The ultimate goal of implant placement is to replace a patient’s missing tooth or teeth in an esthetic and functionally successful way. A recently published study in the International Journal of Oral & Maxillofacial Surgery that analyzed the fate of the buccal crest after immediate implant placement, through the use of cone beam computed tomography (CBCT) has found promising results when using an immediate implant placement protocol with NobelActive implants.1

Retrospective study

Dr. Edith Groenendijk

Dr. Edith Groenendijk of Dental Implant Clinic “Implantologie Den Haag”

In the retrospective study, led by Dr. Edith Groenendijk (left) of Dental Implant Clinic “Implantologie Den Haag” in The Hague, The Netherlands, one surgeon treated 16 consecutive patients with one failing maxillary incisor between natural neighboring teeth. Seven implants were placed at position 11, five at position 21, two at position 12, and two at position 22.

Fig. 1 Tooth 21 is considered lost due to trauma.

Fig. 2 A small FOV (6×6 cm) standard resolution (85 kV, 15 mA) CBCT scan is made for diagnosis (Fig. 2A) and planning (Fig. 2B). A minimum of 4 mm vertical bone dimension at the palato-apical part has to be present to reach primary stability, and a minimum of 2 mm space in between the implant and buccal crest in order to create stable hard tissue in front of the implant.

Fig. 3 After performing the drill protocol, and before implant installation, the socket is filled with bone substitute. To prevent obstruction with bone substitute particles, the last used drill is placed into the implant bed (Fig. 3A). After removal of the last used drill, a tunnel is present through which the NobelActive implant is placed.

Fig.4A & B A temporary abutment is placed onto the NobelActive implant and will not be removed until the impression taking of the final crown.

Fig. 5 The temporary crown is made under rubberdam. A Teflon tape is placed into
the screw access channel to prevent composite material flowing into it.

Fig. 6A. Direct post-operative image of the temporary crown: the interdental spaces are held open to stimulate soft tissue ingrowth. Fig. 6 B. Intra-oral image of the wound healing 2 weeks post-operative: nice and optimal soft-tissue ingrowth with mid-buccal soft-tissue level gain.

Fig. 7 Permanent crown directly after placement. No pressure on the soft tissue is allowed.

The patients who were treated with immediate implant placement were required to have an intact extraction socket present, sufficient occlusal support, an absence of periodontal disease and bruxism. In addition, bone height apical from the failing tooth’s socket had to be at least 4 mm to ensure primary stability. Immediate implant placement was contraindicated by drug or alcohol abuse, daily smoking habits of more than 10 units, and when negative bone reactions caused by severe osteoporosis or other conditions could be inspected.

Another necessity for immediate implant placement to take place was the presence of sufficient palatal bone volume. This would not only ensure sufficient primary stability for the implant to permit immediate restoration, but also allowed for the creation of a distance of at least 2mm between the buccal implant contour and the inner buccal crest.

The study’s protocol

Once atraumatic extraction had taken place, periodontal ligament and inflamed tissue residues were removed with a bone excavator and the socket was cleaned extensively. The keratinized gingiva remained intact since no flaps were raised. For the subsequent osteotomy, a drill protocol in line with the manufacturer’s guidelines for NobelActive implants was used given that this was the implant material employed. After application of a bone substitute the implant was inserted, with the implant seat set 3mm deeper than the buccal gingival margin, at which point a low- dose CBCT scan was conducted to evaluate the implant’s position.

A temporary titanium NobelProcera abutment was then positioned onto the implant. Six months later, either an individualized, screw-retained, zirconia-porcelain crown or an individualized NobelProcera zirconia abutment with a cemented porcelain facing was placed, with another CBCT scan taking place.

Measurement of functional and esthetic outcomes

Changes in the thickness and height of the buccal crest were measured through analysis of preoperative, immediate postoperative, and late postoperative CBCT scans. Esthetic outcomes were analyzed using the White and Pink Esthetic Score (WES and PES).2,3

The results – and what they mean

In terms of both function and esthetics, the results of the 16 patients treated with this immediate implant placement protocol were of a positive nature. Immediate post-operative buccal crest thickness was shown by CBCT scans to increase by 1.5 mm (mean), from 0.9 mm (mean) to 2.4 mm (mean). At a mean of 103 weeks after immediate implant placement, the final thickness of the buccal crest was compacted to 1.8 mm (mean), a result of the settling of the bone substitute or resorption of the buccal cortical crest. In addition, the buccal crest height increased by 1.6 mm (mean) to an average of 1.2 mm coronal on the implant shoulder. These observed changes were both statistically significant.

Esthetically speaking, the WES scores demonstrated a total score of 8.4 out of 10, with the PES scores revealing a total of 11.8 out of 14. Both of these scores were higher than those in other studies4-41 regarding immediate implant placement. An increase in the mid-facial soft tissue level was noticed, and the employed immediate implant placement protocol resulted in a higher PES score than reported for either conventional – or early implant installation.

Within the limitations of this study, the results of this specific immediate implant placement protocol that creates a buccal hard tissue dimension in front of an implant by use of a bone substitute were shown to be promising. The study’s authors recognized long-term, prospective research on this topic with a large number of patients, as a necessary next step.

Images courtesy of Dr. Edith Groenendijk

References

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Posted by Dr. Edith Groenendijk