Clinical note: The oral cavity has a large and varied bacterial flora. Bacteria may accumulate and form a layer (plaque) on a tooth, releasing acids that demineralize the enamel and dentine and produce dental cavities. Other bacteria proliferating in the gingival cleft may destroy the periodontal ligament, cause resorption of alveolar bone, and loosening of teeth.

Ground Tooth:

Which hard component of the tooth most resembles bone histologically?

What do the parallel line (rods or prisms) in enamel represent?

Examine a section of developing tooth. See if you can Identify

• The dental pulp,
• Odontoblasts,
• Dentine,
• Enamel
• Ameloblasts

Explain the relationship of ameloblasts and odontoblasts to the formation of enamel and dentine.

Which layer disappears before eruption of the tooth and which layer persists?

Now for the nervous system.