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No health and dental are two separate orders, you are only required by your order to pay all health associated costs. Keep in mind though if you fail to pay your ex has the right to go back and ask for a modification of the order to grant dental support as well. She will likely be approved as this is a simple matter of it not being considered during the original agreement.
In the end you must decide if it is worth going back to court for. I wish you the best with this situation.