Remember that fit isn't determined by the resin, per se, but by
1) the printer being correctly calibrated and set up, and
2) the exposure settings being correctly tailored to the resin
There is a shrinkage factor specified for all resin-printer parts to compensate for the inevitable shrinkage during post-curing. If that scaling factor is incorrect, your prints won't fit well. Print some calibration cubes and measure them with a good micrometer and see how far off your scale factor is, then tweak it to get your prints bang-on. I've frequently had to do this because the manufacturer's print profile wasn't quite correct for our printer and our setup, it's a good practice to experiment with this a bit to get more control over your process.
In addition, with DLP printers- not sure if the 5100 is DLP, but it sounds about right for a dental printer at that price-point- if the printing area's software dimensions do not match the actual projected printing area, you will also get incorrectly-sized parts. You can often compensate for this being wrong with an adjusted scale factor, but you don't wanna be fixing one error with a second error if you can avoid it, you know? Whoever provides support for your printer can help with this calibration, if you don't wanna tackle it yourself.