Three-Dimensional Measurement Database Establishment Of In Vivo Mandible Of The Han Nationality Adults And Three-Dimensional Measurement Study Based On MSCT

Background:In medical domain,since the structures of human organs are complicated and the shapes are multiplicate,if one is not an expert with enough practical experience,he couldn't schemed the three-dimensional shape of an organ and the relationship of the tissues around it just based on two-dimensional images. Additionally,the way of each person's thought is not always the same,which is bound to bring about some deviation,even mistake.So it is difficult for a doctor in diagnosing diseases,explaining symptoms,even evaluating the correctness and objectivity of a medical treatment just based on two-dimensional images with the increasingly development of medicine.Fortunately,the development of computed tomography and three- dimensional reconstruction and visualization technique have brought a revolution in medicine.Mandible is a relatively significant bone among craniofacial bone structure,which is a crucial factor to influence the low face shape and the mastication function,and it is always dealt with in the field of plastic surgery, craniofacial surgery,dentofacial surgery and even tooth implantation area.So it is especially necessary for us to study the mandible through three-dimensional reconstruction and measurement.Objective:To establish the adults' in vivo mandible three-dimensional measurement database of the Han Nationality and three-dimensional display system of which based on MSCT scan with VRT technique three-dimensional reconstruction and measurement,to establish the normal value and interval value of each measurement index of each side and sex,and to explore the relations and rules among them.In order to guarantee clinical practice,and also to store up data for Visible Human Project of China.This paper included two parts as follows:PartⅠ:Accuracy evaluation and study of mandible three-dimensional reconstruction and measurement based on MSCTMethods:Twenty ex vivo mandibles were studied and measured by two methods as MSCT scan with VRT three-dimensional reconstruction and measurement and dissection measurement(126 distance indexes and 6 angle indexes were measured on each mandible).The accuracy of the former method was evaluated by contrasting of two,and further study was focused on three-dimensional measurement.Results:(1) The indexes' results of MSCT scan with VRT three-dimensional reconstruction and measurement of each side showed no statistical difference(P＞0.05).(2) The indexes' results of dissection measurement of each side showed no statistical difference(P＞0.05) except one.(3) The indexes' results put together by two sides of two methods showed no statistical difference(P＞0.05) except one.PartⅡ:Establishment of adults' in vivo mandible three-dimensional measurement database of the Han Nationality based on MSCTMethods:400 volunteers'(200 males and 200 females) in vivo mandibles of the Han Nationality adults undergone strictly selection were studied through MSCT scan with VRT three-dimensional reconstruction and measurement.202 distance indexes,8 angle indexes and 14 observation indexes were measured on both sides of each mandible.To establish the normal value and interval value of each index of each side and sex,then explore the relations and rules among them.Correlation and regression analysis was done among some indexes,and regression equation was established.Results:(1) The normal value and interval value of each measurement index of each side and sex based on MSCT scan with VRT three-dimensional reconstruction and measurement has been established,most of the indexes between two sides showed no statistical difference(P＞0.05),but there was statistical difference(P＜0.05) in most of the indexes between male and female.(2) Correlation analysis was done among 8 indexes in two teams,which showed that there was positive correlation (r＞0.950,P＜0.001) between every two indexes in each team,so regression analysis was done and equation established.(3) The thickness of mandibular ramus in three different section planes was measured and studied,so the distribution and thickness of the cortex and medulla of the ramus was described precisely.(4) The mental foramen, mandibular foramen and the structures around them were observed and undergone precision measurement,the absolute and relative position of them and the relation of them to their surroundings in the mandible was described.(5) Mental canal was found and confirmed in over 95.75%mandibles,mental canal originated from the end of mandibular canal,went backward,superior and outside in an angle of 62 degree and ended up at mental foreman.(6) The caliber of the mandibular canal and the distance from which to the superior and inferior margin and the medial and lateral wall around in six different sections was measured and studied,the mandibular canal went forward near medial cortex and inferior margin of the mandible body in all six sections,then steped over neutral line in the mental foreman area and went forward for some distance near the lateral cortex,then went backward,superior and outside which was called mental canal.(7) The distance from the mandibular canal to the apex of molar root was measured and the absolute and relative position of which to the apex of molar root in the mandible was described precisely.Conclusions:(1) MSCT scan with VRT three-dimensional reconstruction is now admitted as the most preferable method used for bone scan and reconstruction.The coordinate of every point is constant in the reconstructed image,no reference plane needed when measuring.The result is shown at the same screen when measuring.The figure is constant even if the reconstructed image is rotated,zoomed,cut and so on.(2) MSCT scan with VRT three-dimensional reconstruction and measurement can replace dissection measurement completely in three-dimensional viewing and measuring of human mandible,especially of the mandible in vivo for it's higher accuracy.So the problem of the dissection measurement couldn't directly used in vivo is resolved.(3) The adults' in vivo mandible three-dimensional measurement database of the Han Nationality and three-dimensional display system of which based on MSCT scan with VRT technique is established.The normal value and interval value of every index on each side and sex is established.The three-dimensional image can be viewed and measured in any angle,plane and section.The results can not only guarantee the clinical practice,but also store up data for Visible Human Project of China.(4) Through correlation and regression analysis between some indexes and regression equation's establishment.When one index or more is measured,some other indexes' reference value could be calculated or presumed through regression equation,which can provide reference for clinical practice,especially for mandible defect repairing.(5) The thickness of mandibular ramus in three different section planes had been measured and studied,which can provide reference for condylar fracture repairing when the tunnel of tensile force screw through the ramus is done.The mental foramen, mandibular foramen and the structures surrounding had been observed and measured precisely,which can provide reference for operation and block anesthesia in these areas.Mandibular angle hypertrophy is a synthetic symptom,whose diagnosis and treatment shouldn't base on mandibular angle merely,many other factors should be included.(6) Mental canal's found and confirmed denies the mistake concept that the area between two lateral mental foramens is safe.The distance of mandibular canal to the superior and inferior margin and the medial and lateral wall around in six different sections had been observed and measured precisely,the three-dimensional course of the mandibular canal in mandible is described totally.The relationship between mandibular and apex of molar root had been observed and measured in several different sections,which provide references for inferior alveolar nerve injury prevention and cure.