If you've been opting for sugar-free treats such as diet soft drinks and candies that don't contain any natural sweetener, we have some good news and some bad news. The good news is that cutting down on excessive sugar is definitely in your general dietary interests. The bad news is that sugar-free candy and soda aren't necessarily any better for your teeth.

According to Eric Reynolds, a health researcher at the University of Melbourne in Australia, sugar-free substitutes for sweet treats aren't completely safe for teeth as many people think. And you can't necessarily believe the labelling on popular diet beverage and candy products that tries to tell you otherwise.

Reynolds and fellow researchers at Melbourne University's Oral Health Cooperative Research Centre tested a large range of soft drinks, sport drinks, and confectionary products, and found that the sugar-less versions can also wreak havoc on your dental health.

The findings, collected in an online briefing paper, suggest that while sugar substitutes generally lessen the risk of dental decay (aka dental caries, commonly called cavities), sugar-free products are still potentially harmful to teeth due to high levels of acids that start by stripping away the surface layers of tooth enamel, and in advanced stages can expose the softer dentin or pulp of the tooth.

While pH levels can indicate which products are comparatively acidic – such as soft drinks, sports drinks, energy drinks, fruit juices, cordials, and wine – certain foods also contain chemicals called chelators, like citrate, which bind other chemicals to calcium, giving a particularly erosive combination that can remove calcium from teeth.

Testing 15 soft drinks (including three sugar-free brands) on extracted healthy human molars that were free of dental caries, the researchers found all the drinks produced significant erosion of dental enamel, with teeth showing measurable weight loss and surface loss. There was also no significant difference between the erosive potential of sugared and non-sugar soft drinks.

Testing with eight brands of sport drinks revealed similar results, with three-quarters causing significant enamel surface loss and enamel surface softening (although none as bad as Coca-Cola, which was used, along with bottle spring water, for comparison purposes).

Sugar-free lollies are also risky for teeth due to their use of citric acid and other food acids for flavouring – particularly lemon, orange, and other fruit-flavoured sweets.

So what should you be consuming (and not consuming) in order to minimise your chances of tooth erosion and decay? The researchers recommend fluoridated tap water as the best option for teeth, as bottled water doesn't confer the benefits of fluoride. Milk is also an excellent option, as it's not erosive.

In terms of hydration, water is recommended over things like soft drinks, sport drinks, and juices, which are clearly bad for your teeth, regardless of whether they contain sugar. Chewing sugar-free gum is recommended (especially brands containing bioavailable calcium phosphate), as it stimulates saliva flow and can rinse away acids and re-harden softened enamel.

Interestingly, the researchers say you shouldn't brush your teeth straight away after eating or drinking acidic products, as this can remove the softened tooth layer. Instead, drink some water or rinse your mouth out with water, then wait an hour before you pick up the toothbrush.

And, of course, regular visits to the dentist – which everybody just loves! – are a great way of ensuring your teeth stay in tip-top shape. Pretty obvious, perhaps, but when's the last time you made the trip?