Which of the following is the hardest part of a tooth? A. Pulp B. Enamel C. Dentine D. Pulp cavity
Hint: A tooth consists of enamel, dentin, cementum and pulp tissue. Enamel is the outermost part of a tooth which is made of minerals of calcium and phosphate.
Complete Answer: The teeth are the hardest substances of the human body. It plays an important role in chewing food, speech and protecting the mouth. The typical structure of a tooth consists of three parts: root, neck and crown. The root of the tooth is attached with the jaw bone.
Different parts of a tooth are described below. (I) Enamel: It is the hardest part of the tooth. The outermost white part is basically made of calcium hydroxyapatite. (II) Dentine: It is the underlying layer of enamel. It is made of hard tissue which contains microscopic tubes. In absence of enamel, it acts as a pathway for heat and cold to enter into the tooth. (III) Cementum: The tissue that covers the surface of the tooth root. It connects the alveolar bone with the tooth by the help of periodontal ligament. Its hardness is similar to bone. (IV) Dental pulp: The softer and living part of the internal tooth. Blood vessels, lymph vessels and nerve fibres, are located in the dental pulp, supplying nutrients to the dentine. (V) Pulp cavity: The dental pulp cavity exists in the centre of the tooth, through which the dental pulp, called the nerve, runs. (VI) Periodontal ligament: Tissue consisting mainly of the fibrous tissue which helps in holding the teeth tightly against the jaw.
Hence, the correct answer is (B) enamel.
Note: Enamel is covering the crown of the tooth in mammals. - Enamel is a non-living part of the tooth and contains no nerves. - The thickness and density of enamel vary over the surface of the tooth and it is hardest at the biting edges, or cusps. - Hypoplasia is one of the major malformations of enamel in which the amount of matrix is less, so that there is a lack of enamel and another is the hypocalcification, in which there is insufficient calcium and a soft enamel is produced.