Some dogs may need to have antibiotics after having their teeth cleaned while some other dogs may not need the antibiotics after a dog teeth cleaning.
When I took my dog in for a teeth cleaning by the vet the vet did prescribe some antibiotics to give to the dog for a few days after the teeth cleaning.
Also when a dog goes into the vet for a teeth cleaning they will usually be sedated and the sedation can take around 12 to 24 hours to fully wear off.
So the dog may need assistance with some things for awhile until the sedation wears off and the dog is back to normal.
Having the vet professionally clean a dogs teeth will prevent periodontal disease and other teeth issues in your dog and is well worth the cost to have your vet professionally clean the dogs teeth.