How to Use MI Paste Plus: Step-by-Step Application

MI Paste Plus is applied to clean, dry teeth using a finger, cotton swab, or custom tray, left in contact with the enamel for about three minutes, and then the excess is spit out rather than rinsed away. The product delivers calcium, phosphate, and fluoride directly to tooth surfaces, and getting the technique right matters because careless application can reduce how much mineral actually reaches your enamel. The process is straightforward, but a few details about timing, drying, and what you do afterward make a real difference.

What MI Paste Plus Actually Does on Your Teeth

Before walking through the steps, it helps to know what you’re working with. MI Paste Plus contains casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) combined with 900 parts per million of sodium fluoride, roughly the same fluoride level found in standard adult toothpaste.¹ The CPP acts like a delivery vehicle: it stabilizes clusters of calcium, phosphate, and hydroxide ions as tiny amorphous nanocomplexes, preventing them from clumping together too quickly. When these nanocomplexes sit on your tooth surface, neutral ions can diffuse deep into damaged enamel rather than just coating the outside.² That slow, steady release is what makes the application technique important: you want the paste to stay on long enough for those ions to actually penetrate.

Step-by-Step Application With a Finger or Applicator

This is the most common at-home method and the one most dentists recommend when they send you home with a tube. Here is the full sequence:

Brush first: Use your regular fluoride toothpaste, brush for two minutes as you normally would, and spit thoroughly. Do not rinse with water after brushing, because a thin residual layer of fluoride toothpaste on your teeth can work alongside the MI Paste Plus.
Dry your teeth: Use a clean tissue, gauze pad, or cotton roll to blot the surfaces you plan to treat. You do not need them bone-dry, but removing pooled saliva lets the paste make better contact with the enamel. If you are targeting specific white spot lesions, focus on drying those areas.
Apply a pea-sized amount: Squeeze a small bead of paste onto a clean fingertip, a cotton swab, or a micro-applicator tip. Spread it evenly over the tooth surfaces you want to treat. For general use, cover all the outer (lip-side) surfaces of your teeth. For targeted treatment of a specific spot, concentrate the paste there.
Leave it on for three minutes: Keep your mouth slightly open or relax your lips so your cheeks and tongue do not immediately wipe the paste off. Three minutes is the standard contact time used in most clinical protocols. You will notice saliva building up, and that is fine because saliva actually helps activate the paste.
Spit, don’t rinse: After three minutes, spit out the excess. Do not rinse with water. The goal is to leave a thin residual film of the paste on your teeth so the calcium and phosphate ions continue to work. You can use your tongue to spread the remaining film around.
Avoid eating or drinking: Wait at least 30 minutes before eating, drinking, or rinsing. In clinical studies, participants were sometimes instructed to wait a full hour after treatment.³ The longer the residual film sits undisturbed, the more mineral can diffuse into your enamel.

Most people find bedtime the easiest window for application. You have already brushed, you are not going to eat again, and the paste can sit on your teeth for hours while you sleep. If your dentist wants you to apply it twice a day, the second application often fits after lunch or in the late afternoon.

Using MI Paste Plus With Custom Trays

Some dentists provide custom-fitted trays, the same type used for at-home teeth whitening. Trays hold the paste against your teeth more evenly and keep saliva from diluting it too quickly, which can be helpful if you are treating a full arch of white spots or managing widespread sensitivity. The process is the same as the finger method with a few modifications:

Load a thin ribbon of MI Paste Plus along the inner surface of the tray, similar to how you would apply whitening gel. You do not need a thick layer; a thin smear that covers the tooth-contact surface is enough. Seat the tray over your teeth and leave it in place for three to five minutes. Remove the tray, spit out the excess paste, and again avoid rinsing. Clean the tray with water and a soft brush after each use to prevent buildup.

Trays are not required for MI Paste Plus to work. They are a convenience and consistency tool, not a necessity. If your dentist has not recommended a tray, finger application works well.

Why Saliva Is Part of the Process, Not an Obstacle

People often worry that saliva will wash the paste away before it does anything. In practice, saliva is a partner, not an enemy. When MI Paste Plus contacts saliva, the CPP-ACP complex interacts with the oral environment to help buffer acidity and localize mineral ions near tooth surfaces. Research on CPP-ACPF paste (the fluoride-containing version) has shown it can increase the buffering capacity of saliva and improve remineralization substantially by concentrating amorphous calcium phosphate right where plaque sits.⁴ The xylitol in the paste also stimulates additional saliva flow, which brings its own natural supply of calcium and phosphate to the party.

