## 4 Discussion  
DFs and the dental papillae are the immature tissues that compose the ectomes-enchymal portion of tooth germ [1; 2]. DFs develop into the periodontal ligaments and attachments, and dental papillae provide for the formation of dentin and mature into the pulp tissue [1; 2]. They appear radiographically as semicircular radiolucencies around unerupted or impacted teeth and histologically consist of connective tissue with variable amounts of lining epithelium, epithelial odontogenic remnants, myxoid change and calcifications [4; 13]. DF enlargement or asymmetry may occur, particularly in impacted third molars, and tissue components of the DF may be histologically misinterpreted with diverse pathological conditions [4]. Thus, accurate correlation of the clinical-radiographical and histological findings is mandatory to establish a proper diagnosis. Since impaction of the third molar has been reported to occur in up to 73% [16; 17; 18; 19; 20], third molar removal is one of the most frequently performed operations in dentistry. However, the need for the removal of impacted third molars is still controversial. In symptomatic cases or when curious lesions, orthodontic problems, periodontal disease and cysts/tumors are present, the indication is clear. However, the rationale to remove them when asymptomatic (i.e., prophylatically) is not [4; 5; 6; 8; 9; 10; 11; 13; 18; 21]. Prophylactic removal can be reasonably considered to preserve the results of orthodontic treatment, to avoid operative complications on the inferior alveolar nerve complicating avulsions in adulthood and, in principle, to prevent the development of inflammatory states (pericoronitis) or cysts/tumors (dentigerous cyst, odontogenic keratocyst, ameloblastoma). However, no more than 12% of impacted teeth have been estimated to be associated with pathological conditions, including cysts and damage to adjacent teeth [46; 47]. According to the recommendations of the National Institutes of Health, impacted (and erupted) mandibular third molars with evidence of follicular enlargement should be considered for extraction, and the associated soft tissue always submitted for microscopic examination [48]. A pericoronad radiolucency of <2.5 mm on conventional two-dimensional radiographic methods is considered non-pathologic [3; 4; 9; 11; 12; 13; 14; 22; 23]. In this case series,  
Figure 3: Correlation matrix between the maximum width of the DF and the diverse histological variables considered in this study. The different colors of the circles represent the correlation between the two variables. The diagonal indicates that each variable perfectly correlates with itself. we investigated the tissue changes occurring in the DFs of thirteen mesioangular impacted third molars evaluated through CBCT in which the maximum width of the DF was <2.5 mm. CBCT is more accurate compared to conventional two-dimensional radiographic methods in the general evaluation of impacted third molars. Indeed, it makes it possible to define the relationship between bone structures and the impacted third molars with better spatial resolution. It also permits us to establish the type of impaction, the size of the follicle, the inclination of the long axis of the tooth, the 3D position of the tooth and its relationship with the medullary canal, as well as the amount of bone around the tooth [14; 22; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34]. In one study, [PERSON] et al. evaluated the role of CBCT in the treatment of patients with impacted mandibular third molars at increased risk of inferior alveolar nerve injury [24]. Through CBCT analysis, the authors reclassified significantly more subjects to a lower risk for inferior alveolar nerve injury compared with panoramic radiography, with a consequent change in risk assessment and in the surgical approach. In all cases included in this study, DFs were normal at CBCT evaluation, and third molar extraction was performed based on orthodontic indications.