Abstract:

Objective   To estimate the correlations of the eruption and development of the second molars in patients with different sagittal skeletal patterns at the 11th dental age. Methods   Pretreatment records of 74 patients with a mean dental age of 11 years(according to the Becker′s method)were evaluated for the study，which were divided into skeletal Class Ⅰ, skeletal Class Ⅱof mandible and skeletal Class Ⅲ of maxilla groups according to their ANB, SNA, SNB angles and APDI on digital lateral cephalograms before treatment. The eruptional height, eruptional angle and developmental stages of the second molars were assessed from digital X-ray panoramic radiographs and the lateral cephalograms. SPSS16.0 package was used to analyze and process the data. Significant difference was identified with P<0.05. Results   There was no significant difference in the eruptional height, eruptional angle and developmental stagesof the maxillary or mandibular second molars among different sagittal skeletal patterns in patients with a mean dental age of 11 years(P>0.05). The length of PP had a positive correlation with the eruptional height and developmental stages of the maxillary second molars(P<0.01), but had a negative correlation with the eruptional angle of the maxillary second molars(P<0.05). The length of GM had a positive correlation with the developmental stages of the maxillary and mandibular second molars(P<0.01)，but had no correlation with the eruptional height and eruptional angle of the mandibular second molars(P>0.05). Conclusion   According to the correlative assessment, in children of 11 years dental age, the greater the maxillary length, the higher eruptional height of the maxillary second molars and the smaller the eruptional angle, the earlier the development of the second permanent molar of maxillary and mandible. The greater the mandibular length, the earlier the development of the second permanent molar of maxilla and mandible.

Key words: Sagittal skeletal pattern; Second molar; Eruption; Development; Dental age