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PubMed2000

Diagnostic accuracy of film-based, TIFF, and wavelet compressed digital temporomandibular joint images.

The purpose of this research was to determine if digitization and the application of various compression routines to digital images of temporomandibular joint (TMJ) radiographs would diminish observer accuracy in the detection of specific osseous characteristics associated with TMJ degenerative joint disease (DJD). Nine observers viewed 6 cropped hard-copy radiographic films each of 34 TMJs (17 radiographic series). Regions of interest measuring 2 in x 2 in were digitized using an 8-bit scanner with transparency adapter at 300 dpi. The images were placed into a montage of 6 images and stored as tagged image file format (TIFF), compressed at 4 levels (25:1, 50:1, 75:1, and 100:1) using a wavelet algorithm, and displayed to the observers on a computer monitor. Their observations regarding condylar faceting, sclerosis, osteophyte formation, erosion, and abnormal shape were analyzed using ROC. Kappa values were determined for relative condylar size and condylar position within the glenoid fossa. Indices were compared using ANOVA at a significance level of P < .05. Although significant and substantial observer variability was demonstrated, there were no statistically significant differences between image modalities, except for condylar position, in which TIFF and wavelet (at all compression ratios) performed better than the original image. For faceting, wavelet 100:1 performed better than radiographic film images. Little actual image file reduction was achieved at compression ratios above 25:1.

Analysis of Variance↗
PubMed1991

Digitally subtracted linear tomograms: three techniques for measuring condylar displacement.

Using digital subtraction enhancement, we compared the accuracy of three tomographic technique variations for quantifying small changes of condylar position. A phantom made of skeletal material and an adjustable mechanical stage provided 0.1 mm positioning accuracy of the condylar segment. Linear tomographic images were made with the condyle in a centered position and at each of three 1 mm increments of displacement in two of three directions (inferior, and posterior or lateral). Variations for frontal views included arbitrary (+20 degrees) and individualized (+10 degrees) horizontal correction of the condylar axis. Variations for lateral views included the arbitrary and individualized correction and a fully corrected vertical (+5 degrees) and horizontal (+10 degrees) adjustment. Blinded observers made repeated measurements on randomized subtraction images with a digitizing tablet. Film images were subtracted twice, and each subtraction was read twice by two examiners. The study was repeated with a second series of films treated in an identical manner. Mean values for measurements, standard deviations, and absolute values of differences between measured and expected values were calculated for each subtraction. Analysis of variance identified statistically significant sources of variation in repositioning the phantom and producing exact displacements of the condyle. Average absolute value of differences from expected values were similar for the three techniques and for frontal and lateral orientations and increments of displacement. Typical absolute value of difference for any technique was 0.2 mm for posterior, 0.2 mm for lateral, and 0.1 mm for inferior displacements. Significantly greater accuracy of inferior displacement measures was attributed to greater accuracy of registration of the fossa in its cranio-caudal dimension.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1988

Lateral transcranial radiography of temporomandibular joints. Part I: Validity in skulls and patients.

Left and right TMJs of 10 skulls and 15 patients (50 TMJs) were studied by means of OLTP and tomography to establish optimal condylar position in the glenoid fossae at maximum dental intercuspation. Two OLTP examinations of each joint were made and individualized by submental X ray and by fluoroscopy. A comparison of the recorded data showed fluoroscopy to give the better result. According to this study, OLTP individualized by fluoroscopy may be a useful tool in the determination of condylar position.

Adolescent↗
PubMed1993

The significance of occlusion in restorative dentistry.

