Cristiano Ronaldo had very bad teeth, and later he had a very good dentist. I looked at his pictures which I am sharing with you, while I explain what might have been his treatment like:

In the pictures above, the kind of smile and teeth exposure of the upper front teeth is similar. You can see that one tooth (younger Ronaldo: fourth tooth from his right) seems to be missing. It is placed behind his arch of teeth, because there was no place for it to erupt in the right place. You can also see that his teeth seem a little crooked and he used to have a more gummy smile.

In these pictures you can see how the shape of his teeth have changed.

In these pictures, you can make out that he has a considerable gummy smile in the earlier picture. His picture on the right shows how symmetrical his smile is now. You can also observe the shape and color of his teeth, and the missing tooth is also visible now

In these pictures there is a comparison of his teeth when his treatment had just begun. You can see that his teeth are wired and the gap in his teeth is getting wider and the which did not erupt in its place on his upper right side can be seen underneath the arch of his teeth.

Here, you can see that the gap of the missing tooth is even more pronounced than the previous one.