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Three-dimensional assessment of temporomandibular joints in skeletal Class I, Class II, and Class III malocclusions: Cone beam computed tomography analysis
Journal of the World Federation of Orthodontists 5 (2016) 80e86
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Research
Three-dimensional assessment of temporomandibular joints in skeletal Class I, Class II, and Class III malocclusions: Cone beam computed tomography analysis Maged Sultan Alhammadi a, *, Mona Salah Fayed b, Amr Labib b a b
Department of Orthodontics and Dentofacial Orthopedics, Faculty of Dentistry, Ibb University, Ibb, Republic of Yemen Department of Orthodontics and Dentofacial Orthopedics, Faculty of Oral & Dental Medicine, Cairo University, Cairo, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history: Received 14 March 2016 Accepted 24 July 2016
Background: To investigate three-dimensionally using cone beam computed tomography (CBCT) morphological and spatial characteristics of the temporomandibular joints (TMJs) in different anteroposterior skeletal malocclusions. Materials and Methods: Pretreatment CBCT scans of 60 young adult patients (18e25 years) were obtained. Among those patients, 20 were characterized as Skeletal Class I, 20 as Skeletal Class II, and 20 as Skeletal Class III malocclusion. Bilateral TMJs were evaluated on the CBCT images and the following three-dimensional measurements were assessed: (1) mandibular fossa position, inclination, and parameters; (2) mandibular condyle position, inclination, and parameters; and (3) circumferential TMJ space measurements. Results: Class II patients showed the lowest condylar width (6.47 1.14 mm), the highest condylar height (11.14 1.99 mm), and the highest anterior joint space (2.73 1.14 mm). Class III patients exhibited the lowest anterior (2 0.57 mm), superior (2.92 0.63 mm), and medial joint spaces (2.18 0.72 mm), and the highest mandibular fossa width (19.12 2.48 mm), as well as the highest anteroposterior condylar dimension (7.43 1.50 mm). The three skeletal malocclusions differed significantly in the vertical condylar position (Class III had the most superior and Class II had the most inferior position). Conclusions: There are significant differences in specific TMJ parameters between different skeletal malocclusions that might play a role in development of temporomandibular disorders with or without orthodontic treatment. Ó 2016 World Federation of Orthodontists.
Keywords: Temporomandibular joint Cone beam computed tomography Analysis Skeletal Classes
1. Introduction The morphology of the temporomandibular joint (TMJ) varies among individuals, and one of the factors that could influence its shape is the functional loads imposed on it [1]. This is based on the intimate relationship between morphology and function, and justifies the assumed differences in condyle and mandibular fossa morphology and position among subjects with different types of malocclusion [2]. The influence of occlusion on joint morphology is a matter of controversy; some suggested the existence of direct relation [3], whereas others found negative correlations [4]. Part of this
All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Authors have obtained and submitted the patient signed consent for images publication. * Corresponding author: Faculty of Dentistry, Ibb University, Ibb, Republic of Yemen. E-mail address: [email protected] (M.S. Alhammadi). 2212-4438/$ e see front matter Ó 2016 World Federation of Orthodontists. http://dx.doi.org/10.1016/j.ejwf.2016.07.001
controversy is due to the difference in the evaluation techniques at the time of study, and the use of a subjective scoring systems rather than standardized methods for analyzing this complex area [5]. The sagittal relationship between the maxilla and mandible may influence other adjacent structures of the craniofacial system, such as the TMJ. In significant sagittal discrepancies, the morphology and condyle-glenoid fossa relationship could be compromised due to tension or compression forces that the surrounding tissues exert on the TMJ. This indeed could favor a continuous adaptation through remodeling processes to functional changes in the surrounding tissues [6,7]. Several studies investigated the relation between different anteroposterior components and TMJ configuration with contradictory findings [8e12]. These studies have used different methods and measurements for the TMJ parameters using tomography and computed tomography (CT) with two-dimensional rather than three-dimensional (3D) assessment. Furthermore, these studies have less clear description regarding the way of standardization of extracted data, which is due to variations in orientation of the condyles in the three planes of space.
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Table 1 Definitions of general and temporomandibular joint anatomical landmarks for 3-dimensional cone beam computed tomography analysis (Figs. 1 and 2) No.
Landmark
Definition
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Nasion (N) Sella (S) Right/Orbitale (Or) Left Porion (PO) Subspinale (A) Supramentale (B) Soft tissue mandibular fossa (MFS) Bony mandibular fossa (MF) Medial joint space “fossa point” (MJSf) Superior condylar point (SCP) Lateral condylar point (LCP) Medial condylar point (MCP) Geometric condylar center (GC) Anterior condylar point (ACP) Posterior condylar point (PCP) Condylar width “anterior point” (CWa) Condylar width “posterior point” (CWp) Articular tubercle (AT) Inferior meatus (IM) Anterior fossa point (AF) Posterior fossa point (PF)
22 23 24
Anterior neck point (ANP) Posterior neck point (PNP) Anterior fossa inclination “superior point” (AFIs)
25
Anterior fossa inclination “inferior point” (AFIi)
26
Posterior fossa inclination “superior point” (PFIs)
27
Posterior fossa inclination “inferior point” (PFIi)
28
Anterior joint space “fossa point” (AJSf)
29 30
Anterior joint space “condylar point” (AJSc) Posterior joint space “fossa point” (PJSf)
31
Posterior joint space “condylar point” (PJSc)
Nasofrontal structure in the midline. Center of the pituitary fossa in the middle cranial fossa. The right or left most inferior point on the infraorbital rim of the maxilla. The left most outer and superior bony point of the external acoustic meatus. The deepest point of the middle of the maxillary frontal surface. The deepest point of the middle mandibular frontal surface. The most superior and midpoint of the soft tissue right or left mandibular fossa region. The most superior and midpoint of the bony right or left mandibular fossa. The most right or left lateral point of the medial wall of mandibular fossa. The most right or left superior point of the condylar head. The most right or left lateral point of the condylar head. The most right or left medial point of the condylar head. The center of the right or left condyle. The most right or left anterior point of the condylar head. The most right or left posterior point of the condylar head. The most anterior point of the right or left condyle corresponding to the area of maximum width. The most posterior point of the right or left condyle corresponding to the area of maximum width. The most inferior and posterior point of right or left articular tubercle. The most inferior and lateral point of right or left external auditory meatus. The most anterior and inferior point in the right or left anterior wall of the mandibular fossa. The most posterior and inferior point in the right or left posterior wall of the mandibular fossa opposed to IM point. The deepest anterior point of right or left mandibular condylar neck. The most posterior point of right or left mandibular condylar neck. The right or left superior point of a line tangent to the most posterior mandibular fossa area opposing to anterior condylar area. The right or left inferior point of a line tangent to the most posterior mandibular fossa area opposing to anterior condylar area. The right or left superior point of a line tangent to the most anterior mandibular fossa area opposing to posterior condylar area. The right or left inferior point of a line tangent to the most anterior mandibular fossa area opposing to posterior condylar area. The most posterior point of the right or left anterior wall of the mandibular fossa opposed to the shortest anterior condylar-fossa distance. The most anterior point of the right or left condyle opposed to the shortest anterior condylar-fossa distance. The most anterior point of the right or left posterior wall of the mandibular fossa opposed to the shortest posterior condylar-fossa distance. The most posterior point of the right or left condyle opposed to the shortest posterior condylar-fossa distance.
Reproduced and modified with permission from Alhammadi et al. [16].
