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SA study shows plant substitute less likely to decay teeth than sugar

Researchers from some of SA’s top dental schools found that teeth immersed in a stevia solution after 24 hours were the least likely to develop cavities when compared to solutions of sugar, xylitol, erythritol and stevia.

About 60% of six-year-olds in South Africa have holes in their teeth, thanks to the sugar they consume, reports Business Insider.

The dental researchers put blocks of children’s extracted molars in solutions of sugar, xylitol, erythritol and stevia. After 24 hours, the teeth immersed in stevia solution were the least likely to develop cavities. Stevia is a plant in the chrysanthemum family. It comes as a liquid and a powder, or you can grow it and sweeten drinks with a leaf.

The team said while stevia outperformed the artificial sweeteners xylitol and erythritol, all three alternatives were better for teeth than sucrose, the main constituent of white sugar.

Revealing their findings in the SA Dental Journal, they said the challenge now is to find ways to introduce the sugar substitutes into children’s daily diets.

In their study, the dentists, who were from from the Universities of Pretoria and the Western Cape, fed sugar and the alternative sweeteners to the bacteria that cause most cavities in teeth.

The Streptococcus mutans bacteria were given 2mm x 2mm blocks of enamel from children’s extracted molars to attack, and after six hours the bacteria were multiplying and growing equally in all the petri dishes.

By the end of 24 hours, however, the picture was dramatically different. The colonies of bacteria were far larger in the sucrose solution, which had also become dangerously acidic.

In the stevia solution, a scanning electron microscope found only a few traces of struggling bacterial cells, and acidity was lower than in any other sample. Erythritol came second, and xylitol third.

Cavities in teeth develop after the protective enamel layer is attacked by acid produced when bacteria consume sugar, which is why acidity is a key measurement when testing sugar substitutes.

The sugar solution ended the experiment at pH 4.5, significantly lower than the pH 5.5 which dentists regard as critical.

“This level of acidity and below leads to disintegration of the organic compound of the enamel and dentine, leading to demineralisation and subsequent cavity formation,” said the research team led by Nadine Moelich from Pretoria.

The researchers acknowledged that their study did not fully mimic the environment in the mouth, which they said was influenced by variable saliva flows, different quantities of bacteria on teeth and the variety of bacteria capable of producing acidic or alkaline substances.

Dental caries, or cavities, in children aged six and under are regarded as a significant public health problem in SA, and earlier this year Faheema Kimmie-Dhansay from the UWC dental school sounded a warning for parents.

“Young children are at the highest risk of developing dental caries as they have a lack of autonomy over their diet and oral hygiene practices,” she said.

“Untreated dental caries have many detrimental effects, which can affect the physical development and reduce the quality of life of affected children. Furthermore, long-term untreated dental caries can result in school absenteeism, low body mass index, and poor educational outcomes.

How to use stevia

Stevia comes as a liquid and a powder – or you can grow it from seed and use the leaves to sweeten drinks – but products that use it as a sugar replacement are not widely available.

They include calorie-free drops that can replace sugary drinks by sweetening water and adding different flavours to it. Protein shakes often use stevia as a sweetener, and you can find peanut brittle and ginger beer that include the substance.

If you want to use it in baking, you have to make up the volume of missing sugar with an equivalent amount of something else, such as grated apple or apple sauce.

Stevia is much sweeter than sugar, so the quantity you need is much less: two or three liquid drops or a quarter of a teaspoon of powder to replace a teaspoon of sugar; and a teaspoon of liquid or two tablespoons of powder to replace a cup of sugar.

Study details

The search for a healthy sugar substitute in aid to lower the incidence of Early Childhood Caries: a comparison of sucrose, xylitol, erythritol and stevia

Nadine Moelich, Nicoline Potgieter, Francien Botha, James Wesley-Smith, Candice van Wyk.

Published in SA Dental Journal Volume 77


A pursuit to find a healthy alternative to sucrose with less cariogenic potential, which can potentially lower the incidence of Early Childhood Caries (ECC), by means of comparison. Primary tooth enamel blocks (n=32) were randomly divided into four groups and exposed to 5% concentrations of the respective test groups (sucrose, xylitol, erythritol and stevia). All samples were inoculated
with S. mutans standard strain (ATCC 25175) at room temperature. Analysis of Colony Forming Units (CFUs), acidity measurements (pH) and Scanning Electron Microscopy (SEM) observations were done after 6, 12, 18 and 24 h and compared. After 6 h, the marginal mean CFU count indicated equal S. mutans growth in all groups. Stevia showed lower CFU counts compared to other groups at 12,
18 and 24 h. The pH levels for all non-fermentable sugar substitutes (NSS) initially decreased but never below the critical pH=5.5 and stabilized from 12 to 18 h. The pH levels of sucrose dropped and remained below pH=5.5 at all time intervals. The SEM analysis of
S. mutans supported the CFU results indicating growth in the presence of sucrose and reduction in the presence of the NSS.
Compared to sucrose, xylitol, erythritol and stevia have less cariogenic potential with reduced growth of S. mutans and subsequent acidity levels. Stevia had the least cariogenic potential of all the NSS tested, followed by erythritol and then xylitol.


SA Dental Journal article – The search for a healthy sugar substitute in aid to lower the incidence of Early Childhood Caries: a comparison of sucrose, xylitol, erythritol and stevia (Creative Commons Licence)


Business Insider article – SA dentists tested sugar substitutes on kids’ teeth. You can grow the winner in your garden (Open access)


See more from MedicalBrief archives:


Dental meta-analysis: The best, worst and unproven oral hygiene tools


Natural dentine restoration may revolutionise dental care


Sugar-free gum in pregnancy associated with lower preterm birth rates – Malawi study


Cavity-prevention approach effectively reduces decay


Link between poor oral health and hepatobiliary cancer






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