August 23, 2022

Complete Guide to Shocking Dental Unit Waterlines

A dental assistant placing a dental water bottle back on the dental unit

When you started your journey in dentistry, you probably didn’t know you were entering an epic, grueling battle against infection. Well, if you didn’t know yet, we’re telling you now.

Welcome to the fight.

If you’re feeling a little under…armored, you aren’t alone. Dental unit waterline maintenance generally isn’t a topic that generates as much buzz as the latest ultrasonic scaler (pun intended). However, understanding how to “clean” (or as we will refer to it, shocking and treating ) your dental unit waterlines will keep your favorite gadgets as weapons for good rather than undercover tools for dental infection.

Let’s jump in! In this article we will be covering:

  • What does it mean to shock your dental unit waterlines?
  • What’s the difference between shocking and other dental unit waterline treatment methods?
  • Why does biofilm grow in dental waterlines?
  • What is the difference between flushing, purging, and shocking dental unit waterlines?
  • Do I really need to shock my dental unit waterlines?
  • How does shocking clean dental unit waterlines?
  • When should you shock your dental unit waterlines?
  • How do I shock my dental waterlines?
  • Is a shocking solution safe for my dental equipment?
  • How do I know if shocking is effective?

What does it mean to shock your dental unit waterlines?

Shocking is the process of using a strong disinfectant in your dental unit waterlines (not to be confused with evacuation lines) to clean out bacteria and biofilm that has built up over time. Just like a professional dental treatment provides a cleaning that even the fanciest electric toothbrush cannot replicate, shocking removes what daily treatment cannot. The shock solution runs through the lines, removing biofilm and allowing daily (or continuous) low-level antimicrobial products (like BluTab or BluTube ) to work as intended.

What’s the difference between shocking and other dental unit waterline treatment methods?

Simply put, shocking cleans the waterlines, while treatment maintains the clean environment created by shocking. Treatment products can only do so much, and biofilm is always working to multiply and grow. At some point, your treatment solution will become ineffective against the growth of bacteria in your waterlines. It’s at that point you need to come in with a stronger solution and remove the bacteria that have become a little too comfy in your waterlines.

We describe the various treatment options in detail in our Complete Guide to Treating Dental Unit Waterlines.

Why does biofilm grow in dental waterlines?

It’s important to remember that biofilm is everywhere. It’s the slimy algae on the rocks in the river, it’s the plague on your teeth, and it’s the grime in your waterlines. Biofilm isn’t new to you; it’s just growing in a place that forces you to deal with it in order to keep your practice safe. This leads to the never-ending fight we mentioned earlier.

Unfortunately, the engineering of waterlines sets you at even greater odds as it is perfectly situated to house biofilm. Biofilms are complex organisms and we are still discovering more about them. (To learn more about biofilm, check out our Complete Guide to Biofilm in Dental Unit Waterlines.) The porous surface of waterlines and slow-moving water create the perfect breeding ground for bacteria to multiply and form biofilms.

What is the difference between flushing, purging, and shocking dental unit waterlines?

In simple terms, shocking is using a strong disinfectant to break down biofilm and kill bacteria in the waterline. Flushing is pushing water through the waterlines to remove free-floating bacteria. Purging is emptying all water in the line (typically at the end of the day) to remove as much stagnant water as possible and minimize the wet environment bacteria love to grow in.

While each of those are important steps in waterline maintenance, only shocking can eradicate biofilm that has moved in and made itself comfortable. All other movements of water through your lines attempt to push out already loose bacteria and have no impact on biofilm that has adhered to the walls of the waterline tubing.

Do I really need to shock my dental unit waterlines?

Yes! Here’s why:

Think of it in this way, if your dental unit waterline maintenance protocol were compared to your patients’ dental routine, shocking would be equivalent to getting a professional cleaning whereas treating (with straws or tablets) would be like your daily brushing and flossing habits.

You’ve seen what happens when a patient avoids “the chair” for far too long–biofilm in the form of plaque builds up on their teeth, the same happens when lines go without a shock for too long. So, learn from your patients and be diligent with your “routine” visits.

Unfortunately, shocking is not a step that will get you extra credit in your infection prevention efforts. It is the foundational step required to have any chance against the ever-persistent and potentially dangerous biofilm.

How does shocking clean dental unit waterlines?

Scientifically speaking, the active ingredients in shocking solutions cause the following reaction when it meets stubborn biofilm:

  1. The shock agents latch onto the bacteria and kill it from the inside out.
  2. The shock agent is like a lawnmower, cutting bacteria open as they speed through your water.

But, if you don’t want to memorize this explanation, the short answer is that shocking solutions break down and destroy the bacteria that form biofilms.

When should you shock your dental unit waterlines?

All dental waterlines need to be shocked regularly (we recommend quarterly). The best way to know when to begin the recurring cycle of shocking, treating, and testing is to start by shocking your lines.

While we have heard that some product representatives say shocking isn’t necessary with certain centralized systems or treatment products, has shown that this is almost never the case. All lines need to be shocked regularly, regardless of the water source.

