Mass. Gen. Laws ch. 185 § 70
Mortgages of registered land may be foreclosed in the same manner as mortgages of unregistered land; but in case of foreclosure by entry and possession, the certificate of entry required by section two of chapter two hundred and forty-four shall be filed and registered by an assistant recorder in lieu of recording. After possession has been obtained by the mortgagee or his assigns, by entry or by action, and has continued for the time required by law to complete the foreclosure, he or his assigns may request the land court for the entry of a new certificate, and the court, after notice to all parties in interest, shall have jurisdiction to hear the case, and may order the entry of a new certificate on such terms as equity and justice may require.
In case of foreclosure by action as provided in chapter two hundred and forty-four, and by exercising the power of sale in the mortgage under the direction of the court as provided therein, a certified copy of the final judgment confirming the sale may, after the time for appeal therefrom has expired, be filed with the assistant recorder, and the purchaser shall thereupon be entitled to the entry of a new certificate.
In case of foreclosure by exercising the power of sale without a previous judgement of court, the affidavit required by section fifteen of chapter two hundred and forty-four shall be filed and registered with the assistant recorder, in lieu of recording. The purchaser at the foreclosure sale or his assigns may thereupon at any time present the deed under the power of sale to the assistant recorder for filing and registration, and obtain a new certificate; but this chapter shall not prevent the mortgagor or other person in interest, prior to the entry of a new certificate of title, from directly impeaching, by bill in equity or otherwise, any foreclosure proceedings affecting registered land.
After a new certificate of title has been entered, no judgment recovered on the mortgage note for any balance due thereon shall operate to open the foreclosure or affect the title to registered land.
Mass. Gen. Laws ch. 185, § 70