The planning of the patient's case shall follow consideration of local and general patient-specific risk factors according to the principles of backward planning for implant positioning. If the patient has a bony defect of the jaw such as a horizontal and/or vertical deficit, Yxoss CBR® allows volume augmentation via bone regeneration. It guards undisturbed bone healing and thus impedes competitive wound healing. According to the principles of osteopromotion, slow growing bone cells given an advantage over faster growing soft-tissue fibroblasts that may enter the defect.
Likewise, a volume stability of the augmentation is assured. Indications for the use of Yxoss CBR® are horizontal and three-dimensional alveolar ridge augmentation.
As a basis for further implant therapy, clinical and radiological diagnoses are to be taken into consideration in advance, as well as a documentation of findings using a model analysis with diagnostic setup of the therapeutic zone. On the planning model, an x-ray template can be made for precise three-dimensional planning and later be used as the surgical template. In order to compensate for the bone resorption, a three-dimensional planning of Yxoss CBR® is carried out on the basis of CBCTs, without x-ray template.
The compensation of the deficit is to be constructed mainly with autologous bone, the gold standard, and bone grafting material as resorption protection as well as for its osteoconductive properties. Autologous bone can be harvested from the usual intraoral donor sites. The implantation can be performed in a 1-step or 2-step augmentation, depending on the defect.
Critical for the success of therapy is the soft-tissue management. Adequate soft-tissue coverage to allow for the volume increase should be planned via periosteal mobilization or specific favored-techniques for soft-tissue augmentation. In general, a broad zone of fixed gingiva improves subsequent peri-implant hygiene and thus the long-term prognosis of implant-supported augmentation.
Hygiene and re-evaluation
The usual oral surgery and implantology hygiene provisions apply for the use of Yxoss CBR® intra-operatively. The same applies for patient medication.
The opening incision should be designed in accordance with the extent and location of the region to be augmented with respect to anatomical structures such as the maxillary sinus, nerves, vessels and ligaments. A sufficient blood supply of the flap is ensured by a wide enough base. The periodontal condition of adjacent teeth must be taken into account as well as their prosthetic support. A positive influence on the healing process is accomplished by a full sharp cut, avoiding tissue compression during the mobilization of the flap and a marginal incision, especially in the esthetic zone.When Yxoss CBR® is inserted, the periosteum at the flap should not be injured or perforated and the mobilization of the flap should be sharp and undermining. The incision should in general be made so that a subsequent cover of the mesh is possible, particularly considering that significantly more volume is present in situ.
Insertion of the Yxoss CBR® titanium grid
In general, the surgical sequence can be divided into the careful preparation of the defect, the process of bone harvesting for augmentation, and the combination of the two processes followed by wound closure:
1. Under local anesthesia, a marginal incision along the linea alba (if possible without vestibular discharge) is performed.
2. Subsequent steps are the preparation of a mucoperiosteal flap, debridement of scar tissue and the exposure of the defect. Debridement of the bone under the implant site may be performed. Then, in a one-stage procedure, implants may be aligned at the same time using the positioning rail and inserted in the selected region. The implants should exhibit primary stability in the course of the procedure. Special attention must be devoted to the correct positioning of the implant shoulder level related to the cemento-enamel junction of the adjacent teeth in the crestal area of the intended augmented volume.
3. During the try-in of the prefabricated, custom-fit titanium scaffold Yxoss CBR® a passive tension-free fit should be realized and the biological provisions respected (1.5 mm to the adjacent teeth or nerve structures).
4. From the typical intraoral donor sites, the bone harvesting is carried out and the graft is prepared in particulate form. Then, the mesh is filled with autologous bone and bone substitute material.
5. The stable fixation of Yxoss CBR® takes place on the existing residual bone with an osteosynthesis screw following the principle of mechanical rest as known from membranes to enable undisturbed stable bone regeneration and from the lag screw concept. The titanium screw can be generally introduced, depending on the intended position, through any opening of the titanium grid. The edges of the titanium scaffold rest on the underlying bone tissue. A resorbable membrane should be placed over the Yxoss CBR® titanium scaffold to prevent the ingrowth of soft-tissue into the bone defect and to support soft-tissue regeneration over the titanium frame.
6. During wound closure, the mucoperiosteal flap is positioned tightly over Yxoss CBR® and is sutured tension-free with single-interrupted and deep mattress sutures.
The connective tissue is, if possible, sutured tightly with tension-free sutures over the titanium framework (e.g., single-interrupted and deep mattress sutures). The wound should be closed completely whenever possible to reduce the risk of an inflammatory reaction in the area of surgery.
Clinical experience has revealed that satisfactory healing takes place, also in most cases where a complete wound closure was not possible.
Re-opening and removal of Yxoss CBR®
After suture removal and throughout the course of wound healing the soft-tissue situation should be clinically checked regularly for the absence of dehiscence and controlled for signs of general inflammation. After an appropriate bone healing phase of the augmented area (ca. 4-6 months) Yxoss CBR® can be removed.
For the removal of the mesh and possible simultaneous exposure of implants, the same (marginal) incision should be chosen as for the implantation. After preparation of the mucoperiosteal flap, a well revascularised augmentation volume, and possibly ingrowth of osteoblasts through the grid structure is visible. After removing the fixation screw, the mesh can be carefully removed. Yxoss CBR® usually has a predetermined breaking point at an accessible location. Without much force, the mesh can be mobilized, due to the Easy Removal function, by slight lateral extrusion movements without affecting the augmentation. The implants are to be controlled for complete osseointegration with good vascularization of the surrounding stable adherent bone. For conditioning the soft-tissue and creating a natural emergence profile, gingiva formers are subsequently used. Afterwards, a perio-test can be carried out as an indicator for a stable osseointegration. Tension-free wound closure can be combined with a mucosal graft to increase the amount of keratinized gingiva. Sutures are to be removed one week thereafter.
To avoid a counterproductive compression of the augmentation with possible resultant graft loss, rigorous debridement of the interim restoration is recommended; alternatively the restoration may be delayed in cases of lack of patient compliance.
Prosthetic restoration is carried out in accordance with usual precautions.
Periodic control of the implants and the augmented area is suggested to be planned during the biannual dental routine examination. Radiological evaluation should be performed according to the standardized recommendations of the respective dental societies. Evidence to support that routinely performed professional teeth cleaning protects against periimplantitis also applies here, as well as the dependence of implant survival on patient compliance, oral hygiene, genetic factors, smoking behavior and the exclusion of preexisting periodontal disease.