New Bone for Primary Stability

To obtain primary stability for immediate implant in a large socket, the depth of osteotomy should be 1-3 mm more than expected.  For example, a 17 mm long implant is to be placed (Fig.3 I); initial depth of 17 mm (Fig.1) is not enough.  By the time of placement of 7x17 mm tap (Fig.2 T), it is not stable.  The initial osteotomy has to be approximately 3 mm more (Fig.2,3 red outline) for tap and implant engagement, probably due to the fact that the bone is dense.  Primary stability derives both from engagement of the apical portion of the implant into the new bone (between Fig.3 arrowheads) and from contact between the implant body and the lingual plate (in this case, Fig.4: gap in the mesial, buccal and distal socket, where bone graft (Fig.3 *) and collagen membrane (Fig.4 M) are placed).

Fig.5 is taken 3 weeks postop; loose perio dressing just being removed.  The gingiva has approached the implant (I).

Bone has grown into the implant threads 5.5 months postop (Fig.6 arrowheads) and 2 years 9 month postop (Fig.7).  The crown is cemented 4 years 7 months postop (Fig.8); the bone density increases in spite of nonfunctioning.

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Xin Wei, DDS, PhD, MS 1st edition 10/07/2014, last revision 04/29/2019