Sinus Floor Thickens 3-4 Years after Neighboring Implant

In spite of difference in the sinus floor thickness at #15 between preop CBCT (~1 mm) and post #14 implant 2nd placement PA (~ 4 mm), Magic Lifter is tried with difficulty because of high bone density.  After a 4.8 mm short drill is used from 1 to 4 mm, sinus floor seems to be lifted gradually with the lifter.  Lifting is apparently complete after using the longer drill (4.8 mm) for ~ 6 mm and the lifter for ~7 mm.  Following placing 3 pieces of PRF membrane into the sinus, a 4x11 mm dummy implant for ~ 9 mm with <20 Ncm (Fig.1).  Then one more PRF membrane and allograft are placed before inserting 4.5x11 mm dummy implant.  Finally a 5x9 mm IBS implant is placed with ~ 35 Ncm (Fig.2).  The 1st coronal implant thread is covered by allograft mesiopalatally (Fig.3 *) after placement of a 5.5x4(4) mm abutment.  It appears that the most apical thread is contacted by the possible native bone (Fig.4 >) with apparent sinus lift (open arrow).  In other word, the sinus floor thickens from 1 to 9 mm 3-4 years after implant placement at #14 (twice).

In the end, the loose implant crown at #14 is removed and a straight (not angled) abutment (6x5 mm) is placed (Fig.3 (A),4).  Periodontal dressing is applied around these two abutments and the neighboring teeth.  There is apparently no bone loss with splinted provisional nearly 3 months postop (Fig.5,6 P).

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Xin Wei, DDS, PhD, MS 1st edition 05/19/2017, last revision 02/18/2018