Abstract: PURPOSE: To study the periodontal status of labially inversely impacted maxillary central incisor in mixed dentition after orthodontic treatment. METHODS: Sixteen patients with labially inversely impacted maxillary central incisor in mixed dentition and treated by guided rod appliance and conventional fixed appliance were enrolled in this study. Periodontal examinations were performed and cone-beam CT (CBCT) was taken approximately 2 years post treatment. Central incisors were divided into impacted and contralateral incisor groups. Clinical examinations included plaque index (PLI), gingival index (GI), probing depth (PD), width of attached gingiva (AW) and clinical crown length (CL); Mimics 16.0 software was used to measure the length of alveolar bone around the root (ha and fc), the length from the alveolar bone crest to cemento-enamel junction(CEJ) (ab and cd) on both the labial and palatal side of the central incisors as well as the labial and palatal bone support proportion (LBP and PBP) of the root and tipping of central incisor (U1-SN). The data were analyzed using paired sample t tests with SPSS 17.0 software package. RESULTS: There was no significant difference in PLI, GI, PD, U1-SN; the value of AW, ha,fc, LBP, PBP was significantly smaller in impacted groups(P<0.01); the value of CL, ab and cd was significantly larger in impacted groups (P<0.01). CONCLUSIONS: The periodontal status of the impacted central incisor was on good condition without teeth mobility and inflammation, although a little worse than the contralateral homonymous teeth. There may be a need for periodontal bone grafting and gingival surgery in the future for the asymmetric morphology of gingiva.

Key words: Embedded teeth, Impacted teeth, Periodontal status, Incisor, Cone-beam CT