The relationship between wisdom teeth and crowding of the lower front teeth has been debated for many years, and it is still debated to this day.
Most of the debate stems from observations former patients have of shifting following braces. While it seems to make logical sense that a wisdom tooth angled towards the other teeth would have a pushing and crowding tendency, there is evidence that this may not in fact be completely true (J Am Dent Assoc 123;8:75-79).
The study showed no difference in the amount of pressure exerted when wisdom teeth were present or extracted. They also showed that there was no less crowding on the lower front teeth in patients that had their wisdom teeth out compared to those that had not. The author stated that removal of the wisdom teeth may be needed in certain situations, but that extracting for the sole purpose of preventing shifting is unjustifiable.
What is the bottom line in this debate? There are better reasons to extract the wisdom teeth than to prevent crowding. Most patients do not have enough room for their wisdom teeth, so they may stay in the jaw (impacted), or if they do erupt, they may be in a poor position or difficult to keep clean.
Whether or not the wisdom teeth have been removed, all patients have the possibility of movement and shifting of their teeth as they get older (Am J Orthod Dentofacial Orthop 1988 May;93(5):423-8). Therefore, long-term wear of a retainer would be recommended to help prevent shifting. If the retainers are worn regularly, the debate about wisdom teeth causing shifting or not is mostly irrelevant.
Removal of the wisdom teeth may give some patients a false sense of security. As was just mentioned, changes in the teeth can happen as a person ages even if the wisdom teeth have been removed.