By analyzing the TMJ in Class I, Class II, and Class III malocclusions, Burley [13] concluded that those malocclusions do not produce functional stimuli capable of changing the articular structures of the temporal region. No condyle centralization and no significant articular asymmetry in most measurements between right and left sides were found by Vitral et al. [8] and Vitral and Telles [9] in a sample of Class II Division 1 subdivision patients, and by Rodrigues et al. [7,10] in samples of Class I, Class II Division 1, and Class III patients. The noncentralization of the mandibular condyles was a feature also in other samples of patients with malocclusion [14,15]. The aims of this study was to investigate three-dimensionally using recently innovative analysis described by Alhammadi et al. [16] the morphological and spatial characteristics of the TMJs in different anteroposterior skeletal malocclusions.
2. Materials and methods This study was approved by the Research Ethics Committee, Faculty of Oral and Dental Medicine, Cairo University, Egypt (No. 3010-2011). The sample size was calculated to determine the minimum required study sample. A power analysis of anterior and superior joint space data designed considering a mean difference of 0.5 mm in the anterior joint space and 1.1 mm in the superior joint space between groups. The alpha level was 0.05 (5%), the b level was 0.20 (20%) (i.e., power ¼ 80%). Accordingly, a sample size of 13 or 16 subjects was obtained based on anterior or superior joint
Fig. 1. General anatomical landmarks for 3D CBCT analysis. Reproduced and modified with permission from Alhammadi et al. [16].
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Fig. 2. TMJ landmarks for 3D CBCT analysis [A and C (Sagittal views), B (Coronal view) and D (Axial view)]. Reproduced and modified with permission from Alhammadi et al. [16].
space, respectively. This size was increased to 20 subjects to compensate for any dropouts. Pretreatment cone beam CT (CBCT) scans of 60 young adult (18e25 years) patients were obtained from the available records from the Outpatient Clinic in the Orthodontic Department, Faculty Table 2 Definitions of anatomical reference planes for three-dimensional cone beam computed tomography analysis No.
Reference planes
Definition
1
Horizontal Plane (HP)
2
Midsagittal Plane (MSP)
3
Vertical Plane (VP)
4
Right Mandibular Fossa Horizontal Plane (R-MFH) Left Mandibular Fossa Horizontal Plane (L-MFH)
Plane defined by 3 landmarks: right orbitale and porion and left porion. Plane through sella and nasion and perpendicular to the horizontal plane. Plane through sella and perpendicular to the horizontal plane and midsagittal plane. Line tangent to the right MF point and parallel to the horizontal plane. Line tangent to the left MF point and parallel to the horizontal plane.
5
Reproduced and modified with permission from Alhammadi et al. [16].
of Oral and Dental Medicine, Cairo University, Egypt. Twenty patients were characterized as skeletal Class I, 20 as skeletal Class II, and 20 as skeletal Class III. The inclusion criteria included the following: 1. 2. 3. 4. 5.
No No No No No
missing teeth. functional mandibular deviations or facial asymmetry. history of parafunctional habits. history or clinically diagnosed TMJ disorders. previous history of TMJ operations.
2.1. Three-dimensional analysis The CBCT scan was performed with the next-generation i-CAT CBCT unit (Imaging Sciences International, Hatfield, PA). The TMJ analysis was done by tracing the selected volume and image structures using Anatomage software version 5.01 (Anatomage, San Jose, CA). A recent analysis designed by Alhammadi et al. [16] was performed with 31 different landmarks (Table 1; Figs. 1 and 2). All landmarks were initially digitized in 3D volume and finally
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Table 3 Definitions of three-dimensional measurements of cone beam computed tomography analysis No.
Measurement
Definition
1 ANB Mandibular fossa measurements 2 Interfossae distance 3 Anteroposterior inclination 4 Vertical inclination 5 Mediolateral inclination 6 Mediolateral position 7 Anteroposterior position 8 Vertical position 9 Mandibular fossa height 10 Mandibular fossa width 11 Anterior wall inclination to TM line 12 Posterior wall inclination to TM line 13 Tubercle height Mandibular condyle measurements 14 Medial intercondylar distance 15 Lateral intercondylar distance 16 Geometric intercondylar distance 17 Mediolateral condylar inclination 18 Vertical condylar inclination 19 Anteroposterior condylar inclination 20 Vertical point condylar position 21 Vertical geometric condylar position 22 Anteroposterior condylar point position 23 Anteroposterior condylar geometric position 24 Mediolateral condylar point position 25 Mediolateral geometric condylar position 26 Anteroposterior condylar joint position 27 Vertical condylar joint position 28 Condylar length 29 Condylar width 30 Condylar height Temporomandibular joint spaces 31 Anterior Joint Space 32 Posterior Joint Space 33 Superior Joint Space 34 Medial Joint Space
The angle between three landmarks: A, N, (B) The distance between bony mandibular fossae (MF). The angle between MFH and MSP. The angle between MFH and HP. The angle between MFH and VP. The perpendicular distance between MF and MSP. The perpendicular distance between MF and VP. The perpendicular distance between MF and HP. Perpendicular distance between MF and TM line. The distance between AF and PF. The inner angle between AFL line and TM line. The inner angle between PFL line and TM line. The perpendicular distance between AT and MF-HL. Distance between CdMR and CdML. Distance between CdLR and CdLL. Distance between GCR and GCL. Angle between CdM-CdL and HP. Angle between CdA-CdP and VP. Angle between CdM-CdL and MSP. The vertical distance between the SCP and HP. The vertical distance between the condylar GC and HP. The anteroposterior distance between the ACP and VP. The anteroposterior distance between the condylar GC and VP. The mediolateral distance between the MCP and MSP. The mediolateral distance between the condylar GC and MSP. The anteroposterior position of the condyle inside the joint as determined by Pullinger and Hollender. [3] The linear difference between condylar height and mandibular fossa height. Distance between MCP and LCP. Distance between ACP and PCP. Perpendicular distance between SCP and TM line. The The The The
shortest shortest shortest shortest
distance distance distance distance
between between between between
AJSc and AJSf. PJSc and PJSf. SCP and MFS. MJSf and MCP.
Reproduced and modified with permission from Alhammadi et al. [16].
localized by slice locator. Five 3D reference planes were established (Table 2). The 3D measurements included A point, nasion, B point angle, mandibular fossa measurements, mandibular condyle measurements, and TMJ space measurements (Table 3). The CBCT measurements were measured twice within a 2-week interval with the same observer and by another observer to evaluate the reliability of the measurements.
2.2. Statistical analysis Statistical analysis was carried out by using IBM SPSS Statistics version 20 for Windows (IBM Corporation, Armonk, NY). Intra- and interobserver agreement was measured using Cronbach’s alpha reliability coefficient and intraclass correlation coefficient. The significance level was set at P 0.05. For parametric data, one-way
Table 4 Mean, standard deviation (SD) values, and results of the comparison of mandibular fossa measurements among the three skeletal Classes Mandibular fossa measurements
Class I
Interfossa distance (mm) Inclination Vertical ( ) Mediolateral ( ) Anteroposterior ( ) Position Vertical (mm) Anteroposterior (mm) Mediolateral (mm) Parameters Glenoid fossa height (mm) Glenoid fossa width (mm) Anterior tuberculum inclination/TM ( ) Posterior tuberculum inclination/TM ( ) Glenoid fossa surface area (mm2) Tubercle height (mm)
92.21
Mean
b
0.43 1.94 89.64
Class II SD 5.29
Mean
Class III SD
92.11
6.47
Mean
P SD 2.23
0.755
0.54 0.81 0.77
0.32 2.09 89.27
b
0.28 0.89 0.69
0.037* 0.084 0.053
1.13b 10.03 46.03
1.06 3.80 3.30
3.08a 11.41 46.66
1.28 3.50 1.57
<0.001* 0.275 0.607
8.47 17.39b 59.03 33.91a 103.36a 7.26a
1.12 2.30 11.69 12.17 22.30 1.72
8.53 19.12a 56.38 46.97b 100.02a 5.90b
1.07 2.48 8.30 26.40 30.59 1.19
0.708 <0.001* 0.337 0.024* 0.044* <0.001*
0.21 1.37 0.30
a
0.72 1.23 89.09
1.33b 10.17 46.09
0.77 3.34 2.83
8.31 16.55b 60.21 43.81b 87.89b 7.94a
1.01 2.06 10.42 14.98 20.39 1.60
Different letters in the same row are statistically significant different according to Tukey’s test or Mann-Whitney U test. *Significant at P 0.05.
