To use or not to use Data transfer objects(DTO) in a Web Api Chat Application Backend Server

I have a chat application backend built using Web Api where I am exposing several database entities directly to clients. I was wondering whether there is any positive points to map the entities to DTOs or should I continue exposing the entities as I am currently. Just to clarify I am not asking a DTO vs non-DTO general question but just advantages of using it in this scenario since most of the fields in the entities would probably be used by the client.