Do bulk-fill composites really cure at 4 mm — and do they last?
Measured depth of cure, shrinkage stress, radiopacity, and 3-year wear for the bulk-fill composites dentists actually place — against nine randomised trials comparing bulk placement with incremental layering. Every figure below is taken from the cited source — nothing is estimated or interpolated.
Clinically reviewed by Chithra Durgam, DDS on .
RR 0.82
restoration failure with bulk-fill versus incremental layering across nine randomised trials and 632 restorations — not a significant difference (95% CI 0.33–2.01, p = 0.67, I² = 0%) [2025]
4.1 mm
the deepest cure any of sixteen composites reached at a fixed 10-second exposure — Filtek Bulk Fill Flowable. Every other material tested fell below the 4 mm bulk-fill claim at that time [2024]
3–16%
how much lower measured filler content ran than the figure the manufacturer reports, across the same sixteen composites [2024]
2–4 min
chairtime saved per restoration by bulk placement in primary teeth — the advantage that actually separates the techniques [2025]
The bulk-fill table
What each material or question was measured on, what the source found, and the one-line verdict — with the source for every line.
| Material or question | What was measured | What the evidence says | Verdict | Source |
|---|---|---|---|---|
| Bulk-fill vs incremental (permanent posterior) | Do bulk-filled restorations fail more often? | No. Nine RCTs and 632 Class I and II restorations pooled to RR 0.82 (95% CI 0.33–2.01, p = 0.67) with no heterogeneity (I² = 0%). Subgroups under 24 months and 24 months or longer were both null. Three of the nine trials carried a high risk of bias from their randomisation methods, and only one followed patients past five years. | No difference | 2025 |
| Bulk-fill vs incremental (second synthesis) | Does an independent review reach the same conclusion? | Yes. A separate search of PubMed, Embase, Scopus, and Web of Science found 18 eligible RCTs and reported clinical outcomes similar between the two techniques over review intervals from 6 months to 10 years. Fourteen of the 18 raised some concerns on risk of bias, so the finding is consistent rather than high-certainty. | No difference | 2023 |
| Primary teeth | Does the finding hold in children? | Broadly. Across 13 RCTs both techniques showed retention above 90% and comparable two-year survival of 85–90%, with equivalent marginal integrity — though incremental placement held a modest advantage in complex cavities. Bulk placement cut 2–4 minutes per restoration, which is the meaningful difference in a paediatric appointment. | Equivalent, faster | 2025 |
| Filtek Bulk Fill Flowable | Depth of cure at a fixed 10-second exposure (ISO 4049) | 4.1 mm — the only material of sixteen to clear 4 mm at that exposure, and the deepest cure in the study. Shrinkage stress measured 1.5 MPa against 1.9 MPa for the same manufacturer's non-bulk flowable. The manufacturer specifies 20 seconds for the shade tested, so the clinical figure should be better than this, not worse. | Cures at 4 mm | 2024 |
| SureFil SDR Flow+ | Depth of cure at a fixed 10-second exposure (ISO 4049) | 3.9 mm at 10 seconds, against a manufacturer-specified 25 seconds for the shade tested — so this material was given under half its recommended cure. Shrinkage stress 1.5 MPa, lower than the same manufacturer's conventional flowable at 1.8 MPa. | Cure the full 25 s | 2024 |
| Tetric PowerFlow | Why it cures deep without being more translucent | 3.9 mm at 10 seconds despite being less translucent than its non-bulk counterpart — the authors attribute it to Ivocerin, a more photoactive initiator than camphorquinone. Depth of cure tracked translucency across the other materials but not this one, so translucency alone does not tell you which material cures deep. | Cures deep | 2024 |
| Omnichroma Flow Bulk | Depth of cure at a fixed 10-second exposure (ISO 4049) | 3.3 mm — and the only flowable bulk-fill in the study that did not out-cure its own non-bulk sibling (Omnichroma Flow reached 3.5 mm). The manufacturer specifies 30 seconds for this shade, three times what it was given here. It also recorded the lowest radiopacity of the sixteen materials at 0.8 mm aluminium equivalent; the authors note no ytterbium fluoride in the published composition.Full clinical answer | Needs 30 s | 2024 |
| Conventional composites, for contrast | How deep does a non-bulk composite cure? | Filtek Supreme Ultra 2.6 mm, GrandioSO 2.4 mm, Tetric EvoCeram 2.4 mm, Tetric EvoFlow 2.1 mm at the same 10-second exposure. The 2 mm increment for conventional materials is not conservatism — it is roughly what these composites actually cure.Full clinical answer | Keep 2 mm layers | 2024 |
| Flowable bulk-fill as a base | Does it need capping? | Yes — low-viscosity bulk-fill bases require capping with a conventional composite because of their lower wear resistance, while high-viscosity full-body materials can be left exposed to the oral environment. The meta-analysis found both strategies performed equally, provided the capping instruction is followed. | Cap the flowable | 2025 |
| Injectable vs body vs sonic bulk-fill | Three-year volumetric wear in Class II restorations | Mean volume loss at three years was 0.018 mm³ preheated body, 0.019 mm³ sonic (SonicFill3), 0.020 mm³ body (Filtek One Bulk Fill), and 0.032 mm³ injectable (G-ænial BULK Injectable). All 78 recalled restorations survived and stayed clinically acceptable, but the injectable was the only group whose volume loss differed significantly from the opposing enamel at one, two, and three years. | Watch the injectable | 2026 |
