Incisors And First Molars Inclination Of Average Growth Patterns' Adolescent With Different Sagittal Skeletal Patterns

Objective:Through measuring the lateral cephalograms of average growth patterns' adolescent untreated with different sagittal skeletal patterns,comparing the compensation characteristics and differences of the labial or lingual of incisors and the mesiodistal inclination of first permanent molars among the three different sagittal skeletal patterns,to provide the references for clinical design treatments,anchorage preparation and the long-term stability of orthodontic post-operation.Methods:Select 120 cases of average growth patterns' adolescent according to inclusion criteria and the standard of facial growth patterns classification,dividing these cases into 3 type depending on ANB angle: Skeletal Class?(ANB=0 °-5 °),Skeletal Class ?(ANB ?5 °),Skeletal Class ?(ANB ? 0 °)40 cases in each type,13 angle parameters were measured as the index of incisor and first permanent molar inclination,three groups were analyzed by analysis of variance and two groups compared with LSD-t Test.Results:1.The measurement results of incisor inclination among different sagittal skeletal patterns:There were no statistical significance in the measured values of ?U1-SN,?U1-FH and ?U1-PP in the three different sagittal skeletal patterns.There was statistical significance among the three groups in the measurements of ?L1-MP,the value of skeletal class ? was less than class?,?,the values did not show significant differencebetween class ?and ?;there was statistical significance among the three groups in the measurements of ?U1-L1,the value of skeletal class ? was greater than class?and ?,the values did not show significant difference between class ?and ?.2.The measurement results of first permanent molar inclination among different sagittal skeletal patterns:The measured values of ?U6-SN,?U6-FH,?U6-PP and ?L6-SN in skeletal class ?were all greater than those of skeletal class?and?,the measured values of ?L6-MP in skeletal calss ? were less than those of skeletal class?and?,which all showed statistical significance;The measured value of ?U6-L6 had no statistical significance among the three groups.The inclination of lower teeth in skeletal class ? was less than class ?and?,suggesting that the inclination of the lower incisors was consistent with the inclination of the lower first permanent molar in skeletal class ?.The compensatory change of the lower incisors inclination in skeletal class ? was 9.24°comparing with skeletal class ?,that of the lower first permanent molars was 4.11°,which indicated that the compensatory change of lower incisors was more obvious than the first permanent molars'.Conclusions:1.With a decrease of ANB angle,the lower incisor tipped more lingually,the upper first permanent molar tipped more mesially,the lower first permanent molars tipped more distally in average growth patterns' adolescent,there was no difference about the upper incisors' inclination among three sagittal skeletal patterns.2.The upper first permanent molars of skeletal class ? tipped compensatory mesially in average growth patterns' adolescent,the lower first permanent molars tipped distally,the upper incisors tipped lingually;the trend of compensation inclination of lower incisors was consistent with that of molars',the compensatory change of lower incisors was more obvious than the lower first permanent molars'.3.Comparing with skeletal class I,the upper incisors tipped lingually,the upper first permanent molars tipped distally,the lower incisors tipped proclined,the lower firstpermanent molars tipped mesially in the skeletal class ?.