CPP-ACP (Recaldent): the dairy-derived remineralizer

CPP-ACP, sold under the brand name Recaldent, is a milk-protein-based remineralizer used in MI Paste, sugar-free gum, and clinical fluoride alternatives. Here is what it does, how it compares to fluoride and nano-hydroxyapatite, and why it is the standard in dairy-tolerant cariology.

Walk into any reasonably equipped dental office in Australia, Japan, or Western Europe and there is a good chance the dentist will reach for a small white tube of MI Paste at some point during the visit. The active ingredient on the label, written as CPP-ACP or sometimes Recaldent, looks like industrial chemistry. It is, in fact, a fairly clever piece of dairy science: a fragment of cow's milk protein wrapped around a cluster of calcium and phosphate ions, engineered to release those ions exactly where enamel needs them.

This guide walks through what CPP-ACP actually is, who discovered it and how, the mechanism by which it remineralizes enamel, what the strongest clinical evidence supports, how it stacks up against fluoride and nano-hydroxyapatite, where to find it on shelves, and the small set of people who should not use it. The goal is to leave you with a clear, source-supported understanding of a remineralizer that has been in mainstream dental use for more than 25 years but is still under-explained outside professional circles.

What CPP-ACP actually is

CPP-ACP is a compound ingredient. The name spells out the two halves cleanly: casein phosphopeptide (CPP) bonded with amorphous calcium phosphate (ACP). Each half is doing a different job, and the whole only works because of how they are joined.

Casein is the major protein family in cow's milk, making up roughly 80 percent of total milk protein by weight. It is what makes milk look white, and it is what curdles into cheese. Within the casein family, there are four sub-types (alpha-s1, alpha-s2, beta, and kappa), and three of them carry chemical decorations called phosphoseryl residues. These residues are short clusters of phosphate groups attached to specific serine amino acids along the protein backbone. Their biological function in milk is to bind calcium and phosphate ions so that a nursing calf can absorb minerals without those minerals precipitating into useless crystals in the gut. Casein, in other words, is nature's own calcium-delivery vehicle.

The CPP half of CPP-ACP is what you get when you take that natural mineral-carrying region of casein and isolate it. Through enzymatic digestion (usually with tryptic enzymes that cut casein at predictable points) and ion-exchange chromatography, the manufacturing process extracts the small phosphoseryl-rich fragments from the rest of the milk protein. What is left is a short peptide, typically 25 to 30 amino acids long, decorated with three to five phosphate groups along its length. These are the casein phosphopeptides.

The ACP half is amorphous calcium phosphate, which is a non-crystalline form of the same calcium and phosphate that makes up enamel. Hydroxyapatite (the mineral in enamel) is crystalline calcium phosphate arranged in tight, ordered units. Amorphous calcium phosphate is the same chemistry without the crystal lattice: loose, disordered, and far more soluble in water. By itself, ACP in solution is unstable: the moment you put it in saliva, it precipitates out as solid calcium phosphate and is wasted. It needs a stabilizer.

CPP is that stabilizer. When CPP and ACP are mixed under controlled conditions, the phosphate groups on the peptide latch onto the calcium and phosphate ions in solution and hold them together as a single complex. The peptide effectively forms a tiny molecular cage around clusters of about 25 calcium ions and 15 phosphate ions, preventing them from crystallizing. In that caged form, the calcium and phosphate stay bioavailable until something disrupts the cage, releasing the ions in usable form.

The branded version of this complex, sold under the trademark Recaldent, is the form used in MI Paste, MI Paste Plus, Trident Xtra Care gum, and a handful of clinical formulations. The Recaldent trademark is owned by Mondelez International, which licenses it from the University of Melbourne; the underlying intellectual property was developed by Eric Reynolds and his team starting in the 1980s and patented through the university's commercialization arm.

The discovery: Eric Reynolds and the University of Melbourne

The story of CPP-ACP starts in Melbourne in the late 1970s. Eric Reynolds, then a young biochemist working in dental research at the University of Melbourne, was studying the casein protein system in milk. The starting question was almost incidental to dentistry: why do dairy products appear protective against tooth decay, when the simpler chemistry would suggest that anything containing lactose should be cariogenic?

