If the problem with the teeth is more cosmetic or superficial, I probably wouldn't have a dental done at that age. But if the teeth are causing the dog pain, or the condition of the mouth is raising the risk of infection or heart disease, the dental procedure really just needs to be done. Are they doing pre-op bloodwork? I would definitely pay the extra or that, considering the dog's age.
You can mitigate some risk by having the procedure done by a team that includes a professional veterinary anesthesiologist.
You can mitigate some risk by having the procedure done by a team that includes a professional veterinary anesthesiologist.