The third molar, commonly known as a wisdom tooth, is the final set of molars to emerge in the permanent dentition. These teeth are positioned at the very back of the mouth, typically with one in each corner of the upper and lower jaws. Their eruption, often between the late teenage years and early twenties, is why they are called “wisdom teeth.”
Development and Eruption
The development of third molars begins between the ages of 6 and 12 years, with root formation starting around 16 years of age. These teeth make their appearance in the mouth between the ages of 17 and 22 years, a period when jaw growth is largely complete. Evolutionarily, these molars benefited ancestors with larger jaws and coarser diets, necessitating additional grinding surfaces.
Human jaws have become smaller over time, likely due to changes in diet and food preparation. This evolutionary shift means modern humans have insufficient space in their dental arches for these late-erupting teeth. Third molars are considered vestigial structures, having lost their original function and no longer consistently needed for chewing. This lack of space is a primary reason their eruption can lead to various complications.
Common Complications
A primary issue with third molars is impaction, occurring when the tooth is prevented from erupting fully due to obstruction by adjacent teeth, bone, or soft tissue. This can manifest as a full bony impaction, where the tooth is entirely encased within the jawbone, or a soft tissue impaction, where only gum tissue covers the tooth. Impacted molars are a significant reason for third molar extractions.
Pericoronitis is another problem, an inflammation or infection of the gum tissue surrounding a partially erupted wisdom tooth. This condition arises when bacteria and food debris become trapped beneath the gum flap, leading to pain, swelling, and sometimes difficulty opening the mouth. Partially erupted molars that do not participate in chewing may also be recommended for removal.
Third molars can also contribute to other issues, including the formation of cysts or tumors around the impacted tooth. Their position at the far back of the mouth makes them difficult to clean effectively, increasing the risk of dental decay (caries) and gum disease (periodontitis) in both the third molar itself and the adjacent second molar. Symptoms include localized jaw pain, swelling, bad breath, and an unpleasant taste in the mouth.
Evaluation and Removal
Evaluating third molars involves a thorough clinical examination combined with radiographic imaging. Dentists use panoramic X-rays, which provide a comprehensive view of all teeth, including developing or erupted third molars, and their relationship to surrounding anatomical structures like nerves and the maxillary sinus. This imaging helps assess the tooth’s position, root development, and the presence of any impaction or pathology.
Removal is recommended when existing problems are identified, such as persistent pain, recurrent infections, cysts, or damage to neighboring teeth. If a third molar is completely impacted and shows signs of pathology, or if there is a high likelihood of future complications based on its position, removal may be advised. Early detection and removal of impacted third molars, particularly between the ages of 16 and 25, can help prevent future complications.
Removal is not universally necessary for all third molars. If a wisdom tooth is healthy, has fully erupted into a functional position, is properly aligned, and can be effectively cleaned, it can be maintained like any other tooth. In such cases, regular dental check-ups and good oral hygiene practices are sufficient for its continued care.