You should shock dental unit waterlines in any of the following situations:

  • Before first beginning a treatment protocol or before changing treatment products
  • Immediately After a Failed Test (Microbial Counts < 500 CFU/mL)
  • Recurring “Regular” Removal of Biofilm and Bacteria
  • Continuous Shock-Only Treatment

Here’s what you need to do when shocking your DUWLs in each of these scenarios:

Before the Initial Use of a Water Treatment Product or Before Changing Treatment Products

As mentioned above, continuous water treatment products like tablets, drops, and straws effectively maintain already clean dental waterlines. (followed by flushing the lines with hot water) to clear out different products that can counteract or negate each other, which results in them becoming ineffective at eliminating biofilm.

Immediately After a Failed Test or Results of Microbial Counts < 200 CFU/mL

You will need to shock your lines after a failing test result with microbial counts of < 500 CFU/mL. However, even if your test reveals a line at 200 CFU/mL or above, we recommend shocking to ensure these colonies cannot quickly multiply and exceed the ≤ 500 CFU/mL guideline. Remember that bacteria multiply exponentially. So, if a line is between 200 CFU/mL and 500 CFU/mL, shock within 7 days and continue regular treatment and testing to ensure that the lines get to a safer level.

Recurring “Regular” Removal of Biofilm and Bacteria
Most manufacturers and regulatory agencies  recommend shocking your dental unit waterlines “regularly.” For practices that have already been shocking and treating their lines, we recommend shocking quarterly. For practices that have not been shocking and treating or those that have only been treating, you may need to shock multiple times in a row to thoroughly clean your lines before moving to shocking quarterly.

Continuous Shock-Only Treatment
If you’ve chosen to forego continuous treatment products like straws or tablets, you will need to shock your lines at least once a week. Without using any dental water treatment products designed to be in your waterlines continuously, biofilm can re-attach and begin growth immediately after shocking your waterlines. Studies have shown that within 5 days, bacteria counts can grow to 200,000 CFU/mL.

This is not a method we recommend because 1) it requires constant maintenance, forgetting to shock just one week can lead to failing lines soon after 2) because of the strength of these chemicals, it may be corrosive to lines when done at this frequency 3) it is often not nearly as cost-effective as utilizing continuous treatment products.

Regardless of which situation you are in, remember that biofilm never quits so you can’t either. Shocking your DUWLs once is not going to keep your lines clean of biofilm for long. These colonies are highly organized; they attach, multiply, and spread very efficiently.

How do I shock my dental waterlines?

So, you’re probably wondering how to shock dental waterlines.

To start, always check the manufacturer’s instructions for your operatory equipment and shock product. Different chair manufacturers may suggest different shock protocols and different treatment products call for different techniques and frequencies.

As a starting point, though, our water safety specialist team has found these two methods to be the most effective:

  1. Run diluted bleach through your lines and leave the solution for 10-15 minutes and then flush the lines
  2. Run Liquid Ultra through the lines and let them set overnight and flush in the morning

Keep in mind that while Liquid Ultra is highly effective, it is more costly than bleach which can be equally effective. If you choose to use the diluted bleach option, we’ve got you covered. We put all the details together in a condensed 1-page guide that will walk you through how to shock your dental unit waterlines using diluted bleach.

Here are just a few very important notes as you go through this process:

  • Before shocking, remove anything autoclavable (this may include couplers), shocking through these tools will damage them
  • Bleach does have an expiration date (usually 1 year) and loses effectiveness as it ages. Be sure you use unexpired bleach (yes, bleach expires, who knew?) if using this as your shocking solution.
  • To make the DUWLs patient-safe again, you must flush your lines with warm water for 2 minutes to help break up and remove biofilm as the final step, flush with cold water for 1 minute to cool the lines

As always, if you still have questions or are a bit overwhelmed by the shocking process, give us a call or shoot us an email, we’re here to help you through it regardless of what treatment products you use.

Is a shocking solution safe for my dental equipment?

Shock solution, whether you are using diluted bleach or Liquid Ultra is safe for equipment generally speaking, but some manufacturers do specify not to use diluted bleach. We always recommend following the manufacturer’s guidelines to protect equipment.

However, neither shocking solution is safe for patient consumption. Therefore, it is essential that after shocking you flush your lines with warm water for 2 minutes and cold water for 1 minute.

We also often get asked if shocking will lead to the corrosion of dental equipment. Because dental professionals invest a lot in their equipment, it’s understandable why dental offices would be concerned about this. You should not experience any corrosion or damage to dental equipment if you follow the instructions provided by manufacturers.

How do I know if shocking is effective?

It’s possible that, depending on the level of buildup in the waterline, you may see visible evidence of biofilm coming out of the lines. This can look like anything from small black specs to larger particles. However, this is not always the case.

Regardless of if you see the breakdown or not, the only sure way to know if the shock was effective is to test your lines.

We’ve broken down everything you need to know about this in our Complete Guide to Testing Dental Unit Waterlines.

First, there’s shocking, then there’s…what?

Now that you’re familiar with shocking, arguably the most important step in achieving safe water, you may be wondering what you do from here to ensure your dental waterlines remain biofilm free and whistling clean.

The next step is using a continuous treatment product to maintain the hard work that you’ve done by shocking your lines.

Don’t worry, we won’t leave you high and dry, we have a Complete Guide to Treating Dental Unit Waterlines to help guide you through the entire process.

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Publish Date:

August 23, 2022

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