Effect of orthodontic removal of mandibular first molar on the position change of third molar

Abstract

Objective To investigate the effects of the first molar on the eruption of the third molar by comparing the changes of the third molar position after orthodontic treatment in different tooth extraction modes. Methods 39 cases of adolescent patients were selected and divided into three groups:the first molar extraction, first premolar extrac⁃ tion and non⁃extraction.The pretreatment, posttreatment panoramic radiographs were measured to analyze the change of the third molar position among these groups. Results There were significant differences (P < 0.05) in the average an⁃ nual variation of the third molar eruption space and angle. The changes in first molar extraction group were larger than that in premolar extraction group and non ⁃ extraction group. The average annual variation of the third molar eruption space, three groups were (2.38 ± 1.62) mm, (1.61 ± 0.90) mm and (1.08 ± 1.49) mm; the average annual variation of eruption angle, the three were 1.89° ± 1.93°, 1.37° ± 1.16° and 0.83° ± 1.74°. Conclusion Compared with conven⁃ tional treatment, mandibular first molar extraction can significantly increase the third molar eruption space and improve its eruption angle, which is beneficial to the eruption of the third molar.

Keywords

• Panoramic radiograph
• First molar
• Extraction treatment
• Eruption space
• Eruption angle