93.34
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Table 5 Mean, standard deviation (SD) values, and results of the comparison of mandibular condyle measurements among the three skeletal Classes Mandibular condyle measurements
Class I
Class II
Mean Intercondylar distance Geometric (mm) Medial (mm) Lateral (mm) Mandibular condylar inclination Mediolateral ( ) Vertical ( ) Anteroposterior ( ) Mandibular condyle position AP point condylar position (mm) AP geometric condylar position (mm) ML point condylar position (mm) ML geometric condylar position (mm) V point condylar position (mm) V geometric condylar position (mm) Mandibular condyle parameters Condylar length (mm) Condylar width (mm) Condylar height (mm) Axial surface area (mm2) Sagittal surface area (mm2) Coronal surface area (mm2) Condylar joint position V condylar joint position (mm) AP condylar joint position (mm)
SD
96.57 77.88 114.12
4.11 3.88 5.33
Class III
Mean
SD
98.18 80.56 113.61
7.92 7.46 8.47
Mean
P SD
95.93 77.61 112.28
2.76 4.12 1.67
0.507 0.265 0.677
4.08b 75.67 75.18b
3.18 5.62 4.44
6.82a 74.89 72.83b
3.76 11.58 6.94
4.40b 71.76 82.31a
4.84 11.24 4.98
0.004* 0.272 <0.001*
5.79 10.74 38.92 48.20 3.77a 8.35a
2.41 3.39 2.27 2.23 1.54 1.61
5.11 9.80 40.25 49.07 2.84b 7.39b
4.30 4.65 3.90 3.96 1.82 1.79
5.80 10.17 38.74 47.91 1.97c 4.81c
2.96 3.16 2.16 1.51 1.02 2.08
0.316 0.121 0.092 0.245 <0.001* <0.001*
18.88a 7.30a 8.82b 113.42a 29.82b 73.32b
1.50 1.32 1.07 19.91 7.78 9.90
17.61b 6.47b 11.14a 96.59b 40.96a 70.30b
2.61 1.14 1.99 21.81 15.60 23.46
17.51b 7.43a 10.80a 105.87a 37.11a 84.21a
1.91 1.50 1.03 22.44 11.13 18.62
0.019* 0.012* <0.001* 0.012* 0.002* 0.006*
3.65a 16.72a
0.78 13.26
2.80b 23.48b
1.63 17.33
2.47b 26.03b
0.75 16.62
<0.001* 0.094
Different letters in the same row are statistically significant different according to Tukey’s test or Mann-Whitney U test. AP, anteroposterior; ML, mediolateral. *Significant at P 0.05.
ANOVA followed by Tukey’s test was used and Kruskal-Wallis test followed by Mann-Whitney U test for nonparametric data for the comparison among the three skeletal Classes.
3. Results A very good intra- and interobserver reliability was found, with the intraclass correlation coefficient ranging between 0.790 and 0.993 regarding all measurements. The mean A point, nasion, B point angle in Class I normal occlusion, Class II, and Class III were 2.47 1.39 , 7.14 1.52 , and 2.36 1.54 , respectively. In mandibular fossa measurements (Table 4), there were no significant differences among the three groups except for the Class II group, which showed the significantly highest vertical inclination. The Class III group showed significantly inferior position of the mandibular fossa (3.08 mm). Class III showed significantly highest glenoid fossa width and statistically significant highest posterior wall inclination (46.97 26.40 ). Regarding mandibular condyle measurements (Table 5), the Class II group showed the significantly highest inclination with Horizontal Plane and Class III group showed the highest inclination with Midsagittal Plane (82.31 4.98 ). Class I, Class II, and Class III
showed the statistically significant vertical position from the most inferior to the most superior, respectively. Class I group showed the highest mediolateral dimension (18.88 1.50 mm) and Class I and Class III groups showed the statistically significant highest anteroposterior dimension. Class I normal occlusion showed the statistically significant highest inferior intrajoint position (3.65 0.78 mm). Regarding TMJ spaces (Table 6), the Class II group showed the statistically significant highest anterior joint space and no statistically significant difference between other groups. Class III malocclusions showed the statistically significant lowest medial and superior joint space.
4. Discussion The TMJ is a unique joint. Moreover, the TMJ is a rather difficult area for radiological investigation because there is no possibility for accurate evaluation of this position in conventional radiographs. Thus, more advanced techniques are needed to investigate anatomical relationships accurately [17]. The role of malocclusion in the etiology of temporomandibular disorder (TMD) has been reported as controversial in recent years. A
Table 6 Mean, standard deviation (SD) values, and results of the comparison between joint spaces in the three skeletal Classes Measurements
Anterior joint space (mm) Posterior joint space (mm) Superior joint space (mm) Medial joint space (mm) Sagittal total joint space (mm)
Class I
Class II
Class III
P
Mean
SD
Mean
SD
Mean
SD
2.02b 2.66 4.15a 2.76a 58.06
0.52 0.83 1.01 0.94 13.95
2.73a 3.34 5.03a 2.72a 62.40
1.14 1.90 2.23 1.09 18.90
2.01b 2.81 2.92b 2.18b 62.92
0.57 1.12 0.63 0.72 20.43
Different letters in the same row are statistically significant different according to Tukey’s test. *Significant at P 0.05.
