Cone Beam Computed Tomography (CBCT) Aid in the Management of Apical Root Resorption of Impacted Maximillary Cannes and Physiologically Erupted Maximillary Cannes after Orthodontic Treatment  
[PERSON]  
1 Department of Medicine and Surgery, University of Milano Bicocca, 20900 Milano, Italy; [EMAIL_ADDRESS] (L.M. ); [EMAIL_ADDRESS] (L.D. ); [EMAIL_ADDRESS] (M.M.) [PERSON]  
1 Department of Medicine and Surgery, University of Milano Bicocca, 20900 Milano, Italy; [EMAIL_ADDRESS] (L.M. ); [EMAIL_ADDRESS] (L.D. ); [EMAIL_ADDRESS] (M.M.) [PERSON]  
2 UOSD Special Care Dentistry, Department of Experimental Medicine and Surgery, University of Roma Tor Vergata, 00131 Rome, Italy 23 UniCamillus-Saint  
Permanent impaction typically involves maxillary teeth, which represent 79.1%, while mandibular teeth comprise the remaining 20.9% [4]. The maxillary and mandibular third molars are the most commonly impacted teeth. The frequency of tooth impaction is mandibular and maxillary third molars, maxillary amines (50.4%), maxillary second pre-molars (18.2%), and the mandibular second premolars (12.2%), with less frequent observation of the mandibular canines, maxillary central incisors, maxillary lateral incisors, and mandibular second molars [4; 5]. Mandibular and maxillary first molars and mandibular second molars are rarely affected [6]. There is a difference in the distribution of impacted teeth in males and females [4]. Permanent maxillary canine eruption disorders arise because these elements have the longest period of development within the jaw and the longest eruption path than any other tooth to emerge into the oral cavity [6]. Permanent impaction of teeth can lead to different complications, such as ecchymosis of the soft tissues, infection, paresthesia and damage to adjacent structures, adjacent tooth root resorption, and the development of cystic-like lesions [5; 7; 8]. The surgical-orthodontic approach may represent a viable solution in most cases of canine impaction [3; 6]. Several studies have demonstrated that orthodontic treatment with uncontrolled forces cause an increase in the incidence and severity of root resorption, and that heavy forces can be particularly harmful. To prevent this, it is essential to apply light orthodontic forces in order to reduce the formation of hyalinization areas that favor the reabsorption of the radicular cement. Since the impacted tooth is located in a position that makes it more difficult to position the bracket in the correct location of the crown, the mechanical forces that are applied on the tooth result less controlled. Slightly heavier orthodontic movements are usually needed for bringing the impacted tooth back into the correct position. Moreover, impacted teeth must travel a much longer distance to reach their final location. During this period, the impacted teeth are subject to different types of mechanics and forces with different directions [1; 2; 6]. The orthodontic treatment to disinclude a tooth in bone inclusion is on average longer than an orthodontic treatment performed to correct a simple dental alignment problem, with the presence of all the elements already erupted [9; 10; 11]. During orthodontic treatment, apical root resorption must be taken into consideration. External apical root resorption is a phenomenon consequent to orthodontic therapy, characterized by loss of dentine and cement, which leads to root shortening due to the activity of clastic cells [9]. In most cases, root resorption is clinically insignificant and not visible on X-rays. When it is significant, it can be noticed as a reduction in the radiographic lengths of the maxillary and mandibular teeth from the tip of the incisal edge or the tip of the most prominent cuspid to the root apex. This can be evaluated with several techniques, such as orthopanoramics, intraoral radiographies, or computed tomography (CBCTs) [12]. Only rarely will the tooth resorption be enough to impede the prognosis of tooth mobility or loss, but when it happens, it can cause tooth mobility or its loss [11; 12].