I like the brand of food called Acana. Basically the highest quality of food you can afford and find close by.
Blue Buffalo is pretty decent
Acana
Timberwolf Organics
Wilderness
Old Mother Hubbard
Evo and Innova (before Iams took over)
Fromm
Orijen
Chicken Soup for the canine soul
and there's the raw diets which work for some people too. Supposed to be better on teeth some claim.
The better the diet the better the teeth health i've heard, however brusing daily or every other day is a great habit to get into
also having chew toys and bully sticks to help them chew and break down placque is great. antlers and himalayin chews work great and dental chews from the vet sometimes work. i liked the CET veggie dent chews for mine. no rawhides they are a choking hazzard. no piggie related due to gastro problems for yorkies
for the neuter part, keep him comfy, keep his E-collar on him so he can't lick or tear them out, and give his pain meds regularly. he'll be fine! you can put him in a newborn onsie and snap the snaps around his tail or cut a hold for his tail to stick out. that helped sadie lots for her spay.
good luck and PM me if you need anything.
welcome to YT!