If teeth are not cleaned properly, a sticky layer called plaque builds up on their surface, and this can lead to tooth decay. Fig. 6.1 shows a section cut t...
Question 1 Report
If teeth are not cleaned properly, a sticky layer called plaque builds up on their surface, and this can lead to tooth decay. Fig. 6.1 shows a section cut through a tooth on which a layer of plaque has formed. The outer tissue labelled S forms the hard covering over the crown of the tooth, and the diagram also shows the softer tissues that lie beneath this hard outer layer. Bacteria living in the plaque can damage the tooth over a period of time. Use Fig. 6.1 and your knowledge of dental health to answer the questions.
(a) Name the hard tissue labelled S that covers the crown of the tooth. [1]
(b) Describe how bacteria in the plaque cause tooth decay. [3]
(c) State two ways in which a person can reduce the risk of tooth decay. [2]
(d) Explain how fluoride in toothpaste helps to protect the teeth. [2]
(e) State one reason why regular dental check-ups are recommended. [1]
Answer Details
(a) Tissue S [1]. S is enamel [1], the hard tissue that covers the crown of the tooth.
(b) How plaque bacteria cause decay [3]. Bacteria in the plaque feed on sugar left on the teeth [1]; as they respire they produce acid [1]; the acid dissolves/attacks the enamel, and if it reaches the softer tissue beneath, decay sets in [1].
(c) Two ways to reduce the risk of decay [2]. Any two of: brush the teeth regularly with fluoride toothpaste; reduce the amount of sugar in the diet; visit the dentist regularly [2]. Removing plaque and limiting sugar starves the bacteria and removes the acid.
(d) How fluoride protects teeth [2]. Fluoride strengthens the enamel [1], making it more resistant to attack by acid [1].
(e) One reason for regular check-ups [1]. So that decay can be detected and treated early, before it gets worse [1].
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