Can an employee have health or dental Insurance through his/her spouce's employer and also through his own?

Yes, the insurance you have for yourself, through work, would be your Primary insurance and this is submitted to first. The policy your spouse has would be your Secondary and this would be submitted to after your Primary insurance has paid with an EOB (explaination of benefits) to show what and which procedures and how much the Primary has already paid.~

Yep its called primary and secondary insurance.

But just use the one with the better coverage while you can.

Yes, depending on how the insurance company treats primary and secondary insurance.

In most cases, a person's own insurance will be primary; the spouse's will be secondary. In some cases, the spouse's plan will have a "non-duplication" clause - meaning they only pay when the primary is exhausted or pays far less than they would have paid if they had been primary.

It's complex to say the least. In some cases, dual insurance will leave the patient with NO out-of-pocket expense; in other cases they WILL have to pay.

Ask to speak to the HR people for details of how the two plans coordinate.

YES, IN THIS CASE DENTISTRY SHOULD COST YOU NOTHING OUT OF POCKET