Msmouth
I don't think anyone is ever too old to pursue their dreams. BUT sometimes it simply makes no fiscal sense to do it. Does that mean that your dreams have been crushed?? No. But it does mean you need to be grounded in the decisions that you make.
Numbers make a good starting point. If you have to take out loans (minus living expenses) you will owe from ~150-350K depending on school (maybe 95% of all school tuition rates fall in that range).
Right now, the BEST interest rate you will get on these loans is 6.9%. To pay back a 150K loan, it takes $1733/mo to pay back in 10 years. To pay back a 350K loan, it takes $4045/mo to pay back in 10 years. Avg starting dentists make 100K/yr. This equates to 8,300/mo pretax and ~5,800/mo post tax (30% state/local approximation). The best associateship you can probably find with tons of experience and luck will pay 160K/yr, equating to ~9,800 post tax.
I am not going to continue the calculation with how much more it will cost if you add in the cost of buying a practice, which is usually a 7 yr loan at 7% with prices ranging from 250-800K (median range). I have also not calculated the cost of a mortgage, and malpractice insurance.
As you can see, there is a range of options available to you. If you only need to loan 150K, there is a definite possibility of this working out for you. If you need to loan 350K, then you should probably rethink this.
Anyways, these are just the facts.
On the other hand, WHY would one want to transition from a hygenist to an associate dentist?? The only advantage is the title, and wider range of responsibilities. Since you don't want to own a private practice, you will probably never make more than 160K/yr which is then severely decreased due to student loan payments.
Anyways, regardless of what decision you make, good luck!