All occlusal therapy relates ultimately to the hinge position of the mandible. By consensus, the optimum hinge position is centric relation, the most anterosuperior position of the condyles in the glenoid fossae, articulating against the eminences, with the disks properly interposed. Also by consensus, the optimum occlusal scheme is mutual protection, in which the posterior teeth contact simultaneously and equally in centric occlusion, the canines disclude the posterior teeth in lateral excursions, and the anterior teeth disclude the posterior teeth in protrusion. Whenever CR cannot be used as the starting point of occlusal treatment, or when sufficient canine support is lacking, the clinician may have to prescribe a treatment condylar position other than CR or modify the occlusal scheme. Mutual protection occlusion is the simplest to develop and CR is the simplest starting point. Departures from these ideals create added complexities for the dentist. The greater the number of excursive contacts in the occlusal scheme, the more involved the equilibration of those contacts. A treatment condylar position other than CR may not be repeatable when needed, and two studies suggest that it may change over time. Without a stable, repeatable foundation supporting it, the occlusion may be in jeopardy. The removal of occlusal interferences, although not warranted as a routine prophylactic measure, is indicated under certain conditions. When beginning a significant amount of occlusal treatment, the clinicians may remove closing interference to achieve CR at the desired vertical dimension. They may remove excursive interferences that they do not want to perpetuate in the new scheme. Selective removal may alleviate the signs of trauma from occlusion. There may be periodontal justification for axializing and equilibrating occlusal forces. Nonaxial forces on teeth with cervical erosion should be reduced as a means of limiting further erosion and protecting cervical restorations. When occlusal disharmony has been shown to reactivate a TMD, an equilibration or a more extensive rehabilitation may be necessary in the second phase of TMD treatment. In the symptomatic phase of a TMD, however, only reversible measures are appropriate. In this time of fast-moving change in restorative techniques and products, all operative dentists should raise their consciousness of occlusal principles. Occlusal forces set limits on the selection of materials and often prescribe the design features needed for a successful outcome. With structurally or periodontally compromised teeth, the occlusal planning to minimize nonaxial forces lies at the heart of the restoration. Virtually all restorative dentistry is affected by the occlusal forces of the teeth in function.(ABSTRACT TRUNCATED AT 400 WORDS)

Centric Relation↗
PubMed1987

A cephalometric, tomographic, and dental cast evaluation of Fränkel therapy.

The purpose of this study was to evaluate the skeletal, dental, and condylar positional changes induced by Fränkel FR-2 therapy. The pre- and posttreatment cephalometric, tomographic, and dental cast records of 25 consecutively treated cases were evaluated. Results showed little Class II skeletal correction with no headgear-type restraining effect on the maxilla or mandibular growth stimulation noted. Significant amounts of maxillary incisor retraction and mandibular incisor proclination were observed. The maxillary intermolar width along with the mandibular intercanine and intermolar widths were significantly increased during treatment. No significant changes in condylar position were found during Fränkel therapy and only a small increase in mandibular plane angle was noted.

Activator Appliances↗
PubMed2002

Orthodontic finishing after TMJ disk manipulation and recapture.

Orthodontic treatment has as its goal in most patients to achieve a cosmetic and functional result. There are functional goals for all orthodontic treatment and in some few cases the functional outweigh the cosmetic; an example would be a cleft-palate case. Orthodontic finishing to a specific condylar position is not routinely a goal of orthodontic care. The reason for this is that only patients who have pain, dysfunction and a negative change in quality of life from their temporomandibular apparatus need this tangential type of treatment. Research has shown that most patients suffering from a temporomandibular disorder (TMD) have displacement of the temporomandibular disk(s). Research has shown that when the mandibular condyle is repositioned to the Gelb 4/7 position that the temporomandibular joint disk is recaptured to a normal position between 85% and 96% of the time. The Gelb 4/7 position has been equated to the physiologic position of the mandibular condyle in the glenoid fossa. TMJ condyle repositioning to the physiologic position has been correlated to disk recapture proven by magnetic resonance imaging (MRI). A case is shown in which a displacement without reduction is manipulated into reduction and maintained with orthodontic correction. TMJ disk displacement without reduction is usually preceded by TMJ disk displacement with reduction. Pumping of the upper joint compartment can assist in reducing the TMJ disk displacement without reduction. Magnetic resonance imaging before and after the manipulation and after orthodontic treatment are shown. A detailed method of orthodontic finishing that maintains a specific condylar position and TMJ disk recapture is shown.

Adolescent↗
PubMed1997

Changes in condylar postition and occlusion associated with maxillary expansion for correction of functional unilateral posterior crossbite.

The purpose of this study was to confirm that correction of functional posterior crossbite through maxillary expansion is associated with a change in condylar position and occlusal relationships, and to determine whether maxillary expansion is associated with autonomous increase in mandibular arch width. Pretreatment and posttreatment study models of 61 patients ages 4.1 to 12.0 years (mean 8.5 years, SD 1.5) were available after maxillary expansion with a Quad Helix or a Haas expander for correction of a functional posterior crossbite. Pretreatment and posttreatment tomograms were available for 22 of the patients. Tomographic evaluation revealed that the condyles moved posteriorly and superiorly on the noncrossbite side from before to after treatment (p < 0.05). No differences were observed on the crossbite side. Superior joint space was greatest on the noncrossbite side before treatment, whereas, conversely, it was greatest on the crossbite side after treatment (p < 0.05). Relative condylar position was more anterior on the noncrossbite side before treatment (p < 0.05), but similar on both sides after treatment. Molar and canine relationships were more Class II on the crossbite side before treatment (p < 0.01 and < 0.05, respectively) and similar on both sides after treatment. A significant reduction in midline deviation was seen from before to after treatment (p < 0.001). A small, but significant autonomous increase in mandibular intermolar width (p < 0.001) occurred concomitant with the maxillary expansion.

