T4 meds take 4-6 weeks to reach full potential in the blood. If the person's conversion process works properly, T4 would begin converting right away.
I agree that "regular" dental x-rays, would be unlikely to cause your hypothyroidism.
I bet you have symptoms that you wouldn't of related to thyroid trouble. All of us are so different. That is why there is such a huge list of symptoms everywhere you look.
Joint pain, muscle pain, fatigue, bowel issues, heart issues, brain fog, moodiness, etc...
I was talking to one of my nurses and her only symptom was moodiness. She didn't realize how grouchy she was to her family until treatment! My sister had nodules and hypo. She was put on medication just a little while ago and she can forget to take her meds for days and not feel anything. I, on the other hand, skip for a few hours for a blood test and feel fatigued for a couple of days! Although, I do take an NDT which has T3 and she is on synthetic T4 only. T4 takes about 4 - 6 weeks to convert and T3 is fast acting.
Maybe it will catch up with her - I don't know.
Please post your thyroid test results that your diagnosis was based on. Also, please include reference ranges as they vary lab to lab.
Why was your thyroid tested? Was it part of a screening or routine blood work?
While exposure to radiation can damage thyroid function, dental x-rays are supposedly low enough radiation to be safe. My personal opinion is that you'd probably have had to have had more than the "usual" number of x-rays (more by quite a bit) for that to be the cause.