Team:Mingdao/Model
Mingdao
INTRODUCTION
Our goal is to assess the causes of dental caries and simplify the correlation between several factors based on NMR (nuclear magnetic resonance) spectroscopic data. The data we applied from NMR includes the relevant quantity of S. mutans metabolites as well as the chemical shifting of those signals.
Objective 1: Which metabolites affect the pH value in dental cavities most significantly?
Objective 2: What are the effects on dental caries when consuming different types of sugar?
Objective 3: How long does it take for dental caries to develop after eating candy?
Objective 1: Which metabolites affect the pH value in dental cavities most significantly?
Objective 2: What are the effects on dental caries when consuming different types of sugar?
Objective 3: How long does it take for dental caries to develop after eating candy?
DETERMINE pH VALUE FROM NMR SPECTROSCOPIC DATA
We can determine the pH value by the chemical shift of certain organic compounds. The theoretical chemical shift (δ ̃) is a weighted average of the limiting chemical shifts of the unprotonated (δA) and the protonated (δHA) states of the molecule model.
The theoretical chemical shift is a function of pH and pKa as depicted in the following equation.
The theoretical chemical shift is a function of pH and pKa as depicted in the following equation.
A study by Lifeng Ye, et al (2018) indicated that the theoretical chemical shifting of acetate follows a titration curve (Fig. 1). In our model, we exploited the acetate shifting data from S. mutans metabolites in NMR study to compute the pH levels based on his findings. The model estimated that the pKa value equals to 4.591, δA equals to 2.089 and δHA equals to 1.910.
Fig 1. Correlation between acetate theoretical chemical shifting at NMR spectrum (ppm scale) and pH value in the Lifeng Ye’s study.
In addition, the analysis of NMR data showed that the relative quantities of various carbohydrate metabolites were detected from the 6-hour culture of S. mutans grown in 5% of BHI containing 1% glucose. Lactate production was significantly increased by glucose-consuming S. mutans, implying the product of lactate may be the major factor affecting the pH value.
In addition, the analysis of NMR data showed that the relative quantities of various carbohydrate metabolites were detected from the 6-hour culture of S. mutans grown in 5% of BHI containing 1% glucose. Lactate production was significantly increased by glucose-consuming S. mutans, implying the product of lactate may be the major factor affecting the pH value.
Fig 2. The relative quantity of different metabolites when S. mutans was incubated in 1% of glucose at 37°C for 6 hours.
THE EFFECTS OF DIFFERENT CARBON SOURCES ON DENTAL CARIES
Development of dental caries is highly associated with lactic acid produced in dental cavities. We utilized the function of theoretical chemical shift to determine pH value, which enables us to backtrack to find the acid production of S. mutans in various carbon sources.
In our model, we set the standards of the cultures of S. mutans growing in 5% BHI with 1% glucose in a period of 360 min to determine for a regression curve of lactic acid production. We then developed an empirical equation to describe the acid production of S. mutans in 1% of glucose. The equation was given below.
In our model, we set the standards of the cultures of S. mutans growing in 5% BHI with 1% glucose in a period of 360 min to determine for a regression curve of lactic acid production. We then developed an empirical equation to describe the acid production of S. mutans in 1% of glucose. The equation was given below.
Fig 3. The empirical equation of the standards describing acid production [H+] of S. mutans growing in 5% BHI supplemented with 1% of glucose.
The pH values of other carbon sources (i.e., sucrose, erythritol and xylitol) were derived directly from the equation built in glucose. Obviously, sugar alcohols (i.e., xylitol and erythritol) are supposed to inhibit the acid production of S. mutans.
Fig 4. the acid production of S. mutans growing in various carbon sources
pH CHANGES IN THE DENTAL CAVITIES OVER TIME IN RESPONSE TO SUGAR CONSUMING
Oral pH value plays a vital role in caries assessment. An oral acidity below the critical value at a pH of 5.5 can lead to tooth decays. In our model, we applied the well-known Stephan curve in caries process to illustrate the time dependent variation in the pH values of dental cavities.
Stephan curve, proposed by RM Stephan in 1943, is a description of the change in pH value caused by acid production of a cariogenic bacteria in the response to sugars. The curve was affected by factors including the amount of carbon sources, the acid production ability and saliva buffering, etc.
Stephan curve equation was given below.
Stephan curve, proposed by RM Stephan in 1943, is a description of the change in pH value caused by acid production of a cariogenic bacteria in the response to sugars. The curve was affected by factors including the amount of carbon sources, the acid production ability and saliva buffering, etc.
Stephan curve equation was given below.
The parameters in the equation refer to the microbial composition (Xiα), the acid production (m), time t, and saliva buffering (n). For examples, the decrease in pH value is caused by lactic acid, while bicarbonate in saliva many neutralizes the acids.
The parameter (n) in saliva buffering capacity is determined by the average saliva flow (0.3 ml/min) and a pH variation between 6.6 and 7.1 with the average saliva volume in dental cavities (1.1ml). And we exploited the Stephan curve equation to lactic acid production to define the parameter (m) of acid production.
