Initial situation

Teeth numbers 25 & 27 both exhibited significant bone loss on the OPG (Fig. 1), they were mobile and painful on palpation.

The teeth were extracted after a severe infection was cured. It was decided to wait 6 weeks for completion of soft tissue healing before placing the implants (Fig. 2).

A new OPG recorded at this time (6 weeks) showed significant bone loss and a lack of bone under the maxillary sinus. The first premolar was compromised and mobile. The CBCT confirmed the lack of bone, except near the tuberosity and above the first premolar (Figs. 3,4).

Treatment planning

This clinical situation was typical of a sinus lift procedure indication, combining a sinus floor elevation and the placement of a xenograft. The patient was offered the following alternative: a grafting procedure versus the use of tilted implants combined with a unilateral zygomatic implant. The second solution presents two major advantages:

• One-stage surgery,
• The healing period is greatly reduced: with a sinus lift, it is normally necessary to wait for at least 4 to 6 months before placing the implants, followed by a further 4 months for completion of osseointegration. Combining tilted implants with a zygomatic implant reduces the treatment duration and allows the final bridge to be fitted 4 months after implant placement.

It was decided to restore function and esthetics with a 4-unit ceramic bridge supported by three implants after the extraction of tooth 24. The treatment plan was as follows:

• first implant inserted immediately after the extraction of tooth 24 and tilted to the mesial side.
• second implant placed in the tuberosity and the third under the sinus.

A ZAGA 1/2 anatomical situation was identified on the CBCT, and it was decided to place a Straumann® Zygomatic Implant ZAGA™ Round.

Since, for esthetic reasons, the patient preferred an immediate temporary restoration of tooth 24, a single angulated 15° esthetic abutment was foreseen to support a single provisional crown with no occlusal loading. At final restoration it was then intended to remove this and replace it with an 18°/1.5 mm multi-unit Anthogyr® abutment.

Surgical procedure

The surgery was performed under local sedation. According to the treatment plan, tooth 24 was removed, and a 12/3.4 mm Anthogyr® implant was inserted in the extraction socket. The osteotomy started at the top of the alveolar ridge, 5 mm distal to the canine, and continued towards the mesio-palatal aspect of the crest in order to achieve primary stability with anchorage at the bottom of the alveolar socket, taking care of the root of tooth 23. An esthetic abutment Anthogyr® 15°/4 mm was screwed in to support the future provisional crown. A second Anthogyr® 10/4 mm PX implant was placed close to the tuberosity, along the posterior wall of the sinus, and a 1.5 mm regular multi-unit abutment was placed and covered by a healing cap.

The osteotomy for the placement of the zygomatic implant started with the opening of a window at the upper part of the sinus, right under the zygomatic bone, providing a view of its lower face. Due to the anatomy of the buccal wall of the sinus (ZAGA 1/2) and the remaining bone crest, it was decided to drill through the sinus and keep bone around the head of the implant. This offers two main advantages:

• increases the primary stability of the implant,
• improves soft tissue hygienic maintenance around the cervical end of the implant.

The concavity of the bone at this level required the realization of a small “slot” right after the remaining crest (sinus slot technique according to Stella J. Warner M., Int J Oral Maxillofac Implants, 2000) (Figs. 6,7). Without this, it would have become imperative to start the drilling from the palatal side to allow the insertion of the zygomatic implant. As a consequence, this could have led to a poor emergence situation of the implant head, away from the alveolar crest and too palatal to prevent discomfort for the patient.

The need to preserve alveolar ridge integrity guided our choice towards a Straumann Zygomatic Implant ZAGA™ Round, length 45 mm. During the insertion of the implant, which was wider than the drill, it appeared necessary to increase the size of the slot because the remaining wall between the slot and the window prevented the insertion of the implant. Consequently, the path of the zygomatic implant was extra-maxillary in its middle part. This allowed for an ideal emergence of the implant on the alveolar crest, and a suitable alignment of all three implants. Finally, a 1.5 mm SRA abutment was screwed in and covered with a healing cap (Fig. 6).

The flap was sutured, paying special attention to placing as much of the keratinized gingivae as possible on the buccal aspect of the implants (Fig. 7).

An OPG was recorded to double-check the position of the implants and their respective abutments (Fig. 8).

Prosthetic procedure

After a 4-month healing period, the healing caps were removed, and each abutment was tightened, to 35 Ncm for the zygomatic implant and 25 Ncm for the regular abutments. This step was critical to ensure: - the absence of unscrewing during the healing period. - the osseointegration of each implant. The abutment on tooth 24 was replaced with a multi-unit 18°/1.5 mm (Fig. 9).

An “open tray impression” was made using metallic transfers (Figs. 10,11).

The occlusion was registered with an acrylic bite device screwed onto the abutments. (Figs. 12,13)

A full-zirconia bridge was milled and delivered two weeks later (Figs. 14,15). This was tightened to 15 Ncm (Figs. 16,17), and the occlusion was checked to avoid any lateral interferences and overload.

Treatment outcomes

This clinical case involved a surgical procedure that avoided bone grafting in poor bony conditions under the maxillary sinus.

This patient was treated according to the immediacy concept by placing zygomatic implants without using a graft procedure, thereby shortening the duration of the full treatment. The placement of the Straumann Zygomatic Implant allowed the impression to be taken just 4 months after implant placement, rather than the 12 months needed after a sinus lift procedure. This procedure decreased morbidity by avoiding a second-stage surgery and increased the benefits for the patient.

The use of the Straumann Zygomatic Implant proved to be a reliable alternative to a sinus lift procedure, with placement between two regular tilted implants where the bone quantity was insufficient to accept a third regular implant. This technique allowed the patient to receive a 4-unit screwed retained bridge shortly after a single surgery. The patient expressed his satisfaction with the achieved esthetic and functional results.

Two key points concerning the above surgical procedure should be mentioned:

• the sinus slot technique led to an ideal emergence of the zygomatic implant head and abutment.
• the soft tissue management located the keratinized gingivae around the SRA abutment of the zygomatic implant.

The author would like to thank Dr. Nicolas Renou and Mr. Gilles Giordanengo, Dental Prosthetic Technician, for their outstanding contributions.