Just to let you know, unless he used a cavitat machine, or other device that looks at the density of the bone, you could still have an infection in the jaw bone.[Cavitation]
Of course I haven't had any dental work done for years so maybe there is something new I haven't heard about.
Before the ENT you could try to irrigate your sinuses with CS mixed with distilled water, and [salt to keep it tolerable] Otherwise it will burn some. After draining all the water out, and blowing your nose 3 or 4 times put dropper fulls of CS in each nostril with your head tilted back, and dropper full in each ear as they connect to the sinus. Do this every couple of hours, or as much as you can. One irrigation should be enough as long as followed by the CS.
Do this every day for a week or so. If after that if the infection comes back then see the ENT.
Cavitations can really cause problems. In my case mine was on the bottom directly under the jaw hinge on the right side. My jaw would click and be painfull every time I opened my mouth, and the pain ran down the back of my head, and into the shoulder. After having the jaw scraped, and cleaned out all that went away.
How a cavitation in the upper jaw would act, I don't know but I would think it would cause sinus problems for sure.