Overview and definition
Dentinal dysplasia type I (DD‑I), also termed radicular dentin dysplasia, is a rare, autosomal dominant hereditary dentin defect affecting both the primary and permanent dentitions, with a reported incidence of approximately 1/100,000.[1][2] It is a developmental/genetic disorder of dentin, not a neoplasm. First described as "rootless teeth" by Ballschmiede (Schmiede) around 1920–1922 and named by Rushton in 1939, it was formally placed within the Shields classification of hereditary dentin defects in 1973 (OMIM #125400).[1][2] The condition is genetically heterogeneous, with candidate genes including VPS4B and SSUH2.[2] The expected clinical context is a patient with normal‑appearing crown color and morphology but unexplained mobility, premature exfoliation, or periapical findings in non‑carious teeth.[1]
Radiographic findings
Recognition and location. DD‑I is typically an incidental or mobility‑prompted radiographic finding affecting teeth throughout both arches; crowns look normal while the diagnostic abnormality lies in the roots and pulp.[1]
Appearance. Hallmarks are short, conical, blunted or absent roots; pulp‑chamber obliteration with crescent‑shaped pulpal remnants parallel to the cementoenamel junction (or total obliteration); and periapical radiolucencies in non‑carious teeth.[1][2] Four radiographic subtypes are described within DD‑I: 1a (no pulp/root formation, periapical radiolucency), 1b (short roots with crescent/herringbone pulp), 1c (central dentin island with crescentic pulpal remnants), and 1d (normal‑length roots with visible pulp chamber and coronal pulp stones).[1][2]
Mimics/discriminators. Distinguish from dentinogenesis imperfecta (amber‑translucent bulbous crowns and early pulp obliteration in both dentitions) and DD‑II (similar primary teeth; permanent teeth with normal crowns, thistle‑tube pulp chambers, pulp stones and normal root length).[1] Short roots with large pulp chambers and non‑carious abscesses also occur in vitamin D–dependent and vitamin D–resistant rickets, and chemotherapy/irradiation during root development can mimic DD‑I; associated skeletal sclerosis suggests the Morris–Augsburger syndromic variant.[1]
Management and prognosis
Interpretation centers on the clinical–radiographic paradox: normal crowns with compromised roots explain otherwise unexplained mobility and spontaneous exfoliation.[1] Clinical correlation should include family history and, where available, genetic counseling given autosomal dominant inheritance.[3] Red flags include multiple periapical radiolucencies in non‑carious teeth, progressive mobility, and premature exfoliation, which warrant referral for multidisciplinary evaluation.[1] Reported goals of care emphasize infection control, tooth preservation, prevention, and prosthetic/implant rehabilitation, with outcomes dependent on age and severity; early diagnosis improves functional and esthetic results, while early tooth loss risks maxillomandibular atrophy.[1] Preventive priorities in rare dental disorders include caries and periodontal prevention plus space maintenance after extraction.[4]