Alternative soaking solutions for cleaning Invisalign® aligners

Are there alternatives to using Invisalign’s® Cleaning Crystals?

When you begin your Invisalign® treatment, your dentist will no doubt tell you about the Invisalign® Cleaning System. And you may wonder if there are any alternatives to using this product. Possibly one that’s just as effective but less pricey.

What we found when searching the web.

While gathering background information for this page, it soon became obvious that there are no shortage of alternative cleaning methods suggested on websites. This includes substitutes like bleach, vinegar, or peroxide solutions, denture cleaners, retainer cleansers, mouthwash, etc… See full list.)

(By the way, not all of these options make a good choice, especially for use with orthodontic aligners.)

What we discovered while reading through dental research.

When investigating this issue from the scientific side, we were able to locate several published studies that had evaluated this subject (both specifically and tangentially) and were surprised to discover what a complex subject this is.

As it turns out, there are apparently no perfectly ideal cleaning methods for the types of plastics Invisalign® layers together to make their aligners. (This even includes the use of Invisalign’s® own Cleaning Crystals.)

• The use of all cleaning methods tends to degrade the optical clarity of these plastics over time. (An issue that can affect how noticeable your aligners are when worn.)
• The use of some alternative cleaning methods has the potential to affect aligner surface roughness. (An issue associated with aligner visibility and maintaining appliance hygiene.)
• And concerns with changes in aligner flexibility exist with some cleaning options. (A factor that could affect your aligner’s ability to create tooth movements, and therefore affect your treatment’s progress.)

Coming to a practical conclusion.

Knowing that all of these issues exist makes this subject plenty complex. However, there is one simple saving grace that makes all of these factors less of an issue.

That is, each set of aligners is typically worn for just two weeks. And due to their limited exposure to cleaning agents over this time frame, in most cases, whatever effects are possible typically remain inconsequential.

A plan for choosing an alternative aligner cleaning method.

We do think that in all cases you should get your dentist or orthodontist’s OK on any alternative or substitute cleaning method you choose. But beyond that …

• If the appearance of your aligners (their optical clarity) remains stable during the period while they’re worn.
• And aligner staining, accumulation of debris, and/or odor are not a problem.
• And you transition seamlessly between sets of appliances, on schedule. (Possibly a point your dentist should pass judgment on.)

… Then we’re not sure what other factors would be of concern in regard to the effects of a substitute cleaning agent on aligners. And if it passed the above test points, using your chosen alternative is probably fine.

Do you really need to soak your aligners?

A quest for an alternative cleaning solution implies a mindset that using Invisalign’s® Cleaning Crystals is really necessary or especially beneficial. We don’t entirely agree with this view. Jump to section.

Alternative soaks and cleaning solutions for Invisalign® aligners discussed on this page:

• Commercially prepared products –

  a) Aligner cleansers – Like Retainer Brite®.

  b) Denture cleansers – Like Polident®.

• Homemade cleaners –

  a) Vinegar-based soak.

  b) Bleach-based soak.

  c) Peroxide-based soak.

• Why using mouthwash doesn’t make a good choice.

Something else to know about cleaning orthodontic aligners …

You might be surprised to learn that mechanically cleansing your appliances (brushing and possibly also using an ultrasonic cleaner) plays a vital role in your being able to cleanse them effectively. In fact, the use of any chemical cleanser (any soaking solution like Invisalign®’s Cleaning Crystals or a substitute) should always be accompanied by this step.

And, actually, if you’re interested in paying attention to the findings of dental research, you’ll discover that mechanical cleansing (especially brushing) is the most important step you can take and most likely the only one you need. We discuss all of this in this section: How to mechanically cleanse (brush) your aligners. A necessary step.

Possible alternatives to using Invisalign’s® Cleaning System / Cleaning Crystals.

Note: We’d expect that the information on this page applies to other brands of orthodontic aligners too (ClearCorrect®, ClearPath®, eCligner®, Simpli 5®, etc… ). But the exact composition of the plastic used with each system varies, and therefore we don’t know for certain.

Invisalign® aligners are made using their Smarttrack® material. This is a layered plastic composed of polyurethane and copolyester. These two types of plastic are the main focus of this page.

Note: Cleaners are for external use only.

It’s important to keep in mind that soaking solutions are intended for external usage only (soaking your aligners in a container). Any residual liquid that remains on them after cleaning should be thoroughly rinsed off with lukewarm tap water before they are placed back into your mouth.

Note: Safety concerns about cleansers that contain persulfates.

Some commercial soaking preparations (denture/retainer/aligner cleaners) are formulated with what is generally referred to as “persulfates” and there can be safety issues associated with their use. FDA warning. For this reason, you should evaluate the packaging of the product you choose.

Commercially prepared cleansers –

1) Aligner / Retainer cleansers – like Retainer Brite®

There are several commercially prepared products whose packaging specifically states that they are suitable for use with clear orthodontic aligners (like Invisalign®). Some of the brand names we’ve noticed are Retainer Brite®, SonicBrite®, Dental Duty®, and SmartGuard® but there are others too.

