Digital workflow in sub-periosteal implants for severe atrophy.
Endosseous dental implants provide a highly predictable solution for the prosthetic rehabilitation of partially and totally edentulous patients, with high rates of survival and success in the medium and long terms when there is an adequate quantity (height and width) and quality (density) of bone. Cases may occur, however, of patients with severe bone atrophy, for whom the placement of endosseous dental implants may be impossible without the use of regenerative surgical techniques, these include onlay/inlay bone grating, guided bone regeneration (GBR) with resorbable or nonresorbable membranes, alveolar ridge split, dis- traction osteogenesis , and maxillary sinus augmentation. However, these surgical techniques are complex and are associated with a rather high percentage of complications, together with long treatment time and additional costs to the patient.
To overcome unfavorable anatomical situation (i.e., without bone regeneration) short, narrow, tilted implants, the use of zygoma or pterygomaxillary implants have been proposed. The former three procedures have been very successful in modern implantology and are increasingly used, while the latter two remain niche treatments. In any case, a minimum level of endosseous bone volume is needed to place short, narrow, or tilted endosseous implants; in cases of severe or advanced bone atrophy, the use of such nonregenerative surgical approaches may not be possible. In the past, subperiosteal implants were inserted in cases of severe bone atrophy. A subperiosteal implant is a type of dental implant that is placed between the periosteum and the residual alveolar bone. However, technically were very demanding and it was not possible to produce an accurate implant with bio inert materials such as titanium.Today, however, the world of dentistry has changed, thanks to the powerful impact of the digital revolution. The introduction of new acquisition methods (CBCT) and intrao- ral scanners, along with the spread of process- ing/elaboration such as (CAD/CAM) software, new materials, and fabrication technologies, has dramatically changed the world of implant dentistry, opening up new perspectives. In particular, the new direct metal laser sintering (DMLS) techniques available today provide the ability to fabricate custom-made grids or even implants that perfectly adapt to the specific anatomical requirements of patients. The use of such modern fabrication techniques allows us to revisit some of the past techniques, such as subperiosteal implants, and reinterpret them in a modern and digital way. This can be extremely useful in the case of severe bone atrophy, which does not allow for the placement of endosseous dental implants if a regenerative intervention approach is not followed, particularly in the case of elderly patients with limited financial resources and who do not wish to undergo long and complex regenerative surgeries prior to the insertion of endosseous dental implants.