Biological dentistry’s argument about materials has largely been won. The EU banned dental amalgam from January 2025, and the Minamata Convention’s sixth conference agreed a global phase-out by 2034. Ceramic implants entered mainstream consensus in 2023, when the International Team for Implantology put their five-year survival at 97.2%, comparable to titanium. Practitioners treated as cranks a decade ago for refusing to place metal in a mouth are now doing what the regulations require.

What follows is every material a biological dentist uses in place of the conventional one: what it is, who makes it, what the evidence says about how long it lasts, and, where anyone has established it, what is in it.

For the wider picture see what biological dentistry is, and for what the claims made for these materials are worth, the benefits graded against the evidence.

What materials do biological dentists use instead of amalgam and titanium?

Resin composite or glass ionomer in place of amalgam. Lithium disilicate or zirconia in place of metal-ceramic crowns. Yttria-stabilised zirconia — 3Y-TZP — in place of titanium implants. Platelet-rich fibrin in place of synthetic graft membranes.

Material	What it replaces	What it is	Named products	What the evidence says
Resin composite	Amalgam, direct fillings	Bis-GMA or Bis-EMA resin matrix with glass or silica filler particles	3M Filtek · Dentsply Sirona Ceram.X and SDR · Ivoclar Tetric · Kuraray Clearfil	Contested. Annual failure 3.17% against amalgam’s 1.71% (Moraschini 2015); no significant difference in a 2025 meta-analysis
Glass ionomer	Amalgam in low-load sites, liners	Fluoroaluminosilicate glass with polyacrylic acid; releases fluoride	—	No comparative UK longevity data located
Lithium disilicate ceramic	Metal-ceramic crowns, gold inlays	Glass-ceramic, pressed or milled	Ivoclar IPS e.max	No comparative UK longevity data located
Zirconia ceramic	Metal-ceramic crowns and bridges	Zirconium dioxide with about 3 mol% yttria; a metal oxide, no metallic zirconium	—	Higher yttria (5Y-PSZ) improves translucency but reduces fracture toughness
Zirconia implant	Titanium implant	3Y-TZP — yttria-stabilised tetragonal zirconia polycrystal	Straumann PURE Ceramic Monotype · CERALOG Hexalobe · Z-Systems · Swiss Dental Solutions	ITI 2023 consensus: 97.2% five-year survival. Atalay et al. 2026: 83.8%
Platelet-rich fibrin	Synthetic graft membranes	The patient’s own centrifuged blood; no added anticoagulant	—	Autologous and low risk, but Ghanaati’s 2025 trial found sockets stayed unhealed despite it
Dental amalgam (being replaced)	—	Roughly half mercury, alloyed with silver, tin and copper	—	Annual failure 1.71% (Moraschini 2015). EU use banned since January 2025
Titanium implant (being replaced)	—	Commercially pure titanium or Ti-6Al-4V alloy	—	Particle release through tribocorrosion is established; the link to clinical harm is not
Nickel-chromium alloy (being replaced)	—	Base-metal casting alloy; one studied formulation ran 75% nickel, 15% chromium	—	Nickel sensitisation runs at 14.5% in a European population sample

Nine materials, and comparative longevity data exists for two of them.

Is “metal-free” accurate?

Partly. Zirconia is zirconium dioxide, ZrO₂, and about 3 mol% yttrium oxide is added to hold the material in its tetragonal phase as it cools, which is what gives it the transformation toughening that makes it usable in a mouth. Both are metal oxides. Neither is a metal.

Metallic corrosion, galvanic currents between dissimilar metals and metal ion release all require metal, and a ceramic does none of them. Raising the yttria content to 5 mol% makes zirconia noticeably more translucent, which is why it now appears in aesthetic work. The cost is that it pushes the material largely into its cubic phase and loses the toughening mechanism. Translucency and strength trade directly against each other.

What is in a white filling?

A resin matrix, usually built on bisphenol A-glycidyl methacrylate — Bis-GMA — or its ethoxylated relative Bis-EMA, loaded with glass or silica filler. The filler does the work; the resin holds it together.

