Dental Composite Materials: Fillers, Handling and Why Some Look Better
This page explains dental composite materials for anyone curious what bonding and white fillings are made of: resin and filler, composite classes, strength versus polish, enamel and dentine shades, and translucency. In laboratory studies, more filler generally meant more strength; reviews disagree on whether the finest fillers polish better, and one review concludes there is no one ideal material.
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Medical disclaimer: This page is for general information only. It does not replace an examination or treatment by a dentist.
This page is reviewed by Dr Ibraheem Ijaz, the practice's principal dentist and a General Dental Practitioner (GDC 301711). His qualifications are BDS, BSc (Hons), MSc (Leeds), PG Dip Implant Dentistry and PG Cert Restorative and Aesthetic Dentistry.
What are dental composite materials made of?
Dental composite, also called resin composite, is a tooth-coloured material made of a resin matrix filled with inorganic particles, used for white fillings and bonding. A 2010 literature review describes the most widely known type, hybrid composites, as methacrylate resin with filler coupled to it by silanes, and a 2013 review names camphorquinone as the commonest photoinitiator, the ingredient that starts setting under a curing light. The 2010 review notes that polymerisation shrinkage, bacterial adhesion and side effects due to monomer release remain drawbacks.
How are composites classified by filler type and size?
Composites are traditionally classified by filler, resin chemistry and viscosity, a 2025 review explains, though recent studies indicate this is not always valid.
By filler size, a 2019 review describes macrofilled composites as wearing quickly and polishing poorly, and microfilled composites, with silica particles of about 40 nanometres, as wearing and polishing better but lacking strength because they held less filler. Hybrids mixed particle sizes to balance strength and appearance.
In a 2016 laboratory study of 17 commercial composites, the larger filler particles averaged over 1 micrometre in almost every material, and the authors concluded the classification describes neither filler nor properties accurately.
Handling follows filler content too. A 2021 literature review says early flowable composites held 25 to 30% filler by volume, making them runny but prone to high shrinkage and weaker properties, and that later versions improved, with 45 to 65% filler among other changes.
What is the trade-off between strength and polish in composite?
In laboratory studies, strength generally rose with filler content while polish tended to improve with smaller particles, so one material may not deliver both.
In a 2002 laboratory study of 14 commercial composites, those with the most filler, 59 to 60% by volume, had the highest flexural strength, stiffness and hardness, though fracture toughness peaked at about 55%, within the study's limits.
For polish, a 2022 review of 75 laboratory studies found supra-nano-filled, nanofilled and microfilled composites typically the smoothest and glossiest, ahead of nanohybrid, microhybrid and hybrid ones, within its limitations; in several studies toothbrushing raised roughness and cut gloss. An earlier, 2014 systematic review of 28 laboratory studies differs for nanofilled and submicron composites, finding no evidence they were smoother or glossier than microhybrids, initially or after surface challenges.
A 2015 meta-analysis pooled 21 clinical trials on front teeth, 18 begun before 2001; its first author worked for a composite manufacturer. In the 7 trials analysed as one group, 6 on restorations involving a corner of the tooth and 1 on gap closure, bulk fracture was the main reason restorations were replaced, significantly more often with microfilled than with hybrid and macrofilled composites.
Why does layering use enamel and dentine shades?
Layering builds composite in dentine and enamel shades to copy how a natural tooth handles light. A 2016 British Dental Journal review describes polychromatic layering, using opaque dentine, chromatic enamel and translucent or opalescent enamel shades guided by the tooth's optical make-up, and a simpler natural layering concept: a dentine and an enamel layer, plus effect shades if required.
Layered colour can be hard to predict. In a 2014 laboratory study, systems pairing different dentine shades with one highly translucent enamel shade changed colour more as layer thickness varied than systems with dentine and enamel in the same shade at different translucencies, which the authors judged less predictable in daily clinical routine. A 2021 overview of laboratory studies notes that, with growing variety in composite shades and manufacturers, multi-layer colour is often difficult to predict.
Shade layering on a whole front surface is described on the composite veneer page, and choosing a shade under dental shade matching.