• These products typically claim to be effective in removing accumulated staining and being able to kill bacteria and other microorganisms.
• Ingredient information isn’t always so easily found for these products.

  As a point of comparison, if you do find this information for an alternative product, the composition of Invisalign® Cleaning Crystals is Sodium sulfate (60%), sodium carbonate (30%), sodium tripolyphosphate (7.5%), sodium dichloroisocyanurate (2%), and sodium lauryl sulfate (0.15%).

  At this point in time, we’re unaware of any alternative products that have a substantially similar formulation.

▲ Section references – Shpack

An Invisalign® aligner.

Example – Retainer Brite®.

While collecting information for this page, the only published research we found that included the use of this type of cleanser alternative had evaluated Retainer Brite’s® product. So, the bulk of the information we have to share centers around its use.

Ingredients.

We were able to find the Materials Safety Data Sheet for Retainer Brite®. The active ingredients listed are potassium monopersulfate and sodium perborate monohydrate. That seems to make it more akin to the formulation of denture cleaners as opposed to Invsialign’s® crystals.

Important: See the link above about FDA safety reports concerning cleansers that contain persulfates.

Research.

Study #1 – Albanna

Title: Microbial evaluation of the effectiveness of different methods for cleansing clear orthodontic retainers: A randomized clinical trial.

Background.

This study was designed to evaluate the added value of using a soaking agent (Retainer Brite®) after brushing dental appliances with a toothbrush and toothpaste.

Findings.

This paper reported that the use of the cleanser did not significantly reduce bacterial levels beyond what was accomplished via toothbrush and toothpaste alone.

And in fact, the paper specifically states: “This study shows that brushing retainers is an effective cleaning method.” (Note, the cleaning challenges and needs of retainers and aligners are essentially identical.)

Points to consider.

• Other than just Retainer Brite®, this study also evaluated the use of two other commercial soaks (neither of which are commonly sold in the USA). It was determined that these products also failed to provide an additional level of disinfection.

  As such, we’re inclined to think that this study may be more of a testament to the effectiveness of brushing, as opposed to the ineffectiveness of the soaking products. (Formulating a cleanser that kills bacteria is hardly rocket science. How could three separate companies fail to do so?)

• As a point of comparison, here we discuss two studies conducted by Levrini View findings. that did find that the added use of their Cleaning Crystals after brushing did further reduce bacterial counts.

  (FYI: These studies also stated that just brushing aligners with toothpaste gave excellent results.)

• However, a study by Shpack View findings. states that it found the use of Invisalign’s® crystals ineffective against the bacteria it tested for. So drawing conclusions about how the use of Retainer Bright® stacks up against Invisalign’s® product in regard to disinfection is difficult to gauge.

▲ Section references – Albanna, Levrini, Levrini, Shpack

Study #2 – Wible

Title: Long-term effects of different cleaning methods on copolyester retainer properties.

Background.

Beyond just effectiveness, the use of a cleaning product must not alter the appearance or other physical characteristics of an aligner. Concerns.

Findings.

In regard to having a minimal effect on aligner plastic (specifically copolyester, one of the types of materials used for Invisalign® appliances), this study found that after use over a 6-month period of twice-weekly use, the Invisalign® Cleaning Crystals and Retainer Brite® products both tested similarly.

▲ Section references – Wible

Vibratory cleaning units.

We’ve noticed that some manufacturers that sell retainer cleansers also sell battery-powered vibrating baths. This link discusses the merit of using sonic and ultrasonic cleaning devices. Which is effective?)

► Our conclusions about the use of Retainer Brite® as an alternative to Invisalign’s® Cleaning Crystals.

• In terms of doing no physical harm to your aligners (at least in regard to the copolyester component), the fact that the use of both this product and Invisalign’s® crystals tested similarly is positive.

  (We found no corresponding study about Retainer Brite’s® effects on polyurethane plastic.)

• In terms of cleansing effectiveness, in light of the findings of the studies discussed above it seems very difficult to formulate an opinion about the comparative effectiveness of Retainer Brite® (or similarly formulated product) vs. Invisalign’s® Cleaning Crystals. (More to the point, it seems difficult to see the clear-cut benefit of using either.)

We’ll also point out …

• What we really find noticeable about the Albanna and two Levrini studies is that they each suggest that just brushing your aligners probably makes a perfectly suitable alternative cleaning method on its own.
• We’ll also add that we are totally unaware of any research that suggests that the use of any type of soaking solution alone, without any mechanical cleansing (like brushing), is an effective cleaning method. In fact, the Shpack study mentioned above seems to have demonstrated this in regard to the use of Invisalign’s® crystals.

2) Effervescent denture cleansing products – like Polident®

Background.

Commercially prepared effervescent denture cleaning products (tablets, powders, crystals, and foams) are usually formulated with some type of oxidizing agent that is capable of killing microorganisms and removing stains.

