I have a class 4 cavity in my upper anterior, are veneers possible without composite filling?

Hello and thank you for your question.
There are techniques, using which can avoid filling the space without  composite and directly place porcelain veneeer on the tooth. If color matching to adjacent tooth is the least of your concerns, no problem. Otherwise it is much more challenging to match color to adjacent tooth, even if adjacent tooth will have veneer on. Problem is physics. Veneers are very thin layer of porcelain and light goes through it reflecting  differntly based on the thickness of the restoration. if one veneer is thicker then one next to it, color of the teeth will look different on both. Some people will catch the difference, some will not.
That's the reason to restore the tooth first with a composite and then have UNIFORM and even reduction /cutback on adjacent teeth.Hope this helps to answer your concern.

Hello,If you are planning on having porcelain veneers done there might still be the need for a buildup procedure depending on the size of existing restorations unless the bonding are small. Most dentists do not feel comfortable placing a permanent restoration (e.g. veneers, crowns) on existing bonding/fillings without replacing them to insure there is no recurrent decay, or a weak bond  causing new restoration to fail . Please talk to your dentist about all of your options.Dr. Mazaheri