Dental health in kids - shocked at kids checkup are fillings the norm?

[Piffle]

Took dd 4 and ds 13 to their dental checkup
Both have super teeth, dentist said it was a pleasure to see such good teeth and they were the exception as most 13 yr olds he sees have at least 2 fillings and that most 4 yr old have noticeable if not significant damage to baby teeth sometiems but not always affecting the 2nd teeth.

I was shocked is this really true?

My DS is 7 and has 4 fillings

I have been really vigilant about cleaning his teeth, and he eats a balanced healthy diet, with very few sweets, puddings or sweet drinks. Dentist really could not say where we ahd gone wrong, but I am really sad that he has had to have the fillings.

Some people are lucky to have stronger teeth than others.
But diet and cleaning routine obviously play a part too.
My DCs are 11 and 9, and do not have any fillings.
One poor child at the same primary school as them had six teeth removed at the age of 6, because they had eroded. It came to light that he was given a bottle of cola to go to sleep with every night.