Important: See the link above about FDA safety reports concerning cleansers that contain persulfates.

The research studies that we found that had investigated the use of denture cleaners with the types of plastics used to make Invisalign’s® orthodontic aligners specifically evaluated Polident®, so that product is the focus of our discussion here. Of course, both proprietary and generic equivalents exist.

Cleaning Invisalign® aligners with an effervescent soak.

Research.

Study #1 – Baba

Background.

This study is admittedly off-target to our topic, in the sense that it evaluated the added effectiveness of using Polident® soak with dentures (not aligners).

Findings.

The study found that a protocol that involved both brushing and using the soak was more effective in disinfecting appliances than just brushing alone.

• We’ve mentioned this study to point out that the use of denture cleansers can be effective in sanitizing oral appliances.
• And to suggest that it seems reasonable to assume that it would be similarly effective in disinfecting orthodontic aligners too. (Although we could find no study that had investigated this specific application.)

▲ Section references – Baba, Levrini

Studies #2 and #3 – Wible, Agarwal

Title: Long-term effects of seven cleaning methods on light transmittance, surface roughness, and flexural modulus of polyurethane retainer material.

Title: Long-term effects of seven cleaning methods on light transmittance, surface roughness, and flexural modulus of polyurethane retainer material.

Background.

These studies evaluated the effect of denture cleaner (Polident®) on the physical characteristics/properties of polyurethane and copolyester plastics. Possible effects. (These plastics are the ones layered together to make Invisalign’s® Smarttrack aligner material.)

We think it’s important to point out that these studies evaluated 6 months of twice-weekly use. That’s a total of 48 exposures to the cleaning solution. In comparison, soaking aligners once daily over their common 2-week wear period would create 14 exposures.

Findings.

In some ways, the use of Polident® tested similarly to Invisalign’s® Cleaning Crystals. Both resulted in some decrease in aligner optical clarity. But neither significantly altered the plastic samples’ surface smoothness.

▲ Section references – Wible, Agarwal

Is this effect a big deal?

This same issue also comes up with the homemade cleaning alternatives we discuss below, and it’s hard to know how much of a concern it is.

It is true that a change in an aligner’s flexural modulus (flexibility) can alter its effectiveness in the way it applies forces to your teeth. But …

• These studies evaluated soaking protocol over a longer time frame and a greater number of total exposures than would be common with a single set of Invisalign® aligners.

  And in the case where a person’s primary method of cleaning is via brushing (it’s pretty easy to make a case for using it alone), and a denture soak is only used infrequently as an adjunct (possibly twice weekly, thus creating less than one-tenth the studied exposure), one could speculate about what level of change actually takes place.

  Unfortunately, we found no research study that had evaluated the use of denture cleansers on aligner plastics under these minimal conditions.

• We’ll also mention that a “statistically significant” change identified by a study (meaning from a standpoint of probability that randomness is not responsible for the effect that’s noticed) is not the same as stating that the level of change that occurs amounts to a significant treatment problem.

  For very minute changes, we’re not entirely sure this could be quantified. Admittedly, however, no change created by the cleaning solution would certainly be the ideal.

What causes the effect?

Per discussion in the Wible paper, a proposed culprit for the flexural modulus changes is the exposure of the plastic to free radicals released by oxidative agents in the cleaning solution.

If that’s correct, then it seems this issue is one of cause and effect. Thus suggesting that intermittent use of the cleaning solution would be a way of curbing the potential for the effect.

► Our conclusions about the use of Polident® as an alternative to Invisalign’s® Cleaning Crystals.

• Based on the findings of the study mentioned above, it seems reasonable to presume that similar to the use of Invisalign’s® crystals, the use of denture cleanser (Polident®) can be effective in disinfecting orthodontic aligners if you feel you need an added effect beyond just brushing.

  (We’re unaware of any study that has supported the use of a denture cleanser alone, without brushing, as an effective method for cleaning dental appliances.)

• In the case of short-term (2-weeks) intermittent use as an adjunct to regular brushing, we’d anticipate that using this type of product would make a suitable alternative to using Invisalign’s® crystals. Although doing so should be discussed with your dentist first.
• But for longer-term or more-frequent use, other alternatives would seem to make the wiser choice.

3) Homemade soaking solutions – Bleach-based.

Background.

Bleach-based soaking solutions Preparation. | Use. have a history of being used with dental appliances. They’re effective in killing microorganisms and removing staining (like that caused by exposure to coffee, tea, and colas).

Research.

Background.

This type of solution is typically prepared by mixing 1 part common household bleach (5.25% sodium hypochlorite) with 10 parts room temperature tap water to create a roughly 0.5% sodium hypochlorite solution. (The specific concentration of bleach products varies, so you’ll need to check the labeling of the one you use and make adjustments accordingly.)

Both the Wible and Agarwal studies mentioned above included a 0.6% sodium hypochlorite in their investigation of the effects of cleaning methods on copolyester and polyurethane plastic samples over a 6-month period of twice-weekly soaking. (These are the two types of plastics found in the combination material used to make Invisalign® aligners.)

