In this study, 14 patients (8 female), aged 18 to 75 years, were examined. All patients but one complained of a unilateral TMJ pain (right side n=9). The control group consisted of 19 test subjects (6 female), aged 21 to 77 years. No significant differences were observed in terms of gender distribution between the groups. However, they differed significantly in terms of age (p=.006). The descriptive statistics are shown in Table 1.
Table 2 shows Pearson's correlation analysis for the TMJ arthralgia group. BF on the side ipsilateral to the pain site and age were strongly negatively correlated (r = -.673, p < .05) and the BF on the contralateral side was strongly positively correlated with age (r = .686, p < .05). In addition, a strong negative correlation was observed for the BF between the two sides (r = -.862, p < .01). There was a strong negative correlation between chewing efficiency and protrusion (r = -.583, p < .05). Chewing frequency correlated strongly negatively with laterotrusion to the contralateral side (r = -.646, p < .05). There was a strong positive correlation for the PPT of the temporalis muscle on the ipsi- and contralateral side (r = .881, p < .01). In addition, PPT on the ipsilateral side correlated strongly positively with the PPT of the masseter muscle on the same side (r = .641, p < .05) as well as on the contralateral side (r = .716, p < .01). PPT of the temporalis muscle on the side contralateral to the pain site correlates strongly positively with the PPT on the ipsilateral (r = .733, p < .01) and contralateral side (r = .701, p < .01) the masseter muscle. PPT of the masseter muscle of the ipsi- and contralateral side correlated strongly positively with each other (r = .848, p < .01). There was a strong correlation between the pain-free opening and the maximum mouth opening (r = .897, p < .01) as well as the maximum assisted mouth opening (r = .896, p < .01). In addition, the maximum mouth opening also correlated strongly positively with the maximum assisted mouth opening (r = .985, p < .01). Laterotrusion to the ipsilateral side correlates strongly negatively with PPT in the temporalis muscle of the ipsilateral (r = -.606, p < .05) and contralateral side (r = -.600, p < .05).
Table 1 Descriptive statistics
|
|
n
|
Mean
|
SD
|
Median
|
Maximum
|
Minimum
|
95% Lower CI
|
95% Upper CI
|
Age (y)
|
Asymptomatic
|
19
|
32
|
16
|
25
|
77
|
21
|
57
|
77
|
Arthralgia
|
14
|
49
|
18
|
55
|
75
|
17
|
67
|
75
|
Bite Force Max Ipsi (N)
|
Asymptomatic
|
17
|
292.24
|
100.72
|
274
|
480
|
120
|
418
|
480
|
Arthralgia
|
10
|
68.84
|
74.1
|
32.91
|
231.31
|
10.57
|
64.36
|
231.31
|
Bite Force Max Contra (N)
|
Asymptomatic
|
17
|
292.24
|
100.72
|
274
|
480
|
120
|
418
|
480
|
Arthralgia
|
10
|
99.1
|
162.19
|
30.16
|
538.52
|
23.79
|
62.7
|
538.52
|
Chewing Efficiency (VoH)
|
Asymptomatic
|
0
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
N/A
|
Arthralgia
|
14
|
0.16
|
0.11
|
0.14
|
0.44
|
0.04
|
0.27
|
0.44
|
Chewing Frequency (HZ)
|
Asymptomatic
|
19
|
1.2
|
0.3
|
1.23
|
1.92
|
0.74
|
1.5
|
1.92
|
Arthralgia
|
14
|
0.83
|
0.28
|
0.81
