All things living are composed of cells, the fabric of which is protein. All living cells have a natural life cycle and, upon their death, have to be periodically replaced. In an organism the size of a human, that amounts to billions of new cells and large amounts of replacement protein for their building blocks. Setting aside any vegan considerations, humans have evolved as carnivores (meat eaters) to provide the source of the protein to replace our cells.
Eating meat requires teeth. Teeth are lost through trauma (breakage), periodontal (gum) disease and caries (decay). Carnivores in the wild who loose teeth do not survive. Humans who have lost their teeth and, consequently, have difficulty masticating (chewing) meat, resort to soft foods that are generally high in carbohydrates. The result of such a diet is obesity linked to malnutrition and further body degeneration. To partially offset the loss of teeth, humans can be fitted for removable dentures (George Washington wore dentures). Removable dentures have problems; they move, create sores and have only 15% of the chewing efficiency of natural teeth. Further, they do not exercise the jawbones that supported natural teeth with the result that the jaws tend to shrink (disuse atrophy).
Dental implants are supported by jawbone (same as natural teeth) and are very close to having the appearance and function of natural teeth. Dental implants cannot decay.