Findings.

• In regard to polyurethane, the Agarwal study found that like Invisalign® Cleaning Crystals, bleach-based soak did affect the plastic’s transparency but did not affect its flexural modulus (flexibility).

  But in comparison to the use of Invisalign’s® product, it was found to affect surface roughness.

• In regard to copolyester, the Wible study found that like Invisalign® Cleaning Crystals, the soak did affect the plastic’s transparency but did not affect its surface roughness.

  But in comparison to the use of Invisalign’s® product, it was found to affect the plastic’s flexural modulus (flexibility).

▲ Section references – Agarwal, Wible

► Our conclusions about the use of a bleach-based soaking solution as an alternative to Invisalign’s® Cleaning Crystals.

Generally speaking, it is known that some types of plastics can be affected by sodium hypochlorite (the active ingredient in bleach). (Evidently the studies above demonstrate that.) But this concern is typically associated with exposure to high concentration solutions for long durations.

Much like our discussion above, the infrequent use of a bleach-based soak as an adjunct to a regular routine of aligner brushing can probably be accommodated with limited concern. (Get your dentist’s OK first.)

But for more frequent use or longer durations, other options would seem to make the more prudent choice.

4) Homemade soaking solutions – Vinegar-based.

Background.

There’s nothing new about the use of vinegar-based (acetic acid) soaking solutions to clean dental appliances. Preparation. | Use. It’s effective in killing microorganisms and removing tartar deposits (dental calculus).

Tartar accumulation.

Due to the short 2-week duration that aligners are usually worn for, tartar accumulation typically isn’t much of a problem for most people. In cases where it is, improper brushing habits (brushing ineffectively, or not often enough) are usually the underlying cause.

Research.

Background.

Vinegar soaking solutions are usually prepared by mixing ordinary white table vinegar (5% acetic acid) 50:50 with room temperature tap water to make a 2.5% solution. The appliance is then soaked for 10 minutes.

Both the Wible and Agarwal studies mentioned above included a 2.5% vinegar-based soak in their investigation of the effects of cleaning methods on copolyester and polyurethane plastic samples over a 6-month period of twice-weekly soaking. (These are the two types of plastics found in the combination material used to make Invisalign® aligners.)

Findings.

• The Agarwal study reported that the vinegar solution did affect the transparency but not the surface roughness of polyurethane (similar results as with the use of Invisalign’s® crystals).

  But unlike with the use of Invisalign’s® product, it also affected this plastic’s flexural modulus (a measure of stiffness).

• The same findings were reported in regard to copolyester plastic by the Wible study.

▲ Section references – Agarwal, Wible

► Our conclusions about the use of vinegar-based soak as an alternative to Invisalign’s® Cleaning Crystals.

Vinegar solution’s effect on both types of plastic used in the fabrication of Invisalign® aligners makes it hard to suggest that it makes an appropriate substitution for any type of regular use.

An isolated application used as a means of softening up hard deposits (tartar) that can’t otherwise be removed might be tolerated. (Get your dentist’s OK.)

But there seems to be good reason to use this preparation with caution. And not under circumstances where extended time frames of use, or long soaking durations, are involved.

5) Homemade soaking solutions – Peroxide-based.

Background.

Peroxide-based soak is another homemade alternative that has a history of use with dental appliances.

Research.

Both the Wible and Agarwal studies mentioned above included a 3% hydrogen peroxide-based soak in their investigation of the effects of cleaning methods on copolyester and polyurethane plastic samples over a 6-month period of twice-weekly soaking. (These are the two types of plastics found in the combination material used to make Invisalign® aligners.)

3% hydrogen peroxide is a common pre-mixed concentration sold in stores.

Findings.

• The Agarwal study determined that the use of a 3% peroxide solution (similar to the use of Invisalign® Cleaning Crystals) did affect the transparency but not the surface roughness or flexural modulus (flexibility) of polyurethane.
• The Wible study found that (similar to the use of Invisalign’s crystals) peroxide soak did affect aligner clarity but not the surface roughness of copolyester.

  But unlike with the use of the Invisalign® product, it also affected this plastic’s flexural modulus (a measure of stiffness). And like above, the paper speculated that it was free radicals released by the breakdown of the hydrogen peroxide that caused this effect.

  Probably most notable about the paper is that in its conclusions section, the author specifically states that hydrogen peroxide is not recommended as a cleaning solution for copolyester plastics. (Admittedly, however, under the longer-term conditions evaluated by the study.)

▲ Section references – Agarwal, Wible

► Our conclusions about the use of peroxide-based soak as an alternative to Invisalign’s® Cleaning Crystals.

Considering that the use of a peroxide soak has nothing special to offer over other cleaning methods, and in light of the negative statement found in the Wible study’s conclusions, there seems little reason to consider this cleaning alternative for aligners.

6) Mouthwash – like Listerine®.

