Using an iron to get a dent out of a wood floor can be a great way to save a floor without doing massive repair. You need an iron, a knife, water in a bucket, and rags that you can tear depending on the size of the dent.
First, use the knife to poke very small holes into the wood at the dent location and in line with the wood fiber just enough to get past the clear coat. You only need to make enough nicks into the finish to ensure you have water penetration where the dent is; don’t make them too deep.
Next, wad up a small rag that fits the dent and gets a lot of water on it. Wait at least five hours. The wood should be discolored underneath because water is in the wood fiber under the finish coating. If it is not, then repeat the soak phase with deeper knife pricks. Often, if the dent is very shallow, this process alone will create a flush surface. If there is still a slight depression, you need to lift it out.
Set the iron on its hottest setting. Remove the wad to expose the dent. Soak a larger cloth in water and lay it over the dent. When you apply the iron, it will hiss and steam quite a bit. While steaming, everything remains at 212 degrees Fahrenheit unless all the water evaporates. This is the point that allows the wood to get hotter, where you can leave an iron mark on the floor. Check the progress often, rewetting the rag as needed, repeating the steaming process, and being cautious not to burn the wood.
It is possible the dent might be a little more raised than the surface of the wood floor because there is still some water. Once it dries, it should be flush to the wood floor. Leave it and don’t coat over it until all the water evaporates from the wood fiber and it returns to the color of the normal wood floor in a few hours.
See Lenny Hall do this process in a video.