A temporary crown is a short-term, tooth-shaped cap placed on a prepared tooth while a custom permanent crown is being fabricated in a dental laboratory. While both restorations cover the entire visible portion of a tooth, they differ significantly in their fit, material, and intended purpose. A temporary crown is not the same size or precision fit as a permanent crown. This temporary phase protects the tooth and surrounding tissues before the final, durable restoration is permanently bonded.
The Direct Comparison: Size, Shape, and Fit Precision
Temporary crowns are generally bulkier and less refined than their final counterparts because they are quickly fabricated, often chairside, from pre-formed shells or moldable resin. This rapid process results in less precise marginal integrity, meaning the edge of the crown does not seal perfectly against the prepared tooth at the gum line. The permanent crown, in contrast, is custom-milled or cast from a detailed impression or digital scan of the prepared tooth, which is sent to a specialized lab.
This lab process ensures the permanent restoration achieves an ideal size, contour, and marginal seal, which is important for long-term dental health. A precise marginal fit prevents bacteria and debris from leaking under the crown, which could lead to decay of the underlying tooth structure. Furthermore, the permanent crown is meticulously designed to achieve correct bite alignment, known as occlusion, ensuring it does not interfere with the opposing teeth or cause stress on the jaw joint. Temporary crowns maintain the space and basic bite function but lack this degree of custom precision.
The Primary Function of a Temporary Crown
The temporary crown serves as a protective placeholder between appointments. Its primary function is to shield the newly prepared tooth structure, which is vulnerable because a significant portion of the enamel has been removed. This protection prevents sensitivity to temperature changes and exposure to bacteria, which could cause infection or decay.
The temporary restoration also plays a mechanical role in maintaining the correct spacing within the dental arch. Without this placeholder, adjacent teeth can drift and the opposing tooth can over-erupt, compromising the fit of the final permanent crown. Also, the crown preserves the health of the gum tissue, preventing it from growing over the prepared tooth margin, which would complicate the final seating of the permanent crown.
Material Composition and Expected Lifespan
The differences in size and fit are directly related to the materials used for each type of crown. Temporary crowns are typically constructed from acrylic or composite resin, which are designed for easy manipulation and removal. These materials are relatively soft and are held in place with a weak cement, which allows the dentist to remove them without damaging the prepared tooth.
Conversely, permanent crowns are fabricated from stronger, durable materials, such as zirconia, porcelain, metal alloys, or porcelain-fused-to-metal. These materials are chosen for their ability to withstand the forces of chewing and their longevity, often lasting between five and fifteen years or more with proper care. The inherent strength of permanent crown materials allows them to be milled into the thin, precise shapes required for an optimal fit and natural appearance, a level of refinement not possible with temporary resins.
Practical Care and What to Expect During the Temporary Phase
Because the temporary crown is less durable and is secured with a weak adhesive, patients must adjust their habits to protect it. It is advised to avoid hard, crunchy, or sticky foods, such as nuts or caramel, as these can easily fracture the resin or pull the temporary crown off the tooth. Chewing should be done primarily on the opposite side of the mouth to minimize the force applied to the restoration.
Maintaining oral hygiene requires care, as the marginal seal is not as tight as a permanent crown, making the prepared tooth susceptible to debris accumulation. When flossing near the temporary crown, patients should slide the floss out from the side rather than snapping it upward, which could dislodge the restoration. Mild sensitivity to temperature is a common expectation, but any significant pain or if the crown comes off completely requires immediate contact with the dental office for prompt recementation.