By applying this derived equation, we are able to find out how different carbon sources influence pH values over time.
Fig. 5 showed the pH change in response to various carbon sources. Tooth decay may start to occur (i.e, below a pH of 5.5) after 2 hours exposed to glucose or 80 minutes exposed to sucrose. However, the pH values exposed to sugar alcohols of erythritol and xylitol were kept beyond 6.5, indicating prevention of dental caries and inhibition of lactate production of caries-associated bacteria by the sugar alcohols.
The parameter (n) in saliva buffering capacity is determined by the average saliva flow (0.3 ml/min) and a pH variation between 6.6 and 7.1 with the average saliva volume in dental cavities (1.1ml). And we exploited the Stephan curve equation to lactic acid production to define the parameter (m) of acid production.
By applying this derived equation, we are able to find out how different carbon sources influence pH values over time.
Fig. 5 showed the pH change in response to various carbon sources. Tooth decay may start to occur (i.e, below a pH of 5.5) after 2 hours exposed to glucose or 80 minutes exposed to sucrose. However, the pH values exposed to sugar alcohols of erythritol and xylitol were kept beyond 6.5, indicating prevention of dental caries and inhibition of lactate production of caries-associated bacteria by the sugar alcohols.
Fig 5. change in oral pH value after consuming different carbon sources
CONCLUSION
Through our model, we understood that lactate is the most important factor to oral pH value. Furthermore, the model we developed can facilitate the concept of dental cavities and simplify the correlation of dental caries among several factors. It demonstrated the effects of different carbon sources on dental caries and pH value in dental cavities over time after consuming sugar. Through our modeling, we are able to estimate the development of dental caries and choose the more suitable ingredients of our product.
REFERENCES
- Ye L, De Iorio M, Ebbels TMD. Bayesian estimation of the number of protonation sites for urinary metabolites from NMR spectroscopic data. Metabolomics. 2018;14(5):56. doi: 10.1007/s11306-018-1351-y.
- Abbe K, Takahashi S, Yamada T. Involvement of oxygen-sensitive pyruvate formate-lyase in mixed-acid fermentation by S. mutans under strictly anaerobic conditions. J Bacteriol. 1982 Oct;152(1):175-82.
- Humphrey SP, Williamson RT. A review of saliva: normal composition, flow, and function. J Prosthet Dent. 2001 Feb;85(2):162-9. doi: 10.1067/mpr.2001.113778.
- Liu C, Niu Y, Zhou X, Zheng X, Wang S, Guo Q, Li Y, Li M, Li J, Yang Y, Ding Y, Lamont RJ, Xu X. S. mutans copes with heat stress by multiple transcriptional regulons modulating virulence and energy metabolism. Sci Rep. 2015 Aug 7;5:12929. doi: 10.1038/srep12929.
- Van Houte J, Green DB. Relationship between the concentration of bacteria in saliva and the colonization of teeth in humans. Infect Immun. 1974 Apr;9(4):624-30. doi: 10.1128/IAI.9.4.624-630.1974.
- Iorgulescu G. Saliva between normal and pathological. Important factors in determining systemic and oral health. J Med Life. 2009 Jul-Sep;2(3):303-7.
- Stephan RM, Miller BF. A quantitative method for evaluating physical and chemical agents which modify production of acids in bacterial plaques on human teeth. J Dent Res. 1943;22;45-51.
- Ye L, De Iorio M, Ebbels TMD. Bayesian estimation of the number of protonation sites for urinary metabolites from NMR spectroscopic data. Metabolomics. 2018;14(5):56. doi: 10.1007/s11306-018-1351-y.
- Abbe K, Takahashi S, Yamada T. Involvement of oxygen-sensitive pyruvate formate-lyase in mixed-acid fermentation by S. mutans under strictly anaerobic conditions. J Bacteriol. 1982 Oct;152(1):175-82.
- Humphrey SP, Williamson RT. A review of saliva: normal composition, flow, and function. J Prosthet Dent. 2001 Feb;85(2):162-9. doi: 10.1067/mpr.2001.113778.
- Liu C, Niu Y, Zhou X, Zheng X, Wang S, Guo Q, Li Y, Li M, Li J, Yang Y, Ding Y, Lamont RJ, Xu X. S. mutans copes with heat stress by multiple transcriptional regulons modulating virulence and energy metabolism. Sci Rep. 2015 Aug 7;5:12929. doi: 10.1038/srep12929.
- Van Houte J, Green DB. Relationship between the concentration of bacteria in saliva and the colonization of teeth in humans. Infect Immun. 1974 Apr;9(4):624-30. doi: 10.1128/IAI.9.4.624-630.1974.
- Iorgulescu G. Saliva between normal and pathological. Important factors in determining systemic and oral health. J Med Life. 2009 Jul-Sep;2(3):303-7.
- Stephan RM, Miller BF. A quantitative method for evaluating physical and chemical agents which modify production of acids in bacterial plaques on human teeth. J Dent Res. 1943;22;45-51.