Doesn't a dentist make enough money per lead to pay for clicks and hence ensure #1 listing for their site?
With a good quality score due to high relevance it may be only be a few pennies per click.
It doesn't make sense to me to struggle with SEO for a dentist. Even if it costs 10 Euros per lead, the customer gets their teeth and wallet pulled for 100 Euros or whatever and keeps coming back for checkups with their whole family too etc.
My main aim would be to create a great lead capture page and pay for traffic.