Background.

Discussion about the use of mouthwash products as a cleanser for dental appliances usually centers around antiseptic-type rinses because they’re effective in killing microorganisms. (Many types of mouthwash don’t.)

While many generic equivalents exist, the best-known brand name associated with this type of product is Listerine®.

Research.

Both the Wible and Agarwal studies mentioned above included Listerine® in their investigation of the effects of cleaning methods on copolyester and polyurethane plastic samples over a 6-month period of twice-weekly soaking. (These are the two types of plastics found in the combination material used to make Invisalign® aligners.)

Findings.

Most of the concerns associated with using Listerine® as a cleanser centered on its effect on copolyester.

• It was found to alter the plastic’s translucency, surface roughness, and flexural modulus (flexibility).

  Discussion in the paper suggested that the high level of alcohol (ethanol) found in the formulation of antiseptic mouthwashes (frequently over 20%) might be the causative agent. It also mentioned that ethanol exposure tended to discolor copolyester materials.

• At least in regard to orthodontic retainers (a similar type of plastic appliance but one that’s worn for, and therefore subjected to cleaning for, a much longer time frame than aligners), the author of the study (Wible) specifically states that the use of Listerine® is not recommended as a cleaning solution.

▲ Section references – Agarwal, Wible

► Our conclusions about the use of mouthwash like Listerine® as an alternative to Invisalign’s® Cleaning Crystals.

In light of the issues discussed above, and the fact that better alternative candidates exist, there seems to be no reason to consider the use of antiseptic mouthwash (Listerine®) for cleaning Invisalign® orthodontic aligners.

Brushing orthodontic aligners.

Despite the fact that few website visitors seem to be interested in this aspect of our coverage about cleaning orthodontic aligners, we’d be remiss in not pointing out that research suggests that mechanical cleansing (brushing) provides the most effective method of home care.

And, in fact, based on published findings it’s easy enough to make the case that for most people just brushing alone usually makes a satisfactory cleaning method. (That’s in contrast to just soaking aligners. We’re unaware of any research that has suggested that the use of a soaking solution alone is effective.)

Research also shows that using an ultrasonic cleaning unit (another form of mechanical cleansing) can raise your level of effectiveness.

An Invisalign® aligner.

What’s the proof that brushing alone is effective in cleaning Invisalign® aligners?

Study #1 – Levrini

Study title: Scanning electron microscopy analysis of the growth of dental plaque on the surfaces of removable orthodontic aligners after the use of different cleaning methods.

This study included brushing aligners with toothpaste as one of the alternate cleaning methods it evaluated and stated that – “Simple brushing with toothpaste nevertheless gave excellent results.”

Study #2 – Levrini

Study title: ATP Bioluminometers Analysis on the Surfaces of Removable Orthodontic Aligners after the Use of Different Cleaning Methods.

This study also included just brushing as one of the alternative cleaning methods it evaluated. The paper states in its conclusions – “The mechanical removal of the bacterial biofilm proved to be effective with brushing and toothpaste.”

Study #3 – Albanna

Study title: Microbial evaluation of the effectiveness of different methods for cleansing clear orthodontic retainers: A randomized clinical trial.

The discussion section of this paper states – “This study shows that brushing retainers is an effective cleaning method.”

Study #4 – Chang

Study title: An assessment of the effectiveness of mechanical and chemical cleaning of Essix orthodontic retainer.

This paper’s conclusions state – “All three cleaning methods effectively removed 99% of microorganisms from the Essix retainers. Brushing with fluoride toothpaste can, therefore, be confirmed as an effective method for cleaning retainers in most circumstances.”

► Our conclusions about brushing aligners vs. soaking them.

▲ Section references – Levrini, Levrini, Albanna, Chang

What does Invisalign® formally say about aligner cleaning?

The FAQ page on Invisalign.com states (06/22/2019):

1. “The best way to clean your aligners is to use the Invisalign Cleaning System” … (continued sales pitch).
2. “You can also brush them with a toothbrush and toothpaste and rinse them in lukewarm water.”

We’re unclear about what data this first statement is based on.

▲ Section references – Shpack

Issues and concerns associated with aligner brushing.

Just as the use of alternative soaking solutions can have a detrimental effect on the physical properties of aligners The concerns., you might be surprised to learn that studies have shown that brushing them can too.

Admittedly, due to the short two-week duration aligners are usually worn for, the level of change/deterioration that occurs can be expected to be inconsequential. But as a best practice, each of these issues should be kept in mind.

a) Aligner scratching.

Background.

As you brush, your actions will tend to scuff up and scratch the plastic surface of your aligners. As the number of minute scratches increases with each cleaning session, two possible issues may arise:

• Increased visibility – As an aligner’s surface accumulates scratch marks, it also loses some of its optical clarity. If enough scratches accumulate, your aligners may be more noticeable to others when you wear them.
• Greater biofilm accumulation – Scratched aligner surfaces provide more opportunity for microorganism colonization, thus making them more difficult to thoroughly clean.

