A dental crown is a tooth-shaped cap placed over a damaged tooth to restore its form, size, and strength. The tooth underneath remains alive, containing a pulp chamber with nerves and blood vessels that react to external stimuli. Sharp, brief pain in a crowned tooth upon cold exposure indicates nerve irritation. This sensation, known as dentin hypersensitivity, occurs when the underlying dentin is exposed, allowing temperature changes to stimulate the nerve.
Common Reasons for Crown Sensitivity
Initial sensitivity immediately following crown placement is often due to post-cementation inflammation. The procedure involves preparing the tooth, which temporarily irritates the pulp tissue housing the nerve endings. This short-term inflammation is a normal biological response that typically resolves within a few weeks as the nerve calms down.
A persistent or delayed onset of cold sensitivity suggests a deeper problem, such as an issue with the crown’s fit. If the crown does not fit precisely at the margin where it meets the tooth structure, it can lead to micro-leakage. This tiny gap allows oral fluids, bacteria, and temperature fluctuations to bypass the crown and reach the exposed dentin, causing sharp sensitivity.
Another cause of delayed cold sensitivity is the development of new or recurrent decay beneath the crown. The crown margin is a vulnerable area where plaque can accumulate if not cleaned properly, leading to a cavity that compromises the seal. This hidden decay progresses toward the pulp, causing the nerve to become reactive to cold stimuli. Since the crown hides this process, the primary warning sign is often the onset of cold pain.
Sensitivity can also be related to occlusal trauma, which is how your teeth meet. If the new crown is slightly “high” or uneven, it bears excessive force during chewing or clenching. This constant pressure irritates the tooth’s ligament and nerve, resulting in a throbbing sensation or heightened sensitivity to temperature changes. Addressing this often requires a minor adjustment to reshape the crown’s biting surface.
Immediate Relief and At-Home Management
For temporary or mild cold sensitivity, specialized desensitizing toothpastes can manage the discomfort. These products contain active ingredients that work by either calming the nerve or physically blocking the microscopic pores in the dentin. Ingredients like potassium nitrate depolarize the nerve fiber, preventing it from transmitting the pain signal to the brain.
Other compounds, such as stannous fluoride or calcium sodium phosphosilicate, create a mineral layer to occlude the exposed dentinal tubules. This physical barrier prevents the fluid movement within the tubules that triggers the pain response to cold. Consistent, twice-daily use is necessary for the ingredients to build up and provide lasting relief.
To avoid further nerve irritation, adopt gentle brushing techniques using a soft-bristled toothbrush. Brush with soft, circular motions, paying attention to the gumline where the crown meets the tooth, and avoid aggressive scrubbing that could cause gum recession. Temporarily adjust your diet to avoid extreme temperature foods and drinks, such as ice water or very hot coffee, and highly acidic items like citrus fruits or sodas.
If sensitivity is accompanied by a dull ache, over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can provide temporary relief. Ibuprofen works by inhibiting the cyclooxygenase (COX) enzyme, which reduces the production of prostaglandins that mediate pain and inflammation in the pulp tissue. This addresses the inflammatory component of the pain, offering short-term comfort until the issue resolves or is professionally treated.
When Professional Treatment Is Necessary
If cold sensitivity persists beyond a few weeks, worsens, or includes spontaneous pain, professional diagnosis is required to identify the cause. A dentist performs a thorough clinical examination, often using articulating paper to check for high spots on the crown that may cause occlusal trauma. They then use diagnostic tools to assess the health of the pulp.
The thermal test, which involves applying a cold stimulus, gauges the nerve’s response and helps differentiate temporary irritation from irreversible damage. X-rays detect hidden issues, such as micro-leakage, recurrent decay beneath the crown, or signs of infection at the root tip. For sensitivity caused by a high spot, the dentist performs a selective grinding procedure to slightly reshape the crown’s biting surface.
If minor decay is found, the dentist may remove the crown, clean the area, and place a new, well-fitting crown. If diagnostic tests indicate the pulp is irreversibly inflamed or infected, a root canal is the definitive treatment to save the tooth. This procedure involves accessing the pulp chamber, removing the infected nerve tissue, disinfecting the inner canals, and sealing them. A root canal eliminates the pain source by removing the nerve, resolving cold sensitivity. If the crown is ill-fitting or decay is extensive, the crown must be fully replaced to ensure a proper seal. Treatment depends on the underlying diagnosis, emphasizing the need for professional evaluation.