I am looking for a one-word antonym for "free" in the context of "a lack of something." For example: "pain-free/free of pain," "error-free/free of errors," "gluten-free/free of gluten"? To say "full" isn't quite right. If a forty-page text contains 1-2 typos, it is not "error-free," but it is also not "full of errors." What about "gluten"? If a pizza isn't "gluten-free," what is it? Gluten-full? Gluten-regular?
There is no universal one-word replacement for -free.
In the context of foods the appropriate portmanteau is gluten-containing
-containing can be used universally, although there are other alternatives depending on specific food components (eg, sugared for sugar-free)
another word that can be applied almost universally in the context of nutrition is -fortified
-enriched is another alternative but strictly applied refers to addition of an existing constituent (that has been lost during processing for example).
-full is applied in many instances (as in painful), but doesn't sit well with most foods (although -filled very often does).
The pizza with gluten is "conventional".
"Glutinous" sounds like it would be right, but it isn't necessairly so (a thing can be glutinous with no gluten!). "Glutenous" then ought to make sense, but isn't a word - likewise "glutenated".
"Gluten-inclusive" would be accurate, tolerable, and likely to peeve the gluten-intolerant.
"Gluten, free" or "Free gluten" would be excellent ways to advertise your pizzeria's generosity.
"Non-error-free" is "unedited". "Painful" is a word.
The opposing suffixes for -free are