Convert Database string which is in .DOC format to .DOCX format on the fly

Question

I have retrieved a string which was in Byte array. I converted the byte array to string. byte[] binary = Convert.FromBase64String(entity.Attributes["body"].ToString()); string bodyContent = UnicodeEncoding.UTF8.GetString(binary); The string can be saved as a .DOC file. But my objective is to use open XML. For that i need to Convert the file to .DOCX.without saving the file can i convert the file to .DOCX.