Associations among the occurrence or types of maxillary canine impaction, labial frenum attachment types, lateral incisor anomalies, and midline diastema in patients with and without impaction: A case-control study

Abstract

We tested whether the labial frenum attachment types may affect the occurrence or type of maxillary canine impaction. This case-control study was performed on 96 subjects (48 with maxillary canine impaction [20.50±4.99 years, 32 females], 48 controls [21.94±3.79, 31 females]). Types of canine impaction (buccal/palatal, bilateral/unilateral, left/right), types of upper lip middle frenums (mucosal, gingival, papillary), the anatomy of lateral incisors (impacted, peg shaped, small, normal), and the midline diastema were evaluated clinically and radiographically. Associations were examined using multiple binary logistic regression, 3-way repeated-measures ANCOVA, and Fisher tests (α=0.05, β=0.2). The numbers of mucosal, gingival, and papillary frenums in the case group were '29, 14, and 5', respectively; in the control group, they were '25, 21, and 2' (Fisher, P=0.248). The numbers of mucosal, gingival, and papillary frenums were respectively '25, 11, and 1' in the palatally impacted canine subgroup; they were '4, 3, and 4' in the buccally impacted subgroup (Fisher, P=0.010). Abnormal laterals were present in 12 cases and 4 controls; normal laterals were observed in 36 cases and 44 controls (Fisher, P=0.053). Abnormal laterals were seen in 10 cases with palatally impacted canines and 2 cases with buccally impacted canines; normal laterals existed in 27 cases with palatally impacted canines and 9 cases with buccally impacted canines (Fisher, P=0.705). Lateral anatomy was not associated with frenum attachment (Fisher, P=0.827). Greater midline diastemas were seen in cases with maxillary canine impaction, papillary frenums, and abnormal laterals (ANCOVA, P≤0.016). Buccal type of canine impaction is positively associated with papillary labial frenums. Canine impaction is 3.6 folds more prevalent in cases with lateral abnormality. Midline diastema is positively and independently associated with canine impaction, papillary frenums, and abnormal laterals.