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Dentist Interview

We visited the Peking University Hospital of Stomatology for professional investigations in our field before we conducted our experimentation. We briefly introduced our project and talked to Dr. Li Tiejun and Dr. Chen Feng. We then proposed our questions for a more thorough interview with Dr. Chen Feng, who is an expert in the field of dental health. We received affirmative responses for our project’s significance. He believed that better detection of the dental plaque disease would greatly help prevent damage done to the teeth. However, some issues were noted in our project, such as whether our promoter has a distinctive response to only Bacillus subtilis 168 and not the many other bacteria present in one’s saliva. We also had the special opportunity of being introduced to the most advanced prototype for evaluating dental health, which comes in the form of a paste. Once applied to the surface of teeth, this paste will express purple fluorescent if harmful bacteria are present. More detailed information regarding our interview can be found below.

Figure 1: Dentist explaining dental plaque to us.

Online Chat

After explaining the basic mechanism and theory behind our iGEM project

Dr. Chen Feng: To put it simply, the doctor usually observes the condition of the patient’s teeth, and little color reagent is needed for the detection of dental plaque in clinical trials. In a scientific lab, high throughput sequencing may be used to identify the bacterial colony. Or, qPCR and probe hybridization may be used to detect certain bacteria. There are also some laboratories that conduct in-depth research regarding the mechanism of separately culturing specific bacterial colonies.

THIS-CHINA: If the expression of our circuit was successful, and we could detect dental plaque in the early stages of development of the disease, we wish to have our final product as a form of gargle, which would provide a safer and more convenient method for customers. However, dental plaque is most prevalent on the surface of teeth; would saliva contain a sufficient amount of the bacteria to induce our desired expression of the gene?

Dr. Chen Feng: That is a very brilliant idea; in this case, you would have to distinctly detect your targeted bacteria, eliminating all of the other factors in the complex oral environment, such as other proteins and food remnants, to achieve stable detection of dental plaque.

THIS-CHINA: Do the usual color reagents contain chemical properties?

Dr. Chen Feng: Yes, usually with basic pH levels. Bacterial colonies are very hard to completely clear out, thus it is very important to detect its numbers remaining and the proportion of acid production traits.

From the interview with the expert, we gained a deeper and broader understanding of the current situation of dental health issues among children and elders in China. It has been quite shocking to learn that the occurrence rate of dental caries in China was even higher than our expectations. To illustrate, as Dr. Chen stated in his responses, among adults over 30 years old, 80% have dental caries, and these can directly lead to the loss of teeth and digestion issues. Furthermore, 70% of children in Beijing are prone to dental health issues such as dental caries, and thus awareness must be raised to help people detect dental caries at an early stage and prevent them from developing further.

Most existing products on the market on dental plaque detection can help visualize the number of bacterial on the user's teeth. Nevertheless, according to Dr. Chen, a common shortcoming of most existing products is that their detections do not distinctively respond to specific types of bacteria. This points toward the importance of our product. As suggested by the expert, our product should be able to help its users detect specific bacteria in their mouth, and specifically those that can lead to dental caries. Through signs revealed by our product, doctors and patients will both be able to know whether there is a high possibility of the patient getting dental caries. This led us to exploring the uniqueness of the signal and protein, and we found out that it is very unique to S.mutans. Moreover, from interviewing Dr. Chen, we became aware of a few potential safety concerns of our product and system. Since our product involves coloring parts of the user's mouth for Bacillus subtilis detection, whether the coloration is edible and easily removable is an important factor to consider.

Future Improvements and Integrating Human Practice - Explanation

Based on the interview with experts from the Peking University Hospital of Stomatology, we further developed our project ideas. We explored the uniqueness of the CSP signal and found out that only S.mutans and S.pneumoniae will produce them, so the appearance of these two bacteria will cause the circuit to function. Therefore, it exhibits a good uniqueness on detection. Adding on to that, for the safety problem the doctors mentioned, we have developed the oral rinsed and a hardware to help the patient to safely use our product. More information can be found at https://2021.igem.org/Team:THIS-China/Hardware.

Figure 2: Picture with Dentist.

