In general the answer is YES.
Based on US Department of Labor rules here are the basic guide lines.
1. You can pay your staff a lower rate for events, CE, meetings and such provided it is away from the office and worked out in writing in advance. With the possible exception of hygienists I do not recommend doing so as it has the potential to upset your staff which is counter productive and not the frame of mind you want your staff in while attending such activities. In other words don’t step over dollars to pick up pennies.
Note: In some states if the attendance is outside the employee’s regular hours and if the attendance is voluntary and if it is not directly related to the employee’s job and if the employee does not perform any productive work then you would not need to pay them. That’s a lot of “ifs” and a very unlikely scenario. If there’s any doubt whatsoever you’re much better off to pay the employee as far as I’m concerned.
2. Job related office meetings and any other such activities done in the office must be paid at the employee’s normal pay. And it doesn’t matter whether you are providing lunch or whatever.
3. When a hygienist or anyone else needs to attend some kind of CE or event for their license or credentials, and you are not in anyway in control of the scheduling, you do not need to pay them.
As in all HR matters it is important to check with a local HR pro as rules and regulations are always changing and they vary from state to state.