Aetiology of MALOCCLUSIONS: Prenatal Causes: Phylogenetic; Hereditary: Abnormalities of number, position, form; Malocclusion of II and III class; Hypoplasia or mandibular hyperplasia; Bimascellar protrusion; Ogival palate; Insertion anomalies of the frenules; Congenital: Schisi labio-maxillo-palatine (CENNI) Post-natal causes: General Dystrophic Endocrine disorders (CENNI) Functional Oral respiration; Phonation disorders; Atypical swallowing; Muscle abnormalities; Bad habits. The objective of diagnosis in functional orthopedic orthodontics: intercepting the problems and identifying a priority of intervention The importance of collaboration with other professionals (pediatrician, speech therapist, otolaryngologist, physiotherapist, physiatrist, etc.)