Changes in temporomandibular joint morphology in class II patients treated with fixed mandibular repositioning and evaluated through 3D imaging: a systematic review.

To estimate the effects of skeletal class II malocclusion treatment using fixed mandibular repositioning appliances on the position and morphology of the temporomandibular joint (TMJ). Two independent reviewers performed comprehensive electronic searches of MEDLINE, EMBASE, EBM reviews and Scopus (until May 5, 2015). The references of the identified articles were also manually searched. All studies investigating morphological changes of the TMJ articular disc, condyle and glenoid fossa with 3D imaging following non-surgical fixed mandibular repositioning appliances in growing individuals with class II malocclusions were included in the analysis. Of the 269 articles initially reviewed, only 12 articles used magnetic resonance imaging and two articles used computed tomography (CT) or cone-beam CT images. Treatment effect on condyle and glenoid fossa was discussed in eight articles. Treatment effect on TMJ articular disc position and morphology was discussed in seven articles. All articles showed a high risk of bias due to deficient methodology: inadequate consideration of confounding variables, blinding of image assessment, selection or absence of control group and outcome measurement. Reported changes in osseous remodelling, condylar and disc position were contradictory. The selected articles failed to establish conclusive evidence of the exact nature of TMJ tissue response to fixed mandibular repositioning appliances.

Adolescent TMJ tomography and magnetic resonance imaging: a comparative analysis.

The predictive value of radiographic tomography was assessed using magnetic resonance imaging as a definitive test of TMJ soft-tissue status in a predominantly asymptomatic adolescent sample. Eighty-two TMJs in 41 subjects (mean age = 12.5 years, range = 10 to 17 years) were independently evaluated using axially corrected tomography and magnetic resonance imaging. Tests of comparison and correlation were performed. Correspondence of tomographic classification to magnetic resonance imaging classification of nondisplacement (55%), reducing internal derangement (35%), or nonreducing internal derangement (10%) showed a significant relationship (P < .05). Tomography as a diagnostic test of abnormal disc position had a sensitivity of 0.43, a specificity of 0.80, a positive predictive value of 0.64, and a negative predictive value of 0.63. Tomography is inappropriate as a diagnostic test for TMJ internal derangement.

Landmark identification error in submentovertex cephalometrics. A computerized method for determining the condylar long axis.

The purpose of this study was to examine the identification error of certain submentovertex landmarks and to compare three different methods of determining horizontal condylar angulation in submentovertex radiographs. To determine landmark identification error, a random sampling of 12 submentovertex radiographs from preorthodontic patients between the ages of 10 and 17 years was used to determine both intraexaminer and interexaminer reliability. The error associated with the identification of each of 11 landmarks varied between specific landmarks, between the same landmarks bilaterally, and between the vertical and horizontal components of the same landmark. In general, intraexaminer data showed less landmark identification error in both vertical and horizontal directions than did interexaminer data. The foramen spinosum landmarks demonstrated the lowest identification error in both horizontal and vertical direction (intraexaminer), whereas greater identification error was associated with the condylar lateral poles and posterior condylar points (both intraexaminer and interexaminer). A comparison of three different methods of condylar angulation determination was undertaken through the use of two tracings of each of 101 submentovertex radiographs. A computer-derived method representing the principal axis of minimum moment of inertia of the condyle was shown to be more reliable (p < 0.05) with respect to describing condylar angulation than both a method that used a best-fit line through the anterior condylar border and an interpolar axis method.

Quantitative assessment of temporomandibular joint disk status.

