# Recovery of Post-Traumatic Temporomandibular Joint after
## 3 Rehabilitation of TMJ
### Non-Surgical Treatment
#### 3.1.2 Physical Therapy
It is widely known that the biophysical effects of ultrasound are _thermal_ and _non-thermal_. _Thermal effects_ are the result of the absorption and attenuation of the sound waves in the tissue, promoting local heating (increased tissue temperature), amplified blood flow and enzymatic activity, improved collagen extensibility, decreased muscle guarding, decrease nerve conduction velocity, and, finally, increased pain threshold which is responsible for lessening of pain and muscle spasm. On the other hand, _non-thermal effects_ are the result of cavitation, microstreaming, and acoustic streaming [41]. US is characterized by two main therapeutic parameters, as follows: (i) the _intensity_ (0.1-3 Watts/cm\({}^{2}\)) considered the amount of energy emitted from the transducer divided by the effective radiating area of transducer head) at a penetration depth of up to 5 cm; and (i) the _frequency range_ (1-3 MHz) which is measured in Hertz and represents the number of compression and rarefaction cycles per unit of time of the crystal found within the transducer. The frequency of the ultrasound is typically selected according to the target tissue; a low frequency of 1 MHz is usually used to treat deep lesions, while the 3 MHz frequency is ideal for treating superficial tissues [9; 44; 45; 46]. The intensity required at the lesion can be determined from the tissue state: acute (0.1-0.25 W/cm\({}^{2}\)), subacute, chronic (>0.5 W/cm\({}^{2}\)). At an intensity of 1.25 W/cm\({}^{2}\), the sound waves are responsible for tissue vibration, controlling heat in the treatment field and a local intensification of blood flow and leading to increased tissue cell metabolism responsible for soft tissue healing. Moreover, higher intensities of ultrasound beams produce a significant frictional heat in the tissue [44; 45]. It seems that 3 MHz at 1.5 W/cm\({}^{2}\) is appropriate to attain a 4 \({}^{\circ}\)C increase in local temperature at 4-5 min, while 1 MHz at 2 W/cm\({}^{2}\) is adequate to reach a 4 \({}^{\circ}\)C rise in local temperature at 10 min. Kinetic/Exercise Therapy  
Kinetic therapy aims to ameliorate pain, decrease high muscle activity, improve muscle coordination, and restore normal function. Improvement of mouth opening as well as the range of motion in TMJ can be conducted either manually or with the help of various devices, but only after relaxing the hyperactive masticatory muscles. The patient is instructed to open their mouth until the pain is perceived and then to relax and maintain this position for a few seconds; it is mandatory to repeat the exercise several times a day. Mechanotherapy is also performed with the help of devices that passively open the mouth; they are inserted between the dental arches and activated to mobilize the mandible. Patients can use wooden wedges, mandible retractors, or special devices ([PERSON], Darcisac, Lebedinsky device). Dilation is slow, progressive, and gentle, dosing the force very well and avoiding brutal maneuvers that could cause pain. The amplitude of dilation is increased by 1-2 mm per day and the exercises are continued for 30-40 days [6; 45; 47]. Active and passive joint exercises for increasing the range of motion of the TMJ remain a key component in the post-surgical management of such patients, while long-term follow-up is recommended [6; 36; 46]. The _oclusal appliances_ which represent a noninvasive, conservative option with minimal risks is used to contain the obtained results [9; 38; 44]. Some of the characteristics of the stabilization gutters are significant: they are made of hard self-curing or thermo-polymerizable acrylate; cover all the teeth of an arch (itis usually made at the level of the maxillary arch); have a thickness of about 1.5 mm in the molar area; the occlusal surface is smooth and must make uniform contact with all antagonistic teeth [9; 48]. * Posture correction is related to head, neck, shoulder, and tongue position. The patient must perform exercises related to the improvement of coordination, stability, and jaw alignment [9].