The anatomical structure responsible for linking the dentin to the dental pulp is the odontoblast processes.

- The dental pulp is the innermost part of the tooth, containing nerves and blood vessels essential for tooth vitality.
- Surrounding the pulp is the dentin, a hard tissue that provides structural support.
- Odontoblasts are specialized cells located at the periphery of the dental pulp. They are responsible for the formation of dentin.
- Each odontoblast extends a cellular projection called the odontoblast process into the dentinal tubules within the dentin.
- These odontoblast processes serve as a direct connection between the dentin and the dental pulp, facilitating nutrient and signal exchange.
- In contrast, dentinal tubules are microscopic canals within dentin that house the odontoblast processes but do not themselves link directly to the pulp.
- Hertwig’s epithelial root sheath is involved in root formation, not the linkage between dentin and dental pulp.
- Periodontal ligament fibers connect the tooth root to the alveolar bone, not the dentin to the pulp.

In summary, the odontoblast processes physically link the dentin and the dental pulp by extending through the dentinal tubules, playing a crucial role in tooth physiology and repair.

Reference: Ten Cate's Oral Histology, 9th Edition, Chapter 3: Dentin and Pulp, Pages 50-52