results were as follows: 1. The position of exterior point on sagittal plane, 12 examples shifted in front upward, 9 examples shifted in rear downward, 8 examples shifted in front downward and 1 example shifted in rear upward from condylar center. 2. The inclination of moving front downward of condylar center was 47.0 degrees, and that of exterior point was 50.3 degrees. 3. The shifting direction of exterior point was correlative with the shifting direction of condylar center. However, there was an individual difference in the synchronism between the shifting direction of condylar center and the shifting direction of exterior point during lateral movement. 4. The inclination of front wall of mandibular fossa was 50.9 degrees. 5. A coefficient of correlation between the inclination of front wall of mandibular fossa and the shifting direction of condylar center during 3mm lateral movement was small.

Adult↗

PubMed1982

Correlation of condylar mobility and arthrotomography in patients with internal derangements of the temporomandibular joint.

The objective of this clinical study was to determine the relationship between condylar translation on plain tomographic radiographs and internal derangements assessed by a clinical and arthrographic evaluation. One hundred two joints in sixty-two patients were evaluated by linear tomography in closed versus opened positions and classified according to the type of internal derangement depicted by arthrotomography in sixty-two cases. A decrease in condylar translation was noted in patients diagnosed as having meniscus displacement without reduction. Patients who had meniscus displacement with reduction (painful clicking) were found to have hypermobility of the condyle on the symptomatic side. Meniscus displacement without reduction, which appears to be an advanced stage of internal derangement, is a serious sequela leading to marked restriction of condylar motion.

Humans↗

PubMed1978

Mechanics, growth, and class II corrections.

Growth of the orofacial region is quantitatively described by locating the center of mandibular rotation relative to the cranial base. The center of mandibular rotation is positioned by the ratio of vertical facial growth (AFH/PFH) and the direction of condylar growth. Appliance therapy is associated with changes in the means of both of these parameters. These changes reduce or stop favorable anterior mandibular rotation and redirect the mean condylar growth vector more posteriorly. When appliance therapy is stopped, these parameters return toward their resting values. The mean direction of the condylar growth vector became even more anteriorly directed after treatment than the pretreatment mean value. These data support the hypothesis that orthodontic appliances significantly alter the facial growth pattern and when they are stopped, the growth pattern tends to rebound to or beyond the pretreatment values.

Activator Appliances↗

PubMed1980

Articulator modification for maxillofacial prosthesis.

A modification has been described which will permit the use of a face-bow for maxillofacial prosthesis construction. Any inferior positioning of the maxillary cast can now be compensated for by increasing the condylar inclination to maintain the correct relationship to the occlusal plane. By modifying an existing articulator, versatility has been achieved and the extreme cost of a new instrument has been avoided. While this design does not solve the problems encountered with maxillofacial prostheses, it does serve to make fabrication of prostheses easier for both the dental laboratory technician and the dentist.

Dental Articulators↗

PubMed1983

Mounting casts on a new plasterless plane line articulator.

A technique of mounting casts on a plane line articulator without the aid of plaster or artificial stone has been described. The advantages of this technique are: The dimensional change errors inherent in a plaster or dental stone mounting are avoided. Casts may be routinely mounted and articulated in less than 3 minutes. Casts may be removed and returned to their original position with precise reliability. The disadvantages include the lack of an adjustable horizontal condylar guidance and the lack of an anterior guide pin or anterior guidance. Further studies should be directed toward determining the accuracy of remounting casts on the instrument.

Dental Articulators↗

PubMed1997

Modified condylotomy for chronic nonreducing disk dislocations.

