Comparison Of Rapid And Slow Maxillary Expansion In The Growth Period By CBCT

Objective:Application special dental maxillofacial cone beam CT, in rapidly developing with dental arch stenosis were treated by banded expander, and compared before and after the change of skeletal and tooth,the nasal cavity, so as to provide reference for clinical diagnosis and treatment.Method:Select hospital of tianjin university of orthodontic division in the growth peak dental arch stenosis,40cases (largest:13years old, smallest:11years old, mean age12.3+/-0.4years). Application of CBCT imaging scans before and after the enlargement in patients with bow, and software invivo5reconstruction images, adjust image X axis through the orbital plane, the Y axis through nasal root point and the pogonion attachment, Z axis through double ear point of attachment. Choose coronal images measured the first molars, the second premolar,the first premolar, canine teeth to the amount of open palatal raphe, Angle of buccal and lingual alveolar bone to the Y axis, the distance between the base bone around the pits; the anterior and posterior nasal cavity were taken,measuring the distance between the base width and the nasal lateral wall of nasal cavity; Take a three-dimensional image, remove tooth body outside of all organizations, measured the linear distance between the buccal side of of the first molars, the second premolar, the first premolar, canine teeth, and its distance between the root apex.3D images, measured the distance between the outer point of the zygomatic, zygomatic alveolar crest arc on both sides of the distance between the pits, the midpoint between two points of attachment distance; Choose three dimensional image measurement of soft tissue of nasal soft tissue nose most protruding point and base and the width of the pits.SPSS17.0software was applied to the measurement results after treatment for independent samples t test, and the test results were analyzed.Result:1. The rapid maxillary expansion at central incisor,canine teeth,the first premolar,the second premolar and the first molar long axis open amounted36.7%,34.9%,31.9%,29.5%,23.5%of screw opened; Slow maxillary expansion were29.4%,29.2%,28.5%,26.4%,28.5%. Palatal raphe pyramid open,the bottom located at the incisor tooth position, the top pointing to the rear. Rapid and slow expansion groups statistic different (P<0.05).2. Increased width of jaw from top to bottom rapid maxillary expansion group were18.7%,22.3%,27.7%respectively; Slow expansion were18.3%,21.6%,23.8%respectively. Differences mainly exist in the upper jaw of the nasal floor level (P<0.05), above the nasal floor levels was not statistically difference (P>0.05).3. Basal bone width increased significantly, the rapid expansion in the incisor,the first premolar teeth, the second premolar and the first molar corresponding to the position reached31.9%,28.2%,26.2%,25.7%of the total screw expansion, slow expansion group was26.4%,24.2%,23.1%,24.2%, teeth layer gaining maximum width, back is reduced, in turn, the addition of two groups statistically difference (P<0.05).4. The increase distance of The rapid expansion at the incisor,the first premolar teeth, the second premolar and the first molar between the of total of hole bow respectively33.3%,77.2%,41.1%,77.2%, the distance between the root increase respectively accounted for44.9%,50.2%,29.8%,50.2%of the total expansion bow; The slow expansion of dental crowns accounted for respectively48.1%,96.2%,79.7%,96.2%, between the root the increase amount of the total expansion bow respectively21.2%,36.5%,23.4%,36.5%. the difference has statistical significance (P<0.05).5. Bow group, a rapid expansion of the incisor,the first premolar teeth, the second premolar and the first molar root cap ratio were1.47,0.63,0.48,0.36; Slow expansion bow group were0.48,0.37,0.31,0.37, with statistical difference (P<0.05).6.Rapid and slow group at the first premolar, second premolar and first molar alveolar bone were buccal side tilt, two groups have no statistical difference (P>0.05).7. The front of the nasal cavity, soft tissue and the back of the appearance has increased in rapid and slow expansion group, the base distance between the nasal lateral wall increase obviously than the front. Rapid and slow expansion, the increase larger at the back of the nose, with statistical difference (P<0.05), the front and soft tissue change was not statistically difference (P>0.05), the nasal cavity was positively triangle opened.8. Two groups to have a change, the bow group, a rapidly expanding with the bow group, a slow expansion of mandibular plane and the base plane, orbital ear in front of the plane Angle and high were significantly increased, with statistical difference (P <0.05); High behind the change is very small, but the two groups was statistically significant difference (P<0.05).Conclusion:1. rapid and slow palatal expansion bow group raphe open can be effective, and rapid bony opening greater than slow group. Two groups are in bottom at the front of the palatal raphe incisor, open top toward the back of the pyramid.2. The bow group, a rapidly expanding and slow maxillary expansion bow group were widened, the nasal floor level rapid increase in the slow group is large, and above the low level increase. Maxillary growth was positively triangle changes, the bottom of the nasal floor level, top for maxillary frontal processes.3. Bone bow in the two groups were increased, the increase from the teeth to teeth decreases in turn. And quick group increased more slowly.4. Two sets of teeth occurred buccal, after anterior tooth to tooth buccal pour amount increase, in turn, fast buccal pour amount is less than the slow group; Quick group tooth body integral move more slowly.5. Two groups of alveolar bone occurred cheek, but buccal leans the quantity is no difference between the two groups.6. Two groups of nasal cavity width increased, at the back of the nasal cavity is gaining more front, nose more low than nasal lateral wall increase, rapid increase in the slow group is large, the nasal appearance change is very small.7. Mandible clockwise, in front of the high increase, and the slow group than rapid.