ABSTRACT
Objective@#To provide a clinical reference by evaluating the precision of virtual surgical planning in two⁃ jaw orthognathic surgery.@*Methods @#Thirty consecutive patients who required two⁃jaw orthognathic surgery were includ⁃ ed. A composite skull model was reconstructed using data from spiral computed tomography scan and surface scanning of the dental arch. LeFort I osteotomy of the maxilla and bilateral sagittal split ramus osteotomy of the mandible were simulated using Dolphin Imaging 11.7 Premium. Genioplasty was performed if indicated. Virtual plan was then trans⁃ ferred to operation room using 3D⁃printed surgical templates. Frankfort horizontal plane (FHP), midfacial plane (perpen⁃ dicular to the FHP through the nasion), and coronal plane (perpendicular to the FHP through the sella point) were the selected three symmetry planes.Midpoint of the contact of the maxillary and mandibular central incisors (UI, LI), and the mesio⁃buccal cusp of the first maxillary and mandibular molars (U6⁃R,U6⁃L, L6⁃R, L6⁃L) were the six chosen volu⁃metric landmarks. To calculate the linear difference and overall mean linear difference (mean difference of the distance between UI, LI, U6⁃R, U6⁃L, L6⁃R, L6⁃L to FHP, midfacial and coronal plane) between simulated and postoperative models, the distance between selected landmarks and symmetry planes was measured. To calculate the angular differ⁃ ence and overall mean angular difference, values of the angles constructed by the occlusal, palatal, and mandibular plane to FHP and midfacial plane respectively were determined on simulated and postoperative models@* Results@#The virtual surgical planning was successfully transferred to actual surgery with the help of 3D⁃printed surgical templates. All patients were satisfied with the postoperative facial profile and occlusion. The overall mean linear difference was 0.81 mm (0.71 mm for maxilla and 0.91 mm for mandible); and the overall mean angular difference was 0.95° (the mean angular difference relative to FHP was 1.10°, and that relative to midfacial plane was 0.83°)@* Conclusion@#Virtual sur⁃ gical planning facilitated the diagnosis, treatment planning, and precise bony segments repositioning in two⁃jaw orthog⁃ nathic surgery.
ABSTRACT
Objective To study the relationship of per-capita tobacco consumption and lung cancer mortality in Henan province,and to provide evidence for policy development on tobacco control and reduction of lung cancer mortality.Methods Data regarding lung cancer mortality and per-capita tobacco consumption among household residents from 1992 to 2011,was collected from published almanacs in Henan and Henan Tumor Institutes.Trend Method was used to analyze the development of lung cancer in Henan province and the trend of per-capita tobacco consumption of residents in the household.‘Spearman rank correlation' was used to analyze the correlation between per-capita tobacco consumption of residents in the household from 1992 to 2001 and the lung cancer mortality rates from 2002 to 2011,with the lag time unite as 10 years in this study.Cure Estimation was used to fit the model regarding the relationship between per-capita tobacco consumption of residents in the household and lung cancer.Results Lung cancer mortality among those permanent residents in Henan province increased from 14.75/100 000 in 1992 to 27.00/100 000 in 2011,with an increase of 83.05％.Both the trend of per-capita tobacco consumption among the permanent residents and the lung cancer mortality were uprising,with the tobacco consumption showing a lag effect to the lung cancer mortality.Correlation coefficient between the per-capita tobacco consumption of residents in the household from 1992 to 2001 and the lung cancer mortality from 2002 to 2011 was rs=0.770,P=0.009＜0.05,with statistically significant difference.Along with the uprising trend of lung cancer mortality,the per-capita tobacco consumption of residents in the household was also parallelly rising with the equation of relevance betweenper-capita tobacco consumption of residents in the household in Henna province and lung cancer as y =2.60 x0.46 (F=576.483) and the R2 was 0.667.Conclusion Per-capita tobacco consumption of residents in the household in Henan province appeared a factor that influencing the lung cancer mortality and an association between the per-capita tobacco consumption of residents in the household and lung cancer was noticed.Tobacco consumption had a lag trend to the mortality of lung cancer.