In-vitro Cariogenicity of Isomaltulose on Human Tooth under Multi-species Biofilm

Objective:  To evaluate the in-vitro cariogenicity of isomaltulose on human tooth infected with multi-species biofilm. Method: Sixty tooth blocks with size of 2.0x2.0x4.0 mm were prepared with 1.0x1.0 mm windows on enamel and dentine by applying acid resistant nail varnish on other surfaces. The blocks were randomly allocated into three groups of 20 each and placed in a medium containing (1) 5% isomaltulose in Brain-heart Infusion (BHI) broth, (2) 5% sucrose in BHI broth, or (3) BHI broth only. Initial pH of all mediums was adjusted to 7.0. Four common cariogenic oral bacteria - Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus and Lactobacillus rhamnosus were added to the medium to allow biofilm formation and creation of artificial caries lesions in the tooth blocks. These were then incubated anaerobically at 37°C. After every 24 hours, pH of the medium was measured and the medium was refreshed. Depth of artificial caries lesions created after seven days was measured by micro-CT scanning. Result: The mean 24-hour pH of isomaltulose medium was 4.50±0.20, which was significantly higher than that of sucrose medium, 3.81±0.14 (p<0.001), and slightly lower than that of BHI broth control, 4.59±0.08 (p<0.001). Artificial caries lesions in enamel were found in all of the tooth blocks in the sucrose group but only in 4 of the 20 blocks in the isomaltulose group (p<0.001). The mean depth of lesions in dentine in the isomaltulose group was 117.65 µm, which was not significantly different from that of the BHI broth control, 104.29 µm (p=0.990), but significantly smaller than that of the sucrose group, 245.52 µm (p<0.001). Conclusion: This in-vitro study shows that the carciogenicity of isomaltulose on human tooth is similar to that of non-sugar control and considerably less than that of sucrose. It has good potential for dental caries prevention by substituting sucrose.