Can Bulk-Fill Replace Incremental Composite Placement?

For years, the 2-mm incremental technique has been taught as the safe approach for placing posterior composite. Build the restoration in small increments, cure each layer, reduce polymerization stress and improve adaptation.

But there is an obvious downside: it takes time.

Bulk-fill composites were developed, at least in part, to simplify this process. Depending on the material, clinicians can place increments of around 4–5 mm and cure them in a single step. The pros are obvious—fewer increments, fewer chances for voids and contamination, and potentially shorter appointments.

But the question remains: does placing composite in bulk compromise the long-term clinical performance of the restoration?

A systematic review compared direct composite restorations placed using bulk-fill and conventional incremental techniques in permanent teeth. The review found that, based on the available clinical evidence, bulk-fill restorations performed similarly to incrementally placed composites across the clinical outcomes assessed.

That does not mean that every bulk-fill material or every clinical situation will perform identically. But it does challenge the assumption that incremental layering is automatically superior.

The review focused specifically on randomized clinical trials comparing Class I and Class II direct composite restorations placed using a bulk technique with those placed incrementally.

Because the studies used different composite materials, bonding systems, cavity designs and clinical protocols, the researchers did not perform a meta-analysis. Instead, they synthesized the clinical findings qualitatively.

The outcomes examined included retention, recurrent or secondary caries, marginal discoloration, marginal adaptation, fracture, postoperative sensitivity, surface texture, colour match and anatomical form.

Was incremental layering actually better?

According to the review, no clear clinical advantage emerged for either technique.

Across the included trials, bulk-fill and incrementally layered restorations demonstrated no significant differences in the major clinical parameters evaluated.

This included retention, recurrent or secondary caries, marginal discoloration or staining, marginal adaptation or integrity, fracture, postoperative sensitivity, surface texture or roughness, colour match and anatomical form.

Traditional incremental layering has been recommended to help control polymerization shrinkage and shrinkage stress, improve polymerization and manage the configuration factor. It can also allow the operator greater control over anatomy and adaptation.

But incremental placement is not without its own problems.

Every additional increment introduces another opportunity for contamination, incomplete adaptation or air entrapment. The technique is also more time-consuming, particularly in larger posterior restorations.