Older epidemiological studies, going back to the 1940s, had repeatedly shown that populations consuming substantial amounts of cheese and dairy had lower caries rates than populations on similar diets without dairy. The effect was real and reproducible across cultures, but the mechanism was poorly understood. Some researchers attributed it to the calcium and phosphate content of dairy. Others pointed at the saliva flow stimulated by hard cheeses. Reynolds wanted a more specific answer.

Through a sequence of papers published in the late 1970s and 1980s in journals including Caries Research and Archives of Oral Biology, Reynolds isolated the active fraction of casein responsible for the anti-cariogenic effect. The active component was not the whole protein. It was specifically the phosphopeptide region of casein, the short stretches of amino acid sequence that carry the phosphoseryl groups. When Reynolds isolated those peptides and showed that they could bind calcium and phosphate in solution while maintaining their bioavailability, he had effectively reverse-engineered the mechanism behind dairy's caries protection.

The leap from observation to product took another decade. Through the 1980s and into the early 1990s, Reynolds and his colleagues at the Cooperative Research Centre for Oral Health Science (now the Melbourne Dental School) refined the manufacturing process for casein phosphopeptides at industrial scale, characterized the stoichiometry of how CPP binds ACP, and ran the first remineralization studies. By the mid-1990s, the patents were in place, and by the late 1990s, the university had licensed the technology to Japanese dental manufacturer GC Corporation, which launched MI Paste in 2002.

From the launch of MI Paste onward, the clinical literature on CPP-ACP grew rapidly. Reynolds himself continued publishing through the 2000s and 2010s, expanding the ingredient's applications from simple remineralization into post-bleaching sensitivity management, orthodontic white spot prevention, and erosive tooth wear protection. By 2010, the ingredient had been studied in well over 100 peer-reviewed clinical trials, with a Cochrane review in 2009 cautiously endorsing it for non-cavitated caries lesions. By 2020, CPP-ACP had become one of the few topical remineralizing agents to be widely accepted as an adjunct to fluoride in mainstream dental practice.

How CPP-ACP delivers minerals (the casein cage mechanism)

To understand how CPP-ACP rebuilds enamel, it helps to start with how enamel breaks down. The caries process at the chemical level is straightforward. Bacteria in plaque (primarily Streptococcus mutans, supported by various Lactobacilli) ferment dietary sugars and produce lactic acid. The lactic acid lowers plaque pH below the critical threshold of about 5.5. At that pH, the calcium and phosphate ions in enamel hydroxyapatite become more soluble than the surrounding saliva, and they begin to leach out of the enamel surface in a process called demineralization.

Between meals, when plaque pH recovers and saliva re-saturates the tooth surface with calcium and phosphate, the reverse happens: ions migrate back into the enamel surface in a process called remineralization. As long as remineralization keeps pace with demineralization, the tooth stays intact. When the balance tips toward demineralization (frequent sugar exposure, low saliva flow, acid reflux, dry mouth medications), the enamel slowly loses mineral and a lesion forms.

CPP-ACP is a remineralizing booster. It deposits onto the enamel surface and into the plaque biofilm in a way that increases the supply of bioavailable calcium and phosphate ions during the recovery window after an acid attack. The mechanism, as worked out by Reynolds and confirmed in multiple independent labs, runs in four steps.

In quantitative terms, in vitro studies measured remineralization of artificial subsurface lesions in human enamel and consistently found that CPP-ACP-treated lesions recovered 30 to 60 percent more mineral than saliva-only controls over the same time period. When fluoride is added (as in MI Paste Plus), the recovery is even higher, in the 70 to 100 percent range relative to baseline mineral density. The combined effect is consistently described as additive, not just complementary.

The mechanism also explains why CPP-ACP works on subsurface lesions rather than just surface stains. Because the released calcium and phosphate ions are small and freely diffusing, they can penetrate into the porous network of an early caries lesion (the so-called "white spot lesion") and remineralize the lesion body, not just the outermost enamel layer. This is the same depth advantage that nano-hydroxyapatite has over older calcium-phosphate technologies. The mineral has to get into the lesion before it can rebuild it.

Clinical evidence: white spots, post-orthodontic, post-bleaching

The clinical literature on CPP-ACP is unusually deep for a topical remineralizing ingredient. Over 100 randomized controlled trials, multiple Cochrane reviews, and a handful of large systematic reviews have examined the ingredient in three primary clinical scenarios: post-orthodontic white spot lesions, post-bleaching sensitivity, and management of early caries lesions in general dentistry.

