Metaphysics says that it is better for children to have upper teeth or lower teeth now.

There is no metaphysics, but it is generally a folk saying. Physiologically speaking, most children will grow their teeth first. Of course, there is nothing wrong with growing their teeth first. From the surface, only the shape and number of teeth are judged. The more square and tidy the shape, the better. It is lucky to have more than 28 teeth. Of course, this rule does not apply to children, because children will change their teeth after teething.