|
1.41
|
0.41
|
1.1
|
1.41
|
Pressure Pain Threshold Temp Ipsi (kgf)
|
Asymptomatic
|
18
|
2.68
|
0.85
|
2.9
|
4.2
|
0.9
|
3.45
|
4.2
|
Arthralgia
|
14
|
2.19
|
1.11
|
2
|
4.62
|
0.84
|
3.5
|
4.62
|
Pressure Pain Threshold Temp Contra (kgf)
|
Asymptomatic
|
18
|
2.68
|
0.85
|
2.9
|
4.2
|
0.9
|
3.45
|
4.2
|
Arthralgia
|
14
|
2.28
|
1.05
|
2.06
|
4
|
0.84
|
3.72
|
4
|
Pressure Pain Threshold Mas Ipsi (kgf)
|
Asymptomatic
|
18
|
2.28
|
0.72
|
2.35
|
3.45
|
0.85
|
3.15
|
3.45
|
Arthralgia
|
14
|
1.54
|
0.84
|
1.49
|
3.7
|
0.24
|
2.08
|
3.7
|
Pressure Pain Threshold Mas Contra (kgf)
|
Asymptomatic
|
18
|
2.28
|
0.72
|
2.35
|
3.45
|
0.85
|
3.15
|
3.45
|
Arthralgia
|
14
|
1.68
|
0.89
|
1.46
|
4
|
0.59
|
2.34
|
4
|
Protrusion (mm)
|
Asymptomatic
|
12
|
8
|
2.73
|
7.5
|
13
|
4
|
9
|
13
|
Arthralgia
|
14
|
4.57
|
2.77
|
5
|
10
|
0
|
7
|
10
|
Laterotrusion Ipsi (mm)
|
Asymptomatic
|
12
|
11.63
|
2.85
|
12
|
17
|
7.5
|
13.5
|
17
|
Arthralgia
|
14
|
9
|
2.8
|
9.5
|
13
|
3
|
12
|
13
|
Laterotrusion Contra (mm)
|
Asymptomatic
|
12
|
11.63
|
2.85
|
12
|
17
|
7.5
|
13.5
|
17
|
Arthralgia
|
14
|
10.21
|
3.83
|
9.5
|
16
|
4
|
15
|
16
|
Pain Free Open (mm)
|
Asymptomatic
|
12
|
49.83
|
6.18
|
47.5
|
62
|
42
|
56
|
62
|
Arthralgia
|
14
|
35.21
|
9.29
|
36
|
54
|
15
|
42
|
54
|
Max Unassisted Open (mm)
|
Asymptomatic
|
12
|
51.75
|
6.61
|
49.5
|
67
|
45
|
56
|
67
|
Arthralgia
|
14
|
41.79
|
9.11
|
43
|
60
|
27
|
48
|
60
|
Max Assisted Open (mm)
|
Asymptomatic
|
12
|
52.25
|
6.38
|
51
|
67
|
46
|
57
|
67
|
Arthralgia
|
14
|
45.36
|
7.41
|
46
|
60
|
32
|
51
|
60
|
Table 2 Pearson Correlation Coefficient (r) for the symptomatic (TMJ arthralgia) group, n=14 except BF n=10
While looking at the group differences, the maximum bite force on both sides in the arthralgia group was significantly lower than the values in the control group (p < 0.001) (Fig. 4a). The effect size on the ipsilateral side was d = 2.830 and |d|= |-2.583| on the contralateral side, which corresponds to a large effect.
The average chewing efficiency in the arthralgia group was 0.16 ± 0.11 VOH.
The chewing frequency in the arthralgia group was significantly lower than in the control group (p = 0.001) (Fig. 4b). With a value of d = 1.239, Cohen's effect size corresponded to a large effect.
The PPT in the masseter muscle on both sides was significantly lower in the arthralgia group than in the control group (p = 0.011 ipsilateral and p = 0.041 contralateral). A large effect was detected on the ipsilateral side (d = 0.963) and a medium effect on the side contralateral to the pain (d = 0.761). No significant differences in PPT between the symptomatic and the control group were observed for the temporalis muscle on either side (Fig. 4c).
In the arthralgia group, pain-free opening, maximum unassisted opening and maximum assisted mouth opening were significantly smaller than in the control group (p < .001, p = 0.004 and p = 0.019 respectively) (Fig. 4d), and there was a large effect size according to Cohen’s d (d = 1.824, d= 1.236, d = .991). There were no group differences for the lateral and protrusive movements.