Do bulk-fill composites really cure at 4 mm, or in 3 seconds — and do they last?
Measured depth of cure, 5 mm claims, 3-second curing, composition, 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]
2 of 8
composites that kept their depth of cure when cured for 3 seconds at high irradiance — the two formulated for it. The other six cured significantly shallower [2024]
3 of 6
bulk-fills that held 80% of maximum hardness past 5 mm on a Vickers profile — SonicFill 2, VisCalor, and Admira Fusion x-tra. Two of the six did not reach 4 mm [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 |
| SonicFill 2, VisCalor, Admira Fusion x-tra | Which bulk-fills hold hardness past 5 mm? | Three of six did, on a Vickers profile at 80% of maximum hardness: SonicFill 2, VisCalor, and Admira Fusion x-tra all cured deeper than 5 mm. Filtek Bulk Fill cleared 4 mm but not 5. Fill-Up! and GrandioSO Heavy Flow did not reach 4 mm, and GrandioSO Heavy Flow dropped below the line at 2.9 mm. Turning the light up to high irradiance did not buy depth; it raised volumetric shrinkage and void ratio, and only in SonicFill 2. | Three clear 5 mm | 2025 |
| Filtek One, Tetric EvoCeram Bulk Fill, SonicFill 2 | Does a 5 mm claim survive a wide cavity and a light held off-centre? | Only under the tip. In a simulated 10 × 6 mm cavity filled in one increment, depth of cure ran from 5.7 mm at the centre for Filtek One down to 3.6 mm at the periphery for SonicFill 2, and every material cured shallower 4 mm out from the centre than directly under the light. With the tip 7 mm away and 3 mm off-centre, tolerance fell to 2.4–3.9 mm; distance hurt more than off-centre placement. Not every material reached its 4 or 5 mm increment under those conditions. | 5 mm only under the tip | 2019 |
| Tetric plus Fill | Does shade change how deep a bulk-fill cures? | Yes. At an 80% bottom-to-top hardness cutoff, depth of cure ranged from 3.5 to 4.5 mm depending on shade and exposure protocol. Every shade still met the depth its manufacturer claims for it, with both the 3-second extra-high and the 10-second high exposure from the same light. The claim held, but only for the increment thickness stated for that shade. | Claim held, shade-dependent | 2026 |
| Any bulk-fill, any light | What curing conditions did the depth-of-cure literature find sufficient? | Material-dependent, across 33 laboratory studies. Of 21 microhardness studies, 10 found acceptable bottom-to-top ratios (≥0.8) for every material tested and 9 found it depended on the material; of 19 degree-of-conversion studies, 11 found ≥50% for all. Favourable depth of cure clustered at irradiance ≥1000 mW/cm² and exposure ≥20 seconds. Polywave lights helped with alternative photoinitiators but were not essential. | ≥1000 mW/cm², ≥20 s | 2018 |
| 3-second curing: what it is | Which materials are actually specified for 3 s at 3000 mW/cm²? | The ones formulated for it. In the studies on this page that is Tetric PowerFill and Tetric PowerFlow, paired with the Bluephase PowerCure 3-second mode; every other composite tested carries a 10–20 second instruction at roughly 1000 mW/cm². Watts's review puts it plainly: a few composites have been specially formulated with advanced photoinitiator systems to cure in 5 or even 3 seconds, and for the rest exact reciprocity between irradiance and time should not be assumed. It is a material-plus-light claim, not a curing-light setting. | Material + light | 20242023 |
| 3-second curing, off-label | What happens when another composite gets the 3 s exposure? | It cures shallower. Eight composites, one light: Tetric PowerFill and PowerFlow reached the same depth of cure at 3 s high irradiance as with their longer standard protocol. All six others, three conventional and three bulk-fill, lost depth of cure significantly (p < 0.001) when given the 3 s exposure off-label. | Never off-label | 2024 |
| Fast curing: irradiance versus time | Does the same energy delivered faster cure as deep? | Usually not. Three lights on three bulk-fills, each at its manufacturer's minimum time (3 to 20 seconds): the deepest cure came from the 20-second exposure at the lowest irradiance, and 3–5 second high-irradiance exposures cured shallower except for the Bluephase PowerCure and Tetric PowerFill pairing. Fast curing also raised post-gel shrinkage in every composite and tended to raise temperature. A reciprocity test on Tetric EvoCeram Bulk Fill at an equal 20 J/cm² found no depth-of-cure difference between standard and Xtra-Power modes, but both fell short of the claimed 4 mm. Watts's rule of thumb: apply a safety factor of at least 2 to the time reciprocity predicts, more for dark shades. | Time beats power | 202320212023 |
| 3-second curing at 4 mm | Is the bottom of a 4 mm increment converted after 3 s? | Material by material. Across four bulk-fills, 3 s curing was sufficient for degree of conversion in Tetric PowerFill and SDR Plus, while Tetric PowerFlow and Filtek One converted more with the ISO 20-second protocol. Flexural modulus was lower after 3 s for every material, and strength, modulus, and conversion all fell from 2 to 4 mm and with ethanol aging. | Modulus pays for the speed | 2021 |
| 3-second curing: bond to dentin | Does rapid curing weaken the bond? | Not for the pastes. Microtensile bond strength to dentin was unchanged by 3 s at 2850 mW/cm² for three of four bulk-fills; the flowable Tetric PowerFlow fell from 23.8 to 18.7 MPa. A one-year shear-bond study with a universal adhesive found 3 s equal to or higher than 20 s at most time points, and after 12 months in water every group was similar except Tetric PowerFill cured at 3 s, which was highest at 21.2 MPa. | Holds for pastes | 20222024 |