OBJECTIVES: To retrospectively evaluate the modified condylotomy procedure for patients with chronic nonreducing disk dislocations of the temporomandibular joint. STUDY DESIGNS: Sixty-three patients underwent 78 modified condylotomies on temporomandibular joints that had chronic nonreducing disk dislocations and that were previously treated unsuccessfully with nonsurgical modalities. Patients were asked to evaluate their pain, headaches, bite, and success rate postoperatively. Comparisons of patients' preoperative and postoperative maximum incisal opening were also made. Transpharyngeal and transcranial radiographs were compared to determine condylar changes. RESULTS: Ninety-four percent felt that their pain was better, one patient (2%) said that his pain was the same, and two patients (4%) felt that their pain was worse. Eighty percent considered their headaches were better, and one patient (2%) considered them worse. Seventy-eight percent said that their bite was the same or better, and 22% said it was worse. Three patients underwent a second surgery. Progressive condylar remodeling occurred in 81%, and regressive condylar remodeling occurred in 6%. The maximum incisal opening change was overall a positive change; 35% had a significant positive change, and 10% had a significant negative change. CONCLUSION: This retrospective study shows that the modified condylotomy should be considered as a surgical alternative in treating patients with chronic nonreducing disk dislocations that have been unsuccessfully treated nonsurgically.

Bone Remodeling↗

PubMed1995

[Inter-trochleo-bicondylar fracture of the femur. An unusually traumatic lesion. Mechanism. Therapeutic implications].

UNLABELLED: The authors present a curious type of fracture of the distal end of the femur. They discuss the mechanism and the factors responsible for that lesion. The treatment and results are finally presented. MATERIAL: A 65 years old female, submitted to a crash accident while driving a car, with a seat in maximaly low position. She presented a bilateral open transverse fracture of the patella associated in the right limb to a fracture line between condyles and the patellar surface of the femur. METHOD: Bilateral osteosynthesis of both patella had been realised in emergency through a transverse approach. Through the fractured right patella two anteroposterior screws had been used to fix the fractured femur. RESULT: A plaster cst had been used for three weeks. Full weight bearing was permitted after three months. Full range of motion of both knees was noticed after six months follow-up. DISCUSSION: The femoral fracture could have been fixed by another device like D.C.S. platescreen but it would be weaker. That type of fracture was produced because of flexed low position of the knee at the moment of the accident. Usually, supra-condylar femoral fractures are due to a force vector applied on the upper extremity of the tibia without any patellar fracture. In our case, the patella involved associated to a fracture line between the condyles and the patellar surface. The structural anatomy (noeud sutural de Chevrier) explains the solidarity of the two femoral condyles.

Accidents, Traffic↗

PubMed2006

Neural symmetry and functional asymmetry of the mandible.

Even in the absence of malformation or skull base asymmetry, the mandible may be physiologically asymmetric and this remains a major challenge in the orthodontic treatment. The mandible is a bone formed by a primary subunit, i.e., the neural part, with different functional secondary subunits, so we suggest that in a normal mandible the asymmetry was caused by the secondary functional subunit and the neural part is nearly symmetric. Eighty-three dry human mandible samples were studied. The measurements of the size of the mandible (corpus, ramus, mandible notch, condylar process, the angle of the mandible) and the neural subunit (the mandibular canal and the position of the mental and mandibular foramina) were measured bilaterally. The left and right sides were compared according to the dental status: 60 dentate and 23 edentulous mandibles. The calculation of the symmetry was based on the paired Student t test, the absolute difference |R-L| and the relative absolute difference |R-L|/|R+L|x100. The mandibular canal and the position of the foramina were symmetric, except for the position of the mandibular foramen in relation to the mandible notch. The symmetry was not modified by the dental status. The total length of the mandible and the length of the ramus were greater on the left side independently from the dental status. The length of the corpus and the mandible angle were symmetric in each group. The mandible notch was always asymmetric and its height was greater in the dentate group. The condylar process was the most asymmetric structure in each group. The primary subunit of the mandible, surrounding the mandibular canal, is a symmetric component of the mandible and is not modified by the dental status. The angle of the mandible between the corpus and ramus is another symmetric parameter that is important for the facial architecture. The ramus and especially the mandibular notch as well as the condylar process are the most asymmetric subunits influenced by the functional matrices.

Analysis of Variance↗

PubMed1986

Control of the condylar-proximal mandibular segments after sagittal split osteotomies to advance the mandible.

