Dental Assistant Practice Exam

Dentinal tubules are present in which part of the tooth?

1. Enamel

2. Dentin

3. Clinical crown

4. Cemento-Enamel Junction

The correct answer is: Dentin

Dentin is the part of the tooth that contains dentinal tubules. These tubules are microscopic channels that run through the dentin and house the cytoplasmic processes of odontoblasts, which are cells responsible for forming dentin. The presence of these tubules is crucial as they facilitate the transmission of sensations, nutrients, and fluid movement within the tooth. Enamel, while being the hard, outer layer of the tooth that protects against decay, does not contain dentinal tubules. It is acellular and is primarily composed of hydroxyapatite crystals. The clinical crown is the part of the tooth that is visible above the gum line but does not reference a specific tissue composition in terms of cells or tubules. The cemento-enamel junction is the area where the enamel meets the cementum that covers the roots of the teeth. It does not possess dentinal tubules either, as it includes enamel and cementum, both distinct from dentin. Therefore, the presence of dentinal tubules is a characteristic feature unique to dentin, underscoring its role in sensory perception and the overall health of the tooth.