Toothaches and Dental Health Survey

On July 10th, 2021, THIS-CHINA published an online survey about toothaches and dental health. The survey was written in both English and Chinese, as we intended it for people from different backgrounds to all be able to take the survey. The goal of this survey is to get a general idea of the state of people’s dental health, their thoughts regarding the subject, and their opinions on our project. We discovered that most believed that dental health is important, yet they believe that the state of their dental health is not completely ideal (Q9, 10). The data suggests that brushing teeth is a much more common method of maintaining dental hygiene than flossing or using mouth wash (Q6, 7, 8). The most valued aspect of a dental detection device was safety, while the least was waiting time for the results. (Q13, 14). Additionally, there was no strong preference between whether the bacteria was active and not and no strong preference for the various detection methods (Q16, 17). This will shape the goal of our project, as we will attempt to produce a detection device with both active and inactive bacteria.

Figure 3: A QR code to access our group's survey.

Question 11: How often do you visit a dentist?

Figure 4: Results for Question 11.

The results show that people do go to the dentist, but not so often—typically every few months or every year. This means that there is demand for a dental detection device that people can use at home, demonstrating that our project has certain significance.

Question 12: What aspect of a dental bacteria detection device is MOST important to you?

Figure 5: Results for Question 12.

Safety is the aspect that most people prioritize. Therefore, we decided to prioritize this aspect when developing our product. Originally, we were planning on developing the product in the form of dry powder of inactive bacteria that requires contact. Later, we decided to use living bacterium that doesn’t require contact.

Question 13: What aspect of a dental bacteria detection device is LEAST important to you?

Figure 6: Results for Question 13.

It is clear that the time it takes to get the results is the least important aspect. This question serves a similar purpose as the last question. A flaw to our project is that the time to get the results of the detection is somewhat lengthy: around 12 hours for the chromo-protein, and 2 days for cotA. Since this aspect mattered the least to our participants, we did not focus on it.

Question 14: What would be your limit/tolerable amount of waiting time for the results of a dental bacteria detection?

Figure 7: Results for Question 14.

Almost 40% of people answered “a few days” for their tolerable amount of waiting time. If the time it takes for the results to come out is longer than a few days, than at least 80% of people will be dissatisfied with the product. The time it takes for our detection device to produce a result is less than a few days, which promises that most people will be satisfied.

Question 15: What’s your preference about dental health detection?

Figure 8: Results for Question 15.

There isn’t a clear preference over the type of dental health detection device. The purpose of this question was to find out what suited the majorities, so we could produce a device that satisfies the most amount of people. We decided to produce our product in the form of a combination of mouthwash and indicator paper.

Question 16: Which of the following detection methods do you prefer more?

Figure 9: Results for Question 16.

Once again, the preference was almost equally divided. It could be either because it didn’t matter to the majority or that it just happens to be almost 50-50. We tried to create both types in order to satisfy more people. However, the dry powder form did not work out because it was very difficult to make the membrane protein cell-free.

Question 17: Would you buy a dental detection device (not one of those big machines) that you can use on your own?

Figure 10: Results for Question 17.

More than a third of the people answered yes, which meant that some people were in fact interested in our product. It is likely that many participants who answered no were suspicious of whether our detection device will be safe, accurate, and worthy of purchasing. It could also be because they are fully aware of their state of dental health and find the device to be unnecessary. Overall, the results demonstrate that this detection device is meaningful to many.

Summary of Our Survey Results

This survey influenced our decisions in many stages of the project. 1) Instead of presenting the detection in the form of dry powder, we also created it with living bacterium, because the preference for the form of the detection device was close to half-half. 2) Since the time it takes for the results of the detection was least prioritized by the participants, we decided to not prioritize that aspect. This compromise was made so that we could satisfy more people, hence, increasing the number of people who would be interested in our product. 3) Although participants understood the importance of dental health, many of them were not completely aware of the possible consequences and causes. We decided that it is essential for people to comprehend the relationships, so we made an educational video about synthetic biology.

Another purpose for this survey was to get a general understanding of people’s experiences with toothaches, their current state of dental health, and common methods used to maintain dental hygiene. This was also important as it proved the relevance of our project. We were glad to find out that when we asked participants about how important dental health is to them, they scored an average of 9.37 out of 10. Additionally, we were pleased by how people were interested in our product, and some even stated that they would buy it. These gave us motivation to develop the detection device.

References

WHO. “Oral Health.” World Health Organization, World Health Organization, www.who.int/news-room/fact-sheets/detail/oral-health.