Plaque Analysis: The Oral Health You Can See

by Rachael Straus

While viruses might be on everyone’s mind because of the Covid-19 pandemic, let us not forget about other microscopic creatures that can influence our health, namely bacteria. Just the thought of bacteria makes many people cringe due to their associations with unhygienic or unsanitary conditions. However, due to their microscopic nature, it can be difficult for people to internalize how bacteria can affect their daily lives and habits. But what if we could make every patient see the bacteria that live off their plaque when they visit the dentist? Could that help motivate patients to take control of their oral health?

After graduating from dental hygiene school, one of my first clinical positions was alongside a periodontist. While he loved gingiva and would spend hours describing that and the periodontium, he loved bacteria even more. He enjoyed explaining the transmission and description of each and every species of bacteria that influences oral health. On my first day, I noticed that there was a microscope in the office I was to work in. The room was set up in such a way that the microscope was clearly the focal point. There was a dental chair located in the middle of the room and directly opposite the chair were two large screens, one of which connected directly to the microscope. Below the screens was a chart displaying the different shapes of bacteria. It neatly categorized the variety of bacteria found in different stages of plaque.

The microscope and chart were integral to the periodontist’s process. In his office, we provided a plaque analysis profile for each patient. This entailed taking a small sample of the patient’s plaque and saliva and placing it on a slide. Next, the slide was placed under the microscope and displayed on the screen in the patient’s view. Using the chart on the wall, the patient was encouraged to aid the hygienist in identifying which species of bacteria was found in their plaque. Based off of which species was present, the patient could then discover for themselves how old their plaque was. After following this protocol for a week, I realized how effective this tool was for patient education.

Identifying bacteria might sound like a daunting task to the average patient. However, with the help of the dental hygienist, the process was broken down into simple, easy to follow steps. This periodontal practice saw all age groups, and every one of the patients I saw was able to identify the bacteria in their plaque with the encouragement of their dental hygienist.

To better understand the process of plaque analysis, here is a step by step walk through. Using a chart similar to Figure 1, the patient would be first introduced to the basic bacterial shapes; bacilli look like rods, cocci are spherical and cluster in different sized groups, spirilla are wavy and vibrio are curved like a comma. Next, the patient would be taught with a chart similar to Figure 2 how different bacterial species correlate with the amount of time that plaque has been left undisturbed. Over days 1-2, cocci and short-rods are common. During days 4-7, filamentous (“string-like”) rods appear. Finally, over days 7-14 spirochetes and vibrio predominate.1 Since all of these bacteria have such different shapes, it is simple to identify which are present when shown what lies under the microscope.

Fig. 1

Fig. 2

Figure 3 is a microscopic image of plaque taken from a relatively healthy mouth. As you can see, the plaque contains cocci and bacilli, meaning it is 1-2 days old. Meanwhile, Figure 4 is a microscopic image of a sample taken from a mouth that had not been brushed for a long time. The encircled spiral-shaped spirochete in Figure 4 indicates that the plaque is at least 1-2 weeks old. Another way to understand visually the impact of brushing habits on dental health is the actual amount of bacteria present, not just the particular shapes. In Figure 3, the healthy well-brushed mouth shows very few bacteria. In contrast, in Figure 4, the bacteria have been allowed to fester and interact with one another resulting in a lot more visible build-up.

Fig. 3

Fig. 4

Dental hygienists are constantly discussing patient compliance and trying to come up with ways to encourage patients to take the reins of their own oral hygiene. Encouraging patients to identify bacteria in their own mouths not only allows patients to see the bacteria but also helps them recognize how old the plaque in their mouths is. This, in turn, will encourage them to prevent bacterial growth from overtaking their mouths. Patient education is the key to preventing tooth decay and gingivitis. If patients are actually shown the proof of what is in their mouths, then they are more likely to take ownership over their oral health.


  1. Wilkins EM, Wyche CJ, Boyd LD. Dental Biofilm and Other Soft Deposits. In:Clinical Practice of the Dental Hygienist. Philadelphia: Wolters Kluwer; 2017:258-261.

References for Images

  1. Wilkins EM, Wyche CJ, Boyd LD. Dental Biofilm and Other Soft Deposits. In:Clinical Practice of the Dental Hygienist. Philadelphia: Wolters Kluwer; 2017:258-261.
  2. Only Human. The Happens If You Don’t Brush Teeth for 3 Weeks. YouTube. Published September 5, 2018. Accessed January10,2021.

About the Author

Rachael Straus (AKA The Pink Hygienist) originally is from Atlanta, GA and graduated from New York University’s Dental Hygiene Program. Aside from finding out about the latest and greatest in dental hygiene, her interests include the color pink, makeup artistry, tennis and reading.