0.008* 0.346 <0.001* 0.030* 0.520
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systematic review concluded that there is a significant association between the presence of some occlusal factors and TMD [18]. Other studies showed that there was no significant association between malocclusions and signs and symptoms of TMD [19,20]. The overall summary finding, however, is that there is no consistent data to support the role of the occlusal surface of the teeth in development of TMD. Class I malocclusion had the lowest glenoid fossa surface area and condylar height as well as the highest condylar length. Also, the most inferiorly positioned condyle was found to be a characteristic feature of Class I malocclusion. The condylar length measurement was in agreement with previous study [4,10,21]. All other parameters were not compared with other Classes before. Class II malocclusion had the lowest condylar width and the highest condylar height. The first finding disagreed with the finding of other studies [7,22]; this difference might be due to the different vertical position of the most lateral and medial points of the condyle that was difficult to digitize in one axial slice, whereas the second result was not previously measured. The current study showed that Class II malocclusion had the highest mandibular fossa inclination to HP, but Basili et al. [23] found no differences between skeletal Classes. Class III malocclusion had the lowest anterior, superior, medial joint spaces, and tubercular height and the least anteroposterior condylar rotation. Furthermore, it had the highest mandibular fossa width, posterior wall inclination, and condylar surface area. Class III had the most inferiorly positioned fossa and the most superiorly positioned condyles. The lowest anterior joint space was similar to the finding of other studies [22,24]. The lowest superior joint space was in accordance with that found by Akahane et al. [25]. Because Class III malocclusion has the lowest anterior, superior, and medial joint space, this might infer the decreased possibility of anteromedial disc displacement in this type of malocclusion. Sanromán et al. [26], in their magnetic resonance imaging (MRI) and CT study, concluded that 53.6% of patients with Class II malocclusion had disc displacement, whereas only 10% of patients with Class III malocclusion had the same TMD. The lowest height of the articular eminence was found in the Class III group when compared with Class I and Class II groups; this might explain the increased possibility of spontaneous dislocation in this type of malocclusion [27]. Anteroposterior condylar inclination was significantly higher in Class III malocclusion; this measurement was progressively decreased to be minimal in Class II malocclusion. This may be due to difference in anterior positioning of the condyle that may induce stress on the anteromedial surface of the condyle, causing more anteromedial rotation [28]. This explains the increased condylar volume in this type of malocclusion [29]. The mandibular fossa was inferior in Class III malocclusion. Some researches [23,30] concluded that TMJ position was more posterior in skeletal Class II short face when compared with skeletal Class III long face malocclusions. Basili et al. [23] found anteriorly positioned fossa in Class III and posteriorly positioned in Class II malocclusion. Class II and Class III condyles were superiorly positioned inside the joint space; this was in agreement with other studies [6,22]. This may be due to the vertical growth pattern in both selected Classes. Skeletal Class II malocclusion showed higher anterior joint space than Class III malocclusion; this is in accordance with the results found by Krisjane et al. [22]. As the TMJ is formed of bony structures as well as nonbony elements, it became essential to know whether there is a correlation between CBCT and MRI regarding disc position. CBCT and MRI studies indicated that disc displacement in adolescents and young
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adults could cause the condyle to change its position in the fossa with alterations in joint space, which depended on the direction and extent of disc displacement. In partial disc displacement, the condyles were displaced posteriorly in the fossae with increased anterior and decreased posterior space; in disc displacement with reduction, the condyles displaced posteriorly with slightly reduced superior joint space [31]. 5. Conclusions Class II malocclusions might be more susceptible to TMDs than Class III in the form of disc displacement based on condylar position, circumferential joint spaces, tubercular height, and inclination. Evaluation of condylar position before treatment could give an indication about the possibility of developing TMDs during orthodontic treatment. References [1] Merigue LF, Conti ACCF, Oltramari-Navarro PVP, Navarro RL, Almeida MR. Tomographic evaluation of the temporomandibular joint in malocclusion subjects: condylar morphology and position. Braz Oral Res 2016;30:e17. [2] Katsavrias EG. Morphology of the temporomandibular joint in subjects with Class II Division 2 malocclusions. Am J Orthod Dentofacial Orthop 2006;129:470e8. [3] Pullinger A, Solberg W, Hollender L, Petersson A. Relationship of mandibular condyle position to dental occlusion factors in an asymptomatic population. Am J Orthod Dentofacial Orthop 1987;91:200e6. [4] Vitral RW, da Silva Campos MJ, Rodrigues AF, Fraga MR. Temporomandibular joint and normal occlusion: is there anything singular about it? A computed tomographic evaluation. Am J Orthod Dentofacial Orthop 2011;140:18e24. [5] Mohlin BO, Derweduwen K, Pilley R, Kingdon A, Shaw WC, Kenealy P. Malocclusion and temporomandibular disorder: a comparison of adolescents with moderate to severe dysfunction with those without signs and symptoms of temporomandibular disorder and their further development to 30 years of age. Angle Orthod 2004;74:319e27. [6] Katsavrias EG, Halazonetis DJ. Condyle and fossa shape in class II and class III skeletal patterns: a morphometric tomographic study. Am J Orthod Dentofacial Orthop 2005;128:337e46. [7] Rodrigues AF, Fraga MR, Vitral RW. Computed tomography evaluation of the temporomandibular joint in class II division 1 and class III malocclusion patients: condylar symmetry and condyle-fossa relationship. Am J Orthod Dentofacial Orthop 2009;136:199e206. [8] Vitral RW, Telles Cde S, Fraga MR, de Oliveira RS, Tanaka OM. Computed tomography evaluation of temporomandibular joint alterations in patients with class II division 1 subdivision malocclusions: condyle-fossa relationship. Am J Orthod Dentofacial Orthop 2004;126:48e52. [9] Vitral RW, Telles CS. Computed tomography evaluation of temporomandibular joint alterations in Class II Division 1 subdivision patients: condylar symmetry. Am J Orthod Dentofacial Orthop 2002;121:369e75. [10] Rodrigues AF, Fraga MR, Vitral RW. Computed tomography evaluation of the temporomandibular joint in Class I malocclusion patients: condylar symmetry and condyle-fossa relationship. Am J Orthod Dentofacial Orthop 2009;136:192e8. [11] Giuntini V, De Toffol L, Franchi L, Baccetti T. Glenoid fossa position in Class II malocclusion associated with mandibular retrusion. Angle Orthod 2008;78:808e12. [12] Zhang Y, Che B, Ni Y, et al. Three dimensional condylar positions and forms associated with different anteroposterior skeletal patterns and facial asymmetry in Chinese adolescents. Acta Odontol Scand 2013;71:1174e80. [13] Burley MA. An examination of the relation between the radiographic appearance of the temporomandibular joint and some features of the occlusion. Br Dent J 1961;110:195e200. [14] Schudy F. Treatment of adult midline deviation by condylar repositioning. J Clin Orthod 1996;30:343e7. [15] Cohlmia JT, Ghosh J, Sinha PK, Nanda RS, Currier GF. Tomographic assessment of temporomandibular joints in patients with malocclusion. Angle Orthod 1996;66:27e35. [16] Alhammadi MS, Shafey AS, Fayed MS, Mostafa YA. Temporomandibular joint measurements in normal occlusion: a three-dimensional cone beam computed tomography analysis. J World Fed Orthod 2014;3:155e62. [17] Egemark I, Ronnerman A. Temporomandibular disorders in the active phase of orthodontic treatment. J Oral Rehabil 1995;22:613e8. [18] White SC, Pharoah MJ. Oral radiology principles and interpretation. 5th ed. Los Angeles, CA: Mosby; 2009. p. 475. [19] McNamara Jr JA, Seligman DA, Okeson JP. Occlusion, orthodontic treatment, and temporomandibular disorders: a review. J Orofac Pain 1995;9:73e90.
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[20] Lagerström L, Egemark I, Carlsson GE. Signs and symptoms of temporomandibular disorders in 19-year-old individuals who have undergone orthodontic treatment. Swed Dent J 1998;22:177e86. [21] Dalili Z, Khaki N, Kia SJ. Salamat. Assessing joint space and condylar position in the people with normal function of temporomandibular joint with cone-beam computed tomography. Dent Res J (Isfahan) 2012;9:607e12. [22] Krisjane Z, Urtane I, Krumina G, Zepa K. Three dimensional evaluation of TMJ parameters in Class II and Class III patients. Stomatologija 2009;11:32e6. [23] Basili C, Costa HN, Sasaguri K, Akimoto S, Slavicek R, Sato S. Comparison of the position of the mandibular fossa using 3D CBCT in different skeletal frames in human caucasic skulls. Int J Stomatol Occlusion Med 2009;2:179e90. [24] Seren E, Akan H, Toller MO, Akyar S. An evaluation of the condylar position of the temporomandibular joint by computerized tomography in Class III malocclusions: a preliminary study. Am J Orthod Dentofacial Orthop 1994;105:483e8. [25] Akahane Y, Deguchi T, Hunt NP. Morphology of the temporomandibular joint in skeletal Class III symmetrical and asymmetrical cases: a study by cephalometric laminography. J Orthod 2001;28:119e28.
