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Impacted wisdom teeth either don't erupt at all (and remain within the jaw bone underneath the gum line) or they don't erupt normally. They can get stuck under the gum flap or grow in at an extreme angle — sometimes even horizontally instead of vertically. It's important to remember that impacted wisdom teeth don't always cause problems or symptoms, and don't always need to be removed by a dentist.  It's common to have a combination of fully erupted, partially erupted and impacted wisdom teeth within the same mouth. The longer your wisdom teeth stay in your mouth, the more developed the roots become, making them more difficult to remove if they cause symptoms. Impacted wisdom teeth are not always symptomatic, but when they are, the pain and inflammation tend to be severe. Unlike the mild discomfort that sometimes accompanies normally erupting wisdom teeth, the impacted teeth usually produce severe throbbing pain (in the gums and jaw), swelling, headache, neck stiffness, ear ache and/or reduced ability to open the mouth. If you experience these symptoms, it's not a normally erupting wisdom tooth — see your dentist immediately.  Symptoms that distinguish erupting from impacted teeth is typically a matter of degree. The latter involves more pain and swelling that lasts longer and doesn't usually get better until the tooth is pulled. The discomfort from an erupting wisdom tooth only lasts while the cusps first push through the gum line, whereas impacted teeth cause pain well afterwards or even without being seen. If your wisdom tooth is not erupting vertically in the normal position, you may feel a constant pain or discomfort spreading all over the jaw up to the middle line. Partially erupted or impacted wisdom teeth greatly increase the risk of an infection, which is called pericoronitis. Impacted wisdom teeth can create little spaces underneath the pericoronal flap where bacteria collect and proliferate. Bacteria can eat away at enamel, bone and gum tissue. Common signs of an infected wisdom tooth are: lots of...