The purpose of this study was to quantify temporomandibular joint disk-slice information produced by magnetic resonance imaging by means of a stepwise discriminant analysis. One hundred ninety-four adolescents consented to magnetic resonance imaging evaluation of their temporomandibular joints. Sagittal magnetic resonance imaging slices of each joint were assigned to one of six subjective categories of disk position by an experienced maxillofacial radiologist. Standardized reference planes transferred to each magnetic resonance image from corresponding lateral cephalometric radiographics facilitated the measurement of disk length and disk displacement and the computation of ratio values of these measurements. Discriminant analysis revealed that all three quantitative variables were descriptive and discriminant for grouping slice data into pre-established subjective categories. Cross-validation and misclassification error calculations showed a 69.3% agreement between subjective and discriminant classification. Therefore quantification of disk displacement can be used in place of subjective evaluation. In addition, discriminant analysis disclosed a reduction in disk length associated with increased severity of disk displacement.

Magnetic resonance imaging of the temporomandibular joint: interobserver agreement in subjective classification of disk status.

OBJECTIVES: To determine interobserver agreement in interpretation of magnetic resonance images of the temporomandibular joint by independent observers and to evaluate interobserver agreement within each subjectively assigned category. STUDY DESIGN: Sixty magnetic resonance images of adolescent temporomandibular joints were randomly drawn for evaluation by 4 observers who had not previously worked together. All observers independently classified disk position on sagittal magnetic resonance images according to written classification criteria consisting of 6 categories. RESULTS: Kappa statistics of agreement show moderate agreement among all observers for both medial (95% CI, 0.486-0.622) and lateral (95% CI, 0.450-0.566) components of the joint. Disk displacement without reduction was the category with the greatest agreement among all observers (kappa = 0.914). CONCLUSION: Moderate to substantial observer agreement across all defined categories of disk status may be achieved among a number of observers when standardized classification criteria are used. Interobserver agreement is, however, not uniform across all categories of disk position described.

Interobserver reliability in quantitative MRI assessment of temporomandibular joint disk status.

OBJECTIVE: The purpose of this study was to investigate interobserver reliability of a new technique for quantification of magnetic resonance images of temporomandibular joint disk status. STUDY DESIGN: Sixty magnetic resonance images of adolescent temporomandibular joints were randomly drawn for analysis. Four experienced observers traced the articular disk and osseous structures on sagittal magnetic resonance slice images. Quantitative measurements of disk length and disk displacement were recorded for each slice of 57 joints traced by each observer through use of a new quantification technique. Intraclass correlation coefficients were computed to assess interobserver agreement in the tracing of joint structures. RESULTS: The calculated intraclass correlation coefficient was 0.681 for disk length and 0.830 for disk displacement. In addition, the mean variability among observers was 1.041 mm for measurement of disk length and 0.972 mm for measurement of disk displacement. CONCLUSIONS: Interobserver agreement is high when the new quantification technique is used to interpret magnetic resonance images.

Prevalence of TMJ disc displacement in a pre-orthodontic adolescent sample.

This study evaluated the prevalence of temporomandibular joint (TMJ) disc displacement in preorthodontic adolescents (75 boys, 119 girls) by means of magnetic resonance imaging (MRI). One hundred thirty-eight consecutive subjects were recruited regardless of TMJ signs or symptoms, whereas 56 other subjects were referred with associated signs or symptoms. Quantitative measurements of disc displacement and disc length were used to classify the degree of internal derangement into 6 categories on the basis of sagittal MRI slices of the joints. In addition, sideways disc displacement was determined from coronal MRI images of the joint. Unilateral and bilateral normal disc position was more prevalent in boys compared to girls. All forms of anterior and rotational disc displacement were more prevalent in the female sample than in the male. Sideways displacement was more prevalent in girls than boys and occurred more frequently in a lateral rather than a medial direction. This study supports previous studies in suggesting that disc displacements occur frequently in preorthodontic adolescents.

Craniofacial asymmetry and temporomandibular joint internal derangement in female adolescents: a posteroanterior cephalometric study.

