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Dental fillings: repairing cavities, choosing materials and replacing restorations

6 sources · Latest source check 2026-10-13 UTC
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A filling repairs a tooth damaged by decay by restoring the prepared area with a material. It differs from a crown covering a tooth and from root-canal treatment for infected pulp. The size, depth and location of the problem shape which procedure is considered.[1]

Common direct restoration categories

Common direct restoration categories
TermMeaningBoundary
Composite resinResin reinforced with glass, commonly light-curedTooth-colored; placement conditions matter[3]
Glass ionomerA fluoride-releasing restorative materialUsed for selected indications, including some smaller restorations[3]
Dental amalgamMetal mixture containing elemental mercuryNew placement and existing-filling removal are separate decisions[2]

The category includes different procedures and constraints

FDA distinguishes directly placed fillings from indirect restorations made outside the mouth. Composite can match tooth shade and is commonly placed in layers, while moisture control and cavity size affect suitability. Glass-ionomer uses include selected smaller restorations and its fluoride release is a material property, not a guarantee against future decay. Ask which tooth surfaces the restoration will replace, how it will be retained and whether access or moisture makes a planned material harder to place.[3]

Depth changes the balance between removal and preserving tissue

The ADA’s chairside guide adapting its 2023 recommendations concerns vital permanent teeth without prior endodontic treatment. It suggests selective removal rather than removing all affected tissue for moderate lesions, and selective over stepwise or nonselective removal for advanced lesions. Recommendations depend on location and cavity class and are often conditional. This is a dental procedure performed while protecting the pulp, not advice to leave an untreated open cavity. The guide does not apply automatically to a tooth with pulp necrosis.[4]

Evidence & uncertainty

The July 2026 Cochrane overview compares materials for direct restorations of permanent back teeth. It found limited evidence from general practice and older trial materials, so a category ranking cannot automatically predict the durability of a current filling in a particular mouth.[5]

Selected-source overview · Independent review pending

Published questions

Is a filling the same procedure as covering a tooth with a crown?

Selected-source overview · Independent review pending. Read the evidence context.

No. A filling repairs a prepared area, whereas a crown covers the tooth. Root-canal treatment addresses pulp infection and is another distinct procedure.[1]

Evidence behind this answer
  • Dental treatments

    agency health explanation · Date not stated
    Official page text, relevant sections inspected · Fillings; crowns; root canal treatment; scale and polish, lines 29–57

This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.

Does treatment of deep decay always mean removing every bit of soft dentine?

Selected-source overview · Independent review pending. Read the evidence context.

No. For selected vital teeth, the guide suggests selective removal to preserve tissue near the pulp. Eligibility and a sealed restoration matter; this is not an untreated open-cavity strategy.[4]

Evidence behind this answer

This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.

Does guidance to avoid a new amalgam imply removing every sound existing filling?

Selected-source overview · Independent review pending. Read the evidence context.

No. FDA advises against removing intact fillings without decay solely for disease prevention, because removal has its own exposure and tissue-loss consequences.[2]

Evidence behind this answer

This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.

Does tooth-colored filling material guarantee it will never fail?

Selected-source overview · Independent review pending. Read the evidence context.

No. The material description also involves restoration size, moisture control and placement conditions. Shade matching and durable clinical function are different properties.[3]

Evidence behind this answer
  • Treatment Options for Dental Caries

    agency health explanation · 2020
    Official page text, relevant sections inspected · Treatment Options for Dental Caries: direct/indirect placement, composite layers and moisture conditions, glass-ionomer use/fluoride release

This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.

Did the current overview find bulk-fill composite clearly more durable than layered composite?

Selected-source overview · Independent review pending. Read the evidence context.

No. The selected comparison suggested little or no failure difference, with the estimate spanning a small advantage in either direction. It did not establish a lifespan for an individual filling.[5]

Evidence behind this answer

This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.

Do selective-decay-removal studies decide the best filling material?

Selected-source overview · Independent review pending. Read the evidence context.

No. They compare tissue-removal strategies in defined vital teeth. Choosing a restorative material is a separate comparison involving the tooth and placement conditions.[6]

Evidence behind this answer

This answer summarizes selected sources. An independent appraisal of the complete evidence has not been completed.

Selective removal and filling material are different comparisons

The 2021 Cochrane advanced-decay review explains selective removal as clearing cavity edges while retaining some softened dentine near the pulp. Stepwise removal returns after several months. It included twenty-seven studies, mainly in children, and compared strategies for vital teeth without irreversible pulpitis or necrosis. Selective or stepwise approaches may reduce failures relative to conventional removal for deep lesions, but certainty varied and trials had methodological limitations. These results concern how tissue is removed; they do not establish a universal best filling material.[6]

A contemporary overview is cautious about older comparisons

The 2026 Cochrane overview searched through April 2025 and included fourteen reviews containing fifty-seven studies. Most reviews had high risk of bias and few studies took place in general dental practice. Bulk-fill and layered composites probably differed little in failure: risk difference 0.00, with a 95% confidence interval from minus 0.03 to 0.03, across seven studies and 511 restorations. Older amalgam/composite comparisons may not reflect current formulations or experience. Included reviews did not report tooth loss or time-to-failure, limiting a simple lifespan claim.[5]