Maintenance of the normal or presurgical anatomic position of the mandibular condyles and contiguous proximal mandibular ramus segments after sagittal split ramus osteotomies is important, not only to enhance the stability of results but also to avoid iatrogenic temporomandibular joint complications. Accordingly, during the past few years, we have attempted to improve the surgical control of condyle and proximal segment position while using the sagittal split ramus osteotomy to advance the mandible. After several modifications, the device reported herein was used and the results evaluated in ten consecutive patients who underwent bilateral sagittal split ramus osteotomies with symmetric advancement of the mandible. This device enables the surgeon to obtain very precise reproduction of the "normal" proximal segment and condyle position at the time of surgery. The use of the device and documentation of its efficiency are presented.

Equipment Design↗

PubMed1984

Time-dependent effects of a 'functional'-type orthopedic appliance on the rat mandible growth.

The modus operandi and the time-dependent variations in the effects of the LSU-activator, an orthopedic appliance currently used in human orthodontic therapy, was experimentally analyzed in growing rats. This appliance causes a forward positioning of the lower jaw and a restriction of mandibular motility. After a 4-week treatment, the following changes were observed: (i) the growth rate of the condylar cartilage was accelerated, this growth-promoting effect being more pronounced when the LSU-activator was worn during the animal's rest span. (ii) the direction of condylar growth became more backward-oriented; no significant difference between day and night treatment, i.e. during the rest and activity spans could be detected; (iii) the supplementary lengthening of the mandible was greater in rats treated during rest than in rats treated during waking and (iv) the number of serial sarcomeres in the lateral pterygoid muscle was smaller. This growth retardation of the muscle was greater in rest-time than in waking-time treated individuals. The LSU-type activator's action implies a two-step effect: during the time of wearing the appliance, the more forward positioning of the mandible causes a reduced growth of the lateral pterygoid muscle; during the time the LSU-type activator is not worn, the mandible is functioning in a more forward position such a way that it stimulates the growth rate of the condylar cartilage and the subperiosteal ossification of the posterior border of the ramus. It is therefore essential, for a few hours every day, that the mandible be allowed to move freely from the appliance in a more forward position.

Activity Cycles↗

PubMed2003

Functional appliance therapy accelerates and enhances condylar growth.

The present study was designed to quantitatively assess the temporal pattern of expression of Sox 9, the regulator of chondrocyte differentiation and type II collagen, the major component of the cartilage matrix during forward mandibular positioning, and compare it with the expression during natural growth. Female Sprague-Dawley rats, 5 weeks old, were used. Results showed that the expression of Sox 9 and type II collagen are accelerated and enhanced when the mandible is positioned forward. Furthermore, we monitored the amount of new bone formation during mandibular advancement and after the removal of bite-jumping appliances. A substantial increase was observed in the amount of newly formed bone when the mandible was positioned forward. No significant difference in new bone formation could be found after the appliance was removed when compared with natural growth. Thus, functional appliance therapy accelerates and enhances condylar growth by accelerating the differentiation of mesenchymal cells into chondrocytes, leading to an earlier formation and increase in amount of cartilage matrix. This enhancement of growth did not result in a subsequent pattern of subnormal growth for most of the growth period; this indicates that functional appliance therapy can truly enhance condylar growth.

Activator Appliances↗

PubMed2005

Correlation of different MRI characteristics of anterior disc displacement with reduction and without reduction.