Unilateral or bilateral pathology of the osseous components of the temporomandibular joint (TMJ) can result in pronounced facial asymmetry because of dissimilar size and shape of the right and left sides of the mandible. To date, it is unknown whether abnormalities of the soft tissues of the TMJ are associated with greater than normal craniofacial asymmetry. In this study, we investigated the amount of craniofacial asymmetry in female orthodontic patients with unilateral or bilateral TMJ internal derangement (TMJ ID) relative to the amount in female patients without TMJ ID. The total sample consisted of 80 female adolescents. Bilateral TMJ magnetic resonance images were used as a database for objectively scoring the severity of TMJ ID. Craniofacial asymmetry was measured from posteroanterior cephalograms. Females with bilateral TMJ ID had significantly greater asymmetry in the vertical position of the antegonion. If the TMJ ID was more advanced on the right side, the ipsilateral ramus was shorter, resulting in significant asymmetry in this region. In all other craniofacial regions, the amount of asymmetry was not significant between females with normal TMJs and those with TMJ ID. The results indicate that a female orthodontic patient with bilateral TMJ ID or unilateral right TMJ ID may present with or develop a vertical mandibular discrepancy.

Osseous morphology and spatial relationships of the temporomandibular joint: comparisons of normal and anterior disc positions.

The objective of this study was to determine differences in spatial relationships and osseous morphology between temporomandibular joints with normal and anterior disc positions. Magnetic resonance imaging was employed to determine disc position in 335 temporomandibular joints in 175 subjects (106 female and 69 male) between the ages of 7.27 years and 20.0 years (mean age: 13.08 years). Twelve tomographic variables were measured from preorthodontic tomograms of the same individuals. Tomographic data were cross-referenced with MRI data for those with normal and full anterior disc displacement. Independent sample t-tests revealed significant differences for all measures of joint space, condylar position, and morphology of the articular eminence (P < .05) between joints with normal disc position and with full anterior disc displacement. This study indicated that measures of joint space and eminence morphology might provide diagnostic information for the assessment of joint status in the adolescent population.

TMJ internal derangement and adolescent craniofacial morphology: a pilot study.

Intrinsic and extrinsic factors influence the growth of mandibular condylar cartilage. Local environmental factors, such as temporomandibular disc displacement, may alter condylar cartilage growth resulting in facial changes. The aim of this study was to determine if there was an association between identifiable altered craniofacial morphology and disc displacement. Magnetic resonance imaging (MRI) was employed to determine disc position in 25 preorthodontic adolescent patients (mean age 12.8 years, range 10 to 17 years). Magnetic resonance imaging and lateral cephalometric radiography were performed with the teeth held in centric occlusion by means of a polyvinylsiloxane bite registration. Radiographs were traced and variability between tracings within patients was insignificant for all variables (p > 0.04) except Co-Go, S-Go, and SN/Go-Me (p < 0.01). For each patient, 10 linear, 4 angular, and 3 ratio measurements were compared with an age- and sex-matched population in the Craniofacial Growth Series. Multiple regression analysis showed positive and negative associations between disc displacement and cephalometric variables. R-square value was .91 for the left TMJ and .82 for the right. Disc displacement in an adolescent population may be associated with altered craniofacial morphology.

Use and effectiveness of splint appliance therapy: review of literature.

Interocclusal orthopedic appliances of varied design and application have been employed in the treatment of myofascial pain dysfunction (MPD) and temporomandibular joint disorders (TMD). These appliances provide the practitioner with a non-invasive, reversible form of intervention to manage the patient's symptoms. Literature on the use and effectiveness of these appliances has become readily available and now requires retrospective evaluation. However, comparison of results from studies making use of interocclusal orthopedic appliance therapy is difficult due to the employment of various outcome measurement scales, subjective evaluation of patient outcome, and variability in reporting of treatment outcomes. The aim of this paper is to review the effects and success rates of the various appliances reported in the literature and provide the practitioner with useful information that may be of assistance in the prediction of outcome and success of splint appliance therapy.

Horizontal condylar angulation and condyle position associated with adolescent TMJ disk status.

