Polishing and Gloss Retention: Why Some Bonding Stays Shiny
For anyone asking why composite bonding goes dull: composite polishing leaves a smooth, glossy surface, and brushing and wear can gradually reduce it. This page covers roughness and staining, the polishing sequence, gloss loss, repolishing and the practice's re-polish recommendation. Most evidence is laboratory work, and rougher composite stained more in some studies, not all.
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Clinically reviewed by Dr Ibraheem Ijaz, dentist · GDC 301711
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 is composite polishing and why does gloss matter?
Composite polishing smooths bonding after shaping, and the surface finish it leaves helps decide how it reflects light.
The FDI World Dental Federation criteria say lustre and texture come from light reflecting off a restoration's surface, and should ideally match the surrounding tooth. Surface detail is one part of what makes a smile look natural.
Two measures describe a finish: Ra, average surface roughness in micrometres (µm), and gloss, in gloss units (GU). A 2022 systematic review of 13 laboratory papers found them correlated, with varying strength, and proposed above 55 GU as well polished, though most evidence carried moderate or high risk of bias.
How does surface roughness affect composite staining?
Rougher composite stained more in some laboratory studies, but not all, and none here tested bonding in a mouth.
In a 2005 study of four composites in coffee, discolouration increased with roughness in three; the microfilled one was the exception.
In a 2012 coffee study of five composites and seven polishing methods, the smoothest and most stain-resistant results came from different systems, and staining depended on resin structure as well as surface irregularities. A 2003 study of four composites in a blue dye found no correlation between roughness and staining, which it called highly influenced by each composite's resin and filler.
Does a smoother surface hold less plaque?
A smoother surface may hold less plaque, but two 1996 studies describing the Ra 0.2 µm threshold did not test composite.
A 1997 review reported some in-mouth studies suggesting plaque rises above that level, with no further gain below it. The same group's 1996 studies tested implant abutments in six patients each.
A 2006 systematic review of clinical studies found roughness above that level, or higher surface-free energy, facilitated biofilm on restorative materials. A 2018 systematic review of 18 studies, 12 laboratory and only two at low risk of bias, concluded the effect seems related to a range, not a threshold.
On composite itself, a 2017 laboratory study found six finishing and polishing procedures changed roughness and gloss on four composites, but did not significantly affect biofilm of one bacterial species.
What happens in the polishing sequence?
In general, shaping composite leaves it rougher, so polishing with progressively finer abrasives follows.
In a 2021 systematic review of 17 laboratory studies on nanohybrid and nanofilled composites, average roughness fell as steps increased and no one-step system averaged below Ra 0.2 µm, though two came close and one matched or beat a three-step system in some studies but generally lost to four-step systems. A 2023 network meta-analysis of laboratory studies ranked abrasive paper discs most likely smoothest on those composites, and a silicon carbide brush on microfilled composite; hybrid and microhybrid composites could not be analysed.
A 2023 systematic review of direct composite could not say whether an ideal pairing of polisher and composite exists.
To ask about composite bonding, book online or call 0114 288 2121.
Why does composite bonding lose its gloss over time?
Composite bonding can gradually lose gloss as brushing and wear change its surface.
In a 2012 laboratory test of nine composites, an hour of simulated brushing with toothpaste cut gloss from 68.9–100.5 to 10.6–62.6 GU, while natural enamel kept its gloss. Filler plays a part, explained under how composite materials differ.
A six-year randomised study followed 74 front-tooth composite veneers given no further mechanical polishing. At 6 years, with 15 of 21 patients reviewed, none of 26 template-formed direct veneers still scored excellent for polish, against 11 of 26 prefabricated ones; the rest scored acceptable. Patients recognised the gloss loss, though it showed only on air drying and did not lower their view of the result.
A 2026 meta-analysis of eight clinical studies of freehand front-tooth composite, followed for at least 24 months, pooled surface-quality deterioration at 21% of 896 restorations, varying widely (prediction interval 0 to 74%). The authors call this loss of ideal appearance, not failure. Survival is explained under how long composite bonding lasts.
