Occlusal Adjustment of Composite Restorations
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Direct answer
Two weeks after a posterior composite, "the bite feels high" — and the adjustment that follows has a fixed sequence: centric occlusion first, then working-side excursions, then non-working and protrusive movements. Composite cannot be burnished like amalgam, so every reduction must be finished, not just cut; high spots are located with thin articulating film and removed with fine burs or diamonds, and the ground surface is re-polished with rubber points and paste. An unadjusted composite carries real consequences — polymerisation shrinkage can leave the restoration slightly proud of the occlusal table, and the material's brittleness means a prematurity can crack a marginal ridge rather than wear itself in.
What you must remember
- Marking media: use thin articulating film of about 20-40 micrometres; thick paper records false contacts from the cusp slopes it drags across. Blue for centric, red for excursions is the common chairside convention.
- Sequence (viva favourite): centric/premature contacts first, then laterotrusive (working) interferences, then mediotrusive (non-working) interferences, then protrusive — removing out of order creates new interferences.
- Shimstock foil: a soft foil that marks only firm, high-force contacts — the standard test for whether a contact is true or merely incidental.
- Burs for adjustment: fine diamonds or 30-bladed carbides at low speed with water, because composite chips at margins and overheats without irrigation.
- Finish after cutting: ground composite is rough and plaque-retentive — re-polish with progressively finer rubber points and aluminium oxide paste, exactly as for a fresh restoration.
- Check the marginal ridges: adjacent marginal ridges should be level; a high composite ridge concentrates force and is the commonest cause of post-operative fracture complaints.
- Why composite matters more than amalgam here: amalgam wears and burnishes into the occlusion; composite is wear-resistant and brittle, so a prematurity persists and can crack cusps or the restoration itself.
Working through the "bite feels high" complaint
A patient returns three days after an occlusal composite on 46, reporting pressure on chewing and mild aching by evening. Dry the field, then ask the patient to tap and slide on blue film held against the occlusion: a single heavy ring on the composite while neighbours show only faint marks identifies the prematurity. Confirm with shimstock — if the foil pulls through between 46 and its antagonist but not between untouched teeth, the contact is truly premature. Reduce with a fine diamond at the marked point, aiming to restore the fossa anatomy rather than to flatten the cusp, irrigating between passes. Re-mark after every reduction; the goal is equal-intensity marks across the quadrant. Then run red film through right and left excursions and protrusion for the interference passes, and finish with a rubber point and polishing paste until the surface gloss matches the surrounding enamel. Review in a week: pain that settles confirms occlusion as the cause; pain that persists despite a balanced adjustment shifts suspicion to a crack or pulpitis, and calls for vitality testing rather than more grinding.
Where students slip
The commonest clinical error is adjusting with coarse paper and heavy pressure, which stains the whole occlusal table and tempts the operator to cut sound cusp anatomy. The classic viva trap is the order question: "why centric first?" — because centric prematurities govern the closing arc; an excursion interference ground first simply relocates once the centric stop is corrected. Students also forget that composite must be re-polished after adjustment; a ground, matte patch collects stain within weeks, and examiners reading a restored occlusion always look for that tell-tale rough mark as evidence of an unprofessional finish.
Frequently asked questions
Which contacts are adjusted first after restoring a tooth?
Centric occlusion contacts first, followed by working-side, non-working-side and protrusive interferences, in that order, to avoid creating new prematurities.
Why is thin articulating film preferred over thick paper?
Film of about 20-40 micrometres marks only true contacts, whereas thick paper flexes across cusp slopes and records misleading marks on inclined surfaces.
What does shimstock foil demonstrate?
It marks only under firm contact force, so a contact that fails to transfer foil while adjacent teeth do is confirmed as a genuine prematurity.
How should ground composite be finished after adjustment?
Re-polish sequentially with fine rubber points and aluminium oxide paste under water spray until the gloss matches adjacent enamel, since cut composite is rough and stain-retentive.
Why can a high composite restoration fracture rather than wear down?
Composite is far more wear-resistant than amalgam and behaves as a brittle material, so persistent premature loading transmits cracking forces to cusps and the restoration instead of abrading it away.