Wisdom teeth, commonly known as third molars, are the final set of teeth to emerge in the mouth. These teeth are positioned at the very back, with typically two in the upper jaw and two in the lower jaw. They are named “wisdom teeth” because they appear much later in life than other permanent teeth.
Normal Eruption Timeline
Wisdom teeth generally begin to emerge between the ages of 17 and 25 years. The timing can vary significantly among individuals, with some appearing slightly earlier, around 16, or even later into the late twenties or beyond. Unlike other adult teeth that typically erupt in childhood or early adolescence, wisdom teeth are the last to develop and push through the gums.
Reasons for Non-Eruption
Wisdom teeth often fail to erupt fully or at all, primarily due to a lack of sufficient space in the jaw. The human jaw has evolved to be smaller, frequently leaving inadequate room for these final molars to emerge correctly. When a wisdom tooth is prevented from erupting into its proper position, it is referred to as an impacted tooth. This impaction can occur because of physical barriers, such as other teeth or dense bone, or when the tooth is angled improperly.
Several types of impaction describe the tooth’s angled position:
- Mesial impaction: The wisdom tooth angles forward towards the front of the mouth.
- Distal impaction: The tooth angles towards the back of the mouth.
- Vertical impaction: The tooth is upright but remains trapped beneath the gums or jawbone.
- Horizontal impaction: The tooth lies completely on its side, often pressing against the adjacent molar.
Beyond physical obstruction, genetic factors also play a role in non-eruption. Agenesis refers to the congenital absence of one or more wisdom teeth, meaning they never form at all. Overlying gum tissue or bone can also act as a barrier, preventing a wisdom tooth from breaking through.
Potential Issues from Non-Eruption
When wisdom teeth do not erupt properly, they can lead to various oral health problems, even if they are not causing immediate symptoms. Pain is a common symptom, often localized to the back of the jaw or radiating to the ear or head. Swelling and tenderness in the surrounding gum tissue are also frequently experienced.
One significant issue is pericoronitis, an inflammation and infection of the gum tissue around a partially erupted wisdom tooth. This occurs when a flap of gum, called an operculum, covers part of the tooth, trapping food particles and bacteria beneath it, leading to infection. Left untreated, pericoronitis can cause bad breath, pus discharge, and difficulty opening the mouth.
Impacted wisdom teeth can also damage adjacent teeth by pushing against them, potentially causing resorption or decay. Pressure from an erupting wisdom tooth can contribute to crowding or misalignment of other teeth. Difficult-to-clean areas around partially erupted or impacted wisdom teeth increase the risk of tooth decay and gum disease. In some cases, fluid-filled sacs called dentigerous cysts can form around the crown of an unerupted tooth, which can expand and damage surrounding bone and tooth roots.
When to Seek Professional Advice
Consulting a dental professional is advisable if wisdom teeth have not erupted by the typical age range or if any symptoms arise. Even without symptoms, regular dental check-ups, particularly during the late teens and early twenties, allow dentists to monitor wisdom tooth development. During these visits, dentists conduct a clinical examination and utilize dental X-rays to assess the position of wisdom teeth, identify impaction, and detect potential problems.
Based on the assessment, a dentist can determine the most appropriate course of action. This may involve continued monitoring of asymptomatic wisdom teeth. However, if issues such as pain, infection, or damage to adjacent teeth are present or anticipated, extraction of the wisdom tooth may be recommended. Early evaluation can often lead to simpler removal procedures and faster recovery, as tooth roots are less developed and jawbone density is lower in younger individuals.