[Effect of 2 kinds of appliances on anterior tooth root and alveolar bone in patients with mild to moderate overcrowding of ClassⅠmalocclusion].

Purpose: To analyze the effects of fixed appliance and invisible appliance without bracket on anterior tooth root and alveolar bone in patients with mild to moderate overcrowding of Class Ⅰmalocclusion.

Methods: A total of 120 patients with mild to moderate dental crowding were selected from January 2018 to February 2022,and divided into control group and experimental group by random number table method, with 60 cases in each group. The control group was treated with traditional fixed appliance, while the experimental group was treated with invisible appliance without bracket. Cone-beam CT(CBCT) was taken before and 12 months after treatment to measure the root length and alveolar bone height and thickness of maxillary central incisor teeth, height of alveolar bone of anterior teeth lip and lingual side and cusp teeth in both groups. Statistical analysis was performed with SPSS 22.0 software package.

Results: The root length changes of maxillary central incisor, lateral incisor and cusp teeth in the experimental group were significantly lower than those in the control group before and after treatment(P＜0.05). The alveolar bone height changes in the labial side and lingual palatine side of upper anterior teeth, labial side and lingual palatine side of inferior anterior teeth in the experimental group before and after treatment were significantly lower than those in the control group(P＜0.05). The thickness changes of labiolingual alveolar bone at the neck, middle root and apex of upper and inferior anterior teeth in the experimental group were significantly lower than those in the control group before and after treatment(P＜0.05).

Conclusions: Compared with fixed appliance, invisible appliance without bracket can reduce root resorption and the loss of alveolar bone height and thickness in the treatment of Class I patients with mild to moderate dental crowding.