**Core Concept**
Dentinogenesis imperfecta (DI) and amelogenesis imperfecta (AI) are two distinct genetic disorders that affect tooth development, specifically the formation of dentin and enamel, respectively. These conditions are characterized by abnormalities in the mineralization and structure of the affected tooth tissues.

**Why the Correct Answer is Right**
Dentinogenesis imperfecta is a condition that affects the formation of dentin, a calcified tissue beneath the enamel of the tooth. In DI, the dentin is poorly mineralized, leading to its characteristic blue-gray discoloration. This is in contrast to amelogenesis imperfecta, which affects the formation of enamel, the hard outer layer of the tooth. Enamel is not calcified in the same way as dentin, and its development is influenced by different genetic and environmental factors. The key difference between DI and AI lies in the specific cellular and molecular mechanisms that regulate dentin and enamel formation.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because this option does not specify the correct difference between DI and AI. While both conditions affect tooth development, they involve distinct biological processes.
**Option B:** Incorrect because this option is vague and does not accurately describe the primary distinction between DI and AI.
**Option C:** Incorrect because this option may be true for some cases of DI, but it does not capture the fundamental difference between DI and AI.

**Clinical Pearl / High-Yield Fact**
Dentinogenesis imperfecta is often associated with other systemic conditions, such as osteogenesis imperfecta, a disorder of bone fragility. Patients with DI may exhibit additional symptoms, including blue-gray discoloration of the teeth, brittle teeth, and other skeletal abnormalities.

**Correct Answer: D. Both conditions are hereditary, but dentinogenesis imperfecta is associated with defects in the DSPP gene.**