Tutorial: Hospedar un control de Windows Forms en WPF

<Grid Name="grid1">

</Grid>

private void Window_Loaded(object sender, RoutedEventArgs e) 
{
    // Create the interop host control.
    System.Windows.Forms.Integration.WindowsFormsHost host =
        new System.Windows.Forms.Integration.WindowsFormsHost();

    // Create the MaskedTextBox control.
    MaskedTextBox mtbDate = new MaskedTextBox("00/00/0000");

    // Assign the MaskedTextBox control as the host control's child.
    host.Child = mtbDate;

    // Add the interop host control to the Grid
    // control's collection of child controls.
    this.grid1.Children.Add(host);
}

using System.Windows.Forms;