Study On The Effect Of Face-mask For The Cross-bite At Late Stage Of Primary Dentition Or Early Stage Of Mixed Dentition

To study on the effect of face-mask for the cross-bite at late stage of primary dentition or early stage of mixed dentition.First analyzing the morphous and structural feature of the cranial bone.Whether or not patient have maxilla and the middle face deficiency at this stage.29 anterior cross-bite patients(5-8years) treated with face-mask were included in the treatment group.The therapeutic effect was analyzed by comparing the cephalometric state before treatment(T0)to the state after treatment(T1).The effect was also analyzed by comparing the cephalometric state of the patients after treatment with the state of the anterior cross-bite patients at the same age without orthodontic treatment.Results1.Compared the cephalometric state before treatment to the state after treatment:the angle of ANB,the distance of ANS-Pt,the value of Wits,the angle of mandible Y axle,NA-PA and Me-Go-SN,the overall facial height(N-Me) were increased obviously after orthodontics.At the same time,the angle of SNB,facial angle and U1-L1 were diminished obviously,the labial inclination of the maxillary anterior teeth,the lingual inclination of the mandibular anterior teeth, the mesial shift of the mandibular and maxillary molars.The abnormal molar's relationship,and the overbite and overjet of anterior teeth were all corrected. After the treatment of protraction therapy,the maxilla moved ahead after orthodontics,and maxillary bone mass was also increased obviously,at the same time,the mandible rotated backwards and downwards.Maxillary protraction therapy brought about direct effect that the increase of maxillary bone mass and the maxilla moved ahead,meanwhile,It combinated with the mandible rotated backwards and downwards and mandibular condyle rotated backwards in the course of treatment.These would improved introcession face type and Angleâ…¢malocclusion osteal cross bite.2.Compared the cephalometric state after treatment to the state of untreatment: At the end of maxillary protraction therapy,the position of the maxillas and mandibles was changed a lot,the angle of SNA,ANB,NA-PA,the distance of ANS-Ptm and the value of Wits were increased obviously than those who weren't treated.Meanwhile,compared after treatment group with untreated group at the same age cross-bite patients,the maxilla grew ahead obviously,but there was no significant difference at the growth direction of mandible in such comparison.Conclusions1.To follow 5-9years cross-bite of anterior teeth patients,not only the cross-bite of anterior teeth exist among the tooth arrangement,but also in the aspect of the structure of cranio-ganth exist Angleâ…¢malocclusion osteal relationship causing by maxillary retrusion.If this malocclusion isn't to be corrected in time, it will lead the overgrowth of mandibular and aggravateâ…¢malocclusion osteal.the method of maxillary protraction therapy was effective.It is one of the treatment method on adaptation period mechanism,we can also say it is necessary to use maxillary protraction appliance to such patients.2.For the cross-bite at late stage of primary dentition or early of mixed dentition, the effect of improving the middle face deficiency could be obtained by the face mask treatment,at the same time,cross-bite were correct,the maxilla continued to grow ahead and moved ahead,the quantity of maxilla growth were increased. but this change not much of a natural growth and development that could bring about.Thus,we think it that the face mask for the cross-bite at this stage is a suitable and effective method.It is suggested that the face mask should be recommended for such patients.