The Chalfens are mentors to Irie and Magid, and Joyce works hard to guide Millat (as well as Clara and Alsana). These are not always the easiest mentor-mentee relationships ever, but the Chalfens do assume this role.
It's Joyce Chalfen who finally gets brothers Magid and Millat to speak again after her husband Marcus brought Magid back from Bangladesh. For Irie, the Chalfens show her a way of life that she didn't really know was possible. They are rooted in the present; they talk about interesting things.
The Chalfens also cause a lot of conflict. But White Teeth is probably not the first novel that has mentors who are controversial people.