The Zygoma Anatomy-Guided Approach for Placement of Zygomatic Implants

Key points

  • The essence of the ZAGA Concept is to provide the patient with a zygomatic anchored rehabilitation according to their specific anatomy.

  • ZAGA Concept includes the choice of the adequate implant design able to adapt to the performed osteotomy.

  • The ZAGA concept recommends aiming for a tunnel osteotomy, whenever possible, regardless of the maxillary wall curvature.

  • A channel osteotomy is a groove made on the coronal-alveolar bone and sometimes also in the lateral maxillary wall and zygomatic buttress.

  • It is critical to preserve the sinus membrane integrity and as much bone thickness as possible at the zygomatic implant critical zone crest level.

The zygomatic anatomy-guided approach concept

The zygomatic anatomy-guided approach (ZAGA) was described as a refinement of the extrasinus technique for placement of zygomatic implants (ZI). The concept seeks a patient-specific therapy and applies to all the atrophic maxillary anatomies. According to the ZAGA concept, placement of the ZI is guided by the anatomic and prosthetic requirements. The osteotomy goals ( Box 1 ) are to achieve maximum primary stability, optimal anteroposterior (AP) distribution, and implant trajectory and position that prevent potential long-term complications, such as oral-antral fistula formation or soft tissue dehiscence ( Figs. 1–113 ).

Box 1
The ZAGA minimally invasive zygomatic osteotomy goals

  • Accomplish a prosthetically driven implant trajectory, placing the implant head at the optimal dental position.

  • Achieve optimal AP distribution of the implants.

  • Achieve maximal implant primary stability.

  • Preserve as much bone as possible at the maxillary wall and alveolar bone.

  • Maximize the BIC along the length of the whole implant. This includes alveolar, maxillary wall, and zygomatic bone.

  • Complete sealing of the osteotomy by the implant body.

  • Protect the sinus integrity at the implant head/neck level to prevent late sinus-oral communication.

  • Prevent soft tissue dehiscence.

Fig. 1
Simulation of an extrasinus path in a ZAGA type 3 situation. Implant path will use a ZAGA tunnel-type osteotomy to reach the zygoma.

Fig. 2
Case 1: both coronal and zygomatic entrances are marked previous to drilling.

Fig. 3
Case 1: the antrostomy location also is marked.

Fig. 4
Case 1: the round bur is used to drill a tunnel on alveolar bone.

Fig. 5
Case 1: the round bur has crossed alveolar bone. Membrane integrity was maintained.

Fig. 6
Case 1: the round bur has perforated the zygomatic process of the maxilla.

Fig. 7
Case 1: a stepped Straumann AG 2.9-mm diameter twist drill was used as a final drill.

Fig. 8
Case 1: maxillary wall should be prepared evenly. When there is no roof, drills may trend to drill the air.

Fig. 9
Case 1: the twist drill attacks the zygomatic bone using a sliding movement supported by the alveolar tunnel and the channel.

Fig. 10
Case 1: the ZAGA tunnel type of osteotomy respects sinus integrity at the ZICZ.

Fig. 11
Case 1: a Straumann AG zygomatic double gauge is used to measure the osteotomy length.

Fig. 12
Case 1: a circular section implant (Straumann ZAGA Round) is self-tapping the alveolar tunnel osteotomy.

Fig. 13
Case 1: due to the implant (Straumann ZAGA Round) self-tapping design, BIC is maximized and no gaps are left between alveolar bone and the implant.

Fig. 14
Case 1: the implant (Straumann ZAGA Round) apical flutes are cutting the zygomatic bone facilitating insertion torque values above 50 Ncm.

Fig. 15
Case 1: the implant (Straumann ZAGA Round) neck has macrothreads to help bone integration. The bony side of the implant head has microthreads for bony stabilization.

Fig. 16
Case 1: the implant (Straumann ZAGA Round) mount screw gives the direction of the prostheses screw emergence.

Fig. 17
Case 1: lateral view of the implant design (Straumann ZAGA Round).

Fig. 18
Case 1: a Straumann abutment is being screwed until reaching 35 N∙cm .

Fig. 19
Case 1: final prostheses and soft tissues 1 year postsurgery. Prostheses placed by Drs Peter and Madalina Simon, ZAGA Center Stuttgart, Germany.

