Dental cement is a specialized adhesive that bonds restorations like crowns, bridges, and orthodontic bands to your natural teeth. It serves three core purposes: holding restorations firmly in place, sealing the gap between the restoration and your tooth to keep bacteria out, and protecting the sensitive inner layers of the tooth from further damage. Nearly every fixed dental restoration you receive will involve some form of cement.
Securing Crowns and Bridges
The most common use of dental cement is attaching crowns and bridges to prepared teeth. When a tooth has been shaped down to accept a crown, cement fills the thin space between the crown’s inner surface and the remaining tooth structure. This creates a tight bond that prevents the crown from loosening or falling out during chewing, which generates significant force on every bite.
Just as important as the bond itself is the seal it creates. By filling that microscopic gap at the crown’s margin, cement blocks bacteria and food particles from reaching the vulnerable tooth underneath. Without a good seal, decay can develop silently beneath an otherwise intact-looking crown. A well-cemented crown also distributes biting forces more evenly across the tooth, reducing the risk of fractures.
Temporary vs. Permanent Cement
Not all dental cement is meant to last forever. Temporary cement is designed with lower holding strength so your dentist can remove a restoration easily when needed. This is commonly used for provisional (temporary) crowns placed while a lab fabricates your permanent one, or for implant-supported crowns where the dentist anticipates needing access for adjustments. Temporary cements typically use a urethane-based resin that holds well enough to function but releases cleanly when the time comes.
Permanent cements are chosen when the restoration is intended to stay for years. Resin composite cements and resin-modified glass ionomer cements are the most widely used permanent options today. Your dentist picks between them based on factors like the shape of the prepared tooth, how much natural tooth structure remains, and whether complications are likely. A tooth with a short or heavily tapered preparation, for example, generally calls for a stronger permanent cement because the shape alone doesn’t provide much grip.
Orthodontic Band Cementation
Dental cement plays a key role in orthodontic treatment, particularly for attaching metal bands to molars. These bands wrap around the tooth and anchor the archwire that moves your teeth into alignment. Until the early 1990s, zinc phosphate cement was the standard choice for this job. Most orthodontists have since switched to glass ionomer or glass ionomer-based cements, which bond chemically to tooth enamel rather than relying purely on a tight mechanical fit.
Glass ionomer cements offer a practical advantage in the mouth’s wet environment: moisture contamination during placement doesn’t significantly weaken the bond. They also release fluoride over time, which helps protect enamel around the band from developing white spots or decay during the months or years of orthodontic treatment. Newer variations include polyacid-modified composite resins (compomers) and resin-modified glass ionomers, which combine the fluoride release of traditional glass ionomer with improved strength.
Protecting the Tooth Underneath
Beyond holding things in place, dental cement acts as a buffer for the living tissue inside your tooth. When a tooth is prepared for a crown, some of the hard outer layer is removed, exposing tiny fluid-filled channels called dentin tubules. These channels connect directly to the nerve inside the tooth. External stimuli like cold air or pressure can shift the fluid in these tubules, triggering a pain response.
A good cement seals those tubules. For patients who have a history of tooth sensitivity or whose teeth required more aggressive preparation, dentists may choose a more biocompatible cement, such as polycarboxylate, that is gentler on the underlying tissue. The quality of the cement and how completely it seals the margins directly affects whether you experience lingering sensitivity after a crown is placed.
Main Types of Dental Cement
Several categories of dental cement exist, each with different strengths:
- Glass ionomer cement (GIC): Introduced in the 1970s, this cement bonds chemically to tooth structure and releases fluoride, offering some protection against decay at the margins. It’s widely used for orthodontic bands and in situations where moisture control is difficult. Its mechanical strength is lower than resin-based options.
- Resin-modified glass ionomer cement (RMGIC): A hybrid that combines glass ionomer’s fluoride release with the improved strength and faster setting of resin materials. It’s a popular choice for permanently cementing crowns, though some formulations have shown higher levels of tissue irritation in lab studies due to excess fluoride release and resin components.
- Resin composite cement: The strongest option, hardened by light, chemical activation, or both. Often chosen for porcelain veneers and all-ceramic crowns where both strength and aesthetics matter, since it can be made translucent to avoid showing through thin restorations.
- Zinc phosphate cement: One of the oldest types, relying on mechanical retention rather than chemical bonding. It has a long clinical track record and is still used in some practices, though it has largely been replaced by newer materials for most applications.
How Long Cemented Restorations Last
The longevity of a cemented restoration depends on the cement type, the fit of the restoration, your bite forces, and your oral hygiene. A well-fitted, permanently cemented crown on a natural tooth can last 10 to 15 years or longer. When margins start to break down, glass ionomer cement can sometimes be used to repair just the defective edge rather than replacing the entire crown. Retrospective data on these margin repairs shows a five-year survival rate of about 63%, which, while modest, can buy meaningful extra time before a full replacement becomes necessary.
The most common reasons cemented restorations fail are decay developing at the margins, cement washing out over time due to gradual dissolution in saliva, and fracture of either the cement layer or the restoration itself. Regular dental checkups catch early signs of cement breakdown, like a rough or open margin you can feel with your tongue or floss, before bacteria have a chance to cause deeper damage.
Post-Cementation Sensitivity
Some degree of sensitivity after a crown or bridge is cemented is normal, particularly to cold temperatures. This happens because tooth preparation removes protective enamel, and the cement and restoration need time to fully settle. In most cases, sensitivity fades within a few days to a couple of weeks.
Persistent or worsening sensitivity can signal that the cement didn’t fully seal the margins, that the bite is slightly high (putting extra pressure on the tooth), or that the preparation came close to the nerve. The risk of post-cementation sensitivity increases with the amount of tooth structure removed, the number of exposed dentin tubules, and heat generated during the preparation process itself.