Impacted wisdom teeth. Coloured pan-oral X-ray of the mouth of a young adult, showing impacted wisdom teeth. Here, highlighted in yellow, are the two affected wisdom teeth of the lower jaw, seen at each end of the tooth row. They are growing skew, impacting on the second molars lying beside them. If these wisdom teeth are not surgically removed, their further growth will seriously affect many teeth in the lower jaw. Adults have four wisdom teeth (known as third molars), one each in the rearmost region of the upper and lower jaws. They erupt between the ages of 17 and 21. A pan-oral X-ray provides a view of all the teeth in the mouth.