The aim of this study was to evaluate the correlations between magnetic resonance imaging (MRI) findings in anterior displacement with reduction (ADDR) and anterior displacement without reduction (ADDWR). Two hundred patients with temporomandibular disorder (TMD) symptoms were examined clinically by a clinician experienced with this disorder. There were 130 joints with ADDR and 45 joints with ADDWR; 88 patients were identified according to the clinical and MRI diagnoses of both observers. The MRI characteristics such as position, signal intensity, morphology of disc, degenerative changes, effusion, scar tissue, avascular necrosis, and condylar hypermobility were evaluated in the individual with ADDR and ADDWR. The Chi-square test was used to determine the correlation between MRI characteristics in the ADDR and the ADDWR. There were significant relationships between degenerative changes and increased signal intensity, degenerative changes and side-way displacement, effusion and the deformation of the disc, effusion and subluxation, increased signal intensity and subluxation, elongation deformation and increased signal intensity, and elongation deformation and side-way displacement in ADDR. There were significant relationships between degenerative changes and effusion, degenerative changes and decreased signal intensity, scar tissue and avascular necrosis, deformation of disc and increased signal intensity, as well as deformation of disc and decreased signal intensity in ADDWR. These MRI findings also correlated with the clinical findings, however, this correlation appears to be a synergistic pattern rather than a set of clear-cut relationships. The correlations between these MRIs and different clinical findings such as pain and dysfunction also must be evaluated. Existing correlations must be considered in the diagnosis and treatment planning of TMD, and signs and symptoms of TMD should be monitored after treatment.

Humans↗

PubMed1991

[Intra- and extra-capsular condyle fractures in the growth period. Therapy, clinical course, complications].

37 patients had been reviewed after surgical (n = 25) or conservative (n = 12) treatment of condylar fractures. Morphologic and functional outcomes were equal in spite of the poorer starting position of the patients that had been operated on. Injuries and complications due to the operation, such as facial nerve palsy, growth inhibition or obvious scars have never been found. Conservatively treated and operated patients alike showed a moderate limitation of opening and mediotrusion on the fracture side, and both groups showed a flattening of the protrusion path.

Adolescent↗

PubMed1990

Arthrographic evaluation of disk position following mandibular manipulation technique for internal derangement with closed lock of the temporomandibular joint.

The mandibular manipulation technique is widely used and is considered acceptable conservative therapy for an acute closed lock of the temporomandibular joint. However, there are no studies that prove objective morphologic assessment of this method in patients with unlocked disks. In this study, preoperative and postoperative arthrograms were evaluated to clarify the disk position in patients for whom successful mandibular manipulation was carried out. Postoperative arthrograms in 30 closed lock joints revealed that three joints were normal (complete reduction), eight had anterior disk displacement with reduction (click), 15 had partial reduction at the maximum mouth opening position, and four had anterior disk displacement without reduction. Disk mobility increased with improved condylar translation in all joints. These results indicate that complete anatomic reduction of the disk by mandibular manipulation is difficult, but also that clinical symptoms do not always correspond to how well the disk has been reduced by this treatment. Increasing disk mobilization might be effective treatment for patients with closed lock of the temporomandibular joint.

Adolescent↗

PubMed2003

Propulsive appliance stimulates the synthesis of insulin-like growth factors I and II in the mandibular condylar cartilage of young rats.

Functional orthopedic appliances correct dental malocclusion partially by exerting indirect mechanical stimulus on the condylar cartilage, modulating growth and the adaptation of orofacial structures. However, the exact nature of the biological responses to this therapy is not well understood. Insulin-like growth factors I and II (IGF-I and IGF-II) are important local factors during growth and differentiation of several tissues, including cartilage. The aim of this study was to verify the mRNA and protein expression of IGF-I and IGF-II in the condylar cartilage of young male Wistar rats that used a mandibular propulsive appliance for 3, 5, 7, 9, 11, 13 or 15 days. For this purpose, sagittal sections of decalcified and paraffin-embedded condyles were submitted to immunohistochemistry and in situ hybridization. IGF-I and IGF-II expression increased with developmental age in the control and treated rats. After 9 days of treatment the positivity for both peptides in the animals that wore the propulsive appliance increased even more, expressively different from the age-matched controls. The expression patterns of both IGFs were similar, although IGF-I labelling was stronger. Furthermore, the enhanced expression of both peptides was in parallel with the proliferating cell nuclear antigen (PCNA) positivity, a proliferation cell marker. The modulation of IGF-I and IGF-II expression in the condylar cartilage in response to the propulsive appliance suggests that both peptides are involved in the mandibular adaptation during this therapy.

Animals↗