The purpose of this research was to examine the relationship between horizontal condylar angulation and position and joint status in an adolescent population. Submentovertex (SMV) radiographs and MRI (magnetic resonance images) of 95 subjects (56 females and 39 males) between the ages of 10-17 years (mean age 13.3 years) were used for this study. Horizontal condylar angulation as well as A-P and transverse condyle position were determined in relation to a cranial base reference (a line formed between the two foramina spinosa) from SMV images. Joint status variables consisted of disk length and disk displacement measurements taken from medial, central and lateral sagittal MRI slices of each joint. Additional joint status variables were derived through a principal component analysis which was used to calculate a single disk length, disk displacement, and internal derangement variable for each joint. The results were: 1. No significant correlations (p = .05) were found between any of the joint status variables and horizontal condylar angulation; 2. Statistically significant correlations (r = .14 to .22, p = .05) were observed between certain joint status variables (anterior disk displacement in medial and central joint slices, disk displacement variable, and TMJ internal derangement variable) and transverse condyle position; and, 3. Statistically significant correlations (r = -.22 to .25; p = .05) were observed between condylar angulation and both A-P and transverse condyle position.

Longitudinal study on TMJ disk status and its effect on mandibular growth.

OBJECTIVE: This longitudinal study assessed the potential contribution of temporomandibular joint (TMJ) disk status over mandibular linear and angular changes. DESIGN: Cohort study. SETTING: Edmonton, Alberta, Canada. PARTICIPANTS: Seventy-three adolescent subjects attending TMJ or orthodontic clinics with or without TMJ disk abnormality were followed during a mean 3 years 7 months. From this sample 39 subjects underwent orthodontic treatment. METHODS: Disk displacement and disk length measurements taken from MRIs were utilized to evaluate the TMJ disk status. Mandibular changes were quantified from cephalometric radiographs by superimposing the mandible around the internal cortex of the posterior wall of the mandibular symphysis. Fishman's skeletal maturation system was used to calculate the percentage of mandibular growth remaining during the follow-up. This expected mandibular growth was factored out through a statistical normalization process applied to the actual difference between the initial and final mandibular measurements. In addition, previous orthodontic treatment was also considered for the analysis. A multiple analysis of variance (MANOVA) was used to evaluate interaction between the independent variables (TMJ disk status and previous orthodontic treatment) over the dependent variables (mandibular ramus, mandibular body, mandibular length and gonial angle measurements). RESULTS: No significant contribution was found of any of the evaluated variables or its interactions over the mandibular measurements. CONCLUSIONS: No evidence was found of TMJ disk abnormality as an associated significant factor with mandibular dimensional changes. The findings have to be evaluated with caution because of some limitations identified in this study.

Orthodontic brackets bonded to glazed and deglazed porcelain surfaces.

Edgewise orthodontic brackets were bonded with a light activated composite resin to 100 glazed and 100 deglazed feldspathic porcelain blocks for an in vitro comparative determination of shear/peel bond strengths. The independent variables studied were porcelain surface preparation and the time interval between activation of the composite resin and the debonding procedure. The initial shear/peel bond strength achieved on bonding to deglazed porcelain was statistically significantly greater than that on bonding to glazed porcelain (p<0.05), but after the 10-minute interval, the bond strength in the glazed porcelain sample was greater than in the deglazed sample. Many more porcelain fractures occurred on deglazed porcelain (71%) than on glazed porcelain (36%) during bond strength determination. Scanning electron microscopy evaluation suggests that deglazing does not substantially increase micromechanical adhesion of the composite resin. Bond strength adequate to withstand the application of orthodontic forces were achieved when bonding to glazed porcelain. This study indicates that deglazing may not be necessary for attachment of orthodontic brackets to porcelain surfaces.

Cephalometric landmarks identification and reproducibility: a meta analysis.

