Horizontal Resorption of Fresh-Frozen Corticocancellous Bone Blocks in the Reconstruction of the Atrophic Maxilla at 5 Months

Abstract

Background: Reliable implant-supported rehabilitation of an alveolar ridge needs sufficient volume of bone. In order to achieve a prosthetic-driven positioning, bone graft techniques may be required.

Purpose: This prospective cohort study aims to clinically evaluate the amount of resorption of corticocancellous fresh-frozen allografts bone blocks used in the reconstruction of the severe atrophic maxilla.

Materials and methods: Twenty-two partial and totally edentulous patients underwent bone augmentation procedures with fresh-frozen allogenous blocks from the iliac crest under local anesthesia. Implants were inserted into the grafted sites after a healing period of 5 months. Final fixed prosthesis was delivered ± 4 months later. Ridge width analysis and measurements were performed with a caliper before and after grafting and at implant insertion. Bone biopsies were performed in 16 patients.

Results: A total of 98 onlay block allografts were used in 22 patients with an initial mean alveolar ridge width of 3.41 ± 1.36 mm. Early exposure of blocks was observed in four situations and one of these completely resorbed. Mean horizontal bone gain was 3.63 ± 1.28 mm (p < .01). Mean buccal bone resorption between allograph placement and the reopening stage was 0.49 ± 0.54 mm, meaning approximately 7.1% (95% confidence interval: [5.6%, 8.6%]) of total ridge width loss during the integration period. One hundred thirty dental implants were placed with good primary stability (≥ 30 Ncm). Four implants presented early failure before the prosthetic delivery (96.7% implant survival). All patients were successfully rehabilitated. Histomorphometric analysis revealed 20.9 ± 5.8% of vital bone in close contact to the remaining grafted bone. A positive strong correlation (adjusted R(2) = 0.44, p = .003) was found between healing time and vital bone percentage.

Conclusions: Augmentation procedures performed using fresh-frozen allografts from the iliac crest are a suitable alternative in the reconstruction of the atrophic maxilla with low resorption rate at 5 months, allowing proper stability of dental implants followed by fixed prosthetic rehabilitation.

Keywords: allografts; alveolar ridge augmentation; corticocancellous block; fresh-frozen bone; iliac crest.

Figure 1

Preoperatory computerized tomography (CT) scan of the severely resorbed ridge.

Figure 2

Allogenous fresh-frozen bone block from the iliac crest.

Figure 3

Occlusal view of the severely resorbed maxillary ridge.

Figure 4

Immediate postoperatory. Occlusal view of the eight blocks fixed to the recipient site.

Figure 5

Postoperatory computerized tomography (CT) scan of the augmented area with the onlay blocks fixed to the recipient site.

Figure 6

Occlusal view of the reconstructed ridge during reentry at 5 months with very good incorporation of the blocks.

Figure 7

Detail view of four implants inserted into grafted bone.

Figure 8

Occlusal view of the transmucosal exposition of the implants with healing caps.

Figure 9

Computerized tomography (CT) slices of the grafted area with the implant placed. Note the presence of a good buccal plate from the allogenous block.

Figure 10

Frontal view of the final rehabilitation.

Figure 11

Graphic representation of the mean ridge thickness of each patient measured with a dial caliper during surgery before and after onlay fixation and at reentry, displaying a similar pattern for all cases. Values are in millimeters.

Figure 12

Photomicrograph of the bone biopsy stained with hematoxylin and eosin (HE), where vital bone (VB) surrounds the graft residual non-vital bone (NVB). The newly formed bone presents osteocytes (Oc) in the lacunae, whereas the graft residual is characterized by empty lacunae (L). Note the presence of osteoblast-like cells in the VB margin that contacts the non-mineralized tissue (n-MT). 20, 40 and 100x total magnification.