Composite Vs. Amalgam Fillings: Pros, Cons & Safety

Choosing between composite and amalgam fillings involves more than appearance. Both materials can restore teeth damaged by cavities, but they differ in composition, placement technique, maintenance requirements and cost. The most suitable option depends on the location and size of the cavity, how much healthy tooth structure remains, and the forces placed on the tooth during chewing. Composite fillings offer a tooth-coloured finish, while amalgam has a long history of use in durable restorations. Health considerations and material availability also influence the decision. This guide compares composite vs amalgam fillings to help you understand the differences, discuss your options with your dentist, and make an informed decision about your dental care.

What Are Composite and Amalgam Fillings?

Composite and amalgam fillings are dental restorations used to repair teeth after a dentist removes decay or treats other localized damage. Both restore the tooth’s shape and help it function during everyday activities such as chewing and speaking. Their composition, appearance and placement methods are different.

Composite Resin: A Tooth-Coloured Filling Material

Composite resin is a restorative material made from a resin base reinforced with finely ground filler particles. Dentists can select a shade that blends with the surrounding teeth, making composite a popular choice for patients who prefer a natural-looking result.

This material is commonly used for cavities in front teeth and can also restore selected premolars and molars. Its suitability depends on the amount of damage, the location of the cavity, the patient’s bite and whether the dentist can achieve reliable bonding.

Placing a composite filling involves several steps:

1. The dentist removes decay and prepares the affected area.
2.  An adhesive system is applied to help the composite bond to the tooth.
3.  The material is placed and shaped, often in layers.
4. A curing light hardens the composite.
5.  The restoration is adjusted and polished to fit the bite.

Because composite depends on adhesive bonding, moisture control is particularly important during placement. Saliva or blood contamination can interfere with adhesion and affect the restoration’s performance.

Although composite can preserve healthy tooth structure in suitable cases, it is not always the right choice for a heavily damaged tooth. Extensive cavities may require an inlay, onlay or crown to provide adequate support.

Dental Amalgam: A Metal Alloy Used for Fillings

Dental amalgam is a metallic restorative material made by combining mercury with an alloy containing metals such as silver, tin and copper. It has been used for decades, particularly to restore back teeth exposed to substantial chewing forces.

Amalgam forms a silver-grey restoration that remains visible when a person smiles or speaks. Unlike composite, it does not depend on the same adhesive bonding process. Instead, the dentist prepares the tooth to provide the retention needed to hold the material in place.

Its established performance in appropriate restorations and historically lower initial cost have contributed to its use. However, amalgam contains mercury, and its use is affected by health guidance, environmental policies, local requirements and the materials available at a dental practice.

The decision to use amalgam should account for the patient’s individual circumstances and the condition of the tooth. Its durability does not automatically make it preferable to composite in every situation.

Composite vs Amalgam Fillings

Composite and amalgam fillings differ in appearance, composition, placement requirements and other practical considerations. Neither material guarantees a particular lifespan, and the outcome depends on the restoration, the tooth and the conditions under which treatment is performed.

The following comparison summarizes the main differences.

Comparison Factor Composite Fillings Amalgam Fillings

Appearance Tooth-coloured; blends naturally with surrounding enamel. Silver-grey and more noticeable when smiling or speaking.

Composition Resin matrix reinforced with inorganic filler particles. Mercury combined with a metal alloy.

Bonding Uses an adhesive bonding system to attach the material to the tooth. Relies on mechanical retention and appropriate cavity preparation.

Moisture Control Requires careful moisture control during adhesive placement. Generally less sensitive to moisture during placement.

Common Uses Front teeth and selected back-tooth restorations. Traditionally used for suitable back-tooth restorations.

Tooth Preparation May preserve more healthy tooth structure in suitable cases. Preparation depends on cavity design and retention requirements.

Durability Can last for many years with appropriate selection and placement. Has a long history of durability in suitable situations.