That said, you still want to blot away heavy saliva pooling before applying the paste. The idea is to let the paste make initial contact with the tooth surface and begin releasing ions, then let saliva gradually interact with it. Applying the paste to a tooth that is already flooded with saliva reduces that initial mineral concentration at the enamel surface.

Common Reasons People Use MI Paste Plus

Your dentist may have recommended MI Paste Plus for a specific issue, and the application instructions above stay the same regardless of the reason. But the context behind the recommendation can help you understand how long to keep using it and what kind of results to expect.

White Spot Lesions After Braces

This is one of the most common reasons MI Paste Plus gets prescribed. When brackets come off, many people discover chalky white patches on their enamel where plaque was trapped during treatment. A three-month study found that MI Paste Plus caused a measurable reduction in the area of these white spot lesions and increased their mineral content compared to a control group that used no remineralizing paste.⁵ The appearance of the spots also improved. So the product does work for this purpose, but you need to be patient: changes are gradual and happen over weeks to months, not days.

One thing worth knowing is that the evidence is not uniformly glowing. A randomized controlled trial comparing MI Paste Plus to fluoride varnish and a no-treatment control for post-orthodontic white spots found no statistically significant differences between the three groups in professional assessments of improvement.⁶ The improvements ranged from about 16 to 37 percent across all measures, including the control group, which means natural saliva-driven remineralization was doing a lot of the heavy lifting. This does not mean MI Paste Plus is useless, but it does mean your expectations should be realistic. It is a helpful supplement to your body’s own repair processes, not a magic eraser.

Tooth Sensitivity After Bleaching

If you whiten your teeth professionally or with high-concentration at-home kits, sensitivity is a common side effect. MI Paste (and MI Paste Plus) can reduce bleaching-related sensitivity by depositing calcium and phosphate compounds that occlude exposed dentinal tubules, essentially plugging the tiny channels that transmit pain signals.⁷ A clinical trial found that arches treated with the paste had significantly lower sensitivity scores during a two-week bleaching period compared to untreated arches, with mean pain scores of roughly 28 versus 38 on a standard scale.⁷

For post-bleaching use, the typical approach is to apply MI Paste Plus immediately after removing your whitening trays or after your in-office bleaching session. Some dental offices apply it chairside as the final step before you leave. At home, you can apply it the same way described above: brush, dry, apply, wait three minutes, spit, don’t rinse.

General Sensitivity and Dry Mouth

People with chronic dry mouth from medication side effects, autoimmune conditions, or radiation therapy are at elevated risk for enamel erosion and cavities because they lack saliva’s natural protective minerals. MI Paste Plus can partially substitute for what saliva would normally provide. Lab research shows that both MI Paste and MI Paste Plus significantly reduce enamel weight loss when teeth are exposed to acidic drinks, compared to unprotected enamel.⁸ For people with dry mouth, the paste does double duty: delivering minerals and stimulating whatever residual salivary function exists through its flavor and xylitol content.

How Often and How Long to Use It

Most dental professionals recommend applying MI Paste Plus once or twice daily. The twice-daily approach is typical for active treatment of white spot lesions or during a course of teeth whitening, while once daily (usually at bedtime) is common for maintenance or general sensitivity. In clinical research, children being treated for white spots were instructed to use a pea-sized amount twice daily for the duration of the study.³

There is no hard cutoff for when to stop. For post-orthodontic white spots, a common recommendation is at least three months of consistent use before reassessing. For bleaching-related sensitivity, you typically only need it during and for a few days after your whitening cycle. For ongoing issues like chronic dry mouth, some people use it indefinitely as part of their nightly routine. Follow your dentist’s guidance here, because the duration depends entirely on what you are treating and how your teeth respond.

Who Should Not Use MI Paste Plus

This is a short but important section. MI Paste Plus is derived from milk casein, and the FDA-approved labeling explicitly warns against use in anyone with a milk protein allergy or a hydroxybenzoates (parabens) allergy.⁹ This is a genuine contraindication, not a vague precaution. If you are allergic to milk proteins, even topical oral contact with casein-derived products can trigger a reaction. Use a non-casein remineralizing product instead; there are alternatives based on hydroxyapatite or other calcium-phosphate delivery systems that do not involve dairy proteins.

For people with a lactose intolerance (not a milk protein allergy), MI Paste Plus is generally considered safe because lactose intolerance involves difficulty digesting milk sugar, not an immune reaction to milk protein. Still, mention it to your dentist if you have any doubts.

