In a double-blind study of children aged 1 to 6 years, supplementation with Lactobacillus GG five days a week in milk for seven months reduced the incidence of cavities by 49%, compared with unsupplemented milk.¹ The amount of Lactobacillus added to the milk was 5 to 10 x 10⁵ CFU per ml.

Certain sugar substitutes appear to have anti-caries benefits beyond that of reducing sugar intake. Children chewing gum containing either xylitol or sorbitol for five minutes five times daily for two years had large reductions in caries risk compared with those not chewing gum. Sorbitol is only slowly used by oral bacteria, and it produces less caries than sucrose.³

Xylitol gum was associated with a slightly greater risk reduction than sorbitol gum.³ Bacteria in the mouth do not ferment xylitol, so they cannot produce the acids that cause tooth decay from xylitol.⁵ A double-blind study found 100% xylitol-sweetened gum was superior to gum containing lesser amounts or no xylitol.⁶ Another study found xylitol-containing gums gave long-term protection against caries while sorbitol-only gum did not.⁷

Other research has confirmed the anti-caries benefits of xylitol in various forms, including gum,⁸ chewable lozenges, toothpastes, mouthwashes, and syrups.⁹ Mothers typically transmit one of the decay-causing bacteria to their infant children, but a double-blind trial found that the children of mothers who regularly chewed xylitol-containing gum for 21 months, starting 3 months after delivery, had a greatly reduced risk of acquiring these bacteria,^10,11 and also had 70% less tooth decay.^12,13

One older controlled trial found that children given 3 teaspoons of cod liver oil per day (containing roughly 800 IU of vitamin D) for an entire school year had over 50% fewer new cavities.¹³ These promising results have not been followed up with modern placebo-controlled trials.

In a double-blind trial, 1 gram of neem leaf extract in gel twice per day was more effective than chlorhexidine or placebo gel at reducing plaque and bacteria levels in the mouth in 36 Indian adults.¹⁴ A similar trial found neem gel superior to placebo and equally effective as chlorhexidine at reducing plaque and bacteria levels in the mouth.¹⁵ These promising early studies should be followed by studies regarding prevention of cavities and relief from gingivitis or periodontal disease.

Test tube studies show that vitamin B6 increases growth of beneficial mouth bacteria and decreases growth of cavity-causing bacteria.¹⁶ A double-blind study found that pregnant women who supplemented with 20 mg per day of vitamin B6 had significantly fewer new caries and fillings during pregnancy.¹⁷ Lozenges containing vitamin B6 were more effective than capsules in this study, suggesting an important topical effect. Another double-blind study gave children oral lozenges containing 3 mg of vitamin B6 three times per day for eight months, but reported only insignificant reductions in new cavities.¹⁸

Levels of strontium in the water supply have been shown to correlate with the risk of dental caries in communities with similar fluoride levels.²⁰ Compared with children with fewer cavities, enamel samples from children with high numbers of caries have been found to contain significantly less strontium.²⁰ However, supplementation with strontium has not yet been studied as tooth decay prevention.