Clinically, atypical deglutition is classified in simple or complex [Lescano de Ferrer, 2006].
The former is characterised by contraction of the lips, the chin muscle and elevator jaw muscles, due to the presence of an open bite that forces interposition of the tongue between the dental arches, with the purpose to ensure the anterior seal [Sayin, 2006].
The increase in overjet is typical of these cases, due to the vestibular inclination of the upper incisors and sometimes lingual inclination of the lower incisors [Fellus, 2006].
The complex form is characterised by contraction of labial and facial muscles and of the chin muscle, but not of the elevator muscles [Störmer, 1999].
In this case, stabilisation of the jaw is guaranteed by the mimic muscles and deglutition takes place with separate teeth since the tongue totally falls between the arches and not in a well defined area, as it occurs in the simple form [Polimeni, 1995].
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The existing relationship between atypical deglutition and malocclusion, especially the open bite, is currently one of the most debated subject [Maciel CT, 2004; Cristina Tostes Vieira Maciel, 2005].
The opinions and researches on this topic are fairly conflicting, because some authors state that atypical deglutition causes the open bite, while others believe that atypical swallowing is a consequence of it [Maciel, 2005; Fraser, 2006].
° European Journal of Paediatric Dentistry vol. 13/3-2012
° R. Condò, M. Costacurta, C. Perugia, R. Docimo