Appearance Over Time May stain, wear or chip over time. Can remain functional while retaining its metallic appearance.

Cost Depends on restoration size, complexity and dental practice fees. Historically often less expensive initially; actual costs vary.

Main Consideration Technique-sensitive placement and the need for effective bonding. Mercury-related considerations and visible metallic color.

What Does the Evidence Say About Amalgam Filling Safety?

Dental amalgam contains mercury and can release small amounts of mercury vapour. Health authorities have evaluated the evidence concerning exposure and potential health effects, including considerations for people who may be more vulnerable to mercury.

For Canadian patients, Health Canada’s guidance on mercury and human health is a useful starting point. Its recommendations should be considered alongside your medical history and a dentist’s assessment rather than interpreted as a universal treatment rule.

Amalgam is not appropriate for every patient or every clinical situation. Pregnancy, impaired kidney function and known mercury hypersensitivity are examples of circumstances that warrant specific discussion before amalgam treatment is considered. Current local guidance and material availability also matter.

Composite fillings do not contain mercury, but that fact alone does not make composite the best choice for every tooth. Composite has its own placement requirements and limitations, and the restoration must be suitable for the size and location of the cavity.

The aim is to select an appropriate material using current evidence and the patient’s circumstances, rather than assuming that one option is always superior.

Discussing Individual Health Considerations With Your Dentist

Before treatment, tell your dentist about relevant medical conditions, medications, previous reactions to dental materials and any concerns about mercury exposure.

If you are pregnant, have impaired kidney function or have a known allergy or hypersensitivity to a dental material, raise this information before the restoration is selected. Your dentist can explain whether an alternative is appropriate and discuss the benefits and limitations of the available options.

It is also helpful to explain your priorities. You may be most concerned about appearance, durability, initial cost or avoiding mercury-containing materials. These preferences can guide the discussion, but they should be balanced against the condition of the tooth and the expected performance of the restoration.

For additional scientific context on restorative materials, consult the American Dental Association’s information on materials for direct dental restorations. The material that best meets your needs should be chosen after an individualized assessment.

Should an Existing Amalgam Filling Be Replaced?

An existing amalgam filling does not automatically need replacement because it is old, silver-coloured or contains mercury. If the restoration remains stable, functions properly and shows no clinically significant problems, monitoring it may be more appropriate than removing it.

Assessing the Filling’s Condition and the Surrounding Tooth

A dental examination considers the condition of the filling and the health of the tooth beneath and around it. Your dentist may look for fractures, damaged margins, recurrent decay and signs that the restoration no longer fits or functions properly.

Depending on your symptoms and examination findings, dental X-rays may help identify decay that is not readily visible. The dentist may also review previous treatments, your history of cavities and any changes in sensitivity or biting comfort.

Keep in mind that neither the color of an amalgam filling nor its age reliably indicates whether it has failed. Similarly, the absence of pain does not rule out a problem.

Possible recommendations include:

• Monitoring: Appropriate when the restoration and surrounding tooth remain healthy.
•  Repair: An option for certain localized defects when the remaining restoration is sound.
• Replacement: Considered when the filling is fractured, recurrent decay is present or the restoration can no longer function adequately.
• Alternative restoration: An inlay, onlay or crown may be appropriate when the tooth needs additional structural support.

The recommendation should reflect the clinical findings rather than a fixed replacement schedule.

When Is Replacement Necessary, and What Are the Risks of Removal?

Replacing an amalgam filling may be justified when decay develops around it, the restoration fractures, the surrounding tooth becomes damaged or another clinically significant problem requires treatment.

Removing a filling also has consequences. The procedure can remove additional healthy tooth structure, and amalgam removal can temporarily increase exposure to mercury vapour. The amount of additional treatment required depends on the condition of the tooth and the restoration.

For this reason, removing an intact, functional amalgam filling solely because it contains mercury is generally not recommended. Health Canada’s guidance advises against unnecessary removal of sound amalgam restorations.

