## 3 Discussion  
CPH is often misdiagnosed due to its rarity and the absence of pain [12], even if restrictions in mouth opening and mandibular movements are present since childhood [17]. Thus, a deep knowledge of any clinical and instrumental analyses available to monitor this condition during growth is necessary to make an early diagnosis and correct treatment plan. The normal range of mouth opening is 53-58 mm, measured between the incisal edges of the maxillary and mandibular teeth. Diagnosis of CPH is effective mostly through imaging [17]. First, a panoramic X-ray is recommended [2; 17], and if there are any suspicions, the subsequent step is the prescription of three-dimensional imaging such as CBCT and MRI to detect any intraarticular derangements in hard or soft tissues [5; 18]. In particular, MRI may help differentiate CPH from chronic disk displacement without reduction [17; 18]. The etiology of coronoid hypertrophy is not well-described, but it has been found in association with many conditions [4; 7; 19]. In this case, it may be supposed that the trauma was the main cause for the onset of the pathological process [1]. Studies carried out on postnatal surgeries on laboratory animals showed that changes in muscular connection result in changes in size and form of the coronoid process and deficits in some myogenic factors or in the expression of specific genes that can provoke muscular and articular disorders [17; 20]. Patients with restricted mouth opening tend to eat softer foods, which may lead to reduced temporalis muscle activity. This results in fatigue and chronic hyperemia, further stimulating an inflammatory response. The chronic persistence of inflammatory cells in the muscles induces an excess of cytokines and growth factors, which contributes to the formation of permanent  
Figure 11: EMG/K7 analysis at rest (age 23). The following muscles were recorded: left temporalis anterior (LTA), left maseeter (LMM), right maseeter (RMM), right temporalis anterior (RTA). fibrosis [6; 21]. So, increased duration of TMJ ankylosis leads to an increased incidence of coronoid elongation. The surgical management of CPH patients is very complex, being that the treatment of associated TMJ ankylosis is highly challenging for surgeons [9]. The major problems faced during such surgeries are the risk of excessive blood loss with all of the complications of blood transfusions [7], joint reankylosis [3], function reduction, growth defect postoperatively [8] and the mandibular inability to intubate in an emergency [22]. Obtaining a satisfactory outcome depends largely on proper post-operative rehabilitation [2] to avoid relapse, and to emphasize results, it is suggested to start physiotherapy 5-7 days after surgery [2; 9; 23]. It can be difficult to define the time to administer treatment in infants, although most authors agree that, except in patients with very severe limitations in mouth opening, it is better to perform the operation once the growth process has finished, in order to avoid recurrence, deformity or even restricted movements [2; 12; 24]. [PERSON] et al. demonstrated that patients >16 years old showed greater improvement in mouth opening at >1-year follow-up compared to patients aged <16 years [6]. The rate of joint reankylosis in a child group was 19.1%, which was significantly greater than that in the adult group (7.3%; \(p<0.05\)) [9]. [PERSON] et al. demonstrated that the rate of facial growth and function after the reconstruction of the mandibular condyle in children with ankylosis seemed to be less than on the undisturbed side, even after surgical treatment of the ankylosis [25]. A review of the literature found that vertical amplitude of normal mandibular movements for the production of speech is equal to one-third of the amplitude of the maximum opening of the jaw, around 7-18 mm with a slight anteroposterior component of 2-3 mm [26].