Fig. 20
Case 1: patient satisfaction 1 year postsurgery. Prostheses placed by Drs Peter and Madalina Simon, ZAGA Center Stuttgart, Germany.

Fig. 21
Case 2: right side 3D and 2D images representing the anatomic features of an eventual ZI trajectory. The planning software simulating an intrasinus classic path. An eventual circular tunnel osteotomy would reach the sinus through scarcely 1 mm to 2 mm of alveolar bone thickness. The ZAGA concept recommends visualizing the possibility for bone loss around the implant neck and subsequent development of an oral-antral fistula.

Fig. 22
Case 2: the planning software is simulating an extrasinus path of the same implant of Fig. 21 . ( right side ) According to the ZAGA concept, when facing situations showing less than 4 to 5 mm thickness at the sinus floor, a more reliable bone sealing and maintenance is achieved by buccal shifting of the osteotomy.

Fig. 23
Case 2: left side 3D and 2D images representing the anatomic features of an eventual ZI trajectory. The planning software simulating the figure is showing an intrasinus planning of the same patient as in Fig. 24 . Possibility for late peri-implant bone resorption and oral-antral fistula must be foreseen.

Fig. 24
Case 2: an increased BIC at the ZICZ Is achieved by laterally displacing the osteotomy.

Fig. 25
Case 2: reference points for alveolar and zygomatic bone entrances should be marked.

Fig. 26
Case 2: points to be marked are the ZICZ and the antrostomy zone. Eventually, a line joining the ZICZ and the antrostomy points will help by showing the implant path.

Fig. 27
Case 2: alveolar thickness is less than 4 mm. A ZAGA channel osteotomy was chosen. The lateral cutting bur (Straumann AG) is initiating a narrow channel where the next drill tail will slide.

Fig. 28
Case 2: the round bur tail is supported by the alveolar channel. Direction, depth, and inclination of the implant trajectory now should be evaluated. Once the channel shows the desired depth and its floor surface becomes even, the bur tail gently slides up and down using a grinding-back movement, the goal being to prepare a smooth surface supporting the trajectory for the next drill.

Fig. 29
Case 2: round bur has completed the channel grinding. A notch was marked at the zygomatic process.

Fig. 30
Case 2: a 3.4-mm diameter implant is planned; conditions of zygomatic bone quality and quantity are not ideal. Then, a twist drill of 2.8-mm diameter is advised as final diameter.

Fig. 31
Case 2: using profuse irrigation, the twist drill slides up and down, using short pressure periods of about 4 seconds, allowing the saline to clean and cool the drill.

Fig. 32
Case 2: details of the ZAGA channel osteotomy. Minimal destruction of the alveolar bone and maxillary wall has been achieved. The under-preparation totally matches the chosen implant design. Sinus lining integrity has been maintained. The antrostomy zone was moved to an apical position.

Fig. 33
Case 2: implant length is estimated with a gauge.

Fig. 34
Case 2: a flat body section implant design (Straumann ZAGA Flat) is presented. The round tapered apical part of the implant is provided with cutting flutes.

Fig. 35
Case 2: the unique tapered design feature on a ZI (Straumann ZAGA Flat), together with the use of a ZAGA conservative osteotomy, allows for an enhanced implant primary stability.

Fig. 36
Case 2: the implant (Straumann ZAGA Flat) and transport holder have the same diameter, helping the surgeon manage implant insertion in situations where the implant is inserted close to another implant or to hard bone.

Fig. 37
Case 2: lateral view of the implant design (Straumann ZAGA Flat).

Fig. 38
Case 2: the implant in place is partially outside the bone envelope. To diminish eventual vascular compression of the soft tissues, the implant (Straumann ZAGA Flat) has a flat body section.

Fig. 39
Case 2: the Straumann ZAGA Flat implant from a lateral view. Its flat profile is not protruding from the remaining alveolar bone.

Fig. 40
Case 2: the Straumann AG lateral cutting bur is starting a channel osteotomy on the right posterior area.

Fig. 41
Case 2: the initial alveolar channel is used for a smooth back and forward sliding movement of the round bur tail.

Nov 5, 2021 | Posted by in Oral and Maxillofacial Surgery | Comments Off on The Zygoma Anatomy-Guided Approach for Placement of Zygomatic Implants

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