Azure Service Bus to Event Grid integration

Hi All, 

Having started to investigate the use of event grid with service bus I am trying to determine if both are required when Topics are used or just Event Grid. I use an Event Grid topic currently with a logic app as an event handler. In testing how Service Bus will be configured as an event producer I have the ability to create a Service Bus topic. Can a service bus topic push publish to a Event Grid topic or am I way off. If it can what is the use case?

Thanks