There is no limit for how many teeth can be replaced in a healthy mouth. You do not need to have every tooth replaced. You can replace a few teeth and bridge them together as well.
There are many options.
we can replace a whole arch or row of teeth and even a full mouth of teeth by utilizing dental implants. If you’re missing all your upper teeth, you would need 8–10 implants. You can replace all your teeth with implants. However it's not recommended to have each tooth individually replaced with an dental implant.