Child↗
PubMed1995

Clinical and radiological findings related to treatment outcome in patients with temporomandibular disorders.

OBJECTIVES: To test the hypothesis that the outcome of temporomandibular disorders (TMD) is not influenced by condylar position, asymmetry, angle or structural bone changes. METHODS: Eighty consecutive patients (60 women, 20 men) with an age range of 6-81 years, referred to the Department of Stomatognathic Physiology, were included in the study. The patients were clinically and radiologically examined before and at least 1 year after treatment. RESULTS: The most common clinical diagnoses among the patients were TMD with a neuromuscular background in 35% and osteoarthritis in 21%. Seventy-two per cent of the patients were symptom-free or better, 24% unchanged and 1% worse 1 year or more after treatment. After treatment the bone structure of the TMJ was unchanged in 83% of the patients, in 12% erosions healed and in 5% erosions developed. Almost all patients had some degree of condylar displacement on tomography before treatment. In the majority the condylar position was unchanged after treatment. CONCLUSION: No single radiographic finding was found to be related to the treatment outcome and therefore plain radiography has a minor role in the management of TMD.

Adolescent↗
PubMed1999

Age and gender differences in temporomandibular joint radiographic findings before orthodontic treatment in adolescents.

OBJECTIVE: The purpose of this study was to determine whether there is a relationship between abnormal temporomandibular joint radiographic findings and age or gender in a sample of young preorthodontic patients. STUDY DESIGN: A total of 491 consecutive patients, aged 9 to 15 years, were referred for orthodontic records. Routine preorthodontic radiographs, including corrected sagittal tomographs, were taken for each patient and viewed by an observer blinded to clinical records. Temporomandibular joint radiographic findings were classified as normal or abnormal. For comparative purposes, the study population was divided into 2 age groups (9-11 years and 12-15 years). RESULTS: Frequency of abnormal findings ranged from 2.4% to 11.5% and was similar for both sides. Temporal component abnormalities correlated with abnormalities of condylar position, joint space, and condylar osseous morphology. The frequency of osseous abnormalities was higher in girls and highest in older girls. CONCLUSIONS: There are significant differences between genders for some temporomandibular joint radiographic abnormalities, and in our study sample the frequency of abnormalities was highest in 12-to-15-year-old girls.

Adolescent↗
PubMed1991

Histologic examination of the temporomandibular joint after mandibular advancement with and without rigid fixation: an experimental investigation in adult Macaca mulatta.

This study evaluated the histologic response of the temporomandibular joint (TMJ) following mandibular advancement using rigid and nonrigid fixation in monkeys. Twelve adult female rhesus monkeys underwent sagittal ramus osteotomies with advancement. Six of them were placed into maxillomandibular fixation (MMF); six underwent bicortical bone-screw fixation without MMF. Changes in condylar position were quantified using lateral cephalograms with the aid of bone markers. The animals were killed at 6 weeks and the TMJs were prepared for histologic analysis. Three measures of condylar cartilage thickness were obtained for each animal and were correlated to changes in position of the condyle. Animals who underwent MMF showed a tendency for anterior movement of the condyles; animals who underwent rigid fixation showed a tendency for posterior condylar position. Thicker cartilage layers were found in the MMF animals. Animals who had posterior displacement of the condyles showed evidence of resorption of the posterior surface of the condyle and anterior surface of the postglenoid spine. There was a significant correlation between a change in the horizontal position of the condyle and the thickness of the posterior aspect of the condylar cartilage. The results of this study indicate that alterations in condylar position may induce remodeling changes within the TMJ.

Animals↗
PubMed1986

Condylar retruded contact position and intercuspal position in dentulous patients. Part II: Patients classified by anamnestic questionnaire.

