## 2 Materials and Methods  
### Patient's Clinical Characteristics  
A seven-year-old female attended consultation, having as her chief complaint difficulty in biting and persistent oral breathing pattern. The parents were worried about the negative functional and aesthetic consequences of the presence of an anterior vertical space between upper and lower incisor negative.  
Facial examination revealed a eugnatic jaw growing pattern, slight retrusive profile with opened naso-labial angle, and labial competence (Figure 1). Intra-oral clinical examination, recorded with intra-oral photographs (Figure 2), showed early mixed dentition, a 5 mm anterior openbite, and posterior crossbite at the left side with small loss of coincidence between maxillary and mandibular midlines due to a slight shift of the mandible toward the crossbite side. Both the upper and lower midlines are coincident with the center of maxillary and mandibular arches. Functional examination revealed the presence of infant swallowing pattern with the tongue keeping an anterior position in an attempt to close the anterior space during swallowing or feeding.  
Figure 1: (**A–C**) Extra-oral facial examination.  
Digital models were registered and integrated within digital articulator in order to better assess the dento-alveolar relationship of both arches in centric occlusion (Figure 3) and centric relation (Figure 4).  
Centric occlusion (Figure 3) showed class I relationship on the right side and class II relationship (neutron-occlusion) on the left side. Such discrepancy was attributed to the slight mandibular shift upon closure due to potential occlusal interferences. In fact, when digital models were set in centric relation (Figure 4), i.e., with coincidence of both maxillary and mandibular midlines, posterior occlusal interferences were detected between vestibular cusps of primary molars and first permanent molars. These interferences could be due to a mild maxillary transverse constriction [4].  
Panoramic radiograph showed the presence of all permanent dentition with no signs of ectopic eruptive pattern (Figure 5). We did not request lateral cephalogram considering the patient's age and the absence of relevant clinical signs of skeletal antero-posterior discrepancies; thus, useless radiation exposure was avoided for the patient, according to the A.L.A.R.A. principle [20; 21; 22].  
Figure 4: (**A**) Centric relation, with mandibular and maxillary midlines coincident, showing occlusal interferences leading to mandibular shift upon closure (see intra-oral images). (**B**) Digital articulator used to simulate centric occlusion of the patient in order to detect occlusal interferences.  
Figure 3: (**A**–**C**) Digital models in centric occlusion. (**A**) Right lateral view. (**B**) Frontal view shows the posterior crossbite at the left side with loss of coincidence between maxillary and mandibular midlines, due to a slight shift of the mandible toward the left side. (**C**) Left lateral view.  
Figure 2: (**A**–**C**) Intra-oral examination. See the presence of anterior openbite (**A**). Additionally, posterior crossbite is present at the left side (**B**) with loss of coincidence between maxillary and mandibular midlines due to a slight shift of the mandible toward the crossbite side (left side). Both the upper and lower midlines are coincident with the center of maxillary (**A**) and mandibular (**B**) arches.  
To evaluate maxillary morphology and to identify the potential area of maxillary transversal restriction, i.e., palatal vault and/or dento-alveolar process, including the assessment of symmetry or asymmetry, a preliminary digital morphological evaluation was performed by referring to a specific computer-aided workflow.