I can see that being realistic. A quick search shows a University near me estimates it will cost someone just over $70 000 per year of undergrad at that school. Then you have four years of dental school. Another school near me lists tuition alone at about $270 000 for the four years if you're out of state. Then add 3 years of a specialty like orthodontics. Another search shows UPenn estimates that'll cost over $115 000 per year.
70k * 4 = 280k for undergrad
270k for tuition alone for dental school
$115k * 3 = 345k for a specialty
This gets us to just under $900k. That doesn't include any costs except tuition for the 4 years of dental school so we can assume the total will probably be higher. You can reduce some costs like the undergrad and if you're accepted to an in state school that might make dental school a bit cheaper but it is still an expensive undertaking.
70k * 4 = 280k for undergrad 270k for tuition alone for dental school $115k * 3 = 345k for a specialty
This gets us to just under $900k. That doesn't include any costs except tuition for the 4 years of dental school so we can assume the total will probably be higher. You can reduce some costs like the undergrad and if you're accepted to an in state school that might make dental school a bit cheaper but it is still an expensive undertaking.