Radiographic presentation
Radiographic features include:

Bulbous shape of tooth crown with pronounced cervical constriction
Small pulp, or total pulp obliteration
Small or obliterated root canal
Presence of pulp stones
Narrow and small roots
Periapical radiolucency without any evidence of clinical pathology such as tooth decay (dental caries)

Presentation by sub-type of Dentinogenesis Imperfecta
Clinical and radiographic features can be categorised by the sub-type of dentinogenesis imperfecta (see Shields Classification in the Classification section):

Type I
Clinically, both the baby (primary) and adult (permanent) teeth often appear amber coloured and translucent, and show signs of severe attrition. Primary teeth have a more obvious appearance as they have a thinner layer of enamel overlying dentine, hence the abnormal color of dentine is more noticeable.Radiographically, affected teeth have short and narrow roots, and obliterated pulps due to dentine hypertrophy before or shortly after tooth eruption.The severity of these features is variable, with some teeth presenting with total obliteration of the pulp, while other teeth appear to have normal, healthy dentine.Some type I cases present with no clinical findings, with only radiographic abnormalities. Type II
Type II has a similar clinical and radiographic appearance to type I with some distinguishing features:

Bulbous crowns are common with pronounced cervical constriction
All teeth in the mouth are affected, with severe abnormalities present in both the baby (primary) and adult (permanent) teeth. This is in contrast to type I where the presentation is more variable
Rarely, individuals exhibit sensorineural hearing loss.
Type of DI with similar dental abnormalities usually an autosomal dominant trait with variable expressivity but can be recessive if the associated osteogenesis imperfecta is of recessive type.Recent genetic studies have identified that mutations in the genes coding for the collagen type 1 proteins, COL1A1 and COL1A2, are associated with this type of DI.Not all individuals with OI have dentinogenesis imperfecta, and the prevalence of DI varies depending on the sub-type of OI:

Higher prevalence of DI among individuals with OI type III and IV at 43-82% and 37-100%, respectively
Lower prevalence of DI among individuals with OI type I at 8-40%
No data available for other OI sub-types

Type II
DI not associated with OI. Occurs in people without other inherited disorders (i.e. Osteogenesis imperfecta). It is an autosomal dominant trait. A few families with type II have progressive hearing loss in addition to dental abnormalities. Also called hereditary opalescent dentin. Type III
Brandywine isolate. This type is rare with occurrences only in the secluded populations in Maryland, USA. Similar to DI type II, this type is also not associated with OI. Its predominant characteristic is bell-shaped crowns, especially in the permanent dentition. Unlike Types I and II, it involves teeth with shell-like appearance and multiple pulp exposures.Mutations in the gene coding for the dentine sialophosphoprotein (DSPP) are associated with DI type II and III. DSPP is a polypeptide which gives rise to 3 proteins; dentine sialoprotein (DSP), dentine glycoprotein (DGP), and dentine phosphoprotein (DPP).