Conductive hearing loss associated with dentofacial deformities and orthodontic treatment modalities

The stomatognathic system consists of mouth, teeth, upper respiratory tract, pharynx, and other structures related with mastication, deglutition, respiration and speech. This system consists of 27 bones including maxilla and mandible which constitute two main skeletal parts of face. Congenital and/or developmental disorders in any hard and/or soft tissues of stomatognathic system and/or functional aberrations will affect the other components of this system. The stabilization of various parts of the stomatognathic system together with its functional and anatomic integrity has been the center of interest among orthodontists for years. It has been documented in clinical and experimental studies that a close relationship exists between respiratory disturbances and dentofacial growth and development. Mouth breathing leads to develop some pathologic adaptations in postural and morphological characteristics of the stomatognathic system, and these abnormal habits cause serious negative effects on the normal development of nasomaxillary and dentofacial structures during the growth period. Maxillary deficiency or constriction of the maxillary dental arch, concomitant with a high palatal vault, is one of the most common orthodontic problems seen in the maxillofacial region. Main orthodontic manifestations of this skeletal development syndrome are palatal constriction and deficiency, deep palatal vault, narrowed maxillary arch, and posterior crossbite. Simultaneous presence of this syndrome and abnormal breathing pattern can lead to serious problems such as obstructive sleep apnea, recurrent otitis media, and conductive hearing loss related with Eustachian tube dysfunctions. Congenital deformities such as cleft lip and palate are also serious problems seen in dentofacial region. The cleft patients generally have posterior crossbite, narrowed maxillary arch, deep palatal vault, abnormal breathing pattern, increased nasopharyngeal and middle ear infections as well as Eustachian tube dysfunctions, which cause conductive hearing loss. This chapter aims to evaluate conductive hearing loss associated with dentofacial deformities including the skeletal development syndrome and cleft lip and palate. The present chapter will also assess the effects of dentofacial orthodontic/orthopedic treatment procedures such as semi-rapid or rapid maxillary expansions on conductive