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Direct resin-composite restoration of a proximal (Class II) cavity — MO, DO or MOD — in a posterior permanent tooth, where a tight anatomic proximal contact can be re-established.
⚑ adhesion mandatory
Bonded restoration — always. Selectively etch enamel margins with 37% phosphoric acid (15–30 s); with a mild self-etch / universal adhesive leave cut dentine self-etched. The gingival box margin is the weak link: keep it in enamel and supragingival wherever possible — enamel-etched margins give the best long-term clinical performance, and a cervical margin on dentine/cementum bonds less reliably and leaks more.
Adhesively bonded composite placed against a pre-contoured sectional matrix with a separation ring (for a tight, anatomic proximal contact), placed incrementally or bulk-filled to its rated depth, and fully cured under good moisture control.
▢Shade guide — select shade BEFORE isolation (teeth dehydrate and lighten under dam)
▢Local anaesthetic if needed
▢Rubber dam kit (preferred) or cotton rolls + high-volume suction
▢Diamond/round burs + caries indicator or slow round bur
▢Sectional matrix system — pre-contoured bands, wedges, separation ring + ring-placement forceps (circumferential/Tofflemire as fallback)
▢37% phosphoric acid etch + microbrushes
▢Universal / self-etch adhesive + curing light (verify output with a radiometer)
▢Nanohybrid or bulk-fill composite + placement, condensing & proximal-adaptation instruments
1Select shade before isolation — teeth dehydrate and lighten once the dam is on.
2Anaesthetise if needed and isolate — rubber dam preferred; cotton rolls + high-volume suction are an acceptable alternative.
TIP · Moisture control protects the bond, and the gingival box is the hardest part to keep dry. A Cochrane review found rubber dam may lower direct-restoration failure vs cotton rolls at 6 months (low-certainty evidence); whatever you use, keep the field — especially the cervical margin — dry through curing.
3Remove caries and refine the cavity — selective caries removal over deep, near-pulp dentine; clean and rinse. Place a calcium-silicate / RMGI liner only if indicated by depth. Keep the gingival margin in enamel and supragingival where you can.
TIP · Keep the gingival box margin in enamel and supragingival wherever you can. Enamel-etched margins give the best long-term clinical performance; a deep cervical margin on dentine/cementum bonds less reliably, is harder to isolate, and is the commonest site of leakage and recurrent caries. If the margin is deep, consider deep-margin elevation or rethink toward an indirect option.
4Place the matrix — seat a pre-contoured sectional band, seal the gingival margin with a wedge, then fit the separation ring to compensate for band thickness and create a tight contact. Verify the band is burnished against the adjacent tooth.
TIP · The proximal contact is what makes a Class II hard. A systematic review and in-vitro work agree that a pre-contoured sectional matrix with a separation ring gives a tighter, more anatomic contact than a circumferential (Tofflemire) band — the ring offsets band thickness by separating the teeth. A loose contact traps food and drives the proximal margin failures that sink these restorations.
5Selectively etch enamel margins — 37% phosphoric acid 15–30 s, rinse 15 s, leave dentine moist for the self-etch/universal step (or full etch-and-rinse per your adhesive's IFU).
TIP · Selectively etch the enamel even with a 'no-etch' self-etch or universal adhesive: across clinical trials, the enamel-etch technique gives the best overall performance and lowest margin failure. Keep the acid off freshly cut dentine if your adhesive is self-etch, and make sure adhesive reaches the gingival floor.
6Apply Scotchbond Universal Plus per IFU — scrub into the surface, air-thin to evaporate solvent, light-cure. Make sure the adhesive reaches the gingival floor of the box.
7Build the proximal wall first — place and cure a first increment against the matrix to convert the box into a Class-I-like cavity, then fill Filtek Universal Restorative in increments ≤2 mm (or a bulk-fill to its rated depth ≤4–5 mm), adapting each layer to the floor and walls and curing fully.
TIP · Build the proximal wall first to turn the box into a simpler Class-I-shaped cavity, then layer. The high configuration factor of the box concentrates shrinkage stress, so place thin increments — or a bulk-fill validated for its depth (clinically, bulk-fill performs no worse than incremental conventional composite) — and cure each layer fully.
8Remove the ring, wedge and matrix, sculpt the marginal ridge and occlusal anatomy, then give a final cure (under glycerin gel for the last increment to beat the oxygen-inhibited layer) and remove the dam.
9Check the proximal contact with floss (should snap, not shred) and check occlusion with articulating paper; adjust, then finish & polish margins — pay special attention to a flush, smooth gingival margin.
TIP · What actually sinks Class II composites is secondary caries and fracture — and risk climbs with more restored surfaces and higher caries risk, not with the shade. A tight contact, a smooth flush gingival margin, a polished surface and ongoing caries-risk control buy the restoration its years.