Objectives: To investigate the prevalence and severity of a labial-cervical-vertical groove (LCVG) in maxillary permanent incisors and its effect on the associated gingival tissue. Methods: A total of 600 adolescents (293 boys and 307 girls, mean age 13.6 ± 1.99 years) were randomly selected and examined for the presence of LCVG. The deformity was classified as mild, moderate, or severe according to predetermined criteria. Gingival coverage at the groove site was defined as normal, partial, and irregular. Results: LCVG was found in 27 adolescents (4.5%). It was unilateral in 24 (89%) and bilateral in 3 (11%). The ratio of central to lateral incisors was 29:1. No sexual dimorphism or side prevalence were found. Mild LCVG was found in 22 incisors, moderate LCVG in 7 incisors, and severe LCVG in one incisor. Moderate LCVG was 5 to 6 times more susceptible to partial or irregular coverage of the gingival margin than mild LCVG. The gingival sulcus in teeth with LCVG demonstrated a significant (P = .001) increase in depth compared to non- LCVG teeth (1.55 ± 0.90 mm vs 1.18 ± 0.75 mm). Conclusions: An LCVG is a deformity confined predominantly to a single permanent maxillary central incisor. Its prevalence is not connected with gender. Most LCVGs are mild and often difficult to detect. However, the greater the severity, the more gingival irregularity is associated. This and the increase in sulcus depth in LCVG incisors are adverse predispositions for periodontal sequelae, calling for cautious oral hygiene maintenance. Keywords: congenital deformity, dental deformity, enamel development, gingival contour, gingival margin, labial-cervical-vertical groove, maxillary incisor, periodontal sulcus, tooth development