If you are considering a replacement for cosmetic or health-related reasons, ask your dentist to explain the expected benefit, the risks of removal and whether composite or another material is suitable. A tooth-coloured replacement may address an appearance concern, but it should not be assumed to improve the tooth’s overall health simply because it looks different.

Comparing Costs and Available Options

The cost of composite versus amalgam fillings depends on the size of the restoration, the number of tooth surfaces involved, the complexity of treatment and the fees charged by the dental practice. The most useful comparison considers the complete treatment plan rather than the material alone.

Cost Factor Why It Affects the Estimate Question to Ask Your Dentist

Filling Size Larger restorations can require more material and clinical time. How many tooth surfaces need treatment?

Material Selection Different materials have different placement requirements. Which materials are suitable for my tooth?

Tooth Location Access and chewing forces can affect treatment complexity. Does the location change the recommended approach?

Existing Damage Cracks or extensive decay may require a different restoration. Will a filling provide enough support?

Additional Procedures Diagnostic or restorative work can affect the total cost. Are any additional procedures necessary?

Dental Insurance Coverage and reimbursement rules vary by plan. What portion of the treatment is covered?

How Filling Size, Material and Treatment Requirements Affect Your Estimate

Composite placement involves adhesive preparation, moisture control, shaping and curing. These steps can affect the time required for treatment. Amalgam has traditionally had a lower initial cost, although actual prices and availability depend on the practice and local requirements.

Your estimate may be influenced by:

• The extent of the cavity: A larger or multi-surface filling may require more work.
• The material selected: Each material has its own handling requirements and clinical limitations.
•  The condition of the tooth: Existing cracks, recurrent decay or weakened tooth structure may change the treatment plan.
•  The complexity of the procedure: Additional diagnostic procedures or a more extensive restoration may be necessary.
•  Insurance benefits: Annual maximums, reimbursement limits and material-specific rules can affect out-of-pocket costs.

A direct filling is not always the most appropriate or economical long-term solution for a heavily damaged tooth. An inlay, onlay or crown may provide the support required by the remaining tooth structure.

For more information, read the page on dental filling costs in Newmarket. Your dentist can provide a personalized estimate after examining the tooth and explaining the recommended treatment.

Confirming Material Availability and Dental Insurance Benefits

Before making a decision, confirm which filling materials the dental practice offers and whether your preferred option is appropriate for your tooth.

Insurance coverage varies between policies. Some plans apply different reimbursement limits to different restorative materials, while others specify replacement intervals or calculate benefits using a plan-specific fee schedule. Coverage for replacing an existing filling may also differ from coverage for treating a new cavity.

Ask the dental office for a breakdown of the proposed treatment and any expected out-of-pocket expenses. If you have dental insurance, confirm the details with your insurer before treatment rather than assuming that a particular material will be fully covered.

Cost matters, but the cheapest initial option is not necessarily the most appropriate choice. The condition of the tooth, the expected performance of the restoration and the need for future treatment should all be considered.

Choosing a Filling Material With Your Dentist

The right filling material is one that meets the tooth’s clinical needs while taking your preferences, health history and budget into account. Composite may be attractive because of its natural appearance and adhesive properties, while amalgam has a long history of durability in appropriate situations. Neither is the best option for every patient.

Which Filling Material Is Appropriate for Your Tooth?

Your dentist can recommend composite, amalgam or another restorative option after evaluating the cavity and the remaining tooth structure.

The assessment should consider:

• The size, depth and location of the cavity.
•  The amount of healthy tooth structure remaining.
•  The chewing forces acting on the tooth.
•  Whether reliable adhesive bonding is achievable.
• Relevant medical history and material sensitivities.
•  Your preferences regarding appearance, cost and material composition.

If extensive damage makes a direct filling unsuitable, an inlay, onlay or crown may provide a better restoration. Read dental filling vs. crown vs. inlay and onlay to learn how these options differ.

