Comparison of allogeneic and autogenous bone grafts for augmentation of alveolar ridge defects-A 12-month retrospective radiographic evaluation

Abstract

Objectives: The aim of this study was to compare three-dimensional alterations following the use of autogenous versus allogeneic onlay grafts for augmentation at single tooth defects.

Materials and methods: Alveolar bone width at specific implant sites were assessed using sagittal and cross-sectional CBCT images prior grafting and at three subsequent time points. Twenty-one patients received autogenous bone blocks harvested from the retromolar region and another 21 patients received freeze-dried cancellous allogeneic bone blocks.

Results: The vertical and horizontal dimensions did not significantly differ between autogenous and allogeneic bone grafts at any time point. In addition, there were no statistically significant differences in graft remodeling rates between autogenous (mean shrinkage rate after 12 months: 12.5% ± 7.8%) and allogeneic onlay grafts (mean shrinkage rate after 12 months: 14.4% ± 9.8%).

Conclusions: Freeze-dried cancellous allogeneic bone blocks showed equivalent volumetric shrinkage rates as autogenous bone blocks when used for treating circumscribed bone defects classified as Type-II to Type-IV according to the ITI-treatment guide categories. Therefore, it is not necessary to over-contour the alveolar ridge when using allogeneic blocks for treating single tooth defects, but to apply the same procedure as when using autogenous blocks.

Keywords: allogeneic; alveolar ridge defect; augmentation; autogenous; dental implants; graft remodeling.

Figure 1

Example of an allogeneic bone augmentation in a patient with a Type‐III bone defect of the alveolar ridge. (a) Situation before augmentation; (b) Situation directly after augmentation; (c) Situation before implantation, 6 months after augmentation; (d) Situation after implantation; (e) Final situation, 12 months after implantation

Figure 2

Radiographic evaluation of an alveolar ridge defect before (a) and 6 months after (b) augmentation. The green line at the left side corresponds to the vertical height of the bone in the defect area before augmentation. The green lines at the right side correspond to the defect depth at the apical, at the middle, and at the cervical level before augmentation. The same measurements were taken after augmentation, at 6 and at 12 months after surgery

Figure 3

3D‐Model for visualizing our mathematical approach for calculating the volume of the defect

Figure 4

2‐D Model for visualizing our mathematical approach for calculating the volume of the defect. The lines correspond to the defect widths and depths as described in the section “Radiographic analyses”

Figure 5

Scatterplot of measurement pairs with the graft volume in ml, assessed with the pyramid trunk approach, on the x‐axis and with the graft volume in ml, assessed with the Hounsfield units approach, on the y‐axis. The line corresponds to the regression with the Hounsfield units approach as depending and the pyramid trunk approach as independent variable

Figure 6

Bland–