Bis-GMA is synthesised from bisphenol A, which is why the question of BPA follows composites around. The American Dental Association’s position is that BPA is not itself used in manufacture and appears only as trace residual contamination, and that a small transient rise in urinary and salivary BPA can be detected after placement, typically resolving within 24 to 48 hours. A 2025 review in the Journal of Dental Research using modern mass spectrometry put release from resin composites at roughly 0.01 to 0.1 nanograms per cubic millimetre over 24 hours in water — far below dietary exposure. Sealants release more than composites do.

What has changed, and what most reassurance on this subject predates, is the yardstick. In April 2023 the European Food Safety Authority cut its tolerable daily intake for BPA to 0.2 nanograms per kilogram of body weight per day — roughly twenty thousand times lower than the 2015 figure — on the basis of immune effects. The European Commission adopted the finding and banned BPA in food contact materials from December 2024. The FDA and EMA have questioned EFSA’s methodology, and the FDA’s own BPA statement is a food-contact document dating from 2014 that does not mention dental materials at all.

Do white fillings last as long as amalgam?

Not settled. Three decades of studies have reached three different answers, and the largest dataset in the field suggests the question is aimed at the wrong variable.

Moraschini and colleagues, pooling eight studies in 2015, found 92.8% survival for amalgam against 86.2% for composite, with annual failure rates of 1.71% and 3.17% and a marked difference in secondary caries. A Cochrane review in 2021 reached the same direction — composite failure risk 1.89 times higher — but rated its own certainty low, and noted that composites had advanced considerably since the trials it was pooling were run.

Then, in 2025, a meta-analysis in the International Dental Journal found no statistically significant difference at all: a risk ratio of 0.96, confidence interval 0.68 to 1.34. Opdam’s twelve-year work had already found composite outlasting amalgam in large three- and four-surface restorations, with amalgam ahead only for three-surface work in high-caries-risk patients.

And the largest dataset in the field points somewhere else entirely. Laske and colleagues followed 222,836 Class II restorations placed by 67 general dentists across 61,121 patients. The mean ten-year annual failure rate was 4.9% — but individual operators ranged from 2.6% to 7.0%. The spread between dentists was wider than the spread between materials.

Who places the filling matters more than what it is made of. That applies across every study above, and manufacturer tend not to address the phenomenon.

What are ceramic implants made of?

Yttria-stabilised tetragonal zirconia polycrystal, universally shortened to 3Y-TZP. The named products are Straumann’s PURE Ceramic Monotype, CERALOG Hexalobe, Z-Systems and Swiss Dental Solutions.

The International Team for Implantology’s 2023 consensus put five-year survival at 97.2%, comparable to titanium, and accepted one-piece zirconia for single crowns and three-unit bridges. A 2026 study in Clinical Oral Investigations reported 83.8% at five years. Both numbers are in the literature; the gap between them is the current state of knowledge.

Dr Dominik Nischwitz, who has been placing them since they became commercially available, dates the shift precisely:

“Ever since I finished university, we do not really need metals anymore. For implants it came a bit later, but more than 15 years now ceramic implants are available. So it is possible to restore a bite in every single hole with material that is non-metal.”

Why do biological dentists avoid titanium?

Because it corrodes, and because the particles go somewhere. Nischwitz uses an analogy that turns out to be the correct technical picture:

“Titanium implants rust over time. That’s just normal because it’s metal. It’s like imagine a propeller of a boat underneath the water, and your saliva is kind of like seawater. It’s a miracle solution. It’s an electrolyte. So every metal will oxidize there. It’s called tribocorrosion in the dental world for metal implants.”

Tribocorrosion is an established term and a substantial literature. Dini and colleagues, writing in Frontiers in Mechanical Engineering in 2020, define it as the synergy between mechanical wear and electrochemical corrosion, and describe oral conditions releasing titanium particles and ions into peri-implant tissue. A 2021 narrative review in the Japanese Dental Science Review found higher particle concentrations at peri-implantitis sites than at healthy implants, with particles activating macrophages and lymphocytes to release TNF-α, IL-1β and IL-6.

