Estimating the causal effect of sugar consumption on dental decay: a longitudinal targeted maximum likelihood estimation study

Abstract Dental decay in permanent teeth is the most prevalent disease worldwide, with 54% of young people under the age of 18 having experienced it. Despite these findings, there have been no studies that investigated the causal effects of time-varying exposure to higher sugar consumption throughout childhood on dental decay in late adolescence. We investigated the causal effects of sustained higher sugar consumption, cumulative sugar consumption, and sugar consumption trajectories from ages 4 to 14 on the risk of ever experiencing dental decay at age 16. We used data from the Longitudinal Study of Australian Children, an ongoing national Australian study that started in 2004, with a sample of 4671 young people. Causal effects were estimated using longitudinal targeted maximum likelihood estimation combined with the Super Learner ensemble. Young people with sustained higher sugar consumption (ie, above-median sugar consumption at ages 4, 6, 8, 10, 12, and 14) throughout the study period had a 37 percentage point higher risk of dental decay compared to those with no exposure. Each additional exposure to higher sugar consumption (ie, additional above-median sugar consumption at a certain age) between ages 4 and 14 was associated with a 6% increase in the relative risk of dental decay by age 16. This study provides causal evidence linking higher sugar consumption throughout childhood to dental decay in late adolescence.