Steps you need to take to minimize aligner scratching when brushing.

1) Use a soft toothbrush.

• Read the packaging of the toothbrushes you find available and choose one that’s labeled as having “soft” bristles.
• Before brushing your aligners, moisten your toothbrush’s bristles with water and flex them with your finger as a way of loosening them up.

2) Use toothpaste that has low abrasiveness.

We were really surprised to find that many research studies, and even Invisalign’s® own website, discussed the use of toothpaste when brushing aligners.

Background.

A toothpaste’s formulation almost always includes some type of abrasive compound (especially whitening toothpastes).

To us, that type of product hardly seems the right choice for cleaning plastic surfaces.

Research.

A simple way to make our point about this concern is to take some examples from published papers:

• Studies by both Wible and Agarwal found that just brushing with water caused a reduction in the light transmittance (optical clarity) of the types of plastics Invisalign® aligners are made from (copolyester and polyurethane).

  (These studies evaluated the effect of 48 two-minute brushings. Brushing 3 times a day over a 2 week wear period would create 42 exposures, practically the same number.)

• We couldn’t help but notice that in a pair of aligner brushing studies by Levrini that the first one involved the use of toothpastes that had a “relative dentin abrasion value of less than 150,” (which really includes most products). The second lowered that range to 100 and less.

  The choice of 100-and-less products would help to minimize aligner scratching. But we don’t know if that was the reason for the change in these otherwise very similarly designed studies.

  (FYI: This study lists toothpaste products according to their level of abrasiveness. Go to website. Look for the “click here to view” link.)

▲ Section references – Levrini, Wible, Agarwal

Our opinion.

In regard to the issue of abrasiveness, it may be that while aligner scratching does occur, on a practical level it’s not generally a concern due to the short two-week time frame over which the sets of these appliances are usually worn.

We’re entirely content with this line of thought. But to us, it seems that instead of using toothpaste (which is designed with teeth in mind, not plastic surfaces), using a mild dishwashing detergent solution makes a better choice.

3) Consider using detergent as a cleanser.

This same issue of surface scratching due to brushing is a concern with other types of dental appliances too. And with them, some researchers have recommended the use of dishwashing liquid.

The general recommendation is to mix the detergent with water to create a mild soap solution. (Create a concentration that makes suds but is easy to wash off too. Mix enough that you have it on hand ready to use.)

Research.

While we couldn’t find a study that had evaluated this cleaning option specifically with aligners, we did run across a paper that had addressed this subject in regard to cleaning dentures.

▲ Section references – Rathee

4) Use a dedicated toothbrush for cleaning your aligners.

It’s always best to set aside a toothbrush that you just use for cleaning your appliances.

• Even after rinsing, a toothbrush that has been used with toothpaste will still harbor some of its abrasive particles.
• Having a dedicated brush means that you can choose one that has a size or shape that is especially well suited for this purpose. As an example, you might find that a child-sized toothbrush or a narrow-headed adult one is needed to be able to reach into the deepest recesses of your aligners.

b) Don’t brush too hard.

While reading the Wible and Agarwal studies mentioned above, we were surprised to learn that just brushing with water was found to cause flexibility changes in the types of plastics that Invisalign® aligners are made out of (copolyester and polyurethane) after only 48 two-minute brushing sessions.

▲ Section references – Wible, Agarwal

c) Never rinse your aligners with hot water.

As plastic appliances, exposing your aligners to elevated temperatures has the potential to distort them. After brushing, rinse them in lukewarm to cool tap water.

For all extra-oral events, maintaining a lukewarm/room temperature environment for your aligners always makes the right choice.

d) Consider using an ultrasonic cleaning unit.

Background.

Ultrasonic baths have a long history of being used to clean oral appliances. And like brushing, they create a mechanical cleansing effect. (We discuss ultrasonic units in detail here. How they work. | Benefits.)

Research.

A study by Shpack evaluated the use of ultrasonic cleaners with Invisalign® aligners. Two of the study’s findings were:

• The use of Invisalign’s® Cleaning Crystals on their own was not found to be effective in cleansing aligners (15-minute soaking period with container shaking). Using the solution in combination with an ultrasonic unit was.
• The study also demonstrated that the use of an ultrasonic unit following brushing was substantially more effective than just brushing alone.

Discussion in this paper pointed out that brushing may fail to thoroughly clean deeply recessed portions of aligners, like where they cover over the biting edges of front teeth or Invisalign® attachments. What are these? (So when brushing, give extra attention to these kinds of areas.)

As a way of insuring better effectiveness, the conclusions of this paper stated that it “highly recommended” the use of a vibratory bath protocol.

Sonic cleaners vs. ultrasonic units.

We’ve noticed battery-operated vibrating baths for sale for use with aligners and retainers. These low-end, low-frequency devices don’t offer the same advantages as ultrasonic units and are not a substitute. (Here’s why: Sonic vs. ultrasonic cleaners. They’re not the same.)