General agreement was found among the 75 patients' responses to the anamnestic questionnaire compared with responses in similar epidemiologic studies. An SPO has been proposed as a method of describing condylar position in addition to the MLD and the index of intercuspal asymmetry (described in Part I). The index of asymmetry was statistically significant at the 0.01 level between the group of 38 patients without primary symptoms and the group of 37 patients with one or more primary symptoms and mandibular dysfunction. The SPO hypothesis that the symptom of noise from the TMJ was present outside the SPO and absent inside the SPO was statistically significant in the categories of primary symptoms, oral habits, and psychologic self-evaluation (p less than 0.01) but was not statistically significant in regard to questions of mandibular function and chronic pain. A composite order of symptoms, determined by the sum of their rankings in each of three condylar indexes, places noise from the TMJ, facial pain, ear pain, chewing pain, and TMJ pain symptoms at the top of the list. The right and left side least squares linear analysis of 38 dental patients without primary symptoms yielded a difference of 10 degrees whereas a greater spread of 69.2 degrees was found in the group of 37 dental patients with primary symptoms and patients with mandibular dysfunction. Patients seen because of mandibular dysfunction present condylar recordings outside the SPO with a high level of agreement and a mean index of intercuspal asymmetry of 1.29 mm (SD 0.570). The three-dimensional analysis of condylar position in RCP and intercuspal position offers an explanation of why the correlation of mandibular dysfunction and occlusion has been difficult to recognize.

Bruxism↗
PubMed1993

The use of ultrasound to determine the position of the mandibular condyle.

A randomized, single blind study of 20 patients examined the accuracy of ultrasound in establishing the position of the mandibular condyle in relation to the glenoid fossa. The sonographic technique is described. The temporomandibular joint was imaged sonographically with the patients in an open- and a closed-mouth position as a model for condylar sag and proper condylar seating, respectively, during mandibular ramus osteotomy procedures. One radiologist identified condylar position correctly in 38 of 40 still ultrasound images, with a sensitivity and a specificity of 95%. During real time ultrasound examination, it is possible to visualize varying degrees of condylar movement in relation to the glenoid fossa. The results of this study support the potential use of ultrasound as an adjunct to mandibular orthognathic surgery.

Adult↗
PubMed2003

Orthosis thickness and its effect on temporomandibular joint space.

The object of this study was to determine the effect of varying thicknesses of orthoses on temporomandibular (TM) joint space. The TM joint space was measured using the centric cut view of tomographic images. The measurements used selected fixed landmarks of the joint complex anatomy to find joint space. The fixed points used for the measurement of the joint space are no different than the fixed points methodology used in orthodontic cephalometric measurements. The placement of the fixed points on a radiograph is subjective. Degrees of accuracy can be accomplished with consistent use just as in the practice of cephalometric measurements. Results of such measurements do provide a relatively true record of the actual condyle and fossa relationship. The study concluded that the thickness of the orthosis moved the condyle downward and horizontally without regard to its original positioning. If clinicians know the condylar position before and after orthosis placement, a concentric position of the condyle can be established to assist in the patient's second phase treatment. Further research will prove that the physiological and anatomical balance of the temporomandibular joint complex is important in effectively managing craniofacial pain patients.

Humans↗
PubMed2003

Magnetic resonance imaging assessment of positional relationship between the disk and condyle in asymptomatic young adult mandibular prognathism.

The aim of this study was to clarify disk position relative to the condyle and condylar position relative to the glenoid fossa in clinically asymptomatic and orthodontically untreated young adult Class III patients by magnetic resonance imaging (MRI). In addition, the relationship between skeletal Class III morphology and positional changes of the temporomandibular joint (TMJ) components were investigated. The material consisted of 34 bilateral sagittal oblique TMJ MR images (MRIs) and lateral cephalometric radiographs taken in a closed mouth position. The mean age of the patients was 20.71 +/- 0.82 years (range 16-29 years). Only clinically symptom-free subjects were included in this study. Measurements made on the MRIs and lateral cephalographs were used to calculate means and minimum and maximum values. The right and left TMJ variables were compared with the Student's t-test. Correlation coefficients between bilateral TMJ variables and skeletal variables were calculated. In the right TMJ, the disk was positioned anteriorly and the condyle was positioned posteriorly, whereas the left TMJ was normal. A negative correlation existed between the vertical skeletal morphology and the anterior joint space of the TMJ. A positive correlation was found between the left disk position and the vertical skeletal morphology because of the differentiation of the condylar head angle in each side. As a result, clinically asymptomatic Class III patients may be candidates for TMJ derangements. For this reason, clinical and visual examinations should be performed simultaneously to eliminate diagnostic errors before orthognathic treatment.

Adolescent↗
PubMed1989

A comparative study of axial corrected tomography with magnetic resonance imagery in 35 joints.

