Objective:To prove that index of mandibular shape is a feasible method to the primary dignosis of condylar hyperactivity

and obtain a probalbe reference range of mandibular shape index on the normal side and affected side on mandible and conclude the clinical significance. Methods:Doing the cephalometric analysis on the panormic of 18 unilateral condylar hyperactivity patients by modified obwegeser method

and sign the 5 lines

calculated the IMS1-6 and IMS1’-6’

divided them intonormal group and affected group

calculated the reference range and did the compared samples t test of the two groups one IMS by one IMS

and also calculated the reference range of normal group and affected group.Results:The results of t test:the 6 pairs of MICS has significant differences (P<0.05)

and the reference range of normal group:RRIMS1~6:0264 0~0.652 4;0.245 7~0.552 0;0.099 8~0.205 7;0.094 2~0.171 5;0.084 7~0.150 8;0.077 2~0.128 1

RRIMS1’~6’:0.196 3~0.536 2;0.228 3~0.468 6;0.078 9~0.183 2;0.090 3~0.159 0;0.055 6~0.138 9;0.067 1~0.118 2. Conclusion:The primary dignosis of facial asymmetry deformity by unkown reason

besides the general clinical manifestation

the mandibular shape index which mentioned above can also measure the both sides of mandibule and bilateral condyles

through the measurement we can consern which side of condyle was affect by the condylar hyperactivity

this easy method was a requisite supplement to the traditional dignosis

not only saving the time but also saving the cost of dignosis