Post-operative sensitivity after composite restorations: causes and a prevention checklist

The problem: the call two days later

The restoration looked good, the margins were clean, the patient left comfortable. Two days later the tooth hurts on cold, or on biting, or both. Post-operative sensitivity is the most common complication of a composite restoration and one of the hardest to explain to a patient, because the filling itself looks perfect. In almost every case the cause is one of a short list of technique errors, and each has a specific prevention.

This guide goes through those causes one by one, gives the fix for each, and names the class of material that helps. It ends with a chairside checklist you can print.

Understand: the causes, in order of how often they happen

1. A high spot

Pain on biting that starts the moment the anaesthetic wears off is occlusion until proven otherwise. A composite that is even a fraction high concentrates the whole bite on one cusp, and the ligament complains within hours. Practice: check with thin articulating paper in centric and excursions before the patient leaves; a second check a week later costs nothing.

2. Over-etched or over-dried dentine

Phosphoric acid on dentine for too long demineralises deeper than the adhesive can penetrate. The resin never reaches the bottom of the demineralised zone, and the exposed collagen and open tubules respond to cold and air. Blasting the dentine dry collapses the collagen so the adhesive cannot infiltrate it at all. Practice: etch dentine for no more than about 15 seconds when etch-and-rinse is used, or use selective enamel etching with a universal adhesive; leave dentine visibly moist; scrub the adhesive in; evaporate the solvent gently.

3. A gap at the pulpal floor

Composite shrinks as it cures and the shrinkage pulls on the bond. In a deep box with bonded walls on every side, the weakest bond, usually the pulpal floor, lets go, and a gap forms that fluid moves through on every temperature change. Practice: smaller increments, a flowable or resin-modified glass ionomer liner on the deepest dentine, a bulk-fill material designed for the depth, and soft-start curing where your light supports it.

4. Under-cured composite or adhesive

A light held at a distance, a scratched tip, a battery at the end of its charge, or a bulk-fill placed deeper than its stated depth of cure leaves soft material at the base. Uncured monomer irritates the pulp and the restoration flexes. Practice: know your light's output, cure with the tip as close and as perpendicular as the cavity allows, and cure through the buccal and lingual walls of a deep box as well as from the occlusal.

5. Contamination

Saliva, blood or gingival fluid on etched enamel or primed dentine ruins the bond invisibly. Practice: rubber dam, or at least a dry field with retraction and a fresh cotton roll; re-etch enamel if it is contaminated. Ask about latex allergy before placing the dam and use a non-latex sheet if needed.

6. Deep caries close to the pulp

Sometimes the pulp was already inflamed. A deep cavity, a history of lingering pain, or a tooth that was sensitive before treatment predicts sensitivity after it regardless of technique. Practice: test vitality before treating deep lesions, warn the patient, protect the deepest dentine with a liner or a calcium-silicate material, and record the finding.

7. Cracked tooth

A cusp that was already cracked will hurt on release of biting pressure after any restoration. Practice: bite test each cusp on a tooth with a large old restoration before you replace it.

What the evidence says

• Evidence. Systematic reviews report no significant difference in post-operative sensitivity between bulk-fill and incrementally placed posterior composites.³
• Evidence. In cervical lesions, selective enamel etching with a universal adhesive improved retention compared with self-etch alone, without the dentine over-etching that total-etch invites.⁴
• Practice. Clinical reviews on the topic consistently rank operator technique (etching, drying, curing, occlusion) above the choice of composite as the source of sensitivity.^{1, 2}

Options: what helps, by class

Class	What it does	Stocked examples
Resin-modified glass ionomer liner	Seals tubules on deep dentine, bonds to dentine, releases fluoride, cures in a thin layer	Fusion iSeal LC, Ionoseal, Biner LC
Desensitiser	Occludes tubules or reduces nerve response; used on deep dentine, after bleaching, or in sensitive patients	Shield Activ (HEMA-based), UltraEZ (potassium nitrate and fluoride), CharmSensy (light-curing)
Low-stress bulk-fill	Cures to 4 mm with reduced shrinkage stress on the pulpal floor	SDR Plus
Universal adhesive with selective etch	Avoids over-etching dentine while keeping the enamel bond	See the adhesives guide
Curing light with adequate output	Cures the adhesive and every increment to depth	Woodpecker i LED Plus, VALO Grand
Isolation	Keeps the field dry from etch to final cure	Rubber dam sheets, clamps and frames
Articulating paper	Finds the high spot before the patient does	Thin 50 µm paper, horseshoe 100 µm

Compare: cause, sign, fix

Cause	How it presents	Prevention step	Material that helps
High spot	Pain on biting from day one	Occlusal check in centric and excursions	Articulating paper
Over-etched dentine	Sharp cold sensitivity, air sensitivity	Dentine etch under 15 s, or selective enamel etch; moist bonding	Universal adhesive, etchant applied enamel-first
Gap at the floor	Cold and bite sensitivity, sometimes a radiolucent line	Liner on deep dentine, smaller increments or a low-stress bulk-fill	RMGI liner, SDR Plus
Under-cure	Dull ache, sensitivity that does not settle	Light output known; tip close; cure from more than one direction	Curing light within its stated irradiance
Contamination	Marginal staining, sensitivity, early debond	Rubber dam; re-etch contaminated enamel	Rubber dam kit
Inflamed pulp before treatment	Lingering pain, history of sensitivity	Vitality test; liner or calcium silicate; warn the patient	Calcium hydroxide or calcium silicate liner
Cracked cusp	Pain on release of bite	Bite test before treatment	None; treatment plan changes

The chairside checklist

1. Vitality and bite test on any deep or previously restored tooth.
2. Rubber dam on, or a dry retracted field with fresh rolls.
3. Etch enamel first; keep dentine etch short; rinse; leave dentine moist.
4. Liner or desensitiser on the deepest dentine when the cavity is within a millimetre or two of the pulp.
5. Adhesive scrubbed in, solvent evaporated until the film stops moving, cured for the full time.
6. Increments no thicker than the material's stated depth of cure; bulk-fill only to 4 mm, capped.
7. Cure from the occlusal and, on a deep box, from buccal and lingual after the matrix is removed.
8. Articulating paper in centric and excursions; adjust; polish.
9. Tell the patient what mild sensitivity looks like and what needs a call.

Recommended products: the sensitivity-prevention kit

Liners and desensitisers for the deep dentine step:

The materials that remove the other causes: a low-stress bulk-fill, a light that cures to depth, thin articulating paper and isolation:

Buying advice

If the clinic has none of these, start with a resin-modified glass ionomer liner and a box of thin articulating paper; between them they address the two most frequent causes. Add a desensitiser for bleaching and sensitive patients, and check the curing light's output before buying a bulk-fill that depends on it.