How to Prevent Periimplantitis?

It is surprised to find that there is no granulation tissue to be curetted from the apex of the socket.  Osteotomy is not chosen in the original socket (Fig.1 blue dashed line), since the axis is too oblique for restoration.  Instead osteotomy is initiated in the mesial slope of the socket (Fig.1 (P: parallel pin), 2 (D: 5x17 mm drill)).  The bone is so dense that a 6 mm drill jumps at the opening of the osteotomy and that a 5x14 mm tissue-level implant (Fig.3 I) has insertion torque of >60 Ncm.  The patient feels much pressure while the implant is being placed in spite of large amount of anesthetics.  The superior border of the Inferior Alveolar Canal (red dashed line in Fig.1,2) is not distinct in Fig.3, but the implant should have enough clearance, since it is superior to the line connecting the apices of the teeth #30 and 31 (Fig.3 brown line).  While the most distal portion of the socket (Fig.4 blue dashed line) is filled with Osteoplug, the rest bone graft (*).  Due to limited vertical height, the immediate abutment (4x3 mm) has to be trimmed (Fig.4 double arrows; Fig.5 A).  Collagen dressing (membrane, Fig.5 C) is used to seal the opening of the socket (on the top of the bone graft).  An immediate provisional is fabricated (Fig.6 P) to keep the limited restorative space and the margin.  Four months postop, the lamina dura of the distal socket becomes blurred while the density increases (Fig.7 *).  The threads remains buried in the bone.  The immediate provisional keeps the margin (Fig.8 ^) from the gingiva and also makes a dimple distal to the implant/abutment complex (*).

This case is least likely to develop periimplantitis.  First of all, there is no preop infection.  The most predisposing factor for periimplantiits is a large defect caused by chronic periodontitis or presence of the 3rd molar.  Pack as much bone graft as possible.  Raise a flap if necessary.  Secondly, the implant is placed deep, using 17 mm drills and placing a 14 mm implant.  Make sure that all of implant threads are buried.  If not, pack bone graft and cover with collagen membrane.  Most of time, buccal plate is the lowest.

How to prevent periimplantitis?  Place an implant as low as possible (long drills, short implant) so that there is no thread exposure.  In case of thread exposure, pack sufficient bone graft and cover with collagen membrane.

The crown dislodges 2 months post cementation with loosening abutment.  The latter is too short to be tightened.  Resin cement is used for recementation.  When the vertical dimension is limited, particularly at the 2nd molar, a bone-level implant should be used with an abutment as wide as possible for retention.  Consider screw-retained abutment crown.  Three months post cementation, the patient complains of food impaction between #30 and 31.  The crown is remade.  The implant threads are unexposed 1 year 3 months (Fig.9) and 2 years 3 months (Fig.10) post cementation. 

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Xin Wei, DDS, PhD, MS 1st edition 10/05/2015, last revision 12/20/2018