So my classmates and I are trying to figure out what the difference is between the amalgam and composite(non slot type) Class II requirements for the WREB's. Sturdevant says the only real difference is that the cavosurface margin can be greater than 90 degrees and that composite preps don't usually have secondary retentive features such as grooves. Some of my classmates are saying that there NEEDS to be a .5mm bevel on the gingival, facial, and lingual walls of the box on the cavosurface margin. There is indeed a criteria for this on the grading sheet but it's not clear whether this is for if you choose to do a slot prep or for ALL direct composite class II's. Also, some people say the facial and lingual walls of the prep need to be divergent while in Sturdevant, it says they should be converging towards the occlusal. So is there anyone here that knows FOR CERTAIN what the criteria are (AKA no wild guesses please as I'm already confused as it is)? Thanks!