[26] Fernández Sanromán J, Gómez González JM, del Hoyo JA. Relationship between condylar position, dentofacial deformity and temporomandibular joint dysfunction: an MRI and CT prospective study. J Craniomaxillofac Surg 1998;26:35e42. [27] Barrera-Mora JM, Espinar Escalona E, Abalos Labruzzi C, et al. The relationship between malocclusion, benign joint hypermobility syndrome, condylar position and TMD symptoms. Cranio 2012;30:121e30. [28] Ueki K, Nakagawa K, Takatsuka S, Yamamoto E, Laskin DM. Comparison of the stress direction on the TMJ in patients with Class I, II, and III skeletal relationships. Orthod Craniofac Res 2008;11:43e50. [29] Saccucci M, D’Attilio M, Rodolfino D, Festa F, Polimeni A, Tecco S. Condylar volume and condylar area in Class I, Class II and Class III young adult subjects. Head Face Med 2012;14:34. [30] Baccetti T, Antonini A, Franchi L, Tonti M, Tollaro I. Glenoid fossa position in different facial types: a cephalometric study. Br J Orthod 1997;24:55e9. [31] Ikeda K, Kawamura A. Disc displacement and changes in condylar position. Dentomaxillofac Radiol 2013;42:84227642.
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Research
Three-dimensional assessment of temporomandibular joints in skeletal Class I, Class II, and Class III malocclusions: Cone beam computed tomography analysis Maged Sultan Alhammadi a, *, Mona Salah Fayed b, Amr Labib b a b
Department of Orthodontics and Dentofacial Orthopedics, Faculty of Dentistry, Ibb University, Ibb, Republic of Yemen Department of Orthodontics and Dentofacial Orthopedics, Faculty of Oral & Dental Medicine, Cairo University, Cairo, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history: Received 14 March 2016 Accepted 24 July 2016
Background: To investigate three-dimensionally using cone beam computed tomography (CBCT) morphological and spatial characteristics of the temporomandibular joints (TMJs) in different anteroposterior skeletal malocclusions. Materials and Methods: Pretreatment CBCT scans of 60 young adult patients (18e25 years) were obtained. Among those patients, 20 were characterized as Skeletal Class I, 20 as Skeletal Class II, and 20 as Skeletal Class III malocclusion. Bilateral TMJs were evaluated on the CBCT images and the following three-dimensional measurements were assessed: (1) mandibular fossa position, inclination, and parameters; (2) mandibular condyle position, inclination, and parameters; and (3) circumferential TMJ space measurements. Results: Class II patients showed the lowest condylar width (6.47 1.14 mm), the highest condylar height (11.14 1.99 mm), and the highest anterior joint space (2.73 1.14 mm). Class III patients exhibited the lowest anterior (2 0.57 mm), superior (2.92 0.63 mm), and medial joint spaces (2.18 0.72 mm), and the highest mandibular fossa width (19.12 2.48 mm), as well as the highest anteroposterior condylar dimension (7.43 1.50 mm). The three skeletal malocclusions differed significantly in the vertical condylar position (Class III had the most superior and Class II had the most inferior position). Conclusions: There are significant differences in specific TMJ parameters between different skeletal malocclusions that might play a role in development of temporomandibular disorders with or without orthodontic treatment. Ó 2016 World Federation of Orthodontists.
Keywords: Temporomandibular joint Cone beam computed tomography Analysis Skeletal Classes
1. Introduction The morphology of the temporomandibular joint (TMJ) varies among individuals, and one of the factors that could influence its shape is the functional loads imposed on it [1]. This is based on the intimate relationship between morphology and function, and justifies the assumed differences in condyle and mandibular fossa morphology and position among subjects with different types of malocclusion [2]. The influence of occlusion on joint morphology is a matter of controversy; some suggested the existence of direct relation [3], whereas others found negative correlations [4]. Part of this
All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Authors have obtained and submitted the patient signed consent for images publication. * Corresponding author: Faculty of Dentistry, Ibb University, Ibb, Republic of Yemen. E-mail address: [email protected] (M.S. Alhammadi). 2212-4438/$ e see front matter Ó 2016 World Federation of Orthodontists. http://dx.doi.org/10.1016/j.ejwf.2016.07.001
controversy is due to the difference in the evaluation techniques at the time of study, and the use of a subjective scoring systems rather than standardized methods for analyzing this complex area [5]. The sagittal relationship between the maxilla and mandible may influence other adjacent structures of the craniofacial system, such as the TMJ. In significant sagittal discrepancies, the morphology and condyle-glenoid fossa relationship could be compromised due to tension or compression forces that the surrounding tissues exert on the TMJ. This indeed could favor a continuous adaptation through remodeling processes to functional changes in the surrounding tissues [6,7]. Several studies investigated the relation between different anteroposterior components and TMJ configuration with contradictory findings [8e12]. These studies have used different methods and measurements for the TMJ parameters using tomography and computed tomography (CT) with two-dimensional rather than three-dimensional (3D) assessment. Furthermore, these studies have less clear description regarding the way of standardization of extracted data, which is due to variations in orientation of the condyles in the three planes of space.
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Table 1 Definitions of general and temporomandibular joint anatomical landmarks for 3-dimensional cone beam computed tomography analysis (Figs. 1 and 2) No.
Landmark
Definition
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Nasion (N) Sella (S) Right/Orbitale (Or) Left Porion (PO) Subspinale (A) Supramentale (B) Soft tissue mandibular fossa (MFS) Bony mandibular fossa (MF) Medial joint space “fossa point” (MJSf) Superior condylar point (SCP) Lateral condylar point (LCP) Medial condylar point (MCP) Geometric condylar center (GC) Anterior condylar point (ACP) Posterior condylar point (PCP) Condylar width “anterior point” (CWa) Condylar width “posterior point” (CWp) Articular tubercle (AT) Inferior meatus (IM) Anterior fossa point (AF) Posterior fossa point (PF)
22 23 24
Anterior neck point (ANP) Posterior neck point (PNP) Anterior fossa inclination “superior point” (AFIs)
25
Anterior fossa inclination “inferior point” (AFIi)
26
Posterior fossa inclination “superior point” (PFIs)
27
Posterior fossa inclination “inferior point” (PFIi)
28
Anterior joint space “fossa point” (AJSf)
29 30
Anterior joint space “condylar point” (AJSc) Posterior joint space “fossa point” (PJSf)
31
Posterior joint space “condylar point” (PJSc)
Nasofrontal structure in the midline. Center of the pituitary fossa in the middle cranial fossa. The right or left most inferior point on the infraorbital rim of the maxilla. The left most outer and superior bony point of the external acoustic meatus. The deepest point of the middle of the maxillary frontal surface. The deepest point of the middle mandibular frontal surface. The most superior and midpoint of the soft tissue right or left mandibular fossa region. The most superior and midpoint of the bony right or left mandibular fossa. The most right or left lateral point of the medial wall of mandibular fossa. The most right or left superior point of the condylar head. The most right or left lateral point of the condylar head. The most right or left medial point of the condylar head. The center of the right or left condyle. The most right or left anterior point of the condylar head. The most right or left posterior point of the condylar head. The most anterior point of the right or left condyle corresponding to the area of maximum width. The most posterior point of the right or left condyle corresponding to the area of maximum width. The most inferior and posterior point of right or left articular tubercle. The most inferior and lateral point of right or left external auditory meatus. The most anterior and inferior point in the right or left anterior wall of the mandibular fossa. The most posterior and inferior point in the right or left posterior wall of the mandibular fossa opposed to IM point. The deepest anterior point of right or left mandibular condylar neck. The most posterior point of right or left mandibular condylar neck. The right or left superior point of a line tangent to the most posterior mandibular fossa area opposing to anterior condylar area. The right or left inferior point of a line tangent to the most posterior mandibular fossa area opposing to anterior condylar area. The right or left superior point of a line tangent to the most anterior mandibular fossa area opposing to posterior condylar area. The right or left inferior point of a line tangent to the most anterior mandibular fossa area opposing to posterior condylar area. The most posterior point of the right or left anterior wall of the mandibular fossa opposed to the shortest anterior condylar-fossa distance. The most anterior point of the right or left condyle opposed to the shortest anterior condylar-fossa distance. The most anterior point of the right or left posterior wall of the mandibular fossa opposed to the shortest posterior condylar-fossa distance. The most posterior point of the right or left condyle opposed to the shortest posterior condylar-fossa distance.
