My youngest also kept a dummy (only at night) until almost 4, all I used to do was make sure there was one in his bed that he could get if wanted so it wasn't necessarily part of his bed time routine, just on the periphery so to speak and gradually over a month he just stopped using it. No effort required.
He would go to bed, self settle and once he was asleep I used to sneak in and see if he had his dummy in, the same if he woke in the night, he self settled back to sleep and again when he was asleep I checked the dummy use. Once we had gone 2-3 weeks of him consistently ignoring his dummy I left it one more week and then removed it from the bed. He never noticed.
If you get the correct age/size dummy for child's mouth size and the orthodontic dummies then teeth generally aren't affected (IME).
Is there a reason why you were trying to give up the dummy? Was there a problem with it?
Ds had his till he was 4.5 and then stopped. No effort on my part, no tears on his. He had the dummy at night to sleep, the dentist was happy with that, SIL is a speech therapist and said there was nothing wrong with that, he loved going to bed at night and slept well, win-win all round.
Anyway, the answer to your question is - what do you want to do? Do that!
And firmly representing the other end of the spectrum....me. I wouldn't bother getting him to 'give up' the dummy. Why? It works. It's not bad for you. And it helps and is soothing. My DS continued until he was almost 4 and then it dawned on him that he was a big boy now and probably didn't need it. So stopped. Himself. But each to their own. Good luck with whatever you do!
You persist. Giving back dummy now would be cruel as it would undermine all that work he has done to give it up. Could he cope without a nap? My DD gave up napping completely once we took her dummy away and with that started going to bed at 7pm and sleeping 12 hours straight.
My DS is 2.5 years. He had been a brilliant sleeper from 10 weeks sleeping from 7pm to 7am. We recently gave up his dummy (used only at bedtime) cold turkey & he seemed fine - cried for 2 nights at bedtime but then seemed fine. However after 1.5 weeks he had a cold & started waking at night unsettled a few times wanting a drink, cuddle etc & then after 2.5 weeks he is still doing that but also waking at 5 - 5.30 am as well. We are both so tired now I am tempted to go back to the dummy as he is v tired & so are the rest of the family.. it's a grouchy household - should I go back & try again in 6 months or persist & get through it?? (he still has a nap which I have scaled back bit he is so tired now as waking so early - it is chicken & egg to know the problem)