Axially corrected tomographic examination of 35 temporomandibular joints was compared with respective MRI images. The criteria of joint space measurements, condylar positioning, and degenerative osseous changes were correlated with the MRI image of disk positioning. Joints with disk displacements that reduced with condylar translation and joints with disk dislocation without reduction of the articular disk were compared with normal examinations. The mean measured joint space on tomographic examination decreased with MRI evidence of disk displacement and dislocation. Fourteen of twenty-five joints with MRI documentation of disk displacement or dislocation did show a tendency for some condylar displacement from a centric position. Only the joints with MRI evidence of total disk dislocation showed bony evidence of degenerative changes with tomography. The clinical cross-sectional study suggests that there can be changes seen in axially corrected tomographic examinations that may suggest the presence of disk displacement or significant internal derangement.

Cartilage, Articular↗
PubMed2005

Transverse skeletal and dental asymmetry in adults with unilateral lingual posterior crossbite.

BACKGROUND: Posterior unilateral lingual crossbite (PUXB) is a common malocclusion in children. However, the extent to which PUXB affects the dentition and craniofacial structures in adults has not been fully defined. We investigated dental and skeletal asymmetry in adults with PUXB. METHODS: We randomly selected 15 crossbite subjects (mean age, 26.2 years) and 15 matched controls (mean age, 30.6 years) from 3000 records. Mounted pretreatment dental casts were measured to assess dentoalveolar asymmetry, and posteroanterior radiographs were used to evaluate left-right skeletal asymmetry and positional deviations of the mandible. RESULTS: A statistically significant difference in mandibular transverse dental asymmetry was observed between adults with PUXB and the control group. However, no significant differences were found in the right-left skeletal asymmetry, although the PUXB group showed more positional deviation of the mandible. Moreover, condylar position analysis indicated that the crossbite group did not show any greater functional shifts than the control group. CONCLUSIONS: We concluded that PUXB in adults is primarily due to dentoalveolar asymmetry and positional deviation of the mandible and not simply to right-left skeletal asymmetry of the mandible. These data suggest that untreated PUXB in children might lead to progressive asymmetric compensation of the condyle-fossa relationship and result in a positional deviation of the mandible, which, along with a distinct dentoalveolar asymmetry, maintains the crossbite occlusion in adults.

Adaptation, Physiological↗
PubMed1999

Does 2 years' nocturnal treatment with a mandibular advancement splint in adult patients with snoring and OSAS cause a change in the posture of the mandible?

The aim of this pilot study was to investigate the effects of 2 years' nocturnal treatment with a mandibular advancement splint in adult patients with snoring and obstructive sleep apnea syndrome with respect to possible development of a forward position of the mandible or other dentofacial changes. Thirty snoring and sleep apnea patients, mean age 55.3 years (SD, 8.61; range, 46.5 to 79.8 years), referred from the Ear, Nose, and Throat Department, were treated with an acrylic splint with full tooth coverage that advanced the mandible 5 to 8 mm (70% of maximal protrusion) and used 5 mm opening vertically. The splint was used 6 to 8 hours per night and 5 to 7 nights per week. Two lateral head radiographs were taken in centric occlusion, 1 before and 1 after 2 years of treatment. A small but statistically significant forward and downward change in mandibular position was found after treatment; mean was 0.4 mm (SD, 0.53; range, 0.0 to 2.0 mm; P <.001) and 0.3 mm (SD, 0.43; range, 0. 0 to 1.5 mm; P <.001), respectively. The forward and downward movement of the mandible was accomplished by a statistically significant increase in mandibular length-mean was 0.4 mm (SD, 0.62; range, 0.0 to 2.5 mm; P <.01)-and a significant decrease in overjet (P <.001) and overbite (P <.05). However, none of the patients reported any permanent sense of altered occlusion, and the anteroposterior distance between habitual occlusion (intercuspal position) and centric relation (retruded position) did not exceed 1. 0 mm in any of the patients either before or after the treatment. The change in mandibular position might be a result of a condylar and/or glenoid fossa remodeling or condylar position changes within the fossa as a compensatory reaction to the advancement of the mandible (bite jumping). However, to visualize and analyze such possible changes in detail, additional studies using lateral tomography of the temporomandibular joints or magnetic resonance imaging are required. Furthermore, because the treatment of snoring and OSAS patients is considered to be lifelong, long-term studies are needed to analyze if the small change in mandibular position will continue with further treatment.

Adaptation, Physiological↗