New Delhi, Feb. 21 -- Most of us brush our teeth on autopilot every day, and perhaps with a little more care after a sugary dessert or a skipped dental appointment. It is routine and rarely treated as something that shapes the arc of our lives. But scientists are now beginning to look at this most mundane habit differently. A growing body of research now suggests that people who maintain good oral hygiene and seek regular dental care tend to live longer. Tooth loss, in particular, has emerged as a quiet signal of ill health, with older adults who lose several teeth facing higher risks of heart disease, frailty and other systemic illnesses.

The explanation lies in the slow, cumulative ways the mouth speaks to the rest of the body. Untreat...