Background: Implant placement may be challenging in areas with limited alveolar bone height, therefore augmentation procedures before implants placement become mandatory. Several treatment modalities have been developed for bone incrementation, and it has been reported that the number of complications and failures associated with the various techniques remain high for vertical bone augmentation. The inlay bone graft technique has been recently applied in the posterior mandible with remarkable results in terms of vertical bone augmentation. In the literature there are no strong evidences in relation to the use of allografts
in the inlay technique since they have been previously proposed only as onlay or veneers.
Aim/Hypothesis: In the present case series we describe the histological appearances and histomorphometric evaluation of the regenerated areas of five patients, after two/three months from the inlay augmentation procedure.
Material and Methods: Five subjects with severe atrophy of the posterior lower maxilla requiring bone reconstruction before implants placement were treated with an inlay procedure. At cone beam computed tomography (CBCT) the preoperative mean residual bone height above the mandibular canal was ≤ 7 mm, insufficient to place dental implants with adequate length. The inlay procedure provided the use of an allograft block. Three piezosurgical inserts were used to create a horizontal osteotomy at approximately 2–3 mm above the mandibular canal and two oblique cuts. An allograft bone block was then fitted between the
cranial osteotomized segment and the mandibular basal bone. A titanium miniplate was fixed with miniscrews. Two months after the inlay procedure, presence of adequate bone height was verified through CBCT scan and dental implants were placed.
During tunnel preparation for implants placement, a bone core biopsy was harvested and processed for histological and histomorphometric evaluations.
Results: Histological appearance of the regenerated bone areas was characterized by the presence of newly formed bone and large marrow spaces showing intense cellular activity but also features of mature bone, with well-organized lamellae and numerous osteocytes, revealing connection between the grafted material and the preexisting basal bone. High magnification views revealed the presence of lines of osteoblasts depositing the newly formed bone and this bone in contact with the allograft.
Conclusions and Clinical Implications: When treating severe atrophy of the posterior mandible, the use of allografts can be considered a suitable material for bone regeneration in the inlay grafting procedure in atrophic posterior mandibles, since it seems to permit implant rehabilitation after only two months from the grafting procedure. According to the preliminary results, this material represents a good clinical alternative to autologous and inorganic bovine bone.
