Huge alarms went off in me when you stated
"but my concern is that he will only do some cleaning and prescribe Antibiotics &/ steroid (last time was like this)."
If you know you have adrenal fatigue, then do NOT allow this dentist to put you on steroids! I did not know I had severe adrenal fatigue at the time I had to have the removal of a granuloma and large cyst from my right vocal chord. The ENT surgeon wanted NO swelling after the surgery, therefore, he put me on a steroid inhaler and also a steroid pack post operatively. Taking that round of steroids was the final insult to my already weakened adrenals, I realized in retrospect. I did not sleep AT ALL while on the steroids, prior to the surgery, I slept one hour every 24 hours somewhere between the hours of 5 am to 9 a.m (Dr James Wilson's Book "Adrenal Fatigue: The 21st Century Stress Syndrome" has good insights why at least getting sleep during those hours is important for the adrenal glands). After that surgery I had a steady decline and ever increasing sleep deprivation.
I, too, now am facing the decision of when to have the mercury Amalgams and toxic root canals addressed. I have been studying this for some time and getting opinions from various practitioners, doctors, dentists, friends who have been to holistic/biological dentists, etc.
keep us posted on your decisions and progress. Best wishes