Digital Xrays save time, pain and radiation

Electronic health records

Cordless instruments save pain for the hygienist / dentist and angst of moving around a cord

Cavitrons reduce hygiene pain and do a better job of removing calculus

Invisiline gives a significant part of the population an option of not having metal mouth

Then there's better techniques, materials and various other things. Dental offices have changed quite a bit in the last 25 years.