Patient: A 47-year-old male
He had no noticeable medical problem and no severe periodontal disease.
Diagnosis: Approximately 6mm residual bone height was estimated in the shortest area.
Panoramic view four weeks after extraction. At the #26 site area, a defect of the extraction socket and a concave and inclined sinus floor was seen.
Clinical occlusal view four weeks after extraction. The soft tissue seemed to be well healed.
Gingiva at the surgical area was removed by a tissue punch.
Initial 2mm twist drilling was performed with 5mm stopper, which was expected to be at least 1mm shorter than the residual bone height.
The osteotomy site was enlarged up to 4mm, which was one step narrower than the final drill. In the extraction socket, One-step undersized drilling is generally performed to obtain better stability.
A 3.2mm wide S-reamer was used to drill into the sinus with at least 1200 rpm. This drilling was starting with a 6mm stopper, which is 1mm longer than the previous drilling depth.
Drilling was continued until the inferior wall of the sinus opened. The depth gauge was used to detect the opening of the inferior wall and measure the actual bone length. Feeling or elevating the membrane with the depth gauge should not be done.
Bone graft was performed using the bone carrier and bone condenser. Approximately 0.05cc of bone can be contained at one time in the carrier. This may elevate the membrane about 0.5-1mm. It is much easier and convenient to use the thinner part first rather than the thicker part of the condenser if it is chip type bone material. 0.3cc of Calpore alloplast bone material was used.
From a standard radiographic view, bone material was seen in the sinus elevating the membrane up to 5mm. That amount of easy elevation was possible due to the severe concavity of the sinus.
IS-II active 5×8 fixture was placed with insertion torque of 20 Ncm. The fixation was obtained mainly from the inferior cortical wall of the sinus because of lack of C fixation due to the empty space from the extraction socket.
The defect was filled with an allograft (RegenOss, Seoul, Korea) after closing the internal hole of the fixture by a cover screw. Generally it is unnecessary to cover the graft in the extraction socket by a barrier membrane because it is usually a contained 4-wall defect.
A periapical radiograph shows the implant was placed about 3mm subcrestally, which was 5mm from the gingival level. Although the general rule of the implant depth is 3-4mm from the zenith of the gingival margin of the crown, the reason that the implant was placed deeper was to adjust to the graft level that would be regenerated.
A 7mm wide healing abutment was connected after the graft without any membrane covering. No suture was needed.
One year follow-up panorama showed that the marginal bone was overgrowing even down to the crown margin level. It may imply that subcrestal placement results in minimal bone loss. The grafted bone in the sinus was also well maintained around the implant apex.