Orthodontic white spot lesions

White spot lesions are the most visible failure mode of orthodontic treatment. Fixed appliances (braces) trap plaque around the brackets, and the localized demineralization that follows produces chalky white patches on the enamel adjacent to where each bracket sat. By the end of two years of treatment, somewhere between 25 and 75 percent of orthodontic patients have at least one visible white spot, depending on how strict the hygiene regimen was during treatment. Some white spots fade on their own as saliva slowly remineralizes them; others persist for years and require professional intervention.

A series of randomized controlled trials published between 2008 and 2015 in journals including the American Journal of Orthodontics and Dentofacial Orthopedics, the Journal of Dental Research, and Caries Research tested CPP-ACP (typically as MI Paste applied nightly after brushing) against fluoride toothpaste alone in patients with established post-orthodontic white spots. The pattern of results is consistent: CPP-ACP-treated lesions showed significantly greater visual fading and significantly more remineralization on quantitative laser fluorescence measurements at 12 weeks and 6 months. Effect sizes were moderate to large. A 2013 trial published in the American Journal of Orthodontics reported that 64 percent of CPP-ACP-treated lesions showed clinically meaningful improvement at 6 months versus 32 percent in the fluoride-only group.

A 2017 Cochrane review of interventions for post-orthodontic white spot lesions concluded that CPP-ACP, particularly in combination with fluoride (MI Paste Plus), is among the most effective non-invasive treatments. The reviewers noted that the evidence base was strong enough to recommend CPP-ACP as a routine adjunct in patients who finished orthodontic treatment with visible enamel demineralization.

Post-bleaching sensitivity and erosion

Professional whitening procedures, particularly those using high-concentration hydrogen peroxide, leave enamel temporarily porous and sensitive. The peroxide opens up the enamel surface, which is what allows the bleaching agent to penetrate and lift internal stains, but it also leaves the surface mineral depleted and the dentinal tubules more exposed. Most patients experience some degree of post-bleaching sensitivity, lasting hours to days.

A 2012 study in Operative Dentistry randomized patients to use CPP-ACP paste, a desensitizing toothpaste, or no intervention immediately after in-office bleaching. The CPP-ACP group reported significantly lower sensitivity at 24 hours and 1 week, and a quantitative measurement of enamel surface microhardness showed faster recovery of the post-bleaching surface in the CPP-ACP arm. This finding has been replicated in at least four subsequent trials, and CPP-ACP is now commonly recommended by cosmetic dentists as a post-bleaching protocol.

The same logic applies to erosive tooth wear from dietary acids (citrus, sparkling water, sports drinks) and from gastric reflux. In vitro and in vivo studies have shown that CPP-ACP applied after an acid challenge promotes faster recovery of surface microhardness than saliva alone. The ingredient does not prevent erosion (nothing topical does, in the strict sense), but it speeds the natural repair process during the recovery window.

Early caries lesions in general dentistry

The broader question of whether CPP-ACP prevents or reverses early caries in the general population has been studied through several large school-based and community trials, mostly using sugar-free chewing gum containing Recaldent (the most accessible delivery vehicle outside dental offices). A landmark study by Reynolds and colleagues, published in 2008 in the Journal of Dental Research, randomized about 2,700 children in Melbourne to chew either standard sugar-free gum or sugar-free gum containing 18.8 mg of CPP-ACP per piece, three times daily for two years. The CPP-ACP group showed an 18 percent reduction in caries progression, measured radiographically, compared with the control gum.

A 2009 Cochrane review on casein-derived products for caries prevention was cautiously positive on CPP-ACP for non-cavitated lesions, noting the consistency of the in vitro and intermediate-outcome evidence while pointing out that long-term lesion progression data were still being accumulated. A 2017 updated review in BDJ Open took a similarly measured tone, supporting CPP-ACP as an evidence-based adjunct rather than a replacement for fluoride.

CPP-ACP vs nano-hydroxyapatite vs fluoride

For most people, the practical question is not whether CPP-ACP exists, but whether to choose it, fluoride, or nano-hydroxyapatite for daily remineralization. The honest answer is that all three are legitimate, evidence-supported ingredients with overlapping but distinguishable mechanisms. The right choice depends on your clinical situation, your dietary tolerances, and what you are trying to address.

