The Influence Of Skeletal Discrepancy In Sagittal Plane On The Natural Head Position And Cervical Posture

Objective:To investigate the relationship of natural head position and cervical posture indifferent sagittal skeletal malocclusion patients(Class I, II, III skeletal malocclusion).In view of most of the past research has focused on the correlation analysis betweencraniofacial morphology with natural head position and cervical posture, so weexcluded the vertical uncoordination(average angle as object), and classified theobject as skeletal classⅠ, II, III according to different sagittal skeletal malocclusionwe usually used. This can help us better understand the relationship of the sagitalskeletal facial types with head position and cervical posture, while it will hasimportant reference value for facial growth forecast, early diagnosis and prognosis ofdifferent skeletal malocclusion patients.Methods:Screened86patients’ cephalometric head films (natural head position) of8to15-year-old patients treated in Jilin University Dental Hospital from2007to2013,that the mandibular plane angle (FH/MP) was at the average angle (29.1°±4.8°).40males and46females aged11.32±1.44years old were selected. According to thesagittal skeletal relationship, the subjects were divided into three groups: the skeletalClass I group:0°≤ANB<5°(30cases, including13males); skeletal Class Ⅱ group:ANB≥5°(27cases, including12males); skeletal Class Ⅲ group: ANB<0°(29cases,including15males).86cephalometric head films taken at the natural head position(NHP) obtained by self-balancing method.The related point and positioning planewere traced and the angles reflected the relationship were measured,then deal the datawith Single-factor analysis of variance and LSD test by SPSS17.0statistical software. Results:The value of NSL/VER, FH/VER, NL/VER ML/VER was smallest inskeletal class Ⅲ group,,there is a statistically significant difference among these threegroups, P <0.05or P <0.01; pairwise comparison results: skeletal class Ⅱ group wasstatistically significant difference between skeletal class Ⅰ group and skeletal classⅢ group, P <0.05or P <0.01.NSL/RL, FH/RL, NL/RL, ML/RL between the three groups did not reachstatistical significance, but their value had the same trend as the measurement valueaboved, pairwise comparison results show that there was statistically significantdifferences between skeletal class Ⅱ group and skeletal class Ⅲ group in NSL/RL,P <0.05.Analysis of the measurement items reacting craniocervical relationship,NSL/CVT, NL/CVT, ML/CVT had statistically significant differences in skeletal classⅡ group and skeletal class Ⅲ group, P <0.05. The other measurement items includeNSL/OPT，FH/OPT,NL/OPT，ML/OPT,FH/CVT were no significant difference, butthey all had the maximum value in skeletal class Ⅱ group and minimum in skeletalclass Ⅲ group similar to NSL/CVT, NL/CVT, ML/CVT.Conclusion:1.The skeletal class I, Ⅱ, III malocclusion have significant differences in naturalhead position and neck posture. the angle between the cranial horizontal reference lineand the true vertical line had maximum value in skeletal class Ⅱ malocclusion andminimum in skeletal class Ⅲ malocclusion in natural head position.2. There are significant differences between head posture and cervical vertebraeposture in groups divided by ANB angle, their posture will have adaptive changes tohide the uncoordinated side.3. Therefore, we should take full account of the relationship between craniofacialmorphology and cervical posture in diagnosis and treatment and maintain of malocclusion.