Does every cavity need a filling? How is a filling done?

Does every cavity need a filling? How is a filling done?

Direct answer (source-language limit: 60 characters)

For an early lesion that has not cavitated, evidence supports non-restorative control and follow-up [F5][F7]. A cavitated lesion that cannot be cleaned or sealed is an indication for restoration; staging must be decided by a dentist [F4].

Scope: This is general health education based on international literature. It does not address any particular country's insurance or legal system; care and fee arrangements follow the system where treatment is received. The Taiwan Medical Care Act in the compliance notice only identifies this site's publication status and is tagged geo: TW.

Why the answer depends on stage

Dental caries is the disease; a carious lesion is its consequence and manifestation. Caries management controls disease at patient level with preventive and non-invasive means, while lesion management controls its signs at tooth level [F3]. A filling treats the lesion in that tooth, not the disease that caused it [F3][F4].

For communication, this card uses three stages: a non-cavitated lesion; a cavitated lesion; and a deep lesion near or involving the pulp. This is not a self-diagnostic tool. Visual examination and imaging, including serial bitewings for proximal lesions, are clinical assessment [F2][F11].

When evidence supports not restoring first

The international consensus says to avoid entering the restorative cycle where possible. Restoration is indicated only when a cavitated lesion is non-cleansable or can no longer be sealed; disease activity should first be controlled by approaches aimed at removing or controlling biofilm [F4]. “There is a hole” is therefore not, by itself, an instruction to operate.

The ADA non-restorative guideline made 11 recommendations, each tied to a lesion type, tooth surface, and dentition. Its recommended options include 38% silver diamine fluoride, sealants, 5% sodium-fluoride varnish, 1.23% acidulated-phosphate-fluoride gel, and 5000 ppm fluoride (1.1% sodium-fluoride) toothpaste or gel; it recommends against 10% CPP-ACP [F5]. Those are guideline-linked options, not self-treatment instructions or a claim that every lesion can avoid restoration.

For non-cavitated proximal lesions, a Cochrane review of 8 randomised trials and 365 participants found micro-invasive treatment reduced progression versus non-invasive professional treatment or oral-hygiene advice (OR 0.24, 95% CI 0.14 to 0.41; 602 lesions; 7 studies; I²=32%). It applies to enamel and initial dentinal lesions limited radiographically to the outer third of dentine, not collapsed cavities [F7]. Fluoride varnish and fissure sealants prevent new lesions; they do not establish that an existing cavity disappears [F8][F9].

Silver diamine fluoride can blacken arrested lesions [F10]. Non-restorative care also means active control and follow-up, not going home and doing nothing [F4]. A 2026-08-05 PubMed search using the two specified queries returned 0 direct long-term randomised comparisons of monitoring versus immediate restoration for adults with cavitated lesions; this card therefore gives no “safe delay” time [F22].

Progression and deep caries: do not turn evidence into a slogan

A Swedish prospective radiographic study of 536 children aged 11 to 22 found large variation between surfaces. Seventy-five percent of sound surfaces did not reach state 2 for 6.3 years; from state 2, 75% did not reach state 4 for 4.8 years; from state 3 at the enamel-dentine junction, 75% did not reach state 4 for only 1.3 years, with a median state-3-to-4 survival time of 3.1 years [F11]. This older, single-country, adolescent proximal-lesion cohort under a remineralisation-based strategy is not an individual forecast.

In 2010, an international model estimated untreated caries in 2.4 billion people with permanent teeth and 621 million children with deciduous teeth [F12]. Commonness is not proof that delay is harmless. When a lesion is near or at the pulp, the aim changes to preserving vitality and preventing apical periodontitis; options can include vital-pulp therapy, root-canal treatment, or extraction when the tooth cannot be retained [F15][F16].

For deep caries, evidence is not settled. The 2013 Cochrane review reported lower pulp-exposure incidence with stepwise removal (56%, RR 0.44, 95% CI 0.33 to 0.60; 4 studies: 34.7% versus 15.4%) and partial removal (77%, RR 0.23, 95% CI 0.08 to 0.69; 2 studies: 21.9% versus 5%), but all trials had high risk of bias [F13]. The current 2021 Cochrane update included 27 studies, 3350 participants and 4195 teeth/lesions from 11 countries published between 1977 and 2020; most comparisons had low or very low certainty [F23].

The consensus favours selective removal to firm dentine for shallow/moderate cavities and to soft dentine for deep lesions, with stepwise removal an option in permanent teeth; the ADA gives conditional recommendations for conservative carious-tissue removal [F4][F6]. In contrast, a 2024 double-blind RCT of 124 mature permanent teeth with reversible pulpitis found 17/61 (28%) pulp exposures in total removal and 12-month pulp survival of 98.4% with total removal versus 82.5% with selective removal (P = 0.003) [F14]. Dental maturity, pulp diagnosis and pre-operative pain (above or below 5/10) matter. Neither “always remove all” nor “never remove all” is supported [F13][F14][F15][F22].

What happens during a filling

1. Stage and extent are assessed by examination and images [F4][F11].
2. The tooth is isolated. A Cochrane review of 4 studies and 1270 participants found very-low-certainty evidence that a rubber dam may lower restoration failure versus cotton rolls; it is not a universal legal or clinical requirement [F18].
3. Caries is removed according to the diagnosis. Defined options include selective removal to soft or firm dentine, stepwise removal, and nonselective removal to hard dentine (the former “complete” technique, no longer recommended in the terminology consensus) [F3][F4][F6].
4. A restorative material is chosen. A 2026 overview found no likely difference and less than 5% failure for bulk-fill versus layered composite (RD 0.00, 95% CI −0.03 to 0.03; 7 studies, 511 restorations; 1 to 10 years), while low-certainty evidence suggested amalgam might have 7% less failure than composite (RD 0.07, 95% CI 0.05 to 0.09; 2 studies, 3010 restorations; 5 to 7 years). The older primary studies and only about 10% general-practice setting limit transferability [F17].
5. Margins and bite are finished. In a retrospective study, proximal restorations with marginal overhangs had pockets 0.42 mm deeper than metal restorations without overhangs [F20].

Risk factors, limits, and questions to ask

More prior caries (DMFS > 1 at age 11 to 12), caries risk, occlusal-stress risk, a deep lesion with more marked pre-operative pain, and inability to attend active follow-up can change the picture [F11][F14][F19][F4]. Reported issues include post-operative pain/discomfort (about 5% in both material groups in one very-low-certainty review), restoration failure or secondary caries, pulp exposure, and SDF staining [F17][F19][F14][F10].

Ask: Is there a cavity and what stage is it? Can it be controlled non-restoratively? Which removal strategy and material are proposed, and why? What is the pulp diagnosis? Am I at caries or occlusal-stress risk? Which signs mean I should return? [F3][F4][F5][F6][F17][F20]

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Chinese labels to look for on the official pages

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Compliance notice

This is health education information under Article 87 of Taiwan's Medical Care Act, not medical advertising, and does not recommend a particular clinic [F21]. Caries care—including non-restorative care, restoration, carious-tissue removal, vital-pulp therapy, root-canal treatment, and extraction—has indications, limits and possible adverse effects. Treatment and results vary by person and require a dentist's assessment; this staging framework cannot replace diagnosis or justify delaying care.

Every clinical statement in this article is mapped line by line to its cited source (see the sources and evidence chain below). It has not been clinically reviewed by a licensed practitioner. This is health information, not individual advice; assessment by a clinician is required.