I knew this would happen

ok my hydro dealer said don't worry, roots won't outgrow the rockwool slab. i changed my water today and noticed the roots were coming out of the end of my rockwool slab. usual set up started in small cubes to larger cubes to a slab. was told to and did keep the plasic wrapping on the slabs, cutting both ends for drainage. you can see where the roots look like they're part of the rockwool at the bottom edge right where the water runs down the length of the slab. they look healthy up to the point where they actually exit the end of the slab.
i'm lost for a remedy. will the roots redirect into the slab ???/ the plants look great. this is my first hydro, top drip. i asked the dealer if the roots would outgrow the slab and he said they wouldn't. let her go as long as the plants ok ???? sorry for the rambling post

I don't really know what you're asking, but the roots will grow outward and downward, until they grow out of the rockwool, and if allowed to dry out, will die off, or "air-prune" as we say.

I grow in slabs too, and I have each slab in its own tray, the slab fits tightly into the tray. The trays have drainage channels, and the nute soup drains away, and the channels become filled with healthy roots. This way, the only roots that air-prune are the ones that grow out the ends of the slabs.

HTH