Should you use the Invisalign® Cleaning System instead of a substitute?

There can be some advantages to just going ahead and using Invisalign®’s recommended Cleaning Crystals as opposed to an alternative but we’re not so overwhelmed by the evidence for it. For us, it would be more of a peace-of-mind decision.

1) Research – How effective are Invisalign’s® crystals in disinfecting your aligners?

Study #1 – Levrini

Title: Scanning electron microscopy analysis of the growth of dental plaque on the surfaces of removable orthodontic aligners after the use of different cleaning methods.

Background.

This author has published two studies that have evaluated the effectiveness of the Invisalign® Cleaning System in regard to its ability to sanitize aligners.

An initial one evaluated the use of three alternative cleaning methods (rinsing with water alone, brushing with toothpaste alone, soaking using Invisalign’s® Cleaning Crystals followed by brushing with toothpaste).

The appliances were then evaluated via an electron microscope to determine what level of bacterial colonization remained after each of the cleaning routines had been performed.

One way to clean Invisalign® aligners is by soaking them.

Study findings.

• The cleaning method that included both brushing (before wearing the aligners) and using the Cleaning Crystals (once daily) was found to be the most effective one in reducing the bacterial load found on the appliances.
• However, we think it’s important to point out that the paper specifically stated that just brushing with toothpaste “gave excellent results.”
• We’ll also mention that the study found that none of the three cleaning routines were totally effective in removing all bacteria and debris from aligner surfaces.

Brushing is needed too.

Discussion in this paper elaborated on the fact that studies have generally shown that the most effective methods for cleaning dental appliances (of all types) typically involve a combination of mechanical (brushing) and chemical (soaking) processes. And suggested that its findings corroborate this point. (We report on the need for this two-phase approach with denture cleaning here. Brushing plus soaking.)

What we found curious about this study.

We couldn’t help but notice that this study did not evaluate the effectiveness of just using the Invisalign® crystals on their own. (Just soaking the aligners, without any brushing.)

▲ Section references – Levrini

Study #2 – Levrini

Title: ATP Bioluminometers Analysis on the Surfaces of Removable Orthodontic Aligners after the Use of Different Cleaning Methods.

Background.

This study (whose lead author was the same as the study above) was set up in a similar fashion as the one just discussed. The primary difference between the two was the way in which the level of bacteria remaining on the aligners was detected. (This one used bioluminometry.)

Study findings.

Similar to the first paper, this second study stated that:

• A routine of just brushing with toothpaste “proved to be effective” in removing the accumulation of biofilm (dental plaque) from aligners.
• But also determined that the best results (in terms of reducing the concentration of bacteria on aligner surfaces) were achieved by combining the brushing routine with the use of Invisalign’s® crystals.
• The study did not evaluate the use of the Cleaning Crystals alone (no brushing).

▲ Section references – Levrini

Study #3 – Shpack

Title: Efficacy of three hygienic protocols in reducing biofilm adherence to removable thermoplastic appliance.

Background.

As a preliminary step in this study, it evaluated just soaking aligner samples in Invisalign’s® Cleaning Crystals solution. (15-minute soaking duration with container shaking.)

Study findings.

▲ Section references – Shpack

► Our conclusions about using the Invisalign® Cleaning System.

The disparate findings of these studies make it difficult to know how much emphasis should be placed on the use of Invisalign’s® crystals. It might be stated that:

• A routine of (regularly and diligently) brushing your aligners alone probably provides an adequate level of cleaning … (See discussion above.)

  But yes, the additional use of the Invisalign® Cleaning System may raise the level of disinfection a person can achieve, and therefore might be considered a best practice.

• Considering that brushing seems to provide a satisfactory level of aligner cleansing, and study results have been inconclusive about the effectiveness of the use of the crystals, then the use of this product tends to fall more so into the category of an adjunct.
• In situations where effective brushing measures are not performed, it seems unlikely that using Invisalign’s® crystals provides a level of assistance that can make up for this deficiency. (Thorough aligner cleansing isn’t possible without effective mechanical cleansing.)

An important footnote!

As discussed above in our “brushing” section, we think that it’s important to point out that there are issues and concerns associated with aligner brushing that are important to keep in mind, especially when toothpaste is used.

2) Does using Invisalign’s® Cleaning Crystals affect aligner plastics?

It may not have crossed your mind but there are some very important things that an aligner cleaning method should not do. They include:

An Invisalign® aligner.

• It should not degrade the optical clarity of your appliances. – An issue that’s associated with how visible your aligners may be to others. How noticeable are they?
• It should not affect aligner surface roughness. – An issue associated with aligner visibility and maintaining appliance cleanliness.
• It should not affect the dimensional stability and/or physical properties of your aligners.

  These types of issues might affect the effectiveness of your appliances in creating tooth movements and therefore affect your treatment progress.

Does using Invisalign’s® Cleaning Crystals affect aligner plastics?

