I had orthodontic work done on my son for a phase 1 and used some of his orthodontic lifetime benefits from insurance A. After he was done with phase 1, I changed to insurance B for a couple years. (employer remained the same). If my son is to go back for phase 2 with the same orthodontist, and I switch back to insurance A, do they keep a record of his used benefits even though it was a few years ago? Or would his lifetime orthodontic benefits reset since I am coming from insurance B?
No, the word is "lifetime" for a reason. When I was in this situation, the orthodontist had to supply a form to the new insurance noting how much the previous company had paid and then they picked up the remainder.
That said, not all insurance companies and plans have the lifetime maximum; I was delighted to learn that my company is switching next year to a plan that only has a maximum of what they pay per person.
Since you stayed with the same employer, the employer will have asked the existing provider to transfer lifetime maximums to the new provider. This is standard practice within the insurance business.
If you change employers and the insurer is different, the data may not follow you but I wouldn't change jobs just to get more ortho insurance money.
If you leave and come back to the same employer, the chances are high that the former limits will be remembered.