On how common sensitivity is, Nischwitz’s figure, drawn from his work, is higher than the published range. He puts it at “about 25% of all people” becoming titanium sensitive. The benchmark study, Sicilia and colleagues across 1,500 consecutive patients, found 0.6% positive for titanium allergy. A 2026 systematic review settles on “rare but clinically relevant.”

He also names the laboratory: Volker von Baehr at the IMD institute in Berlin, which does exist and does offer the test — a titanium stimulation test measuring TNF-α and IL-1β release from the patient’s own macrophages, alongside cytokine polymorphism genotyping. Whether it means anything is another matter. A 2022 systematic review in the International Journal of Implant Dentistry assessed ten studies of titanium hypersensitivity testing, rated the risk of bias high throughout, found the results inconsistent in reliability and validity, and argued the underlying mechanism is questionable because titanium oxidises so rapidly that it can no longer act as a hapten. One of that review’s own co-authors is associated with the titanium-testing literature the review is criticising, which makes it harder rather than easier to dismiss.

Which dental materials contain nickel?

Base-metal casting alloys, chiefly nickel-chromium, where nickel is not a trace but the bulk of the material: one studied formulation ran 75% nickel and 15% chromium. Orthodontic wires are the other route — stainless steel wires carry around 8% nickel, nickel-titanium wires more than 50%. Gold and high-noble alloys, titanium, zirconia, ceramics and composites contain none.

It matters because nickel is the most common contact allergen there is. The EDEN study, sampling 3,119 adults at random across five European countries, found 14.5% sensitised to nickel, with women roughly five times more likely than men. The jewellery restriction most people have heard of — REACH Annex XVII entry 27 — covers piercings and skin-contact items. It does not reach into the mouth.

Nischwitz extends the concern to gold, which almost nobody writes about:

“But then there’s also gold. People will ask, but what about gold? I removed my mercury fillings in the 80s, now I have gold. Gold is also a problem for your immune system.”

No population prevalence data for gold sensitisation comparable to the nickel figures could be located, in either direction. The claim is his, and his based on his own surgical experience.

Are you told what is in your filling?

No. Manufacturers must identify every patient-contacting material to their regulator, and are under no obligation to tell you any of it.

Nischwitz’s account of why:

“Oftentimes you find nickel in dental material because, below a certain level, dental material companies do not even have to tell you what’s in it. So you don’t even know what’s in there. That is just a company liability thing.”

ISO 22674, the standard governing metallic materials for dental restorations, requires every element above 1% by mass to be declared — but nickel specifically must be declared down to 0.1%, and only materials at or below 0.1% may be labelled nickel-free. Beryllium, cadmium and lead are capped at 0.02%. Under the EU Medical Device Regulation, carcinogens, mutagens, reprotoxins and endocrine disruptors must be labelled above 0.1%, not 1%. And ISO 4049, the standard for polymer-based restoratives, added a requirement in its 2019 edition for manufacturers to publish details of material composition. The 1% threshold he is describing is the generic listing threshold for safety data sheets under chemicals law, which is a different regime.

His conclusion nevertheless holds. The Medical Device Regulation’s patient-information and implant-card requirements — the provisions that would put composition in a patient’s hand — explicitly exempt dental fillings, dental braces and tooth crowns. Manufacturers must identify every patient-contacting material to their notified body. They are under no obligation to give you a quantitative ingredient list, and dental restorations are named in the regulation as carve-outs from the regime that would require it.

The disclosure exists. It goes to a notified body. On why the profession is incurious about it, he is on firmer ground:

“In university, dentistry is more like a repair business. And you mostly focus on learning chemistry and about the materials you’re using. Who is really interested in the alloy percentages of a metal that you’re going to install in someone’s mouth? That is how you study dentistry.”

Are dental materials tested for toxicity?

