The term "open bite" was coined by Caravelli in 1842 as a distinct classification of malocclusion [1] and can be defined in different manners [2]. Some authors have determined that open bite, or a tendency toward open bite, occurs when overbite is smaller than what is considered normal. Others argue that open bite is characterized by edge to edge incisal relationships. For semantic reasons, and because it is in agreement with most definitions in the literature, [2, 3, 4, 5] anterior open bite (AOB) is herein defined as the lack of incisal contact between upper and lower anterior teeth in centric relation.

Given these different definitions for AOB, its prevalence varies considerably among studies depending on how authors define it. Prevalence in the population ranges from 1.5% to 11% [6]. The age factor, however, affects prevalence, since sucking habits decrease and oral function matures with age. At six years old 4.2% present with AOB whereas at age 14 the prevalence decreases to 2% [5]. Despite its low prevalence, the demand for treatment of this malocclusion is very common as approximately 17% of orthodontic patients have AOB, [6] which means that professionals should treat it in an effective and stable manner.

Teeth and alveolar bones are exposed to antagonistic forces and pressures stemming mostly from muscle function, which may partly determine the position of the teeth. On the other hand, the intrinsic forces of the lips and tongue at rest generate the balance required to position the teeth. By definition, balance occurs when a body at rest is subjected to forces in various directions but does not undergo acceleration or in the case of teeth - is not displaced [7] Every time this balance is altered, changes occur, such as for example contraction of the dental arches in animals subjected to glossectomy when compared to control animals [8]. Thus, when a tooth is extracted its antagonist continues the process of passive eruption, indicating that the mechanism of eruption remains basically unchanged throughout life and that the tooth seeks occlusal or incisal contact until balance is reached [7].

Based on this idea of balance several etiological factors related to oral function have been associated with AOB. For example, sucking habits, presence of hypertrophic lymphoid tissues, mouth breathing, atypical phonation and swallowing, and anterior posture of the tongue at rest [2, 3, 9, 10, 11]

It should be noted, however, that not all of these etiological factors exhibit a perfectly clear cause and effect relationship. The causal relationship between AOB and nonnutritive sucking habits, such as the sucking of fingers and pacifiers, has been very well established [12]. In such cases, AOB self-corrects consistently after removal of the sucking habit, provided that no other secondary dysfunctions