Posterior composite fillings are tooth-colored restorations placed in the back teeth — premolars and molars. They are made of a resin matrix reinforced with glass or ceramic filler particles, creating a material that is both strong enough for chewing forces and aesthetically invisible. Unlike silver amalgam, composite bonds directly to the tooth structure, which means less healthy tooth needs to be removed during preparation.

Modern composite resins have compressive and flexural strengths that meet the demands of posterior occlusion. While amalgam is slightly stronger in pure compressive strength, composite has the advantage of bonding to tooth structure — meaning it reinforces the remaining tooth rather than just filling a hole. Published meta-analyses show median survival times of 12 to 13 years for posterior composites, which is clinically comparable to amalgam.

Not automatically. Dr. Ostovar recommends replacing amalgam fillings when they show clinical signs of failure — marginal breakdown, recurrent decay, cracks in the surrounding tooth structure, or fracture of the amalgam itself. Prophylactic replacement of intact, well-functioning amalgam fillings removes healthy tooth structure unnecessarily. Each filling is evaluated individually based on its clinical condition, not its age or material type.

Published research reports median survival times of 7 to 15 years, with the range depending on filling size, location, the patient’s bite forces, and oral hygiene. Small to medium fillings in premolars tend to last longer than large fillings in molars. Patients who clench or grind their teeth experience higher failure rates unless they wear a night guard. Proper placement technique — particularly moisture control during bonding — is the single most important factor in longevity.

Composite resin shrinks 2 to 5 percent by volume when it polymerizes under the curing light. If a large volume is cured at once, the shrinkage generates internal stresses that can pull the composite away from the cavity walls, creating microscopic gaps where bacteria enter and cause recurrent decay. Layering in 2-millimeter increments manages this shrinkage stress — each small layer contracts minimally and bonds firmly before the next is applied, building a restoration with tight, sealed margins.

No. The tooth is completely numbed with local anesthesia before any work begins. You will feel vibration from the handpiece and occasional water spray, but no pain. If you are anxious about dental procedures, nitrous oxide sedation is available to help you relax during the appointment. The procedure takes 30 to 60 minutes depending on the size and number of fillings being placed.

Posterior composite fillings typically range from $200 to $500 per tooth depending on the number of surfaces involved. A single-surface filling is the least expensive, while a four-surface filling approaching the need for a crown is the most. Most dental insurance plans cover composite fillings at 70 to 80 percent after deductible. We provide exact pricing before treatment and accept CareCredit and Cherry financing.

When the cavity involves more than 50 percent of the tooth’s biting surface width, or when three or more walls of the tooth are compromised, a direct composite filling may not provide adequate structural reinforcement. In these situations, an indirect restoration — an onlay or crown — is stronger and more predictable long-term. Dr. Ostovar makes this determination during the cavity preparation and discusses it with you before proceeding.

Composite resin can absorb surface stains from coffee, tea, red wine, and tobacco over time, though modern nanofilled composites are significantly more stain-resistant than older formulations. Regular professional cleaning and polishing during hygiene appointments keeps the surface smooth and removes superficial stain. In posterior teeth, minor staining is rarely noticeable since back teeth are not visible when you smile.

No. Composite fillings contain no mercury whatsoever. They are made of a BIS-GMA or UDMA resin matrix with glass, quartz, or ceramic filler particles. The mercury concern applies only to dental amalgam, which contains approximately 50 percent elemental mercury bound in a stable alloy. Composite is the mercury-free alternative, and it is the primary direct restorative material used at our practice.

A rubber dam is a thin latex or nitrile sheet that isolates the tooth being worked on from saliva, tongue movement, and cheek interference. For composite bonding, this isolation is critical — salivary contamination during the adhesive step can reduce bond strength by half and dramatically shorten filling lifespan. Studies consistently show that composite fillings placed under rubber dam isolation have significantly lower failure rates than those placed without it.

Most modern dental insurance plans cover composite fillings on posterior teeth at the same rate as amalgam. Some older plans may cover only up to the cost of an amalgam filling, with the patient paying the difference. Our insurance team verifies your specific coverage before treatment and explains any out-of-pocket costs clearly. This should not be a barrier — the difference, when it exists, is typically modest.

In some cases, yes. Small chips or marginal defects can be repaired by roughening the existing composite surface, applying fresh bonding agent, and adding new composite material. This is less invasive than complete replacement and preserves more tooth structure. However, if there is recurrent decay under the filling or the marginal seal is compromised around the entire restoration, complete replacement is the appropriate treatment.

Posterior fillings are technically more demanding. The cavity is deeper, the tooth anatomy is more complex with multiple cusps and grooves, access and visibility are limited, and moisture control is harder due to proximity to salivary glands. The layering protocol requires more increments in a deep posterior preparation than in a shallow anterior one. Additionally, restoring the contact point with the adjacent tooth on a back tooth requires a matrix band and wedge system that adds time to the procedure.

Call (503) 822-0096 as soon as possible. A lost filling exposes the inner tooth structure to bacteria, temperature, and mechanical forces. Avoid chewing on that side and keep the area clean. If the exposed area is sensitive, a small piece of sugar-free gum or temporary dental cement from a pharmacy can provide short-term protection until your appointment. A lost filling should be evaluated within one to two days to prevent further damage or infection.