[Effect of three types of rapid maxillary expansion: a three-dimensional finite element study].

Objective: To evaluate the transverse displacement, stress distribution and tendency of change in tooth, alveolar bone and mid-palatal suture using three kinds of rapid maxillary expansion methods. Methods: Cone-beam CT image data was obtained by scanning skulls of a volunteer. Three-dimensional models of maxillary complex were re-established using Mimics and Geomagic Studio and models of Hyrax expander, Haas expander and miniscrew-assisted rapid palatal expander (MARPE) were established using ANSYS Workbench. Stress distribution, displacement and tendency of change in tooth, alveolar bone and mid-palatal suture were evaluated. Results: Hyrax expander brought 0.105 mm lateral displacement of crown, 0.022 mm mid-palatal suture width increase, wedge opening and clockwise rotation tendency of maxilla. Haas expander created uniform stress distribution, 0.216 mm lateral displacement of crown, and 0.031 mm mid-palatal suture width increase. In MARPE model, the lateral displacement of crown was 0.267 mm, and mid-palatal suture width increased 0.315 mm. The maximum of mid-palatal suture expansion and stress distribution appeared in the middle region, and maxilla had tendency of counterclockwise rotation. Conclusions: The lateral changes of teeth and bones brought by MARPE were the most significant. Haas expander had some advantages in comparison with Hyrax.

[Clinical characteristics and outcome of patients with dilated-hypertrophic cardiomyopathy].

OBJECTIVE: To define the clinical characteristics and outcome of patients with dilated-hypertrophic cardiomyopathy (D-HCM). METHODS: Clinical data of HCM patients hospitalized from January 2002 to December 2015 in our hospital were retrospectively analyzed. Patients were divided into D-HCM and classic HCM patients. The D-HCM patients were followed up by phone. RESULTS: A total of 616 consecutive HCM patients were evaluated. Twenty one patients (3.4%) were diagnosed with D-HCM (average age(58.8±10.4) years, 13 males). It took (14.2±7.1)years for classic HCM patients to develop D-HCM. Compared to classic HCM patients, D-HCM patients were younger at the time of first HCM diagnosis ((39.7±10.4) years old vs. (48.5±9.5) years old, P<0.001) and had higher ratio of sudden cardiac death family history (19.0%(4/21) vs. 2.5%(14/558), P=0.003), more patients of future D-HCM patients had ventricular tachycardia (38.1%(8/21) vs. 5.7%(32/558), P<0.001) and higher Troponin-I(66.7%(14/21) vs. 9.3%(52/558), P<0.001) before the left ventricular cavity enlargement. Moreover, MLVWH ((24.8±4.2) mm vs. (17.2±3.5) mm, P<0.001) was significantly thicker and LAD ((39.8±5.9) mm vs. (35.2±3.3) mm, P<0.001) was significantly larger in D-HCM patients than in classical HCM patients. During the(3.8±1.9) years follow up period, 12 out of 21 D-HCM patients died (57.1%), 5 cases(23.8%)died of severe heart failure and 7 cases(33.3%) died of sudden cardiac death. One patient received heart transplantation. CONCLUSIONS: Few classical HCM patients progressed into D-HCM in this cohort. Patients diagnosed as HCM at young age, HCM patients with abnormal Troponin I and ventricular tachycardia are at higher risk of developing D-HCM. The prognosis of D-HCM is very poor, and heart failure and sudden cardiac death are the main causes of death.