| Objective:The goal of orthodontic treatment is not only the coordination and stability of dentofacial structure and facial appearance but also the normal functioning of the stomatognathic system and airway. This study is based on CBCT measurements to evaluate the effect of extraction and nonextraction treatment on upper airway morphology in adolescent patients by CBCT registration.Materials and Methods:Randomly selected twenty adolescent female patients(mean age 12.5±3.0 years) with bimaxillary protrusion as an extraction group that removal of the maxillary and mandibular first molars, retraction and depression incisors; randomly selected 20 patients (mean age 13.3±2.3 years) adolescent female patients with mild crowding as a non-extraction group, the group does not extractions, neat rows of flat dentition.Before and after the orthodontic treatment, CBCT (KaVo 3D eXam, Germany) scanned and obtained the data of before and after treatment. Reconstruction of three-dimensional model of craniofacial bones, teeth, airway by MIMICS(Version 16.0, Materialise, Belgium) soft.The airways pharynx is divided into three subunits:nasopharynx (nasopharynx from the top to the palate plane), oropharynx (the hard palate to the epiglottis top), hypopharynx (epiglottis epiglottis top to bottom), and then carry out the registration anterior skull base. Measuring the displacement of the maxillary central incisor crown margin, the hyoid bone in the horizontal and vertical displacement of the direction and the bottom plane of the nose (nasal spine point after a plane parallel to FH), epiglottis top plane (parallel to the FH over the top of the epiglottis Each section plane), epiglottis bottom plane (parallel to the bottom over the epiglottis FH plane) around the airways to anteroposterior length (APL), the largest transverse width (LTW), cross-sectional area (CSA) and the volume (V) of the nasopharynx, oropharynx, hypopharynx. Using SPSS (Version 19.0, SPSS, Chicago, USA) software was used for statistical analysis. Evaluating of adolescent patients in the extraction and non-extraction airway morphological changes after treatment by paired t-test.The relationship among variables was analyzed by Pearson correlation coefficient.Results:The retreat amount of maxillary incisor crown margin is 4.17±0.90 mm in extraction group. The forward movement of the hyoid bone in the horizontal direction is 6.87±2.92 mm, the amount of decrease in the vertical direction is 2.96±0.54 mm. The advancement amount of maxillary incisor crown margin is 1.23±0.25 mm in non-extraction group. The forward amount of the hyoid in the horizontal direction is 7.97±2.73 mm, declining volume in the vertical direction is 3.56 ±0.84 mm. Before and after treatment, extraction and non-extraction group nasal floor flat, flat top epiglottis epiglottis before the end of the plane to the length of the airway, the largest lateral width, cross-sectional area were increased (P< 0.05). Extraction and non-extraction group, each segment of the upper airway volume increases were significant (P<0.05). Extraction group nasopharynx, oropharynx and hypopharynx, respectively, the amount of increase is 10.18%±9.51%,18.02%±7.89%, 8.02%±9.89%, non-extraction group nasopharynx, oropharynx and hypopharynx were increasing the amount of 9.17±10.51%,19.52%±6.39%, 10.32%±7.36%, the difference between the amount of change before and after treatment was not statistically significant(P> 0.05).There was a significant correlation among the displacement distance of the hyoid in the horizontal direction, and the increase of the hypopharynx.Conclusion:Adolescent patients with extraction orthodontic treatment have no effect on the growth of the upper airway on the condition that incisors limited retraction... |
PDF Full Text Request