What Should You Ask Before Treatment?

Before agreeing to a filling or replacing an existing restoration, consider asking your dentist:
1. How much healthy tooth structure remains?
2. Why do you recommend this particular material?
3. What are the main benefits and limitations for this tooth?
4. Can the existing filling be monitored or repaired instead of replaced?
5. Would an inlay, onlay or crown provide better support?
6. What will the treatment cost, and what might my insurance cover?
Whichever restoration you choose, daily oral hygiene and regular dental examinations help protect the tooth. Brush twice a day with fluoride toothpaste, clean between your teeth daily and follow your dentist’s advice for managing cavities, clenching or grinding.

If you need a new filling or want an existing restoration assessed, book an appointment with a dentist in Newmarket to discuss your options and receive a treatment recommendation based on your dental needs.
Medically Reviewed by Dr. Reza Sartipi

Frequently Asked Question

Are composite fillings better than amalgam fillings?

Composite fillings are often preferred when appearance and adhesive bonding are priorities. Amalgam has a long record of durability in suitable restorations. Neither material is universally better: the decision depends on the size and location of the cavity, the remaining tooth structure, chewing forces, health considerations and material availability. Your dentist can explain which option is appropriate for your specific tooth.

How long do composite and amalgam fillings last?

Both composite and amalgam fillings can last for many years, but their lifespan varies with restoration size, placement quality, oral hygiene, bite forces and the risk of developing new decay. Larger restorations and teeth exposed to heavy chewing forces may face greater mechanical stress. Regular dental examinations help identify wear, fractures or recurrent decay before a restoration develops more extensive problems.

Are amalgam fillings safe because they contain mercury?

Dental amalgam contains mercury and can release small amounts of mercury vapour. Health authorities have evaluated its safety and identified considerations for certain populations. Pregnancy, impaired kidney function and known mercury hypersensitivity warrant discussion with a dentist. Composite does not contain mercury, but it also has clinical limitations. Material selection should follow current guidance and an assessment of individual health needs.

Should I replace an old silver filling with a white composite filling?

Not necessarily. An intact amalgam filling that functions properly does not usually need removal solely because it is old, silver-coloured or contains mercury. Removing a sound restoration can sacrifice healthy tooth structure and temporarily increase mercury-vapour exposure. If the filling is damaged or you have a cosmetic concern, ask your dentist to assess the tooth and explain the benefits and risks of replacement.

Do composite fillings cost more than amalgam fillings?

Composite fillings may cost more than amalgam in some circumstances, but the actual difference depends on the dental practice, restoration size, treatment complexity and local material availability. Insurance benefits can also affect your final expense. Ask for a personalized estimate that includes the recommended procedure and any additional treatment. The lowest initial price should not be the only factor in choosing a suitable restoration.

Can composite fillings be used on back teeth?

Yes. Composite is used for many back-tooth restorations when the cavity size, remaining tooth structure and biting forces make it appropriate. However, molars experience substantial chewing pressure, and larger restorations may present additional challenges. The dentist must also be able to establish suitable conditions for adhesive bonding. For a heavily damaged tooth, an inlay, onlay or crown may provide more appropriate support.

What are the signs that a filling needs to be replaced?

A loose or fractured filling, persistent pain when biting, new sensitivity, a broken piece of tooth or suspected decay around the restoration warrants dental assessment. These symptoms do not always mean the entire filling must be replaced. A dentist can determine whether monitoring, a localized repair or a new restoration is appropriate after examining the filling and surrounding tooth.

Can a dentist repair a damaged filling instead of replacing it?

Sometimes. A small, localized defect may be repairable when the remaining restoration and surrounding tooth are sound. More extensive fractures, recurrent decay or significant structural damage may require replacement or a different restoration. The appropriate approach depends on the extent and location of the damage. Your dentist can explain whether a repair is likely to provide a predictable result in your situation.