Ran across this webite while bored at in-laws. Am a 35 y.o. board certified periodontist practicing for 5 years now in mid-sized city. Work approx 30 hours/week and posted approx $500k on personal tax returns last year.
But I have GP friends who are same age making about the same.
The key is not to take short cuts. Don't cheat in school - will only catch up to you in private practice. Provide excellent communication to patients and referrals - people like straight talk. Use high quality materials - skimping on products increases failure rate of procedures. If you take your time and strive to complete each dental procedure proficiently, your practice will grow organically (e.g. without having to market a lot), your reputation in the dental community will rise, and you will have more money than you know what to do with.
Oh, one more thing - I was the only person in my class to go for perio and was made fun of. But I found the specialty interesting. Now I'm in a city that could accomodate more periodontists, but limited supply of periodontists in the region (unlike ortho and endo - very saturated)! So do what aspect or specialty of dentistry you enjoy and don't follow the herd.