Reproduced and modified with permission from Alhammadi et al. [16].
By analyzing the TMJ in Class I, Class II, and Class III malocclusions, Burley [13] concluded that those malocclusions do not produce functional stimuli capable of changing the articular structures of the temporal region. No condyle centralization and no significant articular asymmetry in most measurements between right and left sides were found by Vitral et al. [8] and Vitral and Telles [9] in a sample of Class II Division 1 subdivision patients, and by Rodrigues et al. [7,10] in samples of Class I, Class II Division 1, and Class III patients. The noncentralization of the mandibular condyles was a feature also in other samples of patients with malocclusion [14,15]. The aims of this study was to investigate three-dimensionally using recently innovative analysis described by Alhammadi et al. [16] the morphological and spatial characteristics of the TMJs in different anteroposterior skeletal malocclusions.
2. Materials and methods This study was approved by the Research Ethics Committee, Faculty of Oral and Dental Medicine, Cairo University, Egypt (No. 3010-2011). The sample size was calculated to determine the minimum required study sample. A power analysis of anterior and superior joint space data designed considering a mean difference of 0.5 mm in the anterior joint space and 1.1 mm in the superior joint space between groups. The alpha level was 0.05 (5%), the b level was 0.20 (20%) (i.e., power ¼ 80%). Accordingly, a sample size of 13 or 16 subjects was obtained based on anterior or superior joint
Fig. 1. General anatomical landmarks for 3D CBCT analysis. Reproduced and modified with permission from Alhammadi et al. [16].
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Fig. 2. TMJ landmarks for 3D CBCT analysis [A and C (Sagittal views), B (Coronal view) and D (Axial view)]. Reproduced and modified with permission from Alhammadi et al. [16].
space, respectively. This size was increased to 20 subjects to compensate for any dropouts. Pretreatment cone beam CT (CBCT) scans of 60 young adult (18e25 years) patients were obtained from the available records from the Outpatient Clinic in the Orthodontic Department, Faculty Table 2 Definitions of anatomical reference planes for three-dimensional cone beam computed tomography analysis No.
Reference planes
Definition
1
Horizontal Plane (HP)
2
Midsagittal Plane (MSP)
3
Vertical Plane (VP)
4
Right Mandibular Fossa Horizontal Plane (R-MFH) Left Mandibular Fossa Horizontal Plane (L-MFH)
Plane defined by 3 landmarks: right orbitale and porion and left porion. Plane through sella and nasion and perpendicular to the horizontal plane. Plane through sella and perpendicular to the horizontal plane and midsagittal plane. Line tangent to the right MF point and parallel to the horizontal plane. Line tangent to the left MF point and parallel to the horizontal plane.
5
Reproduced and modified with permission from Alhammadi et al. [16].
of Oral and Dental Medicine, Cairo University, Egypt. Twenty patients were characterized as skeletal Class I, 20 as skeletal Class II, and 20 as skeletal Class III. The inclusion criteria included the following: 1. 2. 3. 4. 5.
No No No No No
missing teeth. functional mandibular deviations or facial asymmetry. history of parafunctional habits. history or clinically diagnosed TMJ disorders. previous history of TMJ operations.
2.1. Three-dimensional analysis The CBCT scan was performed with the next-generation i-CAT CBCT unit (Imaging Sciences International, Hatfield, PA). The TMJ analysis was done by tracing the selected volume and image structures using Anatomage software version 5.01 (Anatomage, San Jose, CA). A recent analysis designed by Alhammadi et al. [16] was performed with 31 different landmarks (Table 1; Figs. 1 and 2). All landmarks were initially digitized in 3D volume and finally
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Table 3 Definitions of three-dimensional measurements of cone beam computed tomography analysis No.
Measurement
Definition
1 ANB Mandibular fossa measurements 2 Interfossae distance 3 Anteroposterior inclination 4 Vertical inclination 5 Mediolateral inclination 6 Mediolateral position 7 Anteroposterior position 8 Vertical position 9 Mandibular fossa height 10 Mandibular fossa width 11 Anterior wall inclination to TM line 12 Posterior wall inclination to TM line 13 Tubercle height Mandibular condyle measurements 14 Medial intercondylar distance 15 Lateral intercondylar distance 16 Geometric intercondylar distance 17 Mediolateral condylar inclination 18 Vertical condylar inclination 19 Anteroposterior condylar inclination 20 Vertical point condylar position 21 Vertical geometric condylar position 22 Anteroposterior condylar point position 23 Anteroposterior condylar geometric position 24 Mediolateral condylar point position 25 Mediolateral geometric condylar position 26 Anteroposterior condylar joint position 27 Vertical condylar joint position 28 Condylar length 29 Condylar width 30 Condylar height Temporomandibular joint spaces 31 Anterior Joint Space 32 Posterior Joint Space 33 Superior Joint Space 34 Medial Joint Space
The angle between three landmarks: A, N, (B) The distance between bony mandibular fossae (MF). The angle between MFH and MSP. The angle between MFH and HP. The angle between MFH and VP. The perpendicular distance between MF and MSP. The perpendicular distance between MF and VP. The perpendicular distance between MF and HP. Perpendicular distance between MF and TM line. The distance between AF and PF. The inner angle between AFL line and TM line. The inner angle between PFL line and TM line. The perpendicular distance between AT and MF-HL. Distance between CdMR and CdML. Distance between CdLR and CdLL. Distance between GCR and GCL. Angle between CdM-CdL and HP. Angle between CdA-CdP and VP. Angle between CdM-CdL and MSP. The vertical distance between the SCP and HP. The vertical distance between the condylar GC and HP. The anteroposterior distance between the ACP and VP. The anteroposterior distance between the condylar GC and VP. The mediolateral distance between the MCP and MSP. The mediolateral distance between the condylar GC and MSP. The anteroposterior position of the condyle inside the joint as determined by Pullinger and Hollender. [3] The linear difference between condylar height and mandibular fossa height. Distance between MCP and LCP. Distance between ACP and PCP. Perpendicular distance between SCP and TM line. The The The The
shortest shortest shortest shortest
distance distance distance distance
between between between between
AJSc and AJSf. PJSc and PJSf. SCP and MFS. MJSf and MCP.
Reproduced and modified with permission from Alhammadi et al. [16].
localized by slice locator. Five 3D reference planes were established (Table 2). The 3D measurements included A point, nasion, B point angle, mandibular fossa measurements, mandibular condyle measurements, and TMJ space measurements (Table 3). The CBCT measurements were measured twice within a 2-week interval with the same observer and by another observer to evaluate the reliability of the measurements.
