| Objective:this study is to investigate the growth and development of the maxillary and mandibular, and the change of teeth localization. Methods:The materials for this investigation comprise panoramic radiographs of 300 children (150 girls and 150boys) whose ages ranged from 4 to 14 years. the materials were divided into 5 groups accordingto Hellman's dental developmental stages. Auto-CAD (CAD-computer Aided Design) software was used to analyze the panoramic radiographs, The tracing of each radiograph was digitized by translating the reference points onto an X-Y coordinatesys-tem. The straight line that passes point O (the pointthat nasal septum intersects with hard palate) and point PA (the point that medial wall of maxillary sinus intersects withhard palate) was designated as the X axis. The straight line vertical to the X axis and passing through point O at a right angle was designated as the Y axis. The X and Y coordinate values of reference point were calculated. And then O point is (0,0). and every point have a coordinate values (X, Y), Statistical analysis the data. Results:Maxillary sinus floor localization change:There were on significant differences between males and females from group 1 (â…¡A) to group5 (â…¢C) in (SX, SY) (P>0.05). The differences between group 1 and other groups 2 (â…¡C),3 (â…¢A),4 (â…¢B),5were significant in SX (P<0.01), But 2,3,5 groups have no significant differences, there were significant differences betweengroup 4 and group5 (P<0.01). There were significant differences in SY among 2, 3,4,5groups (P<0.01), but groupl and group2 have no significant differences (P>0.05). The position of maxillary sinus floor grows downward and outward with age. The change of medial wall of maxillary sinus intersects with hard palate (PA) have a more evident backward growth change, from IIC to IIIC medial wall of maxillary sinus intersects with hard palate no obvious backward growth, but there is forward trend. posterior wall of maxillary tuberosity intersects with hard palate (PP). is obvious to the rear of growth and to below growth. The change of teeth localization of maxillary:by statistical analysis in addition to the maxillary canine distal point didn't happen change significantly (P>0.05), the others each point has changed (P<0.05). Beforeâ…¢B period the first and second premolar of maxillary have made distal movement, but to stop inâ…¢B period, and slightly to mesial movement trend. Maxillary first permanent molar from stage IIA to stageâ…¡C to distal and downward movement, fromâ…¡C toâ…¢A the movement to distal and downward is more apparent, formâ…¢A toâ…¢B without opparent change, fromâ…¢B toâ…¢C fail to move to distal and begin to made distal movement slightly instead. Maxillary second molar teeth (accessional teeth) has made the movement to distal and downward all the time. Mandibular growth:LI L8 namely with mandibular body grow faster, and have a peak. L2 L7 namely with ramus also changes obvious, the increasing of L9 is larger also, the rest of the spacing also change, but its variation range is smaller than LI, L2, L8 L7. Mandible of each Angle A1, A2, A3 are all growing smaller accordingly, only (P>0.05) A4 has no statistically different at each stage, namely no change. Conclusion:The growth direction of the maxillary sinus bottom is to outgoing, inward to the underside, and teeth eruption have certain influence on the development of the maxillary sinus, and at the same time the maxillary teeth are all to distal and oeclusal movement, but in different stage changes are different. Mandibular body and ramus are all growing, but apart from the Angle of mandibular Angle has no change, the rest of the angles all growsmaller.
|
PDF Full Text Request