Since Invisalign®’s Cleaning System is the recommended product, one might assume that the use of this cleanser doesn’t affect aligner plastics at all.

From a practical standpoint, that stance seems to be true enough. But as we discuss below, that’s not entirely what research suggests.

What type of plastic are Invisalign® aligners made from?

Obviously, to understand the effects that a cleaning method may have, this is a vital piece of information to know.

Generally, this is proprietary information held by the company. But the Material Safety Data Sheet for their Smarttrack® plastic (the material currently used) states that its composition is multilayered “thermoplastic polyurethane / copolyester.”

What research information is available?

We found published studies that investigated the use of cleaning solutions, including Invisalign’s® Cleaning Crystals, with both polyurethane and separately copolyester test samples.

In our reporting here, we’re making the assumption that known effects on either of these component plastics would have the potential to similarly affect Invisalign’s® multi-layered plastic.

Research – What effects does the Invisalign® Cleaning System have on aligner plastics?

Study #1 – Wible

Title: Long-term effects of different cleaning methods on copolyester retainer properties.

Background.

This study was designed to investigate the effects of 8 cleaning methods on copolyester plastic. (One of the components of the plastic material used for Invisalign® aligners.)

The use of these cleansers was evaluated over a 6-month time frame of twice-weekly use. (48 exposures to the soaking solution.)

The plastic samples were evaluated for changes in:

• Light transmittance – Essentially a measure of optical clarity, a factor that would correlate with how noticeable a person’s appliances might be to others.
• Surface roughness – An increase in surface roughness would affect both an appliance’s appearance and the ease with which microorganisms can adhere to it.
• Flexural modulus – This is a measure of flexibility. Changes in aligner stiffness can affect the way it applies forces to the patient’s teeth and therefore may affect a patient’s treatment progress.

Study findings.

• Did not significantly affect the surface roughness of the plastic. (Only one of the 7 other methods did.)
• Did not significantly affect the flexural modulus of the plastic. (All but one of the other 7 methods did.)
• Did cause a statistically significant effect (decrease) in the plastic’s light transmittance. (All other alternative cleaning methods had this same effect too.)

  (We found it interesting that the change took place after just 48 soaking exposures. Daily usage over the usual 2-week time frame aligners are worn for would create 14 exposures.)

  (The term “statistically significant” does not necessarily correlate with the words “visibly perceptible.” So, how much of a noticeable change actually occurred would be an issue of question.)

▲ Section references – Wible

Study #2 – Agarwal

Title: Long-term effects of seven cleaning methods on light transmittance, surface roughness, and flexural modulus of polyurethane retainer material.

Background.

This study involved many of the same investigators that conducted the Wible study and was set up in a very similar fashion (although only 7 cleaning solutions were investigated).

A primary difference between the two studies was that this one evaluated the effects of the cleaning solutions on polyurethane plastic. (The other of the two types of plastic used for Invisalign® aligners.)

Study findings.

In a nutshell, the findings of this study were very similar to the one just discussed. It found that the use of the Invisalign® Cleaning System (over a 6-month period of twice-weekly use):

• Did not significantly affect the plastic’s surface roughness. (Only one of the other methods did.)
• Did not affect the plastic’s flexural modulus. (Two of the alternative methods did.)
• Did affect the light transmission of the polyurethane samples. (All tested cleaning methods did.)

▲ Section references – Agarwal

► Our conclusions about what these studies suggest.

• The use of Invisalign’s® crystals may deteriorate the optical clarity of aligners over the longer term. (All other evaluated alternative cleaning methods did too.)

  Due to the short 2-week time span over which aligners are most frequently worn, for most patients the level of change that occurs is probably (evidently) inconsequential.

• The formulation of Invisalign’s® Cleaning Crystals (sodium carbonate / sodium sulfate) appears to be one that minimally affects the two-component plastics used to fabricate their aligners.

  While you may consider this a given, we primarily mention this as a point of comparison to some alternative cleaning methods that one might consider using.

► Our conclusions about choosing to use the Invisalign® Cleaning System.

Based on the information and discussion found on this page, we think that it’s justified to conclude that:

• Just brushing your aligners (discussed next) is typically a satisfactory cleaning method on its own.
• Since the use of Invisalign’s® Cleaning Crystals may raise the level of disinfection possible, using them in conjunction with brushing would generally be considered a best practice (chemical + mechanical cleansing). Although from a practical standpoint, we would question the need to do so daily.
• In regard to aligner cleansing and disinfecting, we’d anticipate that just using the Cleaning Crystals alone (no aligner brushing) would make the least effective choice by far.
• All cleaning methods apparently have some effect on the physical properties of the plastics used to make Invisalign® aligners. However, with Invisalign’s® crystals, it seems that only aligner appearance is affected. And from a practical standpoint, probably only very minimally.

  In comparison, with alternative cleaning methods, the question of their level of effect is harder to interpret. By using the Invisalign® Cleaning System, you are in effect purchasing peace of mind on this, possibly inconsequential, point.