This swelling is rather scary but can occur to any tooth following a very deep cleaning. There sometimes is a flap of skin over the wisdom teeth (if they arent fully erupted) called the operculum. When the gum heals over the cleaned site, sometimes some bacteria gets trapped and it multiplies creating pus and pressure/inflammation. Your body tries to fight this with inflammation and swelling. The best treatment is a course of antibiotics, ideally lancing if there is a ball of pus.

Alternatively mouthrinsing with savacol or any chlorhexidine based antiseptic and hot salty water can reduce the swelling, and let blood flow into the area to fight the problem.

DONT PUT ICE ON IT. It only prevents blood flow and often creates a really nasty ball of pussy infection