Yes, extensively. Chemical characterisation, leachables testing against toxicological thresholds, and a dentistry-specific battery including pulp and dentine usage tests — all mandatory, all reviewed by a notified body before the material reaches a mouth.

The biological dentistry account says otherwise. Nischwitz puts it this way:

“Why are we allowed to put metals and stuff inside your mouth or on your teeth or in your jawbone? Because these fillings and crowns are classified as devices. Kind of like this is a device. Your glasses are devices. They’re essentially outside the body. And everything that’s outside of your body, or lying on top of your tooth outside of your body, does not need to have a toxicological report with it.”

Device classification is precisely what triggers the toxicological assessment. Under EU Medical Device Regulation Annex VIII, fillings, crowns and inlays are Class IIa and dental implants Class IIb — both above the threshold at which a manufacturer may self-certify, so both require notified-body assessment. Annex I requires particular attention to the toxicity of materials chosen. Annex II requires the technical file to establish biocompatibility and identify every material in direct or indirect patient contact.

Beneath that sit two standards written for exactly this purpose. ISO 10993 governs biological evaluation of medical devices, requiring chemical characterisation of constituents and comparison of leachables against toxicological thresholds. ISO 7405 is the dentistry-specific companion, adding pulp and dentine usage tests, endodontic usage tests and dental implant usage tests to the general battery of cytotoxicity, irritation, genotoxicity and systemic toxicity work.

The toxicological report he says does not exist is a mandatory part of the file.

There is a defensible complaint underneath, and it is the transparency one from the previous section. The assessment is thorough and invisible: filed with a notified body, never published, never seen by a patient. That is a fair criticism of the system. Saying the testing does not happen is a different claim, and it is checkable and wrong.

How do you choose between them?

The evidence does not resolve easily into an automatic ranking. The practitioner who has spent fifteen years arguing for these materials says so himself — asked how he settles technical arguments about bone grafting materials inside his own network:

“I’m very, very simplified when it comes to these things. I would just say find the best one that works for you. There’s never going to be a solution, only a trade-off.”

Every material on this page proves him right. Zirconia removes the galvanic current and loses toughness when it is made translucent. Composite closes the mercury question and opens the BPA one. Amalgam may outlast its replacement, depending on which meta-analysis was published most recently and how many surfaces are involved. And across 222,836 restorations, the dentist mattered more than any of it.

For what these materials are used for, procedure by procedure, see how biological dentistry treatments compare.

Biological dentistry materials: key facts

The core substitutions: resin composite or glass ionomer for amalgam; lithium disilicate or zirconia for metal-ceramic crowns; 3Y-TZP zirconia implants for titanium.

Zirconia is a metal oxide — zirconium dioxide with about 3 mol% yttria — and contains no metallic zirconium. “Metal-free” is accurate in the sense that matters clinically and narrower than most patients will hear it.

Longevity: contested. Amalgam ahead in Moraschini 2015 and Cochrane 2021 (low certainty), no difference in a 2025 meta-analysis, composite ahead for large restorations. Operator variation across 222,836 restorations ran 2.6% to 7.0% annual failure — wider than the material effect.

Ceramic implants: ITI 2023 puts five-year survival at 97.2%; a 2026 study reports 83.8%.

BPA: release from composites measured at 0.01–0.1 ng/mm³ over 24 hours. EFSA cut its tolerable daily intake roughly twenty-thousandfold in 2023, and no dental-specific assessment against the new figure has been published.

Nickel: up to 75% of some base-metal casting alloys and over 50% of some orthodontic wires. 14.5% of a European population sample is sensitised.

Disclosure: ISO 22674 requires alloy elements above 1% to be declared and nickel above 0.1%. The Medical Device Regulation’s patient-information requirements explicitly exempt dental fillings, braces and crowns.

Toxicological testing: mandatory under ISO 10993 and ISO 7405, assessed by a notified body, and not published.

About this article

Written by Jon Lipsey. Sources are named in the text. Quotations from Dr Dominik Nischwitz are taken from interviews conducted for Unfiltered; the full interview is published separately. Where his claims are contradicted by the standards or the literature, both are given.