Fluoride Content and Children

MI Paste Plus contains about 900 ppm fluoride, which is comparable to a standard adult toothpaste.¹ For adults who are already using fluoride toothpaste, this adds a second low-dose fluoride exposure, which can be helpful for high-risk patients but is worth discussing with your dentist to make sure you are not layering on more fluoride than needed (especially if you also use a fluoride rinse or get professional fluoride treatments).

For young children, the fluoride content raises a concern about ingestion. Young kids tend to swallow toothpaste and topical products rather than spitting them out. If your dentist recommends MI Paste Plus for a child, they will typically advise using only a tiny smear, supervising the application, and making sure the child spits rather than swallows. For children under six who cannot reliably spit, many dentists prefer the fluoride-free version (MI Paste without the “Plus”) to avoid excess fluoride ingestion. The CPP-ACP in the fluoride-free version still provides calcium and phosphate for remineralization; it just does not include the added fluoride boost.

Does MI Paste Plus Replace Your Toothpaste

No. MI Paste Plus is not a substitute for your regular toothpaste. It does not contain abrasives for cleaning, it does not foam, and it is not designed to remove plaque mechanically. Think of it as a treatment product that you use after brushing, the same way you might use a fluoride rinse after brushing rather than instead of it.

It is also worth noting that a 12-month randomized trial comparing MI Varnish and MI Paste Plus to standard care found no statistically significant difference in caries prevention outcomes between the groups. The odds of increased enamel damage were slightly lower in the experimental group, but the difference was not significant, and overall caries scores were essentially the same.¹⁰ This reinforces the point that MI Paste Plus is best understood as a targeted treatment for specific conditions like white spots and sensitivity, not as a general cavity-prevention upgrade over standard fluoride toothpaste and good oral hygiene.

In-Office Application Versus Home Use

Some dental offices apply MI Paste Plus chairside as part of a treatment visit, particularly after professional cleanings, after bracket removal, or after bleaching procedures. The in-office technique is essentially the same as the home method, but your dentist or hygienist has the advantage of better drying (they can use an air syringe to isolate the tooth surface from saliva) and direct visualization. In one study protocol, clinicians applied the paste to the affected tooth surface for five minutes using an applicator tip after cleaning and drying with a cotton roll, then rinsed with water afterward.³

The key difference between in-office and home protocols is often the follow-up. In-office treatment may be a one-time or periodic application paired with daily home use between visits. Your dentist handles the initial intensive treatment, then you maintain the effect at home. If you are being treated for post-orthodontic white spots, for instance, your orthodontist might apply it at the debonding appointment and then send you home with a tube and instructions for nightly use over the next several months.

Mistakes That Reduce Effectiveness

The most common errors people make with MI Paste Plus are not about getting the technique dramatically wrong. They are small habits that chip away at the product’s contact time and mineral delivery:

Rinsing with water immediately after: This is the biggest one. The urge to rinse your mouth is strong, but washing the paste away defeats the purpose. Spit, but keep the residual film.
Applying before brushing: If you apply MI Paste Plus to teeth that still have plaque on them, the paste sits on top of the plaque biofilm rather than making contact with the enamel surface underneath. Brush first, then apply.
Using too much: A thick glob of paste does not remineralize better than a thin coat. A pea-sized amount spread evenly is enough. Excess just means more to spit out.
Eating or drinking too soon: Having a snack or a coffee five minutes after application physically removes the paste and introduces acids that can counteract the mineral delivery.
Inconsistent use: Remineralization is a cumulative process. Using MI Paste Plus enthusiastically for a week and then forgetting about it for a month will not produce the steady mineral supply that your enamel needs to rebuild. Consistent daily use over weeks to months is what the clinical evidence is based on.

What MI Paste Plus Tastes Like and Practical Comfort

MI Paste Plus comes in several flavors including melon, mint, strawberry, and vanilla. The texture is thicker than toothpaste, more like a smooth cream. It does not foam, and there is no strong medicinal taste. Most people find it pleasant or at least neutral, which is actually a functional benefit: the taste stimulates saliva production, and that extra saliva contributes additional minerals and buffering capacity to the oral environment. Kids generally accept it easily because of the fruit flavors, which is helpful since getting a child to hold a paste in their mouth for three minutes requires the product to not taste terrible.

If you find the paste uncomfortably thick on your teeth or if it feels like it is just sitting there in clumps, you are probably using too much. Scale back to a smaller amount and spread it more thinly. The goal is a light coating, not a mouthful of paste. Some people also find it easier to apply with a cotton swab rather than a finger, particularly when targeting a specific tooth or a small white spot lesion, because the swab gives more precision.