Congratulations on your pending purchase.  Believe me, you are not alone in asking that question.  In Massachusetts, title insurance policies protect against unknown defects in your title that are discovered in the FUTURE.  In other words, your closing may go forward because the title defect went unnoticed, but when you try to sell your property (1, 10, or 50 years from now) the title defect is discovered. If a title insurance policy was purchased, then the insurance company will hire an attorney to investigate and determine whether there is, in fact, a title issue. If there is, then the insurance company may be obligated to take whatever action is required to correct the problem. 
 
However, there are two types of title insurance policies: loan policies and owner's policies.  As to the first, you really do not have a choice in the matter if you are financing your purchase, because your lender will require you to purchase the policy.  So the question is, do you need an owner's policy?  All I can tell you is that when I bought my house, I bought the owner's policy.
 
The reason I recommend buying the owner's policy is that the lender's policy only protects the lender's lien on and interest in the property, it does not protect you or your equity in the property.  Let's say your house is worth $400k when you go to sell it and you still owe $300k on your mortgage.  If a title defect pops up that diminishes the value of your house by $75,000, your lender and the lender's title insurance company will not care, because the lender's lien is not impacted.  The lender's insurance company may take no action.  But if you have an owner's policy, then your insurer is obligated to step in, resolve the problem, and protect your equity.  Good luck and please tell your friends about The Forum.