Inclusion criteria | Exclusion criteria |
---|---|
Permanent dentition, completely developed root, no apparent bending and no absorbing | Anterior root with periapical lesions or apparent bending, containing embedded supernumerary teeth in alveolar bone |
Intact contour of the crown, and no apparent abrasion | Crown with obvious abrasion |
Moderate crowding, and no apparent rotation in anterior teeth | Mild to severe crowding, or obvious rotation in anterior teeth |
No caries, filling, restoration history and periodontitis in anterior teeth | Caries, filling or restoration treatment, or periodontitis leading to loosening in anterior teeth |
No orthodontic, functional orthopedic treatment, cleft lip palate, and orthognathic surgery history | With orthodontic, functional orthopedic treatment, cleft lip palate, and orthognathic surgery history |
No oral bad habit, occlusion interference, swallowing and respiratory disorder, and facial or spinal abnormalities | With oral bad habit and the mandibular located in functional and unstable position, or jaw cyst, cancer, injury, and abnormalities |
Clear imaging by CBCT | Blurring image by CBCT |