2.2. Statistical analysis Statistical analysis was carried out by using IBM SPSS Statistics version 20 for Windows (IBM Corporation, Armonk, NY). Intra- and interobserver agreement was measured using Cronbach’s alpha reliability coefficient and intraclass correlation coefficient. The significance level was set at P 0.05. For parametric data, one-way
Table 4 Mean, standard deviation (SD) values, and results of the comparison of mandibular fossa measurements among the three skeletal Classes Mandibular fossa measurements
Class I
Interfossa distance (mm) Inclination Vertical ( ) Mediolateral ( ) Anteroposterior ( ) Position Vertical (mm) Anteroposterior (mm) Mediolateral (mm) Parameters Glenoid fossa height (mm) Glenoid fossa width (mm) Anterior tuberculum inclination/TM ( ) Posterior tuberculum inclination/TM ( ) Glenoid fossa surface area (mm2) Tubercle height (mm)
92.21
Mean
b
0.43 1.94 89.64
Class II SD 5.29
Mean
Class III SD
92.11
6.47
Mean
P SD 2.23
0.755
0.54 0.81 0.77
0.32 2.09 89.27
b
0.28 0.89 0.69
0.037* 0.084 0.053
1.13b 10.03 46.03
1.06 3.80 3.30
3.08a 11.41 46.66
1.28 3.50 1.57
<0.001* 0.275 0.607
8.47 17.39b 59.03 33.91a 103.36a 7.26a
1.12 2.30 11.69 12.17 22.30 1.72
8.53 19.12a 56.38 46.97b 100.02a 5.90b
1.07 2.48 8.30 26.40 30.59 1.19
0.708 <0.001* 0.337 0.024* 0.044* <0.001*
0.21 1.37 0.30
a
0.72 1.23 89.09
1.33b 10.17 46.09
0.77 3.34 2.83
8.31 16.55b 60.21 43.81b 87.89b 7.94a
1.01 2.06 10.42 14.98 20.39 1.60
Different letters in the same row are statistically significant different according to Tukey’s test or Mann-Whitney U test. *Significant at P 0.05.
93.34
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Table 5 Mean, standard deviation (SD) values, and results of the comparison of mandibular condyle measurements among the three skeletal Classes Mandibular condyle measurements
Class I
Class II
Mean Intercondylar distance Geometric (mm) Medial (mm) Lateral (mm) Mandibular condylar inclination Mediolateral ( ) Vertical ( ) Anteroposterior ( ) Mandibular condyle position AP point condylar position (mm) AP geometric condylar position (mm) ML point condylar position (mm) ML geometric condylar position (mm) V point condylar position (mm) V geometric condylar position (mm) Mandibular condyle parameters Condylar length (mm) Condylar width (mm) Condylar height (mm) Axial surface area (mm2) Sagittal surface area (mm2) Coronal surface area (mm2) Condylar joint position V condylar joint position (mm) AP condylar joint position (mm)
SD
96.57 77.88 114.12
4.11 3.88 5.33
Class III
Mean
SD
98.18 80.56 113.61
7.92 7.46 8.47
Mean
P SD
95.93 77.61 112.28
2.76 4.12 1.67
0.507 0.265 0.677
4.08b 75.67 75.18b
3.18 5.62 4.44
6.82a 74.89 72.83b
3.76 11.58 6.94
4.40b 71.76 82.31a
4.84 11.24 4.98
0.004* 0.272 <0.001*
5.79 10.74 38.92 48.20 3.77a 8.35a
2.41 3.39 2.27 2.23 1.54 1.61
5.11 9.80 40.25 49.07 2.84b 7.39b
4.30 4.65 3.90 3.96 1.82 1.79
5.80 10.17 38.74 47.91 1.97c 4.81c
2.96 3.16 2.16 1.51 1.02 2.08
0.316 0.121 0.092 0.245 <0.001* <0.001*
18.88a 7.30a 8.82b 113.42a 29.82b 73.32b
1.50 1.32 1.07 19.91 7.78 9.90
17.61b 6.47b 11.14a 96.59b 40.96a 70.30b
2.61 1.14 1.99 21.81 15.60 23.46
17.51b 7.43a 10.80a 105.87a 37.11a 84.21a
1.91 1.50 1.03 22.44 11.13 18.62
0.019* 0.012* <0.001* 0.012* 0.002* 0.006*
3.65a 16.72a
0.78 13.26
2.80b 23.48b
1.63 17.33
2.47b 26.03b
0.75 16.62
<0.001* 0.094
Different letters in the same row are statistically significant different according to Tukey’s test or Mann-Whitney U test. AP, anteroposterior; ML, mediolateral. *Significant at P 0.05.
ANOVA followed by Tukey’s test was used and Kruskal-Wallis test followed by Mann-Whitney U test for nonparametric data for the comparison among the three skeletal Classes.
3. Results A very good intra- and interobserver reliability was found, with the intraclass correlation coefficient ranging between 0.790 and 0.993 regarding all measurements. The mean A point, nasion, B point angle in Class I normal occlusion, Class II, and Class III were 2.47 1.39 , 7.14 1.52 , and 2.36 1.54 , respectively. In mandibular fossa measurements (Table 4), there were no significant differences among the three groups except for the Class II group, which showed the significantly highest vertical inclination. The Class III group showed significantly inferior position of the mandibular fossa (3.08 mm). Class III showed significantly highest glenoid fossa width and statistically significant highest posterior wall inclination (46.97 26.40 ). Regarding mandibular condyle measurements (Table 5), the Class II group showed the significantly highest inclination with Horizontal Plane and Class III group showed the highest inclination with Midsagittal Plane (82.31 4.98 ). Class I, Class II, and Class III
showed the statistically significant vertical position from the most inferior to the most superior, respectively. Class I group showed the highest mediolateral dimension (18.88 1.50 mm) and Class I and Class III groups showed the statistically significant highest anteroposterior dimension. Class I normal occlusion showed the statistically significant highest inferior intrajoint position (3.65 0.78 mm). Regarding TMJ spaces (Table 6), the Class II group showed the statistically significant highest anterior joint space and no statistically significant difference between other groups. Class III malocclusions showed the statistically significant lowest medial and superior joint space.
4. Discussion The TMJ is a unique joint. Moreover, the TMJ is a rather difficult area for radiological investigation because there is no possibility for accurate evaluation of this position in conventional radiographs. Thus, more advanced techniques are needed to investigate anatomical relationships accurately [17]. The role of malocclusion in the etiology of temporomandibular disorder (TMD) has been reported as controversial in recent years. A
Table 6 Mean, standard deviation (SD) values, and results of the comparison between joint spaces in the three skeletal Classes Measurements
Anterior joint space (mm) Posterior joint space (mm) Superior joint space (mm) Medial joint space (mm) Sagittal total joint space (mm)
Class I
Class II
Class III
P
Mean
SD
Mean
SD
Mean
SD
2.02b 2.66 4.15a 2.76a 58.06
0.52 0.83 1.01 0.94 13.95
2.73a 3.34 5.03a 2.72a 62.40
1.14 1.90 2.23 1.09 18.90
2.01b 2.81 2.92b 2.18b 62.92
0.57 1.12 0.63 0.72 20.43
Different letters in the same row are statistically significant different according to Tukey’s test. *Significant at P 0.05.
