If An employee of a dentist has insurance and the employer files insurance and gives the employee all the money back from the insurance company Is this legal?

No. This would be not only be insurance fraud but would also endanger the license of the dentist involved. Plus if the insurance company ever found out about such a thing, the Dental Practice would have to close down, because no insurance company would contract with someone like that, ever again. If the State Licensing Division didn't revoke the Dentist's license, the insurance carriers no longer processing claims from this business would drive them out of business. The Dentist would have to start working at the 7-11 Store. Crooks are not Professionals.