A toothache that appears and disappears can be confusing, often leading people to assume the problem has resolved itself. This fluctuation in discomfort is a hallmark of many dental issues and should be taken as a signal, not a reprieve. The intermittent nature of the pain is tied to specific biological mechanisms, including external triggers, temporary cycles of internal inflammation, or sources outside the tooth entirely. Fluctuating pain always indicates an underlying issue that requires professional attention.
Pain Triggered By External Stimuli
Pain that comes and goes is often directly linked to an external stimulus, meaning discomfort is only present during or immediately following a specific action. This often occurs when the protective outer layers of the tooth, the enamel and cementum, are compromised, exposing the underlying dentin. The dentin is riddled with microscopic tubes that contain fluid, and when exposed, this fluid moves quickly in response to temperature changes or high sugar concentrations.
This rapid fluid movement triggers the nerve fibers within the pulp, causing a sharp, short-lived sensation known as dentine hypersensitivity. The pain immediately resolves because the nerve is not inflamed; it is merely reacting to fluid displacement. A more serious issue, like a hairline crack in a tooth, may cause “cracked tooth syndrome.” Pain occurs only when the fracture opens briefly under chewing pressure, specifically upon biting or releasing. The pain stops as soon as the pressure is removed and the fracture closes.
Bruxism, or teeth grinding, is another fluctuating cause of pain, concentrating high forces on the teeth and jaw muscles. This grinding primarily happens during sleep or periods of intense stress. The resulting ache is often most severe in the morning due to night-long trauma, but fades throughout the day as the muscles relax. This cycle of pressure and relief dictates the pain’s intermittent nature.
Internal Inflammation and Recovery Cycles
When pain cycles are not tied to an immediate action like chewing or temperature exposure, they are driven by internal inflammation within the tooth’s pulp. The pulp contains the tooth’s nerve and blood vessels, and when bacteria reach it through deep decay or a fracture, the tissue swells. This condition is called pulpitis. Because the pulp is encased in the rigid dentin, even slight swelling causes immense pressure on the nerve.
This is seen in reversible pulpitis, where inflammation has begun but the body’s defenses temporarily manage the swelling. The nerve is irritated, causing pain, but the body’s natural mechanisms, such as increased lymph flow and temporary reductions in blood volume, slightly lower the internal pressure. This temporary reduction causes a lull in the discomfort, giving the false impression that the tooth is healing.
The source of the irritation, such as decay or bacterial presence, has not been removed, so the inflammatory cycle will inevitably repeat. The pain will return spontaneously, often without a direct trigger, as the tissue swells again. This is why the pain comes and goes over periods of hours or days, representing the temporary balance between inflammatory pressure and the pulp’s transient attempts to recover.
Non-Dental Sources of Fluctuating Pain
Not all pain felt in the teeth originates from the teeth themselves; non-dental sources can cause fluctuating discomfort. Referred pain, where discomfort is felt in the jaw or teeth but originates elsewhere, frequently causes confusing, intermittent toothache. Sinus infections are a prime example, as the roots of the upper back teeth often extend close to the maxillary sinuses.
When the sinuses become inflamed or congested, the resulting pressure can press directly on the nerve endings that supply the upper teeth. The intensity of this pain often changes with head position, such as bending over, or with the level of congestion, making the discomfort appear to fluctuate randomly. Unlike a true toothache, this pain typically affects multiple upper teeth rather than a single one.
Temporomandibular Joint (TMJ) disorders are a common non-dental cause, where issues with the jaw joint or surrounding muscles radiate pain to the teeth. This discomfort is often worse after periods of heavy use or when jaw muscles have been tightly clenched, such as during a stressful day or sleep. The pain then subsides during periods of rest, creating a clear “come and go” pattern that mirrors the activity level of the jaw.
When Fluctuating Pain Becomes Urgent
While intermittent pain signals an existing problem, a change in the pain’s pattern signals progression to a more serious stage. The transition from sharp, intermittent pain to a dull, constant, throbbing ache is a warning sign, indicating that inflammation has progressed to irreversible damage. This constant pain suggests that the pressure on the nerve is now unrelenting.
A deceptive sign is the sudden disappearance of pain that was previously severe. This is often not a sign of healing, but rather that the tooth’s nerve tissue has died, relieving the internal pressure. If this pain relief is followed by swelling in the face, jaw, or gums, it means the infection has spread outside the tooth’s root and an abscess is forming. This situation requires immediate professional intervention.
Other urgent signs include a fever accompanying the tooth pain, suggesting a spreading systemic infection, or difficulty swallowing or breathing. Swelling that extends into the face or neck signals a deep-seated infection that may compromise the airway. These symptoms, even when the tooth pain itself seems to fluctuate, indicate that the underlying dental issue has become a severe health concern.