Least probable words: Crafted (veneers), Encase (crowns), Robust (support), Fractures (teeth), Alteration (natural teeth), longevity (veneers and crowns).
Least probable words: enhancing, drawbacks, accommodate, encompass, extensive, initially, straightforward.
In terms of longevity: Veneers can last anywhere from 7 to 15 years depending on how well they're cared for by patients. They also might need replacement if they chip or break since they’re thinner compared to crowns. Crowns typically last longer—about 10 to 15 years—with some even lasting up to 30 years if properly maintained.