What can professional repolishing do for composite bonding?
Repolishing can restore smoothness and reduce surface stain in laboratory studies, but does not always restore colour, and long-term benefit is unproven here.
In a 2010 laboratory study, repolishing after 15 days in coffee brought colour change within an acceptable limit, though still significantly above water or cola. In a 2024 laboratory study of one nanocomposite, repolishing after coffee restored hardness and roughness but not colour.
The FDI criteria define refurbishing as reshaping and polishing with no new material. The trials here are on back-tooth fillings, mostly amalgam, not cosmetic bonding. In a trial of 271 defective fillings, 78 composite, refurbishing improved lustre and roughness at two years, though the three-year report lists roughness, not lustre; replacement improved every measure, and untreated fillings declined on marginal adaptation at two years and on every measure at three.
After 12 years, a trial of 174 fillings with localised defects found no difference in condition or longevity between 85 refurbished (18 composite) and 89 controls (30 composite), apart from better marginal adaptation in composite controls and anatomy in refurbished amalgam.
Studies here do not settle how often to repolish. In a 2026 laboratory study of two milled resin-based materials, repolishing after each simulated year kept them smoother than no repolishing; the authors suggest yearly repolishing may help control surface degradation, particularly for indirect restorations made from such materials. The study did not compare intervals.
What can you do about gloss on composite bonding?
Keep brushing, though laboratory brushing dulled composite: the NHS says it stops plaque building up, and advises fluoride toothpaste twice daily for about 2 minutes.
Toothpaste and daily care are covered under brushing and flossing around bonded teeth, and drinks and smoking under composite staining.
Show a dentist bonding that looks dull or feels rough, or a dark line at its edge, since the FDI criteria warn that staining there should not be confused with decay.
How often does the practice recommend re-polishing direct composite bonding?
At Deepcar Dental Care, a professional re-polish is recommended every 6 months for direct composite bonding.
Where can you read about composite bonding?
Composite bonding is explained on the treatment page, and the steps are under what happens during composite bonding. Other science pages sit within the options in this section. General feedback on the practice is in patient reviews.
If you are considering composite bonding, book an appointment online at book online or call 0114 288 2121.
Frequently asked questions
Can you feel if bonding is rough?
In one 2004 study, 60% of 25 volunteers could. They used the tip of the tongue to rank composite samples and enamel correctly, and told apart differences between 0.25 and 0.50 µm, a range that includes natural enamel.
Why has my composite bonding lost its shine?
Composite can lose shine gradually as its surface wears, so ask a dentist to look. Under FDI criteria, a dull finish with clear marks can be refurbished, localised displeasing dullness or roughness can be repaired, and widespread displeasing dullness cannot reasonably be repaired.
Can professional cleaning dull composite?
Laboratory tests suggest it can. In a 2023 study of two flowable composites, four rounds of brush and paste significantly reduced gloss at every setting tested, without changing colour. A 2025 review of 42 laboratory studies found ultrasonic scaling, with resin composites among the most affected, and air polishing can roughen restorations, to varying degrees, and called for clinical studies.
Does repolishing wear composite away?
Laboratory work suggests it removes a thin layer. In a 2011 laboratory study of five composites, taking off 20 µm once cleared coffee and red wine staining. In a 2026 study, repeated polishing alone did not significantly change the roughness or hardness of two milled materials. Neither tested bonding in a mouth.
Does smoking affect polished composite?
In one 2025 laboratory study, yes: discs of one composite exposed to 600 cigarettes over a simulated 30 days changed colour unacceptably, polished or not. One of two polishing protocols significantly lessened it, though the two did not differ. Heated tobacco caused less colour change, whatever the finish, but more roughening on polished discs.
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We look after patients from Deepcar, Stocksbridge and Oughtibridge, and from across north Sheffield, including Wadsley, Hillsborough and Fulwood. Many travel further, from Penistone, Barnsley and Rotherham. The practice is on the A6102 at 334 Manchester Road, and no referral is needed.
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Deepcar, Sheffield S36 2RH
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