101 Facts About Ageing #60: Ageing Teeth

As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.

For many people, the stereotypical elderly person has false teeth. According to the last NIH survey, over a quarter of US adults had no remaining natural teeth. Fortunately, tooth loss in old age is preventable in the majority of cases, as it is usually the result of periodontal disease, which is not caused by biological ageing. Rather, periodontal disease slowly gets worse if left untreated for decades, and may not lead to very severe problems until the seventh decade of life and beyond. Similarly, the teeth accumulate wear and tear over a lifetime of chewing, which contributes to the thinning of the enamel (the hard, outer layer of the teeth). These aspects of tooth ageing are not related to the ageing process itself, but age-related changes (like reduced secretion of saliva, which protects teeth from decay) can accelerate them.

With increasing age, an increasing number of stem cells (able to give rise to more specialised cell types) within the tooth pulp enter senescence – a state in which they are no longer able to divide. This, alongside other age-related changes such as the build-up of fatty waste, leads to the loss of specialised cell types within the pulp. This includes the loss of odontoblasts, the cells responsible for producing dentin, which forms a hard layer underneath the enamel. As the density of odontoblasts declines with age, the dentin weakens and becomes less resistant to damage. Dentin also becomes more yellow with age, which shows through the increasingly thin layer of enamel and makes teeth appear less white.

Unlike the other layers of the tooth, the cementum, which surrounds the roots, thickens with age, while the gums may start to recede. This exposes the cementum, which is not resistant to acidic conditions, and thereby increases the risk of root decay.

Nerves within the teeth shrink with age, making them less sensitive. This means that older people are less likely to notice signs of tooth decay early, and more prone to damaging their teeth by biting on something hard with too much force.