Studies on allogeneic demineralized dentin matrix (Allo-DDM) implantation in the 1960s and 1970s provided the most reliable preclinical evidence of bone formation and antigenicity in an extraosseous site. Recently, applications of Allo-DDM at skeletal sites were studied, and have provided reliable evidence of bone-forming capacity and negligible antigenicity. However, the osteoinductivity and antigenicity properties of Allo-DDM in extraskeletal sites have not yet been investigated due to the lack of follow-up studies after the initial research. The clinical applications of autogenous DDM (Auto-DDM) have been standardized in some countries. Long-term clinical studies have reported the development of several shapes of Auto-DDM, such as powders, blocks, moldable forms, and composites, with recombinant human bone morphogenetic protein-2. For the development of Allo-DDM as a reliable bone graft substitute next to Auto-DDM, we reviewed preclinical studies on the bone induction capacity of allogeneic dentin at extraskeletal as well as skeletal sites. Electronic databases were screened for this review in January 2020 and searched from 1960 to 2019. This review aims to provide a foundation on the preclinical studies of Allo-DDM, which could enable future researches on its osteogenic capability and antigenicity. In conclusion, Allo-DDM showed great potential for osteoinductivity in extraskeletal sites with low antigenicity, which neither adversely affected osteogenic capability nor provoked immunologic reactions. However, the risk of viral disease transmission should be researched before the clinical application of Allo-DDM.

Background: The rehabilitation of the atrophic maxillae with dental implants represents a challenge that can be addressed with zygomatic dental implants and traditional axial implants. In the event of a severely atrophic pre-maxilla, a quad-zygoma approach may be necessary to provide anchorage for the fixed restoration. The proximity of anatomical features can increase the possible morbidity of the quad-zygoma approach and instead, trans-nasal implants may serve as a viable anterior anchorage alternative in the atrophic pre-maxilla region. Methods: A total of 10 patients diagnosed from a class 2B edentulism received a combined treatment with trans-nasal implants paired with a single zygomatic implant were included in this study. Trans-nasal implant marginal bone level changes were evaluated on CBCT (Cone Bean Computed Tomographic) images taken immediately after trans-nasal implant placement and 1 year of follow-up post loading. The reference point for the CBCT measurement of mesial and distal bone loss after 1 year was the horizontal interface between the implant and the abutment. Secondary measurements taken at the 1 year follow up measured the amount of bone available in the sub-nasal, lateral and apical areas of the dental implant in contact with bone. Results: The retrospective CBCT analysis of 18 trans-nasal implants (size ranging from 22 to 25 mm with an average of 24.1 mm) placed in 10 patients (all 10 patients were female ranging from 38 to 67 years old with an average age of 59.1 years old) shows an average marginal bone loss of 0.70 mm over a time period of 1 year following restorative loading, P < 0.0001. While the sub-nasal, lateral and apical engagement shown respectively 5.46, 12.92, and 2.70 mm of radiographical bone contact with the implant. Conclusion: The marginal bone loss observed in trans-nasal implants 1 year post loading is comparable to the marginal bone loss of conventional implants under similar conditions. The cumulative radiographical bone to implant contact between the subnasal and the apical bone seems to be of a value of 8.16 mm which seems to correspond to the size of a conventional dental implant. Therefore, it is believed that trans-nasal implants can be considered as an acceptable anterior anchorage alternative to the superior/ anterior zygomatic dental implant in the atrophic pre-maxilla region when paired with a single posterior zygomatic implant.