Contact the state dental association and see if you can get access to their dentist directory. The directory usually describes type of dentist, year of graduation, GP or specialist, etc. etc. Use the year of graduation to limit your search to the older dentists. Contact these dentists by letter or email to see if they have a similar future plan as yours.
Contact all the dental supply vendors, sales people, for dental supplies, equipment (Schein, Patterson, etc. etc.) and dental contractors and provide them with your contact information. These individuals usually have a good idea of what is going on in the local dental field. You could also check with the major banks. They usually have a health professions lending team. You'll want to develop a relationship with a bank anyway. The bank will also have information about any "bankrupted" practices that maybe for sale.
Contact dental specific brokers on what practices are for sale. But always remember .... these practices are bright and shiny for a reason. You really need an expert to evaluate these practices.
I'm sure there are some good websites (LinkedIn, etc.) that helps with networking
Find out who the dental specific accountants are in that area. They also have a good feeling for who is selling or looking for an associate.
Reality is that you may need to take any job once your are located in that state. 6 months. Once there .... you can get a better idea of which dentists are looking to retire or sell. This is essentially what I did 26 years ago. Took a job and went to lunch with every orthodontist to get their ideas. Met an older ortho. Started to talk. Associated with him for 6 months. Partnership for 18 months. Then I purchased the remaining 50% 18 months later. Of course all of this was IN WRITING to prevent any misunderstandings.
Good luck.