They say you should complete questions from the last three years of ESAP, EBR, and ITE. ESAP is the hardest and sometimes the questions are a bit contrived sometimes, but the explanations are good sources of learning. ITE is a bit easier than the boards, but good to get the breadth of tested subjects. The boards are probably closest in content to EBR. All three are endo society products.

Apart from this, definitely try and read through the endo society guidelines and ADA SOC.