Restorative dentistry repairs teeth damaged by decay, fracture, or wear, restoring their function and appearance. The two most common methods are dental fillings and dental crowns. While both treatments save the tooth, they differ significantly in application, the extent of damage they address, and the required procedure. A dentist chooses the appropriate approach based on the specific clinical situation.
The Role and Application of Dental Fillings
A dental filling is a direct restoration, meaning the material is placed directly into the prepared tooth cavity during a single dental visit. This treatment is typically reserved for repairing minimal to moderate tooth decay, often called a cavity. Fillings are considered a conservative treatment because they require the removal of only the decayed or damaged portion of the tooth.
The procedure begins after the area is numbed. The dentist uses an instrument to precisely remove the carious tissue. Once the cavity is clean, the remaining healthy tooth structure is prepared to receive the filling material, preserving the integrity of the natural tooth walls.
Modern filling materials include composite resin, which is color-matched for aesthetics. Silver amalgam is a durable alloy used primarily in less visible back teeth where chewing forces are greatest. Glass ionomer is often used in smaller, non-load-bearing areas and releases fluoride.
The selection criteria for a filling hinge on having a strong, intact tooth structure surrounding the decay. If 50% or more of the original tooth structure remains and the damage does not compromise a cusp or cause structural cracks, a filling is the appropriate restoration.
The Role and Application of Dental Crowns
A dental crown is an indirect restoration, fabricated outside the mouth, typically in a dental laboratory, and cemented onto the tooth later. Often called a “cap,” the crown completely covers the entire visible portion of the tooth above the gum line. This full-coverage design restores a tooth that has suffered extensive damage and requires structural reinforcement.
The crown procedure requires significant reshaping of the tooth structure to create a stable base for the cap. The dentist must reduce the tooth on all sides and the biting surface to ensure the crown has sufficient thickness. An impression or digital scan of this prepared tooth is then sent to the laboratory for custom fabrication.
A temporary crown is cemented onto the prepared tooth to protect it while the permanent crown is being made. Permanent crowns can be crafted from materials like zirconia or E-max (lithium disilicate) for high strength and aesthetics, or porcelain-fused-to-metal (PFM). The crown is indicated when decay is extensive, a tooth is fractured, or after a root canal procedure where the tooth requires protection from fracture.
Comparative Factors in Restoration Selection
The determination of whether a crown or a filling is appropriate is based on the specific clinical needs of the damaged tooth, not which restoration is inherently “better.” The most significant deciding factor is the amount of remaining healthy tooth structure. A filling is suitable when the damage is small enough to be contained by the surrounding enamel and dentin. A crown is required when a substantial amount of the tooth is compromised, making it structurally weak.
The invasiveness of the procedure is another major differentiator. Fillings are minimally invasive and preserve the maximum amount of natural tooth material, only removing the decayed area. Conversely, a tooth prepared for a crown is reshaped dramatically to create space for the cap, sacrificing healthy tissue to ensure durability and proper fit.
In terms of durability, crowns typically offer a longer expected lifespan than fillings, often lasting 10 to 20 years or more with proper care. This is due to the crown’s ability to encompass and protect the entire tooth from chewing forces. The longevity of a filling, often cited as 5 to 15 years, is highly dependent on the initial size of the cavity and the patient’s oral habits.
The cost and time commitment also vary considerably. A filling is a single-visit, direct procedure that is significantly less expensive because it uses less material and bypasses laboratory fabrication. The crown procedure requires at least two visits—one for preparation and temporary placement, and a second for final cementation. This makes it a more involved and higher-cost treatment due to the lab work and additional chair time. Ultimately, the choice is a functional decision dictated by the severity of the damage and the necessary structural support required for the tooth’s long-term survival.