Investigation of the effects of functional therapy on nasopharyngeal airway and craniocervical posture in angle class III individuals

The aim of our study is to cephalometrically examine and compare the effects of functional treatments in Angle Class III individuals on skeletal, dental and soft tissue changes as well as nasopharyngeal airway and craniocervical posture in patients in the growth and development period. In this retrospective study, groups treated with Class III monoblock and similar Clark Class III twin-block appliance constituted 2 main groups, while longitudinal material which had been obtained from untreated Class III individuals was used as the control group. The first group was composed of 11 individuals (mean age 11.14±1.43) treated with monoblock, the second group was composed of 12 individuals (mean age 11.42±1.24 years) treated with twin-block, and the control group was composed of 8 untreated individuals ( mean age 9.94±1.94). In the selection of individuals, attention was paid to the fact that all individuals who had functional Class III malocclusion and anterior crossbite, Angle Class III molar and/or canine relationship, no high angle development pattern, being in the growth period, and no history of orthodontic treatment. The first group was treated with monoblock for an average of 14.5 months, while the second group was treated with a twin-block for an average of 14 months. In order to evaluate the treatment effects, prior to application of functional appliance (T1) and after appliance removal (T2) in Groups 1 and 2; considering that no treatment was applied in Group 3, only T1 and T2 materials obtained at an average of 10 months apart were used to monitor the effects of growth and development. Paired T-test was used to compare the changes between T1-T2 periods in the evaluation of measurements made on lateral cephalometric x-rays, and One- Way Analysis of Variance (ANOVA) was used to compare the measurements according to the groups. Duncan test was used to determine different groups following the analysis of variance and statistical significance level was taken as p<0.05 in calculations. With Class III monoblock and twin-block appliances, there was a significant increase in SNA value and a significant decrease in SNB value, while a significant increase in ANB value was observed; with the Class III monoblock appliance, the maxilla (A-Tvert. value) was significantly prominent, while with the Class III twin-block appliance, the mandible (B-Tvert. value) was significantly restored. In both treated groups, protrusion and proclination with tilting motion occurred in the upper incisors, while no significant retrusion and retroclination occurred in the lower incisors. In both treatment and control groups, the amount of linear measurement of the airway increased, but this increase was more significant in the treatment group. According to the airway area measurement results, there was a significant increase in the monoblock and twin-block groups, and an insignificant increase in the control group. While significant increases were observed in the measurements of craniocervical angles in the monoblock and twin-block groups, there was no significant change in the control group. This change results in head extension in the treatment groups, which is important for the treatment and persistence of Angle Class III malocclusion. When these postural changes are evaluated together with the increase in the nasopharyngeal airway area in the monoblock and twin- block groups, the importance of the effects of functional treatment in the growth and development period in terms of changes in the postural and nasopharyngeal airway area is clearly seen.