Clinical Comparative Study Of Leaf Gauge And Traditional Methods In Determining The Centric Relation

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 was30 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?Lower JawScan?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 maked1,2,3,4.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 4.5?m.The calculated values were inputed into the PC-DMIS CAD++ software to make sure the final measure points.Creatingthree-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.