To assess the magnitude of cephalometric landmarks identification error, we performed a Meta analysis on six pertinent studies. We outline the procedures used to compare and integrate the findings of these-studies. The results are a measure of systematic and random errors involved when locating landmarks on lateral head films. They are presented as standard mean errors and 95% confidence intervals for the repeatability and reproducibility of 15 cephalometric landmarks commonly used in growth analysis.

Male adolescent facial pattern associated with TMJ disk displacement and reduction in disk length: Part II.

Dental practitioners continually strive to understand and determine which factors influence craniofacial morphology and how these factors may be controlled to provide the best treatment outcome for patients. Recently, an association between internal derangement of the TMJ and altered facial morphology was shown in an adolescent female sample by means of multiple regression techniques. The present study aims to determine whether similar associations are present between facial patterns exhibited by a preorthodontic male sample (n = 70) and varying degrees of TMJ internal derangement as assessed by magnetic resonance imaging. Multiple regression techniques were used to test the associations in 5 facial regions. Associations between internal derangement and craniofacial morphology differed in 3 of the facial regions when males and females were compared. However, associations between internal derangement and alteration in mandibular morphology and positioning were consistent in both gender groups.

Female adolescent facial pattern associated with TMJ disk displacement and reduction in disk length: part I.

The aim of this study was to determine whether associations exist between temporomandibular joint (TMJ) disk displacement, and craniofacial morphology in an adolescent sample. Craniofacial lateral cephalometric radiographs and magnetic resonance images of the TMJs were obtained of 119 females between the ages of 10 and 17 years. Once the effects of age had been considered, associations between TMJ internal derangement and craniofacial morphology were studied in 5 facial regions making use of 5 separate multiple regression analyses. In females, associations between altered facial morphology and altered disk position were present within each of the facial regions investigated; the mandibular regions showed the strongest associations. This study shows that functional alteration in TMJ disk dynamics may be another factor to consider when craniofacial growth is forecasted for orthodontic treatment planning.

Adolescent female craniofacial morphology associated with advanced bilateral TMJ disc displacement.

The aim of this study was to determine if cephalometric measurement differences occurred between two groups of similarly aged female adolescents which differed with respect to their diagnoses of temporomandibular joint disc position on magnetic resonance images (MRI). One group consisted of 17 female adolescents exhibiting complete bilateral disc displacement affecting the temporomandibular joints (TMJ), while the second group of 17 female adolescents was diagnosed as having bilateral normal disc position on MRI. Independent sample t-tests identified statistically significant differences in cephalometric measurements between the two groups, but no age difference between the two groups was evident. The group with bilateral total disc displacement exhibited the following significant angular differences from the group with normal disc position: an increased mandibular and palatal plane relative to sella-nasion; posterior rotation of the mandible as illustrated by an increased angle between the posterior border of the mandibular ramus and sella-nasion; and a decrease in Rickett's facial axis. Significant differences in linear cephalometric variables were also evident between the two groups. Total posterior facial height and ramus height were reduced in the totally disc displaced group. Furthermore, a slight increase in the middle anterior facial height was noted, with a decrease in the posterior cranial base vertical height in the totally disc displaced group.

Condyle displacement associated with premolar extraction and nonextraction orthodontic treatment of Class I malocclusion.

This study assessed condyle position change with premolar extraction and nonextraction orthodontic treatment in Class I malocclusions. Axially corrected pretreatment and posttreatment tomograms were obtained in 22 extraction and 13 nonextraction cases. Tomographic images were randomized and blinded for joint space measurement. A total of 27 linear anterior, superior, and posterior joint spaces were obtained from each tomogram and averaged. Comparisons of pretreatment and posttreatment joint spaces between groups were done by t test (pool variance estimate) with p < 0.05. Left and right anterior joint spaces were significantly increased during orthodontic treatment of the nonextraction group. No other significant changes in condyle position were determined in either group. There were no significant correlations between mean joint space changes with length of Class II elastic wear. There was no significant difference in condyle position change with extraction space closure using closing arch wires compared with elastic chain.