## 4 Discussion
\begin{table}
\begin{tabular}{l l l l l l l} \hline \hline
**Parameter** & **Group** & **No.** & **Mean \(\pm\) SD** & **Median** & **Min–Max** & **\(p\)-Value** \\ \hline \multirow{3}{*}{MAX} & Experimental & 25 & 2.08 \(\pm\) 0.80 & 2.01 & 0.80–4.01 & \\  & Control & 25 & 1.74 \(\pm\) 0.67 & 1.69 & 0.62–3.17 & 0.113 \({}^{*}\) \\ \cline{1-1}  & Experimental & 25 & 52.89 \(\pm\) 55.77 & 26.84 & 4.49–254.58 & \\ \cline{1-1}  & Control & 25 & 28.16 \(\pm\) 36.01 & 12.37 & 1.67–148.11 & 0.007 \({}^{**}\) \\ \hline \hline \end{tabular} \(p\)-value: the comparison of intergroup age, \({}^{*}\)—Student’s \(t\)-test, \({}^{**}\)—Mann-Whitney test.  
\end{table} 
Table 4: Comparison of the range of two mandibular deviation parameters—MAX and MSE between experimental and control groups. The aim of our study was also to present a new method for assessing mandibular movement. We assume that the method may constitute an attractive alternative to other methods for measuring the mouth opening-closing movement, especially useful for a physiotherapist. The proposed method may be compared with existing ones by focusing on a few aspects. First of all, the way measuring equipment is attached to a patient's head seems relevant for both the patient's comfort and obtained results [15; 17; 18]. The method we are proposing uses a camera connected to adjustable headgear through an aluminum extension arm. Besides markers placed on the medial cleft and chin, no other element of the equipment was in contact with the area measured. Additionally, the patient did not report any discomfort related to the equipment's weight or attachment. The material markers were made of a proven good choice: it was safe for the patient, was easily and firmly fixed to the skin, and, most importantly, had a distinct color that the camera could simply isolate from the background. Other researchers used pieces of metal or simple paper cubes to act as markers [14; 15]. We placed the markers in a straight line. The first one was on the medial cleft, and the second one was in the middle of the chin. [PERSON] et al. [14] used the same marker positions. In many other methods, the main marker had direct contact with the inferior dental arch, which was supposed to eliminate the influence of skin movement during opening and closing to raise accuracy [15; 16; 34]. To achieve such positioning, plastic splits [35; 36; 37; 36] or thermoplastic material [14; 15] was applied. The authors of these methods admit that such marker attachment results in improved measurement accuracy; nevertheless, it potentially affects the proprioceptive system and the patient's comfort, which may also have an impact on results [15; 18]. Available methods examine the mouth opening-closing trajectory by assessing the maximum range in two or three planes, depending on the method [37; 38]. Besides the MAX, our method also includes an MSE parameter. It is an analysis of the entire cycle from initiating opening to closing the mouth; the parameter informs us about the degree the mandible deviated from the optimal trajectory per one second. The disadvantage of our method is the evaluation of movement only in 2D, so it is not possible to differentiate the range of rotation and translation when opening the mouth. However, this method gives the possibility to evaluate the coordination between the right and left temporomandibular joint through the maximum deviation from the reference line and MSE parameter, which is mean square error from the ideal reference track. The need for assessing the deviation of the mouth opening and closing was also noted by other researchers [21; 39]. Another problem that needs to be addressed in vision systems used for recording movements of the mandible is measurement accuracy. The relevant literature contains many methods proven to deliver very high accuracy. A paper by [PERSON] et al. [15] compares the accuracy levels of different equipment, and in almost all cases, they are in the region of tenths of a millimeter.