The development of occlusion is an interplay between genetically determined developmental factors along with environmental and few external and internal factors related to orofacial function. McLoughlin and Hanson reviewed the current and historical information on myofunctional factors such as negative oral habits, mouth breathing, lingual rest, swallowing patterns, and other behaviors that have been shown to affect dentition and facial growth. The environmental factor most widely viewed as influential in the development of dentofacial anomalies is the “open mouth posture” associated with mouth breathing.

Nasal breathing, which is inherent to human beings, has an important role in preparing the air to reach the greater structures of the respiratory system, stimulates adequate growth of the craniofacial complex, with a direct influence on the development of the jawbones, posture of the jaw, positioning of the tongue, and maintenance of the rhino pharyngeal space. Any factor that interferes with the upper airway may partially or completely substitute nasal breathing with mouth breathing, and the persistence of this can lead to muscle imbalance. Imbalances in these forces causes repercussion on craniofacial structures and the stomatognathic system in the form of  reduction in nasal patency, and maxillary atresia. The result would be open-mouth posture, a nose that appears to be flattened, nostrils that are small and poorly developed, a short upper lip, and a fuller lower lip. Studies have shown that these individuals  display retroclined incisors, a narrow V-shaped upper jaw with a high palatal vault, a class II skeletal relationship or a posterior cross-bite, and a reduced overbite. It has been argued that these morphological alterations are a result of transformed activity of specific facial muscles related to mouth breathing. Gottlieb recommends further studies and attention to the role of muscles and airway in the cause and course of the treatment. In view of this, a careful anatomical examination is indispensable. Therefore, the size of the dental arches during the deciduous and mixed dentition period becomes potentially crucial in determining the correct tooth alignment. As it is a common clinical condition, one should recognize the need for awareness of parents, teachers, and professionals about the systemic impact of improper breathing mode and the compromised quality of life in these patients. The comprehensive knowledge on habit related structural variations in maxilla and mandible helps the clinician in planning early and targeted intervention and thus, timely interception and precise correction of muscular and dentofacial habit related deviations become possible. Therefore, this current study aims to assess the possible dimensional variations in the maxillary and mandibular arches in children exhibiting mouth breathing habit.