Gold crowns are common in restorative dentistry due to their durability, biocompatibility, and resistance to wear. Cementation is the final step, permanently securing the restoration and ensuring its long-term success and function. This procedure creates a durable seal between the prepared tooth and the gold crown. Meticulous attention to detail is required at every stage to prevent microleakage and maintain the health of the underlying tooth structure.
Preparing the Tooth and Crown
Successful permanent cementation requires preparation of both the tooth and the gold crown. The first step involves thoroughly cleaning the prepared tooth structure by removing all traces of temporary cement residue, debris, and biological contaminants. Cleaning is often accomplished using a non-oil-based pumice slurry or specialized cleaning agents to ensure the tooth surface is chemically receptive to the cement.
Achieving a dry, uncontaminated field is mandatory for proper cement adhesion. Dental professionals utilize isolation techniques, such as cotton rolls or a rubber dam, to protect the working area from moisture contamination. The gold crown is then tried in one last time to verify its fit, confirming the marginal integrity is flush with the tooth structure and that the proximal contact points are correct. Any minor adjustments to the crown or margins are completed at this stage, ensuring passive and complete seating before the cement is introduced.
Choosing and Preparing the Permanent Cement
Selecting the correct permanent cement, or luting agent, depends on the gold crown’s material and the underlying tooth’s condition. For non-bonded metal restorations like gold, conventional luting agents such as Resin-Modified Glass Ionomer (RMGI) or Zinc Phosphate cement are often preferred. Zinc Phosphate is favored for its high compressive strength and low film thickness, which allows the crown to seat fully.
RMGI cements offer chemical adhesion to the tooth structure and the slow release of fluoride ions, providing protection against recurrent decay at the crown margins. Regardless of the material chosen, the cement must be prepared precisely according to the manufacturer’s powder-to-liquid ratio instructions. Inaccurate mixing compromises the cement’s physical properties, leading to a viscosity that prevents full seating or a weakened final set.
The mixed cement is applied thinly and evenly to the internal surface of the gold crown, avoiding overfilling. A thin layer is sufficient to coat the inner surface without creating a large hydraulic force that would prevent complete seating. The cement should be fluid enough to flow out easily when seated but viscous enough to maintain its structure and fill the microscopic gap.
Seating the Crown and Checking the Bite
With the gold crown loaded with cement, the dentist gently positions it over the prepared tooth, applying firm, steady pressure until the restoration is fully seated. This seating pressure minimizes the cement film thickness, allowing the crown margins to fully adapt to the tooth preparation. Excess cement, known as flash, will extrude around the margins.
Before the cement reaches its final set, checking the occlusion, or the patient’s bite, must be performed. The patient is asked to bite down gently on articulating paper, which leaves marks on the crown and opposing teeth where contact is made. Heavy or premature contact points, which could lead to discomfort or damage, are identified and carefully adjusted.
The crown should not interfere with the patient’s normal centric occlusion or their excursive movements. Once the bite is confirmed to be stable and comfortable, the cement is allowed to enter its initial setting phase. For certain cements, a brief light-curing period may be applied to the margins to facilitate this initial set, making subsequent cleanup easier and safer.
Finalizing the Cementation and Post-Procedure Care
The final and most critical step is the meticulous removal of all excess cement flash from around the crown margins and the interproximal spaces. Retained cement in the gingival sulcus (the space between the tooth and the gum) acts as a foreign body that can cause significant irritation and inflammation, potentially leading to periodontal problems. The dental professional uses specialized instruments like explorers, scalers, and knotted dental floss to ensure every particle is cleared from the area.
This cleanup must be thorough, often involving a final inspection under magnification to confirm the margins are perfectly smooth and clean. Once the cement has completely hardened, the patient is given specific post-procedure instructions to protect the newly cemented crown. Patients are advised to avoid chewing on hard or sticky foods for several hours to allow the cement to reach its maximum strength.
Temporary sensitivity to hot or cold temperatures is common and usually subsides within a few days or weeks. Maintaining excellent oral hygiene, including regular brushing and flossing, is emphasized to ensure the long-term health of the surrounding gum tissue and the longevity of the gold crown.