How to hide pdf importer popup in word automation

When I open a PDF file with Word automation, it show a dialog that ask me to confirm the convertion (With a "do not show again" checkbox).

Word will now convert your PDF to an editable Word document. This may take a while. The resulting Word document will be optimized to allow you to edit the text, so it might not look exactly like the original PDF, especially if the file contained lots of graphics.

How to hide this dialog ?

var application = new Microsoft.Office.Interop.Word.Application();
application.Visible = false;

try { application.ShowStartupDialog = false; }
catch { }
try { application.DisplayAlerts = WdAlertLevel.wdAlertsNone; }
catch { }

var doc = application.Documents.Open(
    inputFilePath,
    ConfirmConversions: false,
    ReadOnly: true,
    AddToRecentFiles: false,
    Revert: true,
    NoEncodingDialog: true);

PS : ConfirmConversions:true add an other dialog.