Great question - local marketing is absolutely essential nowadays. Especially as few people are navigating social media looking for tooth whitening services, these will become more profitable than online over time.

Here's a quick list of tools I suggest using to bolster your current social media work.
1 - Set up Google My Business account and get it address-verified (they mail you a code)
2 - Key words - ensure city/ town / suburb / state or county are all included in meta data
3 - Directory listings - Get yourself listed on free and paid sites. If you can afford a small spend www.brightlocal.com is worthwhile
4 - Use Facebook local targeting for advertising / brand building
5 - Set up Google Alerts for key phrases in the news that could allow you to comment / contact / build a mailing list
6 - Join the local Business Associations and contact all the relevant local business members
7 - Go to Networking events (BNI, Chamber of Commerce, Meetup.com, Eventbrite)
8 - get happy customers to write Testimonials on Google My Business, Also reproduce them on your website
9 - Use media relations to get articles in local newspaper, local radio, local newsletters, (check out Yahoo Groups for local lists)
10 - Ask for Referrals - by sending two business cards with your invoice
11 - Make specific requests for social sharing via your accounts
12 - Surprise and delight the customer - e.g. pay it forward - you pay to have your teeth whitened and I give a free treatment each month to a deserving individual and use that for publicity.

I hope that gives you a load of great ideas to be getting on with. But if you'd like specific coaching on what to do for this client - get in touch. You can buy 30 minutes of my time and I'll add to this.