Tissue defect regeneration and multiple implant placement

Tissue defect regenerationMarcus Seiler uses an innovative titanium lattice to help regenerate tissue defects while reducing treatment time.

This 66-year-old patient presented in 2014 with periodontal problems. She requested a restoration of the posterior region of the lower mandible.

The patient was receiving statins for the management of hypercholesterolaemia and Euthyrox to treat thyroid problems. She was also a moderate smoker.

Teeth LL5, LL7, LR5, and LR7 could not be retained and were extracted, resulting in a bilateral free-end situation with both horizontal and vertical osseous and soft tissue defects (Figure 1). A preoperative CBCT showed significant transverse defects in the LL5-LL7 and LR4-LR7 regions.

Figure 1: Transversal contour deficit in presenting clinical situation

Titanium mesh

The CBCT scan was uploaded to the Reoss website – a company that produces a 3D PDF design of the titanium mesh for clinician approval – before delivering the Yxoss CBR titanium framework for the augmentation area.

The Yxoss CBR titanium lattice structure is designed on the basis of CBCT data from the affected region of the jaw and is produced using a CAD/CAM procedure.

Titanium screws can then be used to secure the structure to the augmentation area. Subsequently, it defines the target contour of the regenerated alveolar ridge for later or simultaneous implant placement, and stabilises the introduced bone-biomaterial mixture.

Prior to the surgical procedure, the lattice structure must be steam sterilised for five minutes at 134°C.

Surgical stage

Figure 2: A split-thickness flap was raised

A split thickness flap was raised (Figure 2) and the bone was augmented using a 1:1 mixture of autologous bone chips (retro-molar removal), used for the osseoinductive properties, and Geistlich Bio-Oss, which provides a scaffold and protects against resorption.

Figure 3: A 1:1 ratio mix of Geistlich Bio-Oss and autologous bone was introduced into the Yxoss CBR titanium grid

The bone graft substitute was loaded into the lattice structure prior to fixation (Figure 3). The titanium mesh was fixed onto the extant bone using two titanium screws. The screws can be secured in the intended position through openings in the titanium lattice (Figure 4).

Figure 4: The titanium grid with a fixing screw and slightly compressed graft material in situ

A Geistlich Bio-Gide collagen membrane shielded the graft from the soft tissue.

A dual-sided split-flap permitted a tension-free wound closure and allowed a sufficiently wide keratinised mucosa to form later in the implant area.

Figure 5: Well-vascularised bone can be seen following removal of the Yxoss CBR by applying small extrusion movements to the target breakpoint (easy removal)

After six months

Re-entry occurred after six months (Figure 5). The soft tissue conditions were clinically stable and free of dehiscence. The radiography taken at this point (Figure 6) clearly demonstrates vertical and horizontal bone gain.

Figure 6: The augmented volume can be seen in the transverse CBCT angle

A ridge incision was made in order to remove the grid structure. After loosening the fixing screws, the grid structure could be separated carefully into two parts by applying small extrusion movements to the target break point with a periosteal elevator and be removed.

The implants (Camlog Screw Line) were then inserted into the LL5, LL6, and LL7, and LR5, LR6, and LR7 regions. Good primary stability was achieved (bone quality class II according to Adell) and there was a tension-free wound closure. The implants were loaded following a further four-month healing period (Figure 7).

Figure 7: Final situation showing the individually separated crowns

Summary

The treatment of three-dimensional defects is still a challenge in everyday implant surgery. However, conventional autogenous bone blocks increase patient morbidity and are known to suffer from resorption of the bone volume.

The introduction of patient specific individual structures utilising digital workflow significantly shortens the intervention period and offers predictable results. It also defines the target contour of the regenerated alveolar ridge for later implant insertion and, in combination with bone augmentation material, provides stability for complex, three-dimensional cases.


This article was commissioned for Implant Dentistry Today. Read the latest issue of Implant Dentistry Today here.

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