You can submit to these search engines and directories for free just by filling in the form and clicking submit; some of the engines on the form actually use this vey form for their official submit form. To keep from duplicating submissions, and so you don't get banned for spamming your link, uncheck all the negines which you may have previously submitted to in the past month. Also uncheck any which obviously are not categorized for your site; web portal don't exactly fit with dental search engines.