We present the clinical case of a 56-year-old female patient, who has been wearing an upper complete removable prosthesis and a lower partial prosthesis for more than 20 years. She comes for consultation requesting implant rehabilitation to replace her current prosthesis to improve her masticatory function. In the intraoral examination we can observe that the prosthesis meets quite satisfactorily the aesthetic requirements of the patient, but according to her, they move when chewing. When removing the prosthesis, a maxillary edentulous ridge with an evident centripetal resorption that has left the starting situation close to that of a skeletal class III (Figures 1 and 2).
To start the diagnostic phase, a panoramic radiograph is performed that gives us an idea of the general condition of both jaws to start the treatment plan.
It shows that there is apparently some height in the maxillary ridge both anterior and posterior and a low dental nerve in the jaw that allows us to have a greater residual bone crest available for the insertion of the implants (Figure 3).
Subsequently, we proceed to perform a dental cone beam that offers a more accurate view of the type of implant rehabilitation that can be proposed. In the sections corresponding to the upper maxilla, there are areas where the direct insertion of the implants can be performed such as those corresponding to 16 and the central incisor zone of this quadrant (Figures 4-5) or in the second quadrant the area of the 27.

implant rehabilitation that can be proposed. In the sections corresponding to the upper maxilla, there are areas where the direct insertion of the implants can be performed such as those corresponding to 16 and the central incisor zone of this quadrant (Figures 4-5) or in the second quadrant the area of the 27. On the other hand, in the area corresponding to teeth 21 and 23 there is a significant horizontal atrophy, with a residual bone width of approximately 3.5 mm in the middle zone of the crest, with an enlargement in the most basal area of the same and conservation of both corticals. This leads to choose a split crest technique, in this case in two phases to achieve a greater final width and correct the inclination of the final implant as much as possible to achieve adequate aesthetics in the final prosthesis (Figure 6).

In the areas corresponding to teeth 11 and 13 the horizontal atrophy is even more marked. There is no trabecular bone separating the two corticals (vestibular and palatine) and the width is less than 2mm in some areas which is why block grafts are planned in this area. Short implants are planned in the mandible by direct insertion, and the area corresponding to the mandibular branch will be the donor area for the block grafts.
Once the case is planned, the insertion of the lower and upper implants and the different techniques of bone volume increase described is performed. It starts with mandibular surgery to obtain autologous bone obtained from miling that will be preserved during the whole surgery in PRGF-Endoret fraction 2 without activation, to be used in the maxilla where it will be necessary for the grafts in block, according to the technique described by our study group19 (Figures 7 and 8). Once the block graft is obtained it will be divided and maintained in PRGF-Endoret fraction 2 without activation, to maintain its hydration and cell viability until its placement according to the technique described by Khoury where the cortical of the block graft is used as a formwork (Figures 9 and 10)²⁰.

Once the mandibular surgery is finished, the opening of the upper flap is performed, where the great atrophy in horizontal direction that exists in certain locations is noted, as described above, that require performing block grafts (Figures 11 and 12). We proceed to perform the Split technique in two phases (Figure 13) with the insertion of the transitional implants and the insertion of the implants that could be placed directly. Once the insertion of all the implants is completed, the corticals of the grafts are fixed in block, trying to adapt them to the residual morphology as best as possible, avoiding edges that can damage the soft tissue. Once fixed, the gaps are filled mainly with autologous particulated bone obtained from the milling of the lower implants, as well as bone obtained from scraping the mandibular branch (Figures 14-18).

Four months after the initial regeneration of the maxilla surgery a new dental cone-beam is performed, in which the next surgery phase is planned based on the bone gain that has been achieved with the block grafts and the Split technique in two phases. In the images we can see how in the maximum atrophy areas, where the blocks are placed a width has been achieved that triples the initial width (Figures 19 and 20). At the flap opening it is seen as the planification CT images correspond to reality, and also that the area treated by Split in two phases has achieved a crest width that now allows the removal of the transitional implants and the insertion of the new implants in this position, with a better starting and axis situation for the subsequent construction of the prosthesis (Figures 21-22). The implants are inserted and a temporary prosthesis of progressive load is made supported on the implants placed in the first surgical phase. In this way, the patient can have a fixed prosthesis on
implants that will serve to shape the provisional ones in terms of aesthetics and function before the final prosthesis (Figures 23-24).
After four months the loading of the inserted implants in this second surgical phase is carried out. Again, a second provisional prosthesis of progressive loading is chosen, elaborated in the same way as the previous ones. three months aft er the occlusion is prepared for the manufacture of the fi nal prosthesis, so the prosthesis is transformed into a metal-ceramic prosthesis, screwed on transepithelial made by CAD-CAM (Figures 25-26).
The pati ent has recovered the requested functi on, as well as the correction of the occlusion of the complete prosthesis, which presented a right lateral cross bite with decrease in the vertical dimension at the beginning of the treatment. The patient comes to her review and the treatment remains stable as shown in the images taken after 10 years of follow-up (Figures 27-28).

The regeneration technique of horizontal atrophies with grafts in block and particulate bone as described by Khoury in 2007²¹, presents predictable results in multiple publications in which autologous bone has been used, such as the case that has been studied, as well as with the fusion of autologous bone and biomaterials in cases where the availability of the patient’s bone is not enough²⁰.
The PRGF-Endoret with the particulate bone mixture maintains the viability of the cells until the moment of their use in the block grafting attached to the particle graft technique, and improves the manageability properties of the same, at the same time it increases the ostoinductive potential by increasing the cellular signals contained in the platelet growth factors^22-25.
The use of ultrasound to obtain the block graft and the need for a smaller amount of depth of the same, since it will later be divided to be used in different fragments makes the necessary donor block volume smaller and, therefore, the volume of the donor block is lower, so the risk of nerve injury is also minimized by leaving a layer of bone under the extracted graft and separating the donor area of the dental nerve path^16.18.
Similarly, the Split technique in two phases, with the use of a transitional expander implant maintains the space of the separation between the vestibular and palatal corticals so that a new bone bridge is formed between both. This increases the width of the residual crest to then be permanently replaced by another implant with the correction of the insertion axis that would give us a conventional Split technique. These advantages have been reported in the technique described by our study group with good results^14-26. This type of procedure, in complex cases such as the one addressed in this clinical case, where different surgeries are going to be performed does not increase the morbidity in the patient and guarantees an improvement in the longterm result, by achieving greater bone volume around the definitive implant^27,28.

Complex cases require multidisciplinary approaches in which different surgical techniques can be implemented and achieve a successful result. The selection of the correct surgical technique and being able to perform it with the least possible trauma in the patient minimizes the risks of surgery and improves the obtained results.