Wisdom teeth, the third molars at the back of the mouth, are the last adult teeth to come in. Most people have four wisdom teeth — two on the top and two on the bottom. When wisdom teeth become impacted, they don't have enough room to emerge or develop in the usual way. Impacted wisdom teeth can cause pain, damage other teeth and lead to other dental problems. Sometimes they don't cause any problems. But because wisdom teeth are hard to clean, they may be more prone to tooth decay and gum disease than other teeth. Impacted wisdom teeth that cause pain or other dental problems usually are taken out. Some dentists and oral surgeons also recommend taking out impacted wisdom teeth that don't cause symptoms to prevent future problems.