ABSTRACT
Midpalatal corticotomy-assisted rapid maxillary expansion (MCRME) is a minimally invasive treatment of maxillary transverse deficiency (MTD) in young adults. However, the effect of MCRME on respiratory function still needs to be determined. In this study, we evaluated the changes in maxillary morphology and the upper airway following MCRME using computational fluid dynamics (CFD). Twenty patients with MTD (8 males, 12 females; mean age 20.55 years) had cone-beam computed tomography (CBCT) images taken before and after MCRME. The CBCT data were used to construct a three-dimensional (3D) upper airway model. The upper airway flow characteristics were simulated using CFD, and measurements were made based on the CBCT images and CFD. The results showed that the widths of the palatal bone and nasal cavity, and the intermolar width were increased significantly after MCRME. The volume of the nasal cavity and nasopharynx increased significantly, while there were no obvious changes in the volumes of the oropharynx and hypopharynx. CFD simulation of the upper airway showed that the pressure drop and maximum velocity of the upper airway decreased significantly after treatment. Our results suggest that in these young adults with MTD, increasing the maxillary width, upper airway volume, and quantity of airflow by MCRME substantially improved upper airway ventilation.
ABSTRACT
Objective To investigate the dynamic change of T-lymphocyte subpopulations in the patients with SARS to understand the pathogenesis of SARS,and to find the specific early diagnostic and warning indexes for SARS.Methods T-lymphocytes in the peripheral blood were labelled by specific fluorescein antibodies and examined by flow cytometry in 252 cases of patients with SARS.The relationship between the dynamic change of T-lymphocyte subpopulations and the clinical progression was analyzed.Results The CD 3 +,CD 4 + and CD 8 + T cells,especially CD 4 + T cells decreased at the fist two-week of the disease course and reached to the lowest level at the second week,and began to increase from the third week in all patients.The change pattern of CD 3 +,CD 4 + and CD 8 + T cells in the severe type of SARS was the same as that of the mild type of SARS,but with more serious extent and longer time.The CD 4 + cell amount of the first,second and third weeks in the mild type of SARS was 515?444/?l,421?350/?l and 600?389/?l respectively,and was up to normal level at the fourth week.The CD 4 + cell amount of the first,second,third and fourth weeks in the severe type of SARS was 312?158/?l,255?187/?l,435?343/?l and 539?394/?l respectively,and still lower than normal level at the fourth week.There was a significant difference in the CD 3 +,CD 4 + and CD 8 + cell amount among the different weeks of disease course in both types.NK cell amount also decreased during the course of disease.The CD 4 +/CD 8 + ratio did not change much and was within the normal range.Conclusions The decrease of CD 3 +,CD 4 + and CD 8 + T cells is a sensitive index for early diagnosis of SARS.The continuous decrease of them may indicate the severe condition of the patients with SARS.