Radiographically, evidence of partial pulp obliteration with a "thistle-shaped appearance". Moderate type
Teeth are moderately discoloured (blue, grey or amber opalescent). More attrition is evident with shortening of crown height. Crowns may appear bulbous with prominent constriction at the CEJ. Radiographically, the pulp is small or is totally obliterated. Roots appear thinner and shorter than average. There may be periapical pathology. Severe type
Teeth are markedly discoloured (brown opalescent). The crowns are very short due to severe attrition. Crowns may appear bulbous with prominent constriction at the CEJ. Radiographically, pulp appears large and the dentine layer is thin ("shell teeth" as described in Presentation section). Roots are thin and short. There may be multiple periapical pathologies. Radicular dentin dysplasia
This sub-type is used in place of Shields dentine dysplasia type I, in which only the roots of the teeth are affected. Both primary and permanent teeth are affected. The teeth appear normal clinically. Radiographically, the roots are shorter and fused together with a rounded apex. Presentation
Clinical presentation
Clinical features include:

Discoloured teeth - teeth may be amber, brown, blue or opalescent
Bulbous shape to the tooth crown due to cervical constriction
Tooth wear/Non-carious tooth surface loss (NCTSL) - due to the poorly mineralised dentine, the enamel of the tooth is unsupported and subsequently shears or chips off as it is subjected to biting forces. This exposes the underlying poorly mineralised dentine which is less resistant to wear. Therefore, features of abrasion and attrition may become apparent. Reduction in occlusal vertical dimension (OVD) - this is secondary to the tooth wear/NCTSL.
Drug Information Portal. U.S. National Library of Medicine. Clinical trial number NCT02230566 for "A Phase 3 Study of UX003 Recombinant Human Betaglucuronidase (rhGUS) Enzyme Replacement Therapy in Patients With Mucopolysaccharidosis Type 7 (MPS 7)" at ClinicalTrials.gov