## 1 Introduction  
Dento-alveolar incongruence with crowding is defined as the discrepancy between dental structures and jaw size, a condition responsible for malpositions and/or teeth rotations [1]. [PERSON] and [PERSON] described dental crowding as the difference between the space needed for proper teeth alignment in the dental arch and the space available in that arch [2]. Crowding is a dynamic process that might be influenced by dental and paradatical factors [3]. According to severity, crowding is classified as mild, moderate, or severe. Malcoluscusions involving dental crowding are much more common in the current population than those consisting of interdental spacing and widening of dental arches. Dental crowding is not a disease in itself, but it can be considered a catalyst for various diseases such as: periodontal disease, dental caries, and dysfunctions of the temporomandibular joint [4]. Several studies in recent years have confirmed that severe malocclusion is likely to be a \"social handicap\" [5]. In a sample of Brazilian schoolchildren, dento-alveolar disharmony with crowding was the most common reason for patients to come to an orthodontic consultation, especially due to a high impairment of aesthetics [6]. However, the causes of crowded dento-alveolar incongruence are not fully understood or unequivocally demonstrated. Many authors discussed the involvement of combined etiological factors, recognizing that heredity, environment, ethnicity, and phylogenetic evolution of facial skeleton may play an important role [7; 8; 9]. Simplifying, dento-alveolar disharmony with crowding, as clinical expression of discrepancies between tooth size and jaw size, is determined by excessively large teeth, excessively small alveolar bones, or a combination of these two conditions. Regardless of the causes of dento-alveolar disharmony with crowding, several studies have analyzed the extent to which dental size and maxillary size contribute to this pathology. Some authors concluded that groups of individuals with dental crowding have smaller sizes of dental arches compared to those of groups with physiological alignments [1; 10]. Other studies indicated that teeth sizes are significantly linked to crowding along dental arches: [PERSON] and [PERSON] pointed out that sizes and morphology of incisors are related with crowding, [PERSON] and his co-workers demonstrated that in a group with crowding, the teeth were significantly wider compared to those in the control group [11; 12]. [PERSON] and collaborators stated that both meso-distal tooth diameters and dental arch width are responsible for the onset of crowding [13]. [PERSON] concluded that neither meso-distal crown diameter nor arch dimensions are significantly correlated with dental crowding; his results showed rather a complex interrelationship among cumulative meso-distal crown dimensions, arch dimensions, and primary dental crowding [14]. Some studies suggested that the trend toward the reduction of the mandibular base size and the maintaining of the size of teeth may also be responsible for the increased number of crowding cases [15]. The majority of the previously mentioned studies were conducted on permanent dentition cases. For diagnosis and treatment necessities, it is important to quantify the amount of crowding as early as possible using dental casts. Space analysis on dental casts is particularly useful in the mixed dentition period in order to evaluate the potential degree of crowding for children without skeletal problems and with good facial proportions [5]. With the development of technology, the metric analyses of the dental structures are increasingly reliable when performed with three-dimensional modelling software programs, in particular with CBCT, or with other diagnostic tools without continuous ionizing radiation, such as MRI [16]. In addition, the evaluation of the proportions of the face and the soft tissue facial profile measurements benefit from the use of wrapped CBCT images from non-standardized random frontal photographs [17].