Seniors tend to have dry mouth because their salivary glands have degenerated over the years. Chances of dental caries increase because there isn't enough saliva to neutralize the acid produced by dental plaque. Some of them also take anti-hypertensive and anti-depressant drugs which will cause dryness in the mouth.

Amount of salivary production will significantly decrease for those who had received radiotherapy in the head and neck area. Therefore, chances of having dental caries will greatly increase because there isn't enough saliva to neutralize the acid produced by dental plaque after they eat and drink.