| 3-second curing: margins | Do margins open up after 3 s? | Not in the laboratory. Class II restorations in extracted primary molars showed the same marginal integrity after thermo-mechanical loading whether Tetric PowerFill was cured 3 s at 3000 mW/cm² (77.6%) or 10 s at 1200 mW/cm² (79.7%). The bulk-fill beat the conventional composite in both modes. An SEM endpoint on extracted teeth, not a clinical one. | Same margins, in vitro | 2023 |
| High-intensity curing: patients | Is there clinical-outcome evidence for fast curing? | Thin. One single-centre randomised trial of posterior bulk-fill restorations found no difference in USPHS clinical parameters at 6 and 12 months between a light-amplified high-intensity curing unit and a conventional LED; only the SEM marginal analysis differed, at 12 months. We found no randomised trial reporting clinical outcomes for the 3-second, 3000 mW/cm² protocol itself. Every 3-second row above this one is a laboratory result. | No 3 s trial yet | 2019 |
| 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 |
| What makes a bulk-fill a bulk-fill | What is different in the formulation? | Light has to reach the bottom of a 4 mm increment. It is scattered mainly at resin–filler interfaces, more where the refractive indices of resin and filler differ and more for violet than blue wavelengths, while particles around 100 nm are too small to scatter it. Bulk-fills are therefore designed for light transmission, with filler and resin chosen to scatter less, and use high-efficiency photoinitiator mixtures rather than camphorquinone alone. The trade-off is optical: a restoration translucent enough to cure deep can fail to match the tooth. | Transmission + initiators | 2023 |
| Photoinitiators: Ivocerin and TPO | Does the initiator change how the material behaves? | It changes shrinkage stress most. Under a polywave light at 1450 mW/cm², the camphorquinone-only Filtek Ultimate was hardest and strongest but had the highest contraction stress (13.7 MPa). Tetric PowerFill, with camphorquinone plus Ivocerin and TPO, had the lowest (7.4 MPa) with adequate microhardness (54 HV) and flexural strength (79 MPa). Initiator choice also decides which curing-light wavelengths, blue or violet, the material needs. | Initiator sets stress | 20212023 |
| 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.
- Three seconds is a material claim, not a light setting. Only composites formulated for it kept their depth of cure at 3 s in independent testing; every other composite cured shallower and post-gel shrinkage rose. If the box does not say 3 s, use the standard time. No randomised trial has yet reported clinical outcomes for the 3-second protocol.
- A 5 mm claim is measured under the light tip in a small slot. In a 10 mm wide cavity, depth of cure fell 4 mm out from the centre, and holding the tip 7 mm away cost more than holding it off-centre. Cure wide restorations from more than one position and keep the tip close.
How this brief was built
Every clinical row reports the cited trial or review's own result for its own population. The 10-second 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 there. The 5 mm and rapid-curing rows come from separate laboratories and each names the light, irradiance, exposure time, and endpoint it used, because those are what the result depends on. 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 sourceEvaluation of Polymerization Shrinkage, Microhardness, and Depth of Cure of Different Types of Bulk-Fill Composites
Journal of Esthetic and Restorative Dentistry · 2025 · Laboratory study
Open the sourceSufficiency of curing in high-viscosity bulk-fill resin composites with enhanced opacity
Clinical Oral Investigations · 2019 · Laboratory study
Open the sourceDepth of Cure of a Simplified Bulk-Fill Universal Composite and a Conventional Resin-Based Composite
Materials · 2026 · Laboratory study
Open the sourceDepth of cure of bulk fill resin composites: A systematic review
Journal of Esthetic and Restorative Dentistry · 2018 · Systematic review
Open the sourceEffect of a 3-second Off-label Exposure on the Depth of Cure of Eight Resin-based Composites
Operative Dentistry · 2024 · Laboratory study
Open the sourceFast Curing with High-power Curing Lights Affects Depth of Cure and Post-gel Shrinkage and Increases Temperature in Bulk-fill Composites
Operative Dentistry · 2023 · Laboratory study
Open the sourceLight Transmittance and Depth of Cure of a Bulk Fill Composite Based on the Exposure Reciprocity Law
Brazilian Dental Journal · 2021 · Laboratory study
Open the sourceRapid 3 s Curing: What Happens in Deep Layers of New Bulk-Fill Composites?
Materials · 2021 · Laboratory study
Open the sourceEffect of Fast High-Irradiance Photo-Polymerization of Resin Composites on the Dentin Bond Strength
Materials · 2022 · Laboratory study
Open the sourceOne-Year Evaluation of High-Power Rapid Curing on Dentin Bond Strength
Materials · 2024 · Laboratory study
Open the sourceInfluence of high-irradiance light curing on the marginal integrity of composite restorations in primary teeth
BMC Oral Health · 2023 · Laboratory study
Open the sourceClinical Behaviour and Marginal Sealing of Bulk-Fill Resin Composite Restorations Using Light Amplified High-Intensity LEDs Curing: A Randomized Controlled Clinical Trial
Open Access Macedonian Journal of Medical Sciences · 2019 · Randomised controlled trial
Open the sourceLight-curing dental resin-based composites: How it works and how you can make it work
Frontiers in Dental Medicine · 2023 · Narrative review
Open the sourceThe Influence of Various Photoinitiators on the Properties of Commercial Dental Composites
Polymers · 2021 · Laboratory study
Open the source
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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.