0.008* 0.346 <0.001* 0.030* 0.520
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systematic review concluded that there is a significant association between the presence of some occlusal factors and TMD [18]. Other studies showed that there was no significant association between malocclusions and signs and symptoms of TMD [19,20]. The overall summary finding, however, is that there is no consistent data to support the role of the occlusal surface of the teeth in development of TMD. Class I malocclusion had the lowest glenoid fossa surface area and condylar height as well as the highest condylar length. Also, the most inferiorly positioned condyle was found to be a characteristic feature of Class I malocclusion. The condylar length measurement was in agreement with previous study [4,10,21]. All other parameters were not compared with other Classes before. Class II malocclusion had the lowest condylar width and the highest condylar height. The first finding disagreed with the finding of other studies [7,22]; this difference might be due to the different vertical position of the most lateral and medial points of the condyle that was difficult to digitize in one axial slice, whereas the second result was not previously measured. The current study showed that Class II malocclusion had the highest mandibular fossa inclination to HP, but Basili et al. [23] found no differences between skeletal Classes. Class III malocclusion had the lowest anterior, superior, medial joint spaces, and tubercular height and the least anteroposterior condylar rotation. Furthermore, it had the highest mandibular fossa width, posterior wall inclination, and condylar surface area. Class III had the most inferiorly positioned fossa and the most superiorly positioned condyles. The lowest anterior joint space was similar to the finding of other studies [22,24]. The lowest superior joint space was in accordance with that found by Akahane et al. [25]. Because Class III malocclusion has the lowest anterior, superior, and medial joint space, this might infer the decreased possibility of anteromedial disc displacement in this type of malocclusion. Sanromán et al. [26], in their magnetic resonance imaging (MRI) and CT study, concluded that 53.6% of patients with Class II malocclusion had disc displacement, whereas only 10% of patients with Class III malocclusion had the same TMD. The lowest height of the articular eminence was found in the Class III group when compared with Class I and Class II groups; this might explain the increased possibility of spontaneous dislocation in this type of malocclusion [27]. Anteroposterior condylar inclination was significantly higher in Class III malocclusion; this measurement was progressively decreased to be minimal in Class II malocclusion. This may be due to difference in anterior positioning of the condyle that may induce stress on the anteromedial surface of the condyle, causing more anteromedial rotation [28]. This explains the increased condylar volume in this type of malocclusion [29]. The mandibular fossa was inferior in Class III malocclusion. Some researches [23,30] concluded that TMJ position was more posterior in skeletal Class II short face when compared with skeletal Class III long face malocclusions. Basili et al. [23] found anteriorly positioned fossa in Class III and posteriorly positioned in Class II malocclusion. Class II and Class III condyles were superiorly positioned inside the joint space; this was in agreement with other studies [6,22]. This may be due to the vertical growth pattern in both selected Classes. Skeletal Class II malocclusion showed higher anterior joint space than Class III malocclusion; this is in accordance with the results found by Krisjane et al. [22]. As the TMJ is formed of bony structures as well as nonbony elements, it became essential to know whether there is a correlation between CBCT and MRI regarding disc position. CBCT and MRI studies indicated that disc displacement in adolescents and young
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adults could cause the condyle to change its position in the fossa with alterations in joint space, which depended on the direction and extent of disc displacement. In partial disc displacement, the condyles were displaced posteriorly in the fossae with increased anterior and decreased posterior space; in disc displacement with reduction, the condyles displaced posteriorly with slightly reduced superior joint space [31]. 5. Conclusions Class II malocclusions might be more susceptible to TMDs than Class III in the form of disc displacement based on condylar position, circumferential joint spaces, tubercular height, and inclination. Evaluation of condylar position before treatment could give an indication about the possibility of developing TMDs during orthodontic treatment. References [1] Merigue LF, Conti ACCF, Oltramari-Navarro PVP, Navarro RL, Almeida MR. Tomographic evaluation of the temporomandibular joint in malocclusion subjects: condylar morphology and position. Braz Oral Res 2016;30:e17. [2] Katsavrias EG. Morphology of the temporomandibular joint in subjects with Class II Division 2 malocclusions. Am J Orthod Dentofacial Orthop 2006;129:470e8. [3] Pullinger A, Solberg W, Hollender L, Petersson A. Relationship of mandibular condyle position to dental occlusion factors in an asymptomatic population. Am J Orthod Dentofacial Orthop 1987;91:200e6. [4] Vitral RW, da Silva Campos MJ, Rodrigues AF, Fraga MR. Temporomandibular joint and normal occlusion: is there anything singular about it? A computed tomographic evaluation. Am J Orthod Dentofacial Orthop 2011;140:18e24. [5] Mohlin BO, Derweduwen K, Pilley R, Kingdon A, Shaw WC, Kenealy P. Malocclusion and temporomandibular disorder: a comparison of adolescents with moderate to severe dysfunction with those without signs and symptoms of temporomandibular disorder and their further development to 30 years of age. Angle Orthod 2004;74:319e27. [6] Katsavrias EG, Halazonetis DJ. Condyle and fossa shape in class II and class III skeletal patterns: a morphometric tomographic study. Am J Orthod Dentofacial Orthop 2005;128:337e46. [7] Rodrigues AF, Fraga MR, Vitral RW. Computed tomography evaluation of the temporomandibular joint in class II division 1 and class III malocclusion patients: condylar symmetry and condyle-fossa relationship. Am J Orthod Dentofacial Orthop 2009;136:199e206. [8] Vitral RW, Telles Cde S, Fraga MR, de Oliveira RS, Tanaka OM. Computed tomography evaluation of temporomandibular joint alterations in patients with class II division 1 subdivision malocclusions: condyle-fossa relationship. Am J Orthod Dentofacial Orthop 2004;126:48e52. [9] Vitral RW, Telles CS. Computed tomography evaluation of temporomandibular joint alterations in Class II Division 1 subdivision patients: condylar symmetry. Am J Orthod Dentofacial Orthop 2002;121:369e75. [10] Rodrigues AF, Fraga MR, Vitral RW. Computed tomography evaluation of the temporomandibular joint in Class I malocclusion patients: condylar symmetry and condyle-fossa relationship. Am J Orthod Dentofacial Orthop 2009;136:192e8. [11] Giuntini V, De Toffol L, Franchi L, Baccetti T. Glenoid fossa position in Class II malocclusion associated with mandibular retrusion. Angle Orthod 2008;78:808e12. [12] Zhang Y, Che B, Ni Y, et al. Three dimensional condylar positions and forms associated with different anteroposterior skeletal patterns and facial asymmetry in Chinese adolescents. Acta Odontol Scand 2013;71:1174e80. [13] Burley MA. An examination of the relation between the radiographic appearance of the temporomandibular joint and some features of the occlusion. Br Dent J 1961;110:195e200. [14] Schudy F. Treatment of adult midline deviation by condylar repositioning. J Clin Orthod 1996;30:343e7. [15] Cohlmia JT, Ghosh J, Sinha PK, Nanda RS, Currier GF. Tomographic assessment of temporomandibular joints in patients with malocclusion. Angle Orthod 1996;66:27e35. [16] Alhammadi MS, Shafey AS, Fayed MS, Mostafa YA. Temporomandibular joint measurements in normal occlusion: a three-dimensional cone beam computed tomography analysis. J World Fed Orthod 2014;3:155e62. [17] Egemark I, Ronnerman A. Temporomandibular disorders in the active phase of orthodontic treatment. J Oral Rehabil 1995;22:613e8. [18] White SC, Pharoah MJ. Oral radiology principles and interpretation. 5th ed. Los Angeles, CA: Mosby; 2009. p. 475. [19] McNamara Jr JA, Seligman DA, Okeson JP. Occlusion, orthodontic treatment, and temporomandibular disorders: a review. J Orofac Pain 1995;9:73e90.
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