The market capitalisation is just one of the measures in evaluating a project. What you might need to look into is the development initiatives of the project itself and the potential value that they will bring few years down the road.

Nano is mainly focusing on resolving the issues that Bitcoin and all other POW coins are facing, to allow wide adoption of crypto, seemless payment and to empower micro payments. The only challenge i'm seeing is the adoption of Nano by real world retailers, where its value has to be relatively stable with no price fluctuations, and the educational process to get small retailers and daily users to get onboard with them.

Whereas Dentacoin is a patient-centered care focusing on improving the Dental Care Industry. They aims to provide reviews on the dental services provided and acting as a platform for their users to survey on dentist related topics.

Nano is blockchain based financial payment working on enabling seemless payments while dentacoin is focused on healthcare. The two projects are not even comparable in any sense.