To ask about composite bonding, book online or call 0114 288 2121.
What do opacity, translucency and refractive index mean in composite?
Opacity is how much light a material blocks, and translucency how much it lets through. Refractive index measures how strongly a material bends light, and chroma is a colour's saturation.
In a 2014 laboratory study of two enamel-shade composites, thicker enamel layers lowered translucency and chroma in both, but raised lightness in the high refractive index material and lowered it in the conventional one. In a 2021 laboratory study of experimental composites, a filler with a refractive index of 1.53 in a resin of 1.524 gave a good colour match with the surrounding structure, called a chameleon effect.
Why is there no one ideal composite material?
Composites trade strength, wear and polish differently, and a 2011 review concluded there is no one ideal material. It added that the materials then available, used appropriately, had proven to deliver excellent clinical outcomes of adequate longevity.
Newer nano-sized filler classes have not clearly outperformed microhybrids in trials. A 2018 systematic review of 21 reports of randomised trials found nanofilled and nanohybrid composites, as a general trend, performed similarly to microhybrids without better surface characteristics, but risk of bias was unclear or high, front-tooth data were insufficient and the evidence was low-level.
How long bonding typically survives is covered under how long composite bonding lasts, and the material choice for veneers under choosing between porcelain and composite veneers.
What are the limits of dental composite materials?
Composite's limits include fracture, shrinkage as it sets and weakening in laboratory solvent tests. A 2015 systematic review of 1,821 front-tooth restorations in 17 studies with at least 3 years of follow-up found 24.1% failed in total, with annual failure rates of 0 to 4.1% and survival as low as 53.4% in one study; fracture, whether of tooth or composite, was the commonest reason, while failures of colour, shape or surface staining were more frequent in restorations placed for appearance.
Shrinkage stress may harm the bond to the tooth, a 2011 review notes, and in a 2016 laboratory study of 17 commercial composites, properties generally fell after a week in a 75% ethanol and water solvent test, compared with water alone, by up to 86%.
Where is composite bonding at Deepcar Dental Care explained?
At Deepcar Dental Care, bonding techniques are chosen case by case, and they include layering several shades or using one shade. The treatment has its own page on composite bonding; related science pages are gathered in the options in this section.
If you are considering composite bonding, book an appointment online at book online or call 0114 288 2121.
Frequently asked questions
What is a nanohybrid composite?
A nanohybrid composite mixes nano-sized filler with larger particles. A 2021 literature review describes silicon particles of 20 to 60 nanometres with larger ones of 100 to 2,500 nanometres. Nanofilled composites hold nanoparticles of more uniform size and clusters of them, it explains, and both can be up to 80% filler by volume.
Do nanohybrid, nanofilled and microhybrid composites last differently in front teeth?
Not in one 4-year study. In a 2021 retrospective study of 216 front-tooth restorations in 53 people, mostly gap closures, each in a single shade of microhybrid, nanohybrid or nanofilled composite, survival was similar across the three, with 90.3% overall and annual failure rates of 0.9 to 3.4%.
What does supra-nano filler mean?
Supra-nano describes composites filled with fine spherical particles. In a 2016 laboratory study, they scattered and transmitted the most light compared with nanofilled, nanohybrid and microhybrid composites, probably because of filler shape and size. All the types showed similar spectral behaviour, though generally with statistically significant differences, and the calculation used overestimated transmittance.
Does filler particle size affect how composite wears?
It can in laboratory tests. In a 2018 study of experimental flowable composites, filler averaging 400 nanometres wore significantly more than 70 or 200 nanometre filler; filler loading between 50 and 60% by weight made no significant difference. A 2021 review notes clinical trials in back teeth found no significant wear difference between conventional and nanofilled composites.
Why does the resin matter as well as the filler?
The resin affects translucency, water uptake and stability. In a 2021 laboratory study of experimental composites, high or low proportions of Bis-GMA, a common base resin, made them less translucent. A 2019 review lists high water uptake, weaker mechanical properties and lower colour stability as drawbacks of TEGDMA, a thinner resin that eases handling.
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