US precautions for a new amalgam filling are specific

FDA’s patient guidance identifies amalgam as a mixture approximately half elemental mercury by weight. It recommends avoiding new amalgam where possible and appropriate in pregnancy or planned pregnancy, nursing, children especially under six, neurological or kidney dysfunction and relevant allergy. This is US guidance about susceptible groups and new placement. A clinician weighs tooth condition and alternatives; it is not a claim that every metal restoration causes illness or that every tooth-colored formulation is suitable in every cavity.[2]

A local defect may prompt a different decision from replacing every filling

FDA does not recommend removing intact amalgam without underlying decay solely to prevent disease. Removal can briefly increase mercury-vapor exposure and remove healthy tooth tissue. A damaged restoration, new decay, a bite problem and a requested material change need separate assessment. In particular, guidance about avoiding a new placement cannot be converted into an instruction to remove all existing restorations during pregnancy. Ask what finding motivates replacement and how the proposed repair or replacement preserves the remaining tooth.[2]

References

  1. Dental treatments

    Agency health explanation

    NHS · Content/publication date: not stated
    Accessed: 2026-10-13 UTC · Official page text, relevant sections inspected
    Cited sections: Fillings; crowns; root canal treatment; scale and polish, lines 29–57

    Simple patient guide; does not establish any fixed cleaning interval or material lifespan.

  2. Information for Patients About Dental Amalgam Fillings

    Agency safety guidance

    US Food and Drug Administration · Content/publication date: 2020
    Accessed: 2026-10-13 UTC · Official page text, relevant sections inspected
    Cited sections: What Is Dental Amalgam; Who Should Be Concerned; Should Fillings Be Removed; durability and alternatives

    US FDA guidance. New-placement precautions differ from existing-filling removal. General-population studies do not establish conclusive harmful effects; avoid universal safety or toxicity claims.

  3. Treatment Options for Dental Caries

    Agency health explanation

    US Food and Drug Administration · Content/publication date: 2020
    Accessed: 2026-10-13 UTC · Official page text, relevant sections inspected
    Cited sections: Treatment Options for Dental Caries: direct/indirect placement, composite layers and moisture conditions, glass-ionomer use/fluoride release

    2020 description. Avoid its questionable generic glass-ionomer ingredient list or promises of a fixed lifespan.

  4. ADA chairside guide: Restorative treatments for caries lesions in permanent teeth

    Professional guideline

    American Dental Association · Content/publication date: 2023
    Accessed: 2026-10-13 UTC · Original 2-page chairside PDF relevant recommendations inspected; full journal guideline not retrieved
    Cited sections: Pages1–2: vital nonendodontically treated permanent teeth, moderate/advanced lesions, selective removal and conditional material recommendations

    The guide has 2024 copyright and adapts July 2023 recommendations. Does not apply to pulp necrosis; not all soft dentine must always be removed. Full journal guideline was not retrieved.

  5. Restorative materials for direct coronal restoration of permanent posterior teeth: an overview of systematic reviews

    Original systematic review overview

    Lewis et al.; Cochrane · Content/publication date: 2026
    Accessed: 2026-10-13 UTC · Original review overview summary and abstract inspected
    Cited sections: July2026 summary and abstract: April2025 search, fourteen reviews, older-material limitations, bulk-fill risk difference and missing tooth-loss/time outcomes

    Abstract reports 23 unique studies prioritized while plain summary says 25; avoid an exact prioritized study count without qualification. Includes older Cochrane trials rather than independent replication.

  6. Interventions for treating cavitated or dentine carious lesions

    Original systematic review

    Cochrane · Content/publication date: 2021
    Accessed: 2026-10-13 UTC · Original review summary and abstract inspected
    Cited sections: Definitions of selective/stepwise removal; selection criteria for vital pulps; study characteristics and authors conclusions

    All trials had high risk of bias in some respect and most results had low or very low certainty. Tissue-removal strategy and material choice are different questions.

Scope & review

Population
General readers considering dental care; study-specific populations and ages identified
Exposure or intervention
Dental fillings
Comparison
Direct filling materials separated from crowns/root-canal care, tissue-removal strategies, and new-amalgam precautions versus existing-restoration removal
Outcomes
Definitions, practical distinctions, source-specific clinical outcomes and uncertainty
Timeframe
Selected historical and current evidence checked 2026-10-13
Jurisdiction
Selected US agency sources, dated professional guidance and original international research; jurisdiction and eligibility are source-specific

Bounded selected-source educational explanation distinguishing official guidance, original research and editorial interpretation. No exhaustive search, independent systematic synthesis or qualified dental review has been completed.

Sources checked on their individual access dates. Selected sources were checked; ongoing surveillance and qualified review have separate statuses on the coverage page.

Revision history
  • 2026-10-13 UTC: Added a definition-first dental explanation; qualified independent review remains pending.

What this article still leaves open

  • Which lesion depth, pulp status, defect and placement conditions support repair, replacement or another procedure?
  • Material-specific allergy, contemporary lifespan, local regulatory differences and qualified independent review remain incomplete.
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