Correlation Of The Development And Eruption Of The Second Molars With The Sagittal Skeletal Patterns

Objective:To explore the influence factors and the correlations with different sagittal skeletal patterns through the evaluation of the development and eruption status of the second molars of patients in different dental age.Methods:74 malocclusion patients of Stomatology Hospital of Shandong Province were selected, of which 32 cases were males, and 42 cases were females, aged from 11.2 to 15.1 years old, with the average age of 12.7 years and the average dental age of 11 years (Dental age based on Becker's dental age evaluation standard) . Patients were divided into skeletal Class I group, mandibular skeletal Class II group and maxillary skeletal Classâ…¢group, according to the measured ANB angle, SNA angle and SNB angle values of digital X-ray skull lateral cephalograms before treatment. It is determined the developmental and eruptional status of the second permanent molars by means of observation, delineation and measurement of digital X-ray panoramic radiographs.Criteria excluded: (1) Congenital malformations or endocrine disease; (2) Those who had received orthodontic treatment; (3) Abnormal dentition such as over 2mm crowding of each arch, congenital missing teeth , microdontia, the mesial and distal surfaces of the first permanent molars with filling materials, extraction of deciduous teeth, and so on.SPSS12.0 package was used for data processing and analysis.Results:(1) There was no significant difference of the maxillary or mandibular second molars at Nolla developmental stages among different sagittal skeletal patterns(P> 0.05).(2) There was positive correlation between PP and the Nolla developmental stages,eruption height of maxillary second molars(r=0.284.. r=0.233); there was negative correlation between PP and eruption angle of the maxillary second molars (r =-0.236) ; There was positive correlation between GM and the developmental stages of the maxillary and mandibular second molars(r =0.328).(3) There was a high positive correlation between ANB angle and the eruption height of the maxillary second molar(r =0.205).Conclusion:(1) There were no significant differences in the developmental status, eruption height and angle of the second molars in different sagittal skeletal pattern children of 11 years dental age.(2) In children of 11 years dental age, the greater PP length is, the earlier development of the maxillary second permanent molar is; The lower eruption height of the maxillary second molars is, the smaller eruption angle of the maxillary second molar is; The greater GM length is, the earlier development of the second permanent molar is.(3) In children of 11 years dental age, the greater ANB angle is, the higher of the maxillary second molar eruption height is.