| Objects: Using cephalometrics to study the occlusal plane and vertical dimension of persons with normal occlu- sion and try to find a method to place the occlusal plane and vertical dimension of edentulous patients in the positions that were previously occupied by the natural teeth .Methods: 1,74 peoples with normal occlusion were selected and divided into two groups: male and female.2,Ev- eryone took a cephalometic roentgenogram ,and the cephalo- metric tracings were drew by author and then analysed by cephalometric software.3,The occlusal plane was determined in two sides:the front and the inclination.4,The anterior piont of occlusal plane was determind in vertical and horizontal directions.In vertical direction: Frankfort plane was regared as the standard plane ,the distances from Ptm (pterygomax- illary),N(nasion),ANS(anterior nasal spine),UIE(upper incisor edge),Me(menton),Sn (subnasal point),Pn(pronasale) to Frankfort Plane were measured and named as Ptm-FH,N-FH,ANS-FH,UIE-FH,Me-FH,Sn-FH,Pn-FH.In horizontal direction:The vertical line from Ptm,N,ANS,UIE ,Sn,Pn to Frankfort plane were drew and the ponitwere marked as Ptm',N',ANS',UIE',Sn',Pn',the distances from N',ANS',UIE',Sn',Pn' to Ptm' were measured and named as Ptm'-N',Ptm'-ANS',Ptm'-UIE',Ptm'-Sn',Ptm'-Pn'.5,The angles of PoNANS,Ar-Go-Me,ANS-Go-Me,OP-FH,MP-FH were measured.6,The linear correlation and regression analysis were performed by SAS 6.02 software.Results : 1,UIE-FH had positive correlation with ANS-FH,Sn-FH,Pn-FH in male,while Ptm-FH ,ANS- FH ,Sn-FH,Pn-FH in female.It demonstrated that in two groups UIE-FH had high correlation with ANS-FH in hard tissue,the formular Y= 39.6438 + 0.7785X was applied for male and Y= 30.4455 +1.0128X for female;and had high correlation with Sn-FH in soft tissue,the formular Y = 31.5510+0.9290X was applied for male and Y = 27.3476 + 0.9863 X for female.2,Ptm'-UIE' had positive correlation with Ptm'-ANS', Ptm'- Sn' ,Ptm'-Pn' in two groups.It demonstrated that Ptm'-UIE' had high correlation with Ptm' -ANS' in hard tissue, the formular Y=1.5872+0.9978X was applied for male and Y= 2.8964 +0.9662X for female; and Ptm'-UIE' had high correlation with Ptm'-Sn' in soft tissue,the formular Y= -1.1 668+0.9958X was applied for male and Y=-2.9813 + 0.8883 X for female。3,It demonstrated that OP-FH had positive correlation with MP-FH ,ANS-Go-Me in male and had high correlation with MP-FH, the formular was Y=0.9508 +0.3132 X;whileOP-FH had negtive correlation with PoNANS and positive correlation with MP-FH in female,and had high correlation with PoNANS, the formular was Y=48.19- 0.4982 X。4,There were no statistical significant difference between the middle-aged and aged persons with normal occlusion in PoNANS,MP-FH,OP-FH.5,Me-FH had positive correlation with ANS-FH,Sn-FH,Pn-FH in male,while Ptm-FH,ANS-FH,Sn-FH in female .In two groups,it demonstrated that Me-FH had high correlation with ANS-FH in hard tissue ,the formular was Y=86.574+0.6539X for male , and Y=65.4427+1.1156X for female;and Me-FH had high corr- elation with Sn-FH in soft tissue,the formular was Y= 74.4634+0.9368X for male and Y=62.766+1.0634X for female.Conclusions : 1,The anterior point of occlusal plane could be determined in vertical direction by the formular Y= 39.6438 + 0.7785X which was formed by UIE-FH and ANS-FH or Y=31.5510+0.9290X fomred by UIE-FH and Sn-FH for male , accordingly Y= 30.4455+1.0128X or Y=27.3476+0.9863X for female.In horizontal direction by the formular Y=1.5872+0.9978X which was formed by Ptm'-UIE' and Ptm'-ANS' or Y=-1.1668+0.9958X formed by Ptm'-UIE' and Ptm'-Sn' for male ,accordingly Y=2.8964+0.9662X or Y=-2.9813+0.883X for female .2,The inclination of occlusal plane could be determined by applying the formular Y=48.19-0.4982X which was fomedby OP-FH and PoNANS for female; the formular Y=0.9508+0.3132X which was formed by OP-FH and MP-FH for male。3,There were no statistical difference between the middle-aged and aged persons...
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