Which one of the following is an effect that often occurs in older patients due to age-related changes to their teeth?

The correct alternative highlights a common phenomenon among older individuals that leads to a decrease in tooth sensitivity. As people age, several factors contribute to this reduction. One significant factor is the natural wear and tear on the teeth, including the thickening of the enamel and the secondary dentin formation. This process can provide a sort of protective barrier, making the nerves less responsive to stimuli such as temperature changes or certain foods.

In contrast, other options represent conditions that may not typically decrease with age. Occlusal caries, for instance, are a type of cavity commonly found in older adults due to various factors, including prolonged exposure to plaque and a decrease in oral hygiene effectiveness. Root curvature and the whitening of teeth are also not universally accepted outcomes of aging, with root curvature being more associated with individual anatomical variations rather than a direct consequence of aging. Whitening of teeth generally becomes less common as staining occurs and enamel thins, resulting in a yellower appearance instead. Thus, understanding the biological changes occurring in the dentition as patients age is crucial, and the decrease in tooth sensitivity is a notable effect often observed in older demographics.