Severe gingival recession in trisomy 18 primary dentition. A clinicopathologic case report of self-inflicted injury associated with mental retardation.

This clinicopathologic case report documents severe gingival recession in the primary dentition of a trisomy 18 patient. Primary molar and canine teeth exhibited recession extending beyond the midpoint of the buccal aspect of the root, occasionally reaching the root apex. Radiographic examination revealed taurodontism in both primary and permanent teeth. Clinical and histopathologic findings, along with case history, eliminated the possibility of prepubertal periodontitis and suggested a diagnosis of self-inflicted injury associated with mental retardation. Histologic examination of the primary teeth revealed normal cementum and dentin structure. Taurodontism, histologic structure of the dentition, and severe attachment loss in the primary dentition have not been described previously in trisomy 18.