When it comes to dental cavities, most of us instinctively point fingers at sugar. We've all heard the warnings about candy, soda, and sweets being the main culprits behind those pesky cavities. But what if I told you that sugar isn't the only player in this game? Enter salivary amylase, a digestive enzyme found in our saliva, plays a significant role in the development of dental caries, particularly through its interaction with starches like those found in bread, pasta, crackers, etc.

Understanding Salivary Amylase

Salivary amylase is an enzyme secreted by the salivary glands. Its primary function is to break down starches into simpler sugars. This enzymatic activity begins the process of carbohydrate digestion right in the mouth. When we eat starchy foods like bread, salivary amylase gets to work, hydrolyzing these complex carbohydrates into maltose and glucose, which the plaque in the mouth digests, creating acids and toxins that contribute to cavities and gum disease.

The Study on Salivary Amylase and Dental Caries

A study conducted by Dr. S. Vijaya Nirmala and colleagues at the Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research, Chennai, sheds light on the relationship between salivary amylase and dental caries. This study involved 30 young volunteers aged 18-23 and aimed to investigate the levels of salivary alpha-amylase and its correlation with dental caries.

The study found that individuals with higher levels of salivary amylase also had a higher incidence of dental caries. The results were statistically significant, indicating a strong association between the enzyme levels and the presence of cavities. This suggests that salivary amylase could be used as a biomarker for caries susceptibility. Interestingly, humans have high levels of amylase in their saliva, some more than others. This may make some of us more prone to decay than others, as the study suggests. I wrote this post on this phenomenon nine years ago.

How Starches Contribute to Cavities

The key takeaway from the study is that it's not just sugar that we need to worry about. Starches, particularly those found in potato and tapioca starch, can also contribute to tooth decay, but they do so in a specific context – in the presence of salivary amylase.

When we consume starches, especially those that are processed, salivary amylase breaks them down into simpler sugars. These sugars are then fermented by bacteria in the mouth, producing acids as a byproduct. It's these acids that lead to the demineralization of tooth enamel, eventually resulting in cavities.

Potato Starch and Salivary Amylase

One interesting aspect of the study is the role of potato starch. Potato starch on its own isn't directly cariogenic. However, when it interacts with salivary amylase, it is broken down into fermentable sugars that bacteria can then convert into acids. Without salivary amylase, potato starch would not pose the same risk for cavity formation because the bacteria in our mouths wouldn't have the necessary simple sugars to feed on and produce acid.

The Role of pH in Dental Caries

Another critical factor in the development of dental caries is the pH level of the saliva. Saliva naturally has a slightly alkaline pH, which helps to neutralize acids and protect tooth enamel. However, the study noted that individuals with higher levels of salivary amylase also had changes in their salivary pH, which became more acidic.

This acidification of saliva creates an environment where acidogenic bacteria thrive, leading to a higher rate of tooth demineralization and, subsequently, cavities. Therefore, the combination of high salivary amylase activity and lowered pH creates a perfect storm for dental caries.

Salivary Amylase and Cariogenic Bacteria

Salivary amylase also has a unique relationship with certain bacteria in the mouth. For instance, it can bind to the surface of oral streptococci, such as Streptococcus mutans, which is known to be a major contributor to tooth decay. This binding facilitates the bacteria's ability to adhere to tooth surfaces and form dental plaque. Within this plaque, the bacteria can produce more acid from the sugars provided by the action of salivary amylase on starches.

Evidence from Other Studies

The findings from Dr. Nirmala's study are supported by other research that has shown the role of salivary amylase in dental caries. For example, studies have demonstrated that cooked starches, which are more easily broken down by salivary amylase, can be just as cariogenic as sugars when they are processed by the bacteria in dental plaque. As I wrote about here, even Paleolithic people developed cavities by processing and cooking acorns! Additionally, animal studies have shown that diets high in processed starches lead to higher rates of cavities compared to those high in raw starches.

Implications for Dental Health

These findings have significant implications for preventive dentistry. Understanding the role of salivary amylase in dental caries can help develop new strategies to reduce the risk of cavities. For example, dietary recommendations might focus not only on reducing sugar intake but also on limiting starchy foods that can be broken down by salivary amylase.

Preventive Measures

1. Dietary Choices: Limiting the intake of highly processed starches and combining them with foods that have a low glycemic index can help reduce a diet's cariogenic potential. Ideally, we should all eat a whole food diet devoid of processed carbohydrates and seed oils that include animal-based food with its fat.

2. Oral Hygiene: Regular brushing and flossing can help remove dental plaque, reducing the number of bacteria that can convert starches into acids.

3. Saliva Management: Staying hydrated and chewing sugar-free gum can stimulate saliva production, helping to maintain a healthy pH balance in the mouth.

4. Regular Dental Check-ups: Professional cleanings can help reduce the risk of cavities and other oral problems.

Conclusion

While sugar has long been recognized as a major contributor to dental caries, it's essential to broaden our understanding of other dietary components that can impact oral health. Salivary amylase plays a crucial role in the breakdown of starches into fermentable sugars, facilitating the production of acids by oral bacteria and contributing to tooth decay. By recognizing the interplay between salivary amylase, pH levels, and starches, we can better prevent and manage dental caries, ensuring healthier smiles for everyone.

Sources:

Scannapieco FA, Torres G, Levine MJ. Salivary α-Amylase: Role in Dental Plaque and Caries Formation. Critical Reviews in Oral Biology & Medicine. 1993;4(3):301-307. doi:10.1177/10454411930040030701

Krishnamurthy, Preetha & Nirmala, Dr & Rajan, Sharada & Student, Bds & Subramani, Vijaya. (2019). An Evaluation of Role of Salivary Alpha-Amylase in the Caries Activity among Young Individuals.