A few observations worth pulling out of that table. First, fluoride has the strongest acid-resistance signal because it actually changes the chemistry of enamel: fluorapatite is harder and less soluble than hydroxyapatite. CPP-ACP and nano-hydroxyapatite restore the original hydroxyapatite chemistry; they do not toughen it against the next acid attack the way fluoride does. This is why the strongest formulations (like MI Paste Plus) combine fluoride with CPP-ACP.

Second, the swallow-safety difference matters for very young children, for people in regions where water fluoridation already provides systemic exposure, and for adults who simply want to minimize cumulative fluoride load. Both CPP-ACP and nano-hydroxyapatite are food-grade or inert, with no upper limit concerns at consumer doses. Fluoride, while extensively studied and safe at standard concentrations, is dose-limited.

Third, the vegan and allergen question is binary. CPP-ACP is milk-derived. For people who avoid dairy for ethical reasons or because of cow's milk protein allergy, CPP-ACP is simply not an option. Nano-hydroxyapatite, which is synthetic and contains no animal derivatives, is the natural alternative in that case. The deeper comparison between nano-hydroxyapatite and fluoride covers the synthetic mineral side of the equation in detail.

Where to find CPP-ACP

CPP-ACP is sold under a handful of brand names and in a small set of product formats. The Recaldent trademark is the most commonly seen, but it is essentially a marketing identity for the same underlying ingredient.

Topical pastes

MI Paste (GC Corporation, Japan) is the original consumer paste, containing 10 percent CPP-ACP in a flavored, water-based cream. It is applied to the teeth after brushing, left in place for several minutes, and is intended to be spat out but not rinsed. MI Paste Plus is the same formulation with 900 ppm sodium fluoride added, marketed for higher-risk patients. In Australia and parts of Europe, the same product is sold under the name Tooth Mousse and Tooth Mousse Plus. The active ingredient is identical; the branding is regional.

Both products are available in flavored variants (vanilla, strawberry, mint, melon, tutti-frutti) primarily to make them palatable for pediatric use. The flavored versions are otherwise chemically identical to the unflavored base. A small number of toothpaste formulations also contain CPP-ACP at lower concentrations as part of a daily-use product rather than a clinical-application paste.

Chewing gum

Recaldent-labeled chewing gum was historically sold by Cadbury Adams (now Mondelez) under the Trident Xtra Care brand in the United States and Trident Recaldent in Asia. Each piece typically contained around 18.8 mg of CPP-ACP, the dose used in Reynolds's 2008 trial. Availability has fluctuated over the years. As of 2024, Recaldent-branded gum is widely available in Japan and parts of Asia, less consistently in North America, and rarely in Europe. The same ingredient appears in a handful of dental-office-sold gum brands.

Some smaller dental-product companies also incorporate CPP-ACP into mouth rinses, lozenges, and remineralizing foams sold primarily through dental offices. Outside of MI Paste and Tooth Mousse, none of these have anywhere near the same clinical footprint, and most are regional products.

Professional-use products

In addition to the consumer paste line, GC sells professional-only formulations including MI Varnish (a fluoride varnish with added CPP-ACP for in-office application after cleanings) and a range of dental sealants and bonding agents that incorporate CPP-ACP into the bonded surface. These are not directly available to consumers and are used by dentists during preventive procedures.

Who should not use CPP-ACP

CPP-ACP has an excellent safety profile for the general population. Two clear categories of people should still avoid it, and a third should approach it with caution.

People with cow's milk protein allergy

CPP-ACP is derived from cow's milk casein and contains residual casein protein. For people with diagnosed IgE-mediated cow's milk protein allergy (CMPA), exposure to even small amounts of casein can trigger a reaction ranging from oral discomfort to anaphylaxis in severe cases. The amount of casein-derived peptide in MI Paste or Recaldent gum is small, but it is not zero. GC Corporation explicitly contraindicates the product in patients with milk protein allergy, and all packaging carries clear allergen warnings.

It is worth distinguishing milk protein allergy from lactose intolerance, which is a different condition. Lactose intolerance is the inability to digest milk sugar (lactose); it has nothing to do with casein and does not contraindicate CPP-ACP. CPP-ACP contains essentially no lactose. People with lactose intolerance can use CPP-ACP without issue.

