Abstract:

Objective To explore the treatment plan in patients with congenital lower incisor missing. Methods Thirty- six patients with congenital lower incisor missing were included in the investigation. The missing location, missing quantity, malocclusion type and treatment method were analyzed. Bolton index of two groups were analyzed. The first group was congenital missing one lower incisor who treated by extracting two upper first premolars and one lower first premolar. The second group was congenital missing two lower incisors who treated by exacting two upper first premolars. Results The therapeutic effect of 36 cases were better. Overall ratio in two groups were 91.70%± 1.85% and 92.83%±2.74%, anterior ratio were 81.69%±2.12% and 85.46%±2.39%, anterior tooth- size discrepancy were（2.16±0.64）mm and（4.27±1.14）mm. There were no significance difference on overall ratio in two groups（P>0.05）. There were significance difference in anterior ratio and anterior tooth- size discrepancy（P<0.01）. Conclusion For patients with congenital missing one lower incisor who need extraction in upper and lower jaws, it is less affection on Bolton index that extracting one premolar at non- missing side than extracting one center incisor in mandibe.

Key words: lower incisor missing, treatment plan, Bolton index