While brushing teeth is a universal modern practice, its prominence in China reflects broader societal shifts. Historically, Chinese dental hygiene involved methods like chewing on willow twigs (which have natural cleaning properties) or using salt to rub the teeth. The widespread adoption of the toothbrush and toothpaste is a 20th-century phenomenon, mirroring global trends and China's increasing focus on public health and modern living standards. Today, dental hygiene is strongly promoted in China through public service announcements and education in schools. The concept doesn't carry a deep philosophical weight like 关系 (guānxi), but it is a clear indicator of personal upkeep and modernity. For a learner, using 刷牙 (shuāyá) correctly shows an understanding of everyday, contemporary Chinese life. It's a simple action, but one that connects you to the daily rhythm of hundreds of millions of people.
刷牙 (shuāyá) is used exactly as you would expect “to brush teeth” to be used in English. It's a fundamental part of describing your morning or evening routine.