The Study On Female Craniofacial Growth With Three Different Facial Growth Pattern In Skeletal Class â…¡ Subjects In Chong Qing

In this study, 250 skeletal ClassⅡsubjects with low (The horizontal facial growth pattern) (＜28°), average (the medial facial growth pattern) (28°-40°), and high (The vertical facial growth pattern) (40°) mandibular plane angles (MP-SN) which met the internalzing criteria were selected as samples. In them, 72 are in early puberty, 92 are in just puberty, 86 are in late puberty. Cephalograms of each subject were traced by Winceph 8.0 software, and 27 parameters were measured. The difference in each parameter was calculated, and comparisons were made between the groups with different facial growth patterns. The following results of statistical analysis can be showed from this investigation:1.In the same period, forming mechanics of different facial growth pattern and internal structure of craniofacial bones are different in the females with skeletal classⅡsubjects(1) At three facial growth patterns, the three groups didn't show significant differences of the variables N-S-Ar, S-Ar-Go and S-N, but the S-Ar were significantly different among the three groups. The S-Ar of vertical growth is larger than it of horizontal facial growth(2)The angle of SNA in the horizontal facial growth is larger than it in the vertical facial growth; However, the SNB in the vertical facial growth is smaller than it in the horizontal facial growth.(3)Compared with the medial pattern: The vertical growth pattern showed a increase of SN-PP, The main reason that causes vertical growth pattern is the increasing anterior facial growth, ramus hypolasia invertical and increasing distance in vertical of mandibular body base, which means the mandible is in the rear and rotated in the clock wise direction. The main reason that causes horizontal facial growth pattern is the increasing posterior facial height. The craniofacial structure difference is regared as mandibular ramus hyperplasis in vertical in the female horizontal facial growth pattern, which means the mandible is in ahead and rotated in the counter-clockwise direction;(4) The vertical facial growth groups showed greater convexity, larger Y-anxis and gonial angles,and greater anterior facial height,and the horizontal facial growth groups had larger SNA and SNB angles, and greater posterior cranial base, mandibular body, ramus height, and posterior facial height.(5)The incisors were not significantly different among the groups2..During female puberty, there are differences in the growth of mandible with the same facial growth pattern. (1)The cranial base angle N-S-Ar had a rather limited effect on the development; However the linears of S-N and S-Ar had a significant differences at the longitudinal follow-up.(2)From ealy to late female puberty, All the three facial growth patterns showed a decrease of convexity(more flatterned face) and a mandibular forward rotation (decreased MP-SN). The horizontal facial growth pattern displayed significantly more facial flattening and more mandibular forward rotation than did the vertical group(3)During female puberty, the increasing height of mandibular ramus take the most important role in full mandibular height increasing, while the increasing length of mandibular base take the most important role in the full mandibular length increasing.(4)All groups showed mandibular forward rotation with age. The horizontal facial growth patterns had significantly more rotation than did the vertical groups.