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Leaf Gauge法与传统方法确定正中关系的临床对比研究
摘要
目的：
应用数字化技术比较Leaf Gauge法与吞咽法、双手扶持法在确定正中关系时的差异性，为临床确定正中关系时方法的选择及临床工作中更好的应用Leaf Gauge确定正中关系提供理论依据与实验数据，为Leaf Gauge的推广应用提供实验支持。
方法：
选取8名年轻志愿者，制取口内牙列上下颌研究模型，采用比单双层底座灌注石膏模型底座。随机先后使用Leaf Gauge法、吞咽法、双手扶持法确定正中关系，每种方法重复确定三次，每次间隔半小时以上。面弓转移颞下颌关节的位置关系，再将牙合 位记录所确定的上下颌位置关系转移到基尔巴赫牙合 架上，取下咬合记录材料，松开切导指针，使上下颌模型接触。3Shape TRIOS口内扫描仪扫描
牙合 架上的模型及咬合关系，导出同一副咬合关系的UpperJawScan、LowerJawScan、BiteScan、BiteScan2四个数据。Exchange 2016格式转化软件将扫描仪扫描的.dcm格式的文件转化为.stl格式的文件。将数据导入PC-DMIS CAD++软件，选择软件中的“分层”菜单，将同一副咬合关系的四个数据分别建立层次标记为1、2、3、4。两上颌第一磨牙近中颊尖及左侧上下颌第一中切牙近中切点四个测量点分别定点100次，根据二分法理论编辑MATLAB运算程序，将测量点的100个坐标值输入MATLAB数学软件中，计算4个测量点的理论值，设置精确度为4.5µm。将计算后测量点的理论值输入PC-DMIS CAD++软件中，确定最终的测量点。创建三维坐标系，以左右两上颌第一磨牙近中颊尖及左侧第一中切牙近中切点三点建立平面，代表人体的牙合 平面，以左右两上颌第一磨牙近中颊尖的连线为Y轴代表人体的左右，以左侧第一中切牙近中切点与Y轴的垂线为X轴代表人体的前后。测量所确定正中关系位上下颌中切牙切点在水平向（平行于X轴向）间的距离，利用Spss17.0软件进行统计分析，单因素方差分析比较其数据差异，计算同一种方法对同一志愿者三次测量值的变异系数，F检验比较其统计学差异性并比较其波动性及平均值大小。
结果：
Leaf Gauge法、吞咽法、双手扶持法确定正中关系，测量上下颌中切牙近中切点的水平距离，结果分别为1.112±0.970、1.074±1.031、1.195±0.930，p＞0.05，差异无统计学意义。统计三种方法三次测量的变异系数，F检验得F值为4.227，差异有统计学意义。计算变异系数的均值，Leaf Gauge法为0.058、吞咽法为0.207、双手扶持法为0.140，Leaf Gauge法变异程度更小。
结论：
1.Leaf Gauge法、吞咽法、双手扶持法均是临床中确定正中关系的可靠方法。
2.Leaf Gauge法在确定正中关系时稳定性、重复性更好。
关键词：
Leaf Gauge 正中关系 切点 吞咽法 双手扶持法
Clinical comparative study of Leaf Gauge and traditional
methods in determining the centric relation
Abstract
Objective：
In order to compare the differences in determining the centric relation ,we evaluate three different methods including Leaf Gauge method ,Swallowing method and bimanual manipulation method by digital technique.The purpose of this comparison was to supply some information for choosing the proper methods in determing the centric relation.Otherwise it could also provide some reliable evidence for using Leaf Gauge method in clinics.
Method ：
Eight young volunteers are included in this study. The impressions of upper and lower dental arch were made followed by the corresponding casts.Leaf Gauge method, Swallowing method and bimanual manipulation method are all used to determined the centric relation in clinic.Every method was tested three times and the internal time was 30 mins. Facebow was used to transfer the relations of temporomandibular joint.Then, study models were transferred to the articulator and remove the biting materials. 3Shape TRIOS scanning device was used to scan informations about casts and occlusion relationships. UpperJawScan、LowerJawScan、BiteScan、BiteScan2 datas were exported. Exchange 2016 software could be used to transform documents in .dcm form to documents in .stl form.Then, datas were imported to the PC-DMIS CAD++ software.Datas from the same occlusion were divided into four different parts maked 1,2,3,4. The position of the mesial buccal cusp in upper first molar and mesial cut point in left upper and lower incisor were tested in 100 times. According to the theory of dichotomy edit computing program MATLAB, the 100 pointswere inputed into MATLAB mathematical software.Then , 4 measure points were calculated in values with the Setting accuracy of 4.5μm.The calculated values were inputed into the PC-DMIS CAD++ software to make sure the final measure points. Creating three-dimensional coordinate system, maxillary first molar buccal cusps and left first incisor near the cut-off point established three plane which represented the occlusal plane. The connection of Maxillary first molar left and right buccal cusps was defined as the Y-axis which represented the left and right direction. The line perpendicular to the Y-axis from left central incisor mesial cut point was defined as the X-axis which meaned the forward and backward.We evaluate the horizontal distances between upper and lower incision.Spss 17.0 software was used to analyze the datas.The One-Way ANOVA was used to analyze the datas.The coefficient of variation from the same volunteers in three times with the same method was calculated.F statistical test were used to compare their differences and average .
Results：
The centric relations from eight volunteers were achieved by three different methods . The horizontal distances between upper and lower incision were calculated with PC-DMIS CAD software.The average datas was 1.112±0.970 in Leaf Gauge group, 1.074±1.031 in Swallowing group, 1.195±0.930 in bimanual manipulation group . There was no significant differences in three groups (p＞0.05).F test obtained F value is 4.227, the difference was statistically significant.The average coefficient of variation was 0.058 in Leaf Gauge group, 0.207 in Swallowing group, 0.140 in bimanual manipulation group. There was significant differences among three groups .The coefficient of variation in Leaf Gauge group was minimum.
Conclusion：
1. Leaf Gauge method ,Swallowing method and bimanual manipulation method are all reliable methods in determining the centric relation.
2. Leaf Gauge method could achieve a better stability and repeatability.
Key words: Leaf Gauge Centric relation Incisor point Swalling method Bimanual manipulation method