| Dual-cure vs light-cure bulk-fill | Does dual-cure chemistry buy anything clinically? | Not measurably at two years. One dual-cure (Fill-Up) and two light-cure bulk-fills (QuiXfil, Tetric N-Ceram Bulk Fill) across 120 Class II restorations showed no statistically significant difference on any FDI parameter at any recall, and no parameter differed from baseline. | Equivalent | 2024 |
| Preheating the syringe | Does repeated preheating cause postoperative sensitivity? | No. Across 105 patients randomised to no preheating, one cycle, or ten cycles, VAS scores were essentially zero at one week and one month; only the non-preheated group showed a significant day-one-to-later change. Repeated preheating had no adverse effect on postoperative dentine hypersensitivity. | Safe | 2024 |
| Preheating the syringe | Does repeated preheating degrade the restoration in service? | Not at two years. Eighty-four Class II restorations placed with composite preheated zero, one, five, or ten times at 68 °C showed no significant difference on any parameter at 6, 12, 18, or 24 months, and none needed replacement — so a syringe can be rewarmed across a working week without a durability penalty. | Up to 10 cycles | 2024 |
| ORMOCER bulk-fill vs nanohybrid | Split-mouth comparison in children's first molars, 2 years | All restorations in 89 children stayed clinically acceptable. The incrementally placed nanohybrid (Grandio) scored significantly worse on surface luster and superficial change, while the bulk-fill ORMOCER (Admira Fusion x-tra) scored significantly worse on surface staining and colour match. Neither material won outright — the tradeoff is gloss against stain. | Tradeoff, not a winner | 2024 |
| Filler content on the box | Does the stated filler percentage match the material? | Not exactly. Burned-ash measurement of sixteen composites ran 3–16% below the manufacturer-reported filler weight — partly because reported figures include silanes, pigments, opacifiers, and pre-polymerised resin that burn off. Filler weight predicted elastic modulus strongly (r = 0.78) and flexural strength only moderately (r = 0.46), and predicted shrinkage stress and depth of cure not at all. | Filler % misleads | 2024 |
How to use this table
- Cure time is the variable that decides whether 4 mm is real. At a uniform 10-second exposure most bulk-fills fell short of their claimed depth, and the three that came closest are specified by their manufacturers at 20, 25, and 30 seconds. Use the time on the box, not the habit.
- Survival does not separate the techniques — chairtime does. Two independent syntheses found no failure-rate difference over follow-ups reaching 6 to 10 years, while bulk placement saved 2–4 minutes per restoration.
- The choices that still matter within the category are capping a flowable base, and watching wear on injectable materials, which lost 0.032 mm³ at three years against 0.018–0.020 mm³ for body, sonic, and preheated body composites.
- Filler percentage on a brochure predicts stiffness reasonably well and predicts depth of cure and shrinkage stress not at all — so it is the wrong number to shop on.
How this brief was built
Every clinical row reports the cited trial or review's own result for its own population. The bench rows come from a single laboratory that tested sixteen commercial composites side by side under ISO 4049 — one curing light, and the same 10-second cure for every material, which is shorter than several manufacturers specify. That is stated on each row, because it is the reason some materials fall short of their marketing claim here. Nothing on this page is a manufacturer figure unless the row says so.
Cited sources
Where every figure comes from
Clinical Performance and Survival of Bulk-Fill Resin Composites Compared to Conventional Resin Composites in Posterior Permanent Teeth: A Systematic Review and Meta-analysis
Cureus · 2025 · Meta-analysis
Open the sourceThe clinical performance of bulk-fill versus the incremental layered application of direct resin composite restorations: a systematic review
Evidence-Based Dentistry · 2023 · Systematic review
Open the sourceClinical Performance of Bulk-Fill Versus Incremental Composite Restorations in Primary Teeth: A Systematic Review of In Vivo Evidence
Dentistry Journal · 2025 · Systematic review
Open the sourceCorrelation between Dental Composite Filler Percentage and Strength, Modulus, Shrinkage Stress, Translucency, Depth of Cure and Radiopacity
Materials · 2024 · Laboratory study
Open the sourceWear performance of different bulk-fill class II resin composite restorations: 3-year clinical evaluation
Scientific Reports · 2026 · Randomised controlled trial
Open the sourceTwo-year clinical performance of dual- and light-cure bulk-fill resin composites in Class II restorations: a randomized clinical trial
Clinical Oral Investigations · 2024 · Randomised controlled trial
Open the sourceTwo-year evaluation of a nano-hybrid and a bulk-fill resin composite: a randomized, double-blind split-mouth clinical study
Clinical Oral Investigations · 2024 · Randomised controlled trial
Open the sourceImpact of repeated preheating of bulk-fill resin composite on postoperative hypersensitivity; a randomized controlled clinical trial
BMC Oral Health · 2024 · Randomised controlled trial
Open the source24 Months clinical prospective of proximal restorations with repeated preheating bulk fill composite up to ten cycles: randomized controlled trial
Scientific Reports · 2024 · Randomised controlled trial
Open the source
Ask this against the live evidence.
This brief is a stored snapshot of the published literature. Run the search yourself for sources matched to the case in front of you.
This brief was compiled from the published reviews, guidelines, and trials listed above. Findings reflect each source’s own populations, materials, and test conditions.
Compiled on . Verify against current evidence and apply professional judgment before clinical use.