ABSTRACT
The prevalence of Cl II malocclusion with tongue thrust and open bite is high. The pressure of the tongue during swallowing and its physiological activity could be transferred to the maxillary complex by the tongue crib and might advance the maxilla to an unfavorable position. This study aimed to evaluate the dentoskeletal change in the Cl II division 1 patients with anterior tongue thrust and mandibular deficiency treated by mandibular tongue guard, from a private office and orthodontic department of Azad University in Tehran. The sample consisted of 23 patients, [14 females aged 8 years and 9 months and 9 males aged 10 years and 6 months], with Cl II div 1 malocclusion in late mixed dentition with anterior tongue thrust. The patients were treated by mandibular tongue guard. Lateral Cephalograms were obtained and traced before and after treatment and certain angular and linear variables were measured. The pretreatment and post treatment measurements were compared using Paired t test to evaluate the significance of the results. The findings indicated that SNB, facial angle, the distance between B and Pogonion to the reference line and Interincisal angle were significantly increased [P<0.05]. The changes were mainly caused by mandibular growth, were observed after treatment by mandibular tongue guard. Decrease of IMPA, 1-SN, ANB, Wits were significant [P<0.05]. The changes of Jarabak index, SN-MP, SNA, Y-axis were not significant. In Cl II div 1 patients with mandibular deficiency combined with tongue thrust, mandibular tongue guard caused slight increase in mandibular growth