Why is Calvin using toothpaste even if they were using powder for brushing teeth, not paste in 1920s?

lackadaisycats:

Hmm? Toothpaste was old news by the 1920s. It was even fluoridated.
It has been around since the late 1800s, initially as ‘dental cream’. It became available in tubes in 1908, and it began overtaking tooth-powder as the popular choice ~1915.