Most of things do not need to be disposed. Disposing .NET objects with only .NET types  is not really meaningful as they still need to be garbaged.... A counter example is the SQLConnection and his pooling that needs to be disposed if you are running multiple threads at a same time, as each connection use a pool slot, you need to dispose the object to be sure to free the slot used, otherwise you could run out of space.

So in most cases IDisposable is useful when the object is using interacting with non managed objects, that can not free his memory from himself. Like SQL Pools, Twain drivers, some Windows API, ...

The SqlConnection needs to be disposed indeed. (SqlConnection.Close() is not enough, the pool will only be freed when the garbage collector will catch that object and dispose it before deleting it). It can takes a while before the collector is called 10, 20, 30 seconds and depending on the pool size (if you are using pooling with SQL) and the number of requests you can reach the limit.

So now I don't know about your code samples, and I didn't read the data accessors of DNN, but what I meant is that a class that has two INT properties, and three strings does not need to have a IDisposable function.