Influence Of Trans-sutural Maxillary Distraction On The Morphologic Development Of Craniofacial Skeleton: Experimental Studies In Growing Dogs

PartⅠThe Possibility of Advancing Maxillae by Tans-sutural Distraction with Internal DistractorsObjective To probe the possibility of advancing maxilla by tans-sutural distraction with internal distractors;To provide a new technique for treatment of mid-facial hypoplasia.Method Three 12-week,a brood of dogs were randomly assigned as one normal Control(NC)dog and two experimental(SDO)dog.Distractors with initial force of 480g×2 and 760g×2 was inserted into the patatine bone,across the transverse palatine suture of the experimental dogs respectively.Clinical observation and X-ray cephalometric analysis were performed during distraction period.Result 3 dogs survived to predicted observation period.The experimental animals showed a progressively maxillary advancement without obvious stationary period.The occlusal relationship turned into deep overjet.There was no obviously change in the basilar-maxillary angle.Conclusion The maxilla of growing dogs can be advanced successfully by trans-palatine sutural distraction with the new design of internal distractor;the larger force having a more obvious results.PartⅡInfluence of Trans-sutural Maxillary Distraction on the Morphologic Development of Craniofacial Skeletons Objective To analyze the structural changes of craniofacial skeleton during and after trans-sutural maxillary distraction.Method Sixteen 12-week mongred dogs,with body weight about 4Kg, were randomly assigned into three groups:the Normal Control(NC) group(n=4),experimental groupⅠ(n=6)and experimental groupⅡ(n=6).Internal distractors made of TiNical memory alloy,with two initial force levels of 480g×2 and 760g×2 were inserted into palatine bones across the transvers palatine suture of the two experimentmental group respectively.The animals were fed for additional 8-146 days until they were sacrificed.Clinical observation and X-ray cephalometric analysis were performed regularly during the experimental period. The data of 9 variables that represent the length and width of craniofacial skeleton were analyzed statistically.Results The SDO technique had no significant influence on body development of the animals.Compared with the NC group,dogs of the experimental groupⅠandⅡshowed significant increase in the length of facial cranium,the length of mandible and the length of A-B.The growth velocity of posterior skull width had no significant difference between the control and experimental groups.The increased value of the length of cerebral cranium had no significant difference between the control and experimental groups.The increase value of the width of inter-zygomatic arch in SDO groupⅠandⅡand the width of maxillary alveoli in SDO groupⅠwas slower than the NC group during distraction period,but it had no significant difference with that of the NC group 4 weeks after insertion of the distractors.The basilar-maxillary angle had no significant difference between SDO groupⅠ,Ⅱand NC group.Conclusion(1)The SDO technique can significantly prolong the length of facial cranium and the length of A-B.There is no obvious relaps after long-term observation.The length of facial cranium of experimental dogs groupⅡmove quickly and more obvious than groupⅠ;(2)In a degree,The length of mandible increase accompanied with anterior displacement of maxilla;(3)The internal fixation have no effect on the young animal's development of cranium width and the length of cerebral cranium.The distraction force have no effects on basilar-maxillary angle;(4)The maxilla of the experimental dogs groupⅡmove more quickly and obvious than groupⅠ;(5)The development of the width of inter-zygomatic arch and the width of maxillary alveoli were inhibited during distraction period.The two index recovered 4 weeks later and had no significant difference with NC group.