Final answer:
The outer layer of a tooth embedded in the gums is made of cementum, which covers the root and assists with anchoring the tooth in the jaw.
Step-by-step explanation:
The outer layer of a tooth where it is embedded in the gums is made of cementum. This layer covers the root of the tooth and works in conjunction with the periodontal ligament to anchor the tooth securely in the jaw bone. Unlike the crown of the tooth, which is covered by enamel, the root's outer layer is cementum, which is not as hard as enamel but still provides a sturdy covering over the dentin. The pulp cavity, containing nerves and blood vessels, is surrounded by dentin and is not the outermost layer of any part of the tooth.