The perceived “hole” behind a tooth is concerning, but it can represent anything from normal, harmless anatomical structures to serious dental disease. Determining the nature of this irregularity requires professional examination, as what feels like a simple gap may signal progressive infection or structural failure. Understanding the potential causes—including natural contours, temporary healing sites, tooth decay, physical damage, and gum disease—is the first step toward seeking appropriate care.
Distinguishing Normal Anatomy from Abnormal Gaps
The area directly behind the last molar, particularly on the lower jaw, contains a normal anatomical feature known as the retromolar pad. This small, rounded area of dense tissue sits at the end of the jaw ridge. It may feel like a soft mound or a slight depression, which can be mistakenly interpreted as a cavity or a gap. These natural contours vary in size and prominence between individuals.
A second common reason for feeling a hole is the temporary healing site following a tooth removal. When a tooth is extracted, the remaining socket is initially a deep void that fills with a blood clot to start healing. While gum tissue often closes over the site within a few weeks, the underlying bone can take several months to completely fill in. The area may feel like a persistent indentation or hole even when healing is progressing normally.
Holes Caused by Dental Caries and Structural Damage
A true hole in the hard structure of the tooth is most frequently the result of dental caries, commonly known as a cavity. This is a progressive destruction of the tooth’s mineralized tissue caused by acid-producing bacteria. Decay often initiates in hard-to-clean areas, such as the deep grooves or the backside (lingual surface) of the molars.
As acid dissolves the protective enamel and penetrates the softer underlying dentin, the surface layer eventually collapses, creating a physical cavitation. This hole can be easily detected by the tongue, feeling rough or sticky, and serves as an efficient trap for food debris and bacteria. The location behind the tooth makes it difficult to keep clean, accelerating the destructive process.
Structural damage to the tooth or a restoration can also create an abrupt, noticeable gap. A filling, which is material used to repair a previous cavity, can weaken over time due to constant chewing pressure or recurrent decay underneath it. When a filling cracks, leaks, or falls out entirely, it leaves a large, deep void. A fractured cusp, one of the pointed projections on the molar, can also break off due to biting hard objects or clenching. This fracture leaves a sharp, jagged edge and a missing piece of the tooth, which feels like a hole or deep notch.
Gaps Resulting from Gum Disease and Infection
When the perceived hole is not in the tooth structure but rather a pocket alongside or behind it, the cause is often advanced gum disease, or periodontitis. This condition begins when bacterial plaque accumulation causes inflammation and swelling of the gum tissue. Chronic inflammation causes the gum tissue to detach from the tooth root, creating a deepened space called a periodontal pocket.
The depth of this pocket is measured in millimeters, and as it progresses, it feels like a significant gap or separation between the tooth and the gum line. This pocketing is dangerous because it allows plaque and hardened tartar to spread further down the tooth root, where routine cleaning cannot reach. This process also leads to the loss of the underlying jawbone that supports the tooth, increasing the perceived size of the gap.
Another serious cause is a dental abscess, an infection at the tooth root or surrounding bone, which can create a drainage channel called a fistula or sinus tract. This channel is the body’s way of relieving pressure by guiding pus to the surface. A fistula appears as a small, often painless, pimple-like bump on the gum tissue behind the tooth, which may periodically release fluid. The presence of a draining fistula indicates a persistent infection that requires immediate professional treatment.
Next Steps and Seeking Professional Care
Any sensation of a new or persistent hole behind a tooth warrants a visit to a dental professional for an accurate diagnosis. If the observation is accompanied by severe pain, swelling, fever, or continuous discharge, the situation is urgent, signaling an active infection or a large structural failure. Conversely, if the perceived hole is painless and feels like a smooth indentation following an old tooth extraction, it is likely a normal healing contour, but a checkup is still beneficial.
The dentist will typically use a small instrument to gently probe the area and measure the depth of any pockets. Dental X-rays will be taken to evaluate the hard tissues, detecting decay between teeth, assessing bone loss from periodontitis, and identifying infections at the tooth root. Treatment will be matched to the diagnosis, ranging from a simple filling for a small cavity to deep cleaning (scaling and root planing) for periodontal pockets, or root canal therapy or extraction for an abscessed tooth.