Evaluation of changes in the upper airway after Twin Block treatment in patients with Class II malocclusion

Abstract

The purpose of this prospective case control study is to describe in growing patients with mandibular hypoplasia, treatment outcomes following functional therapy in terms of volumetric changes in nasopharynx and oropharynx, that is, upper and lower pharynx. We recruited 60 study participants aged between 8 and 12 years having mandibular Class II malocclusion and a reduced upper airway (UA) size, as determined by McNamara cephalometric analyses. Forty patients received Twin Block treatment, whereas the remaining 20 patients did not receive treatment, thus constituting the control group. The control group included patients who did not start treatment after their first visit but returned for a consultation one or 2 years later. All patients underwent an initial teleradiography examination of the skull and a final teleradiography examination to measure changes using McNamara cephalometric analysis of the UA. Pretreatment and posttreatment changes were assessed using Student's t test for independent samples with a significance level of 0.05. Both anatomical structures analyzed—the upper pharynx (nasopharynx) and lower pharynx (oropharynx)—showed significant increases after treatment regardless of whether the patients were boys or girls. The controls showed a decrease in UA size on average after approximately 2 years of growth. A clear relationship exists between the mandibular advancement achieved with TB treatment and an increased UA size. Therefore, the appliance is considered suitable for improving the respiratory quality of growing patients with a decreased UA size.

Volumetric Evaluation of Pharyngeal Airway after Functional Therapy

“…Additionally, Zhang et al [ 21 ] and Shete and Bhad [ 22 ] reported that TB appliance may improve the obstructive sleep apnea (OSA) symptoms in patients with mandibular retrognathia. Generally, the pharyngeal airway dimension changes following functional therapy were examined through two-dimensional (2D) lateral cephalograms [ 23 – 25 ] or 2D cephalometry extracted from cone beam computed tomography (CBCT) [ 26 , 27 ]. However, because of its 2D nature and inability to provide volumetric data, the value of lateral cephalograms is limited in the studies concerning the airway.…”

Orthopedic Treatment for Class II Malocclusion with Functional Appliances and Its Effect on Upper Airways: A Systematic Review with Meta-Analysis

“…All 20 included studies [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] were nonrandomized (Table 1), with only 4 studies (20%) being prospective. All studies were conducted within a university setting (one jointly with a hospital) in 9 different countries (Brazil, Egypt, India, Italy, Pakistan, Spain, Sweden, Turkey, and the United States of America).…”

Effects of Twin-Block with expanding device on the upper airway in growing children with skeletal class II malocclusion -a retrospective study based on the consistency of three-dimensional data and two-dimensional data

“…As functional appliances, the Twin-Block appliances with maxillary expander are used at an early stage to wide the maxillary arch, release the retracted mandible, balance the muscles and beautify the facial pro le to a certain extent [5] . With the improved anteroposterior relation between maxilla and mandible, the tongue and hyoid bone following move forward, which may increase the volume of the UA theoretically [4,6] and be gradually concerned by orthodontists.…”