Tooth veneers are for life and composite resin to fill in the top teeth triangular space, as gums recedes, maintains more of the natural teeth?

Veneers: Nothing is for life- the longest lasting thing in dentistry is actually gold, but most people don't want it on their front teeth. Veneers when done well can last a long time. Composites need to be shaped well and follow the lines of each tooth. If they are too bulky they could be a food trap.

Contours: The contours, shape of your veneers and/or resin-composites have to be developed precisely-- if overcontoured or overhang, not good at all for your gums, --inflammation and other issues, also need to consider durability when flossing, proximal contact, biologic width--needs to be a natural emergence and blended in naturally. Note, nothing lasts forever, important good homecare and hygiene, too!

'Black Triangles': As they are called can be a cosmetic problem. How to treat them, if at all, is a subject too lengthy ; complex to discuss on this site. Having said that, composites are usually more conservative but may be more difficult to properly contour. Periodontal health is also a major concern (either way). Find the best periodontist ; restorative dentist you can for a consult. Don't focus on 1 factor alone.

Wrong way around: Gum recession needs attention first. See periodontist to halt recession. Then work w your dentist or a prosthodontist to reshape and re contour teeth. Know that "permanent" restorations have a finite life span and need periodic maintenance.