Rename font using Itextsharp

Question

I want to rename font using itextsharp I have Managed to rename the font in the pdf using the following code

        PdfName baseFont = dict.GetAsName(PdfName.BASEFONT);            
        if (baseFont.GetBytes()[7] == '+')
        {
            string rename = baseFont.ToString().Substring(8);

            string temp = baseFont.ToString().Replace(rename, "Changed" + cnt).Replace("/", "");
            baseFont = new PdfName(temp);                
            dict.Put(PdfName.BASEFONT, baseFont);
            cnt++;
        }

        PdfDictionary fontDescriptor = dict.GetAsDict(PdfName.FONTDESCRIPTOR);
        PdfDictionary Encoding = dict.GetAsDict(PdfName.ENCODING);


        if (fontDescriptor == null)
            return;
        fontDescriptor.Put(PdfName.FONTNAME, baseFont);

by using the above code i am able to change the font name in acrobat document property.

but old name is visible when i select the text using edit text and image using acrobat 10