In my life, I have eaten very little refined/added sugar (i.e. very rarely do I eat such things). Aged 30 I have no fillings: the only dental work I have had done was having my teeth straightened and having eight of them removed (yes eight, though not all at once) that didn't fit in my mouth (I have big teeth). When I was a child, my dental hygiene wasn't always very good.

A single data point doesn't tell you anything. But there it is, anyway.