A dental crown, often called a cap, is a custom-made restoration that completely covers a damaged tooth, restoring its shape, size, strength, and appearance. Crowns serve as a protective shield for teeth too compromised for a standard filling. Concerns often stem from the necessary changes to the tooth structure and the potential for temporary discomfort afterward. Understanding the clinical need, material properties, and maintenance helps separate the facts from common anxieties.
When a Dental Crown Is Medically Necessary
A crown becomes a necessity when the structural integrity of a tooth is severely compromised. This is frequently the case after a root canal procedure, where the tooth becomes brittle and requires full coverage to prevent fracture under normal chewing forces. The crown acts as a structural reinforcement, distributing forces across the remaining tooth structure.
Crowns are also indicated when a tooth has a fracture or crack that extends deep into the dentin. Furthermore, teeth with extensive decay or those that have lost significant structure due to a very large, failing filling cannot be reliably restored with composite material. The crown prevents catastrophic breakage by fully encasing the weakened tooth structure.
Potential Material and Structural Concerns
The choice of crown material involves a trade-off between strength, aesthetics, and potential secondary effects. Regardless of material, a crown’s fit is paramount, as an improper margin—where the crown meets the tooth—can allow bacteria to infiltrate and cause decay underneath the restoration.
Porcelain-Fused-to-Metal (PFM)
PFM crowns offer excellent durability due to their metal substructure. However, they can sometimes develop a visible dark line at the gumline if the gum tissue recedes, caused by the underlying metal showing through or staining the adjacent gum tissue.
All-Ceramic Options
All-ceramic options like lithium disilicate (E-max) and zirconia are popular for their natural appearance and high strength. E-max crowns provide exceptional translucency, making them ideal for front teeth, but they are generally less robust than zirconia. Conversely, zirconia is highly fracture-resistant, suitable for molars, but its hardness can lead to accelerated wear on the opposing natural teeth if not polished correctly.
Gold Alloys
Gold alloy crowns require the least removal of natural tooth structure and are gentle on opposing teeth. Their metallic color limits their use primarily to back teeth.
Common Post-Procedure Sensitivities and Complications
Temporary sensitivity to hot or cold temperatures is common immediately following permanent crown placement. This is usually due to inflammation within the tooth’s pulp tissue, irritated by the preparation and cementation process. This post-operative sensitivity should subside naturally within a few days to a week as the tissue heals.
A more persistent issue is sensitivity caused by a malocclusion, where the new crown sits slightly too high. This excess pressure on the tooth during biting irritates the nerve and must be corrected by a dentist with a quick adjustment.
Gum irritation (gingivitis) can also occur if the crown margin is poorly contoured or extends too far below the gumline, creating an area where plaque accumulates easily. In rare cases, the preparation process can severely damage the pulp, leading to irreversible pulpitis, necessitating a root canal procedure to save the tooth.
Maintaining Crown Longevity and Recognizing Failure
Dental crowns are not permanent and typically have an expected lifespan ranging from five to 15 years, depending on material and patient care. The primary reason for failure is the development of new decay, known as recurrent caries, at the vulnerable margin where the crown meets the remaining tooth structure. The natural tooth beneath the crown remains susceptible to bacteria.
Longevity is significantly impacted by patient habits, such as teeth grinding (bruxism) and poor oral hygiene. Bruxism can cause the crown to chip, crack, or loosen, while insufficient cleaning allows plaque to accumulate at the margin.
Signs that a crown is failing include noticeable loosening, sudden pain when chewing, or a visible dark line or gap appearing at the gumline. Regular dental check-ups are essential for detecting issues like decay or poor fit early, ensuring the maximum possible lifespan for the restoration.