Vegans and strict plant-based eaters

For ethical vegans, CPP-ACP is not vegan-compatible. The casein is extracted from bovine milk, and there is no commercially available plant-based or synthetic version of the same peptide complex. Vegans who want a comparable remineralizing ingredient typically use nano-hydroxyapatite, which is fully synthetic and contains no animal derivatives. The performance of nano-hydroxyapatite for daily remineralization is comparable to CPP-ACP in head-to-head laboratory studies, although the clinical evidence base is younger.

Cautious populations: kosher and halal observance

CPP-ACP can be kosher and halal depending on the source milk and the certification of the manufacturer. GC Corporation has at various times offered specifically certified product lines, and consumers concerned about religious dietary observance should check the specific packaging or contact the manufacturer. The standard product is not automatically certified.

How to use CPP-ACP daily for maximum effect

The dosing and timing protocols for CPP-ACP differ depending on the delivery vehicle. For most users, the goal is daily contact between CPP-ACP and the enamel surface, ideally during the same recovery windows when natural saliva-driven remineralization is happening.

Topical paste protocol

The standard MI Paste protocol is straightforward. After brushing and flossing in the evening, dispense a pea-sized amount of MI Paste onto a clean finger or onto the head of a soft brush. Apply the paste evenly across all tooth surfaces, paying particular attention to areas of concern (white spots, sensitive zones, post-orthodontic surfaces). Leave the paste in place for three to five minutes. Spit out any excess; do not rinse. Avoid eating or drinking for at least 30 minutes afterward so the residual paste continues to interact with the enamel surface overnight.

For active white spot lesions or post-bleaching recovery, twice-daily application (morning and evening) for two to four weeks is the typical clinical regimen. Once the lesion has visibly improved or sensitivity has resolved, the protocol drops back to a single evening application as a maintenance dose. Some dentists prescribe MI Paste Plus (the fluoride-containing version) for the active treatment phase and switch patients to MI Paste alone for maintenance.

Chewing gum protocol

For Recaldent-containing gum, the protocol used in the Reynolds 2008 trial was three pieces per day, each chewed for 20 minutes, taken after meals. This dosage delivers approximately 56 mg of CPP-ACP per day. Shorter chew sessions extract less of the active ingredient, and the salivary clearance is too fast to deposit a meaningful reservoir of ions at the enamel surface. As with any functional gum, the chewing time matters more than most users realize. A 30-second post-coffee chew is not delivering the dose the studies measured.

CPP-ACP gum is best used after meals rather than between meals. The post-meal window is precisely when plaque pH is dropping, dietary calcium is being cleared from the mouth, and natural remineralization needs the most support. A piece of CPP-ACP gum chewed for 15 to 20 minutes after lunch and dinner is the simplest way to align the dose with the biological window.

Combining with fluoride toothpaste

CPP-ACP and fluoride toothpaste are not mutually exclusive. The standard recommendation is to use a fluoride toothpaste for daily brushing (twice a day) and to apply MI Paste or use CPP-ACP gum as additional remineralizing support. Some users worry about chemical incompatibility between the two; in practice, the fluoride is rinsed out before the CPP-ACP paste is applied, so the two ingredients are not competing for the same surface chemistry at the same moment.

For users who prefer to avoid fluoride entirely (for medical, dietary, or personal reasons), CPP-ACP can be used as the primary remineralizing input, ideally paired with a nano-hydroxyapatite or natural-mineral toothpaste. Readers wanting a deeper look at how nano-hydroxyapatite and other natural remineralizing inputs combine to keep enamel intact can read the longer guide on how to remineralize teeth naturally.

Realistic timeline

Visible improvements in white spot lesions typically take 8 to 12 weeks of consistent daily use. Post-bleaching sensitivity usually resolves within 24 to 72 hours of starting CPP-ACP. Subjective improvement in surface smoothness or "feel" of enamel is often reported in the first two weeks, though this is partly a perceptual response to the protein film the paste leaves behind. The deepest remineralization (filling in subsurface porosity, restoring near-baseline mineral density) takes the longest and may not be perceptible to the user even when it is happening at the microscopic level.

As with any non-restorative oral care intervention, CPP-ACP cannot reverse cavitated decay. Once a lesion has broken through the surface enamel into the underlying dentin, the only treatment is mechanical removal and a filling. CPP-ACP, like fluoride and nano-hydroxyapatite, works in the early, pre-cavitated stage of caries, which is the largest and most under-treated category of dental disease.

Frequently asked questions