How to Remove Loose Abutment?

Mr. Young (55 years old) has had a bridge (Fig.1: #29-31).  One of the abutment teeth (#31) has caries under the retainer (<) and periapical radiolucency (*).  There is a residual root in the distal socket of #30.  Six weeks after extraction of the teeth, two implants are placed (Fig.2: 30 (6x17mm), 31 (7x14 mm)).

Four months postop, the implant at the site of #30 is found to be lingual (Fig.3,4).  With bone graft or better bone expansion technique, the implant might have been placed in an ideal position (Fig.5,6). 

Angulated abutment (20 degree) is inserted into the implant at the site of #30, cemented and an antirotational groove is placed lingually (Fig.7).  PFM crowns are cemented (Fig.8,9).

Six months later, there is porcelain chip from the mesiobuccal area of #30 crown (Fig.10: *).  The crown is also loose.  It appears that the crown/post is detached from the implant.  The patient is apparently a bruxer.

What should I do?  It appears that the crown has to be cut off from the abutment.  How to remove the abutment from the implant?

If everything turns out fine, an extra antirotational groove will be placed mesially.  A Zirconia crown will be fabricated.  Pay attention to marginal fit (Fig.9>).

Xin Wei, DDS, PhD, MS 1st edition 02/02/2011, last revision 08/11/2013