Dental cement is a specialized material dentists use to bond restorations like crowns, bridges, and veneers to your natural teeth. It also serves as a protective liner inside cavities and, in some forms, as a filling material itself. There are several types, each designed for different situations, and the one your dentist chooses affects how long your restoration lasts, how your tooth feels afterward, and whether you get any added protection against future decay.
How Dental Cement Works
At its simplest, dental cement fills the microscopic gap between a restoration and your prepared tooth, locking the two together. Some cements do this through purely mechanical means: they harden in the space between surfaces and hold on through friction and the shape of the tooth. Others form a true chemical bond, adhering to both the tooth structure and the restoration at a molecular level. These adhesive cements tend to create a stronger, more durable seal.
Beyond holding things in place, dental cement also acts as a barrier. It seals the exposed inner layers of your tooth from bacteria, temperature changes, and the acids in your mouth. When that seal fails, bacteria can creep underneath a crown and cause decay you can’t see, which is one of the main reasons crowns eventually need to be replaced.
Types of Dental Cement
Zinc Phosphate Cement
This is the oldest and most traditional option, used since the late 1800s. The powder is about 90% zinc oxide with a small amount of magnesium oxide, and the liquid is a phosphoric acid solution. When mixed, the acid reacts with the powder and hardens into a rigid mass with a compressive strength around 90 MPa, which is strong enough to hold a crown under normal chewing forces. It sets quickly and is easy to work with, but it doesn’t chemically bond to the tooth. It simply locks into place through the shape of the preparation. Its main drawbacks are that the acid can irritate the nerve inside the tooth, it tends to be brittle, and it slowly dissolves in saliva over many years.
Glass Ionomer Cement
Glass ionomer cements have been in clinical use since the 1970s and offer something zinc phosphate can’t: they chemically bond to tooth structure and continuously release fluoride. That fluoride release follows a two-step pattern. In the first days and weeks, a larger burst washes out from the cement’s surface. After that, a slower, steady diffusion continues for months or longer. Studies measuring fluoride levels in saliva around glass ionomer restorations found concentrations of 0.8 to 1.2 parts per million after three weeks, dropping to 0.3 to 0.4 ppm by six weeks and holding at that level for at least a year.
Those numbers matter because even tiny amounts of fluoride, as low as 0.01 to 0.2 ppm, promote the rebuilding of tooth mineral. The levels needed to actually suppress the bacteria responsible for cavities are about 10 to 20 times higher than what’s needed for remineralization, yet glass ionomer cements have been shown to raise salivary fluoride enough to reduce the activity of cavity-causing bacteria in children. This makes glass ionomer a popular choice for patients at higher risk of decay.
Resin Cement
Resin cements are chemically similar to the tooth-colored composite materials used for fillings. They provide the strongest bond and are the go-to choice for porcelain veneers, ceramic crowns, and other restorations that need maximum adhesion. Cementation with resin is a multi-step adhesive process. Both the tooth surface and the inside of the restoration are pretreated: the tooth is cleaned, and often etched or primed so the cement can grip the microscopic structure of enamel and dentin. The restoration’s inner surface is also treated to improve bonding.
Once the cement is mixed and applied to both surfaces, the restoration is seated with slow, steady pressure to let excess cement flow out and minimize air pockets. The dentist then uses a curing light for a brief one-to-two-second “tack cure,” which partially sets the cement just enough to peel away the excess cleanly. After cleanup, the cement is fully light-cured to reach its final hardness. In a study tracking metal-ceramic crowns cemented with self-adhesive resin cement for an average of 62 months (just over five years), the survival rate was 91.5%.
Temporary Cement
When you’re waiting for a permanent crown to be made, your dentist places a temporary one using a weaker cement designed to come off easily at your next visit. The most common type is zinc oxide mixed with eugenol, a compound derived from clove oil that has a mild numbing effect. Non-eugenol versions, resin-based temporaries, and calcium hydroxide-based options also exist. These cements have lower strength and a thicker consistency than permanent types, which is intentional. They need to hold a temporary restoration in place for a couple of weeks without making it impossible to remove.
Why Some Teeth Feel Sensitive After Cementation
If you’ve had a crown or bridge cemented and noticed a zing of sensitivity to cold or pressure afterward, several things can contribute. During tooth preparation, the outer protective enamel is removed, exposing the softer dentin layer underneath. Dentin contains millions of microscopic tubes that lead toward the tooth’s nerve. When acid-etching is used to prepare the surface for bonding, it cleans away the natural debris plugging those tubes, temporarily opening pathways that let stimuli reach the nerve more easily.
Heat from the curing light can also cause fluid inside those tubes to shift, pushing uncured resin components toward the nerve. If any of those resin monomers reach the pulp tissue, they can trigger a mild inflammatory response. Insufficient water-cooling during the drilling phase and excessive air-drying during cementation are two other recognized causes of post-operative sensitivity. For most people, this sensitivity is temporary and fades within a few weeks as the tooth settles.
How Dentists Choose the Right Cement
The choice depends on what’s being cemented and what the tooth needs. A porcelain veneer on a front tooth demands a resin cement because the veneer is too thin to rely on mechanical retention alone; it needs that chemical bond to stay put. A gold or metal crown on a back tooth, with its robust shape providing plenty of mechanical grip, might do fine with zinc phosphate or glass ionomer. A patient prone to cavities might benefit from glass ionomer’s fluoride release, even if resin cement would offer a slightly stronger bond.
The condition of the tooth also plays a role. If the nerve is close to the surface after a deep preparation, a dentist may place a protective liner of calcium hydroxide cement beneath the final restoration to shield the pulp from chemical irritation. In root canal-treated teeth, where there’s no living nerve to protect, the priority shifts entirely to retention and strength.
Bioactive Cements and Newer Options
A newer category of dental cement, broadly called bioceramics, goes beyond simply holding things together. These materials can stimulate the body’s own repair processes. Bioceramic cements have been shown to promote the growth and specialization of stem cells in dental tissue, encouraging the formation of new mineralized material. They’re used most often in root canal treatments, where the goal is to seal the inside of the tooth and encourage healing at the root tip.
Researchers have been refining these materials to set faster, resist fracture better, and actively support tissue regeneration. Adding nanoparticles of hydroxyapatite (a mineral naturally found in teeth and bone) or zinc oxide to bioceramic formulations has improved their compatibility with living tissue and their ability to fight bacteria without sacrificing strength. Some experimental versions incorporate compounds that stimulate the cells responsible for forming new dentin, pointing toward cements that don’t just repair damage but help the tooth rebuild itself.