How to preserve the form fields when silent printing the PDF document?

//Load the template document           
PdfLoadedDocument doc = new PdfLoadedDocument(@"..\..\Data\FormFillingDocument.pdf");
PdfLoadedForm form = doc.Form;
//Fill the fields from the first page  
(form.Fields["Name"] as PdfLoadedTextBoxField).Text = "xxx";
(form.Fields["Email"] as PdfLoadedTextBoxField).Text = "yyy";
//Flatten the form fields
doc.Form.Flatten = true;
MemoryStream stream = new MemoryStream();
//Save the changes
doc.Save(stream);
PdfViewerControl viewer = new PdfViewerControl();
viewer.Load(stream);
//Initialize print dialog.
PrintDialog dialog = new PrintDialog();
//Get the list of installed printers in a list.
List<string> printersList = new List<string>();
foreach (string printer in System.Drawing.Printing.PrinterSettings.InstalledPrinters)
{
     printersList.Add(printer);
}
dialog.AllowPrintToFile = true;
dialog.AllowSomePages = true;
dialog.AllowCurrentPage = true;
dialog.Document = viewer.PrintDocument;
//Assign any of the printers you wish to print to the printer settings  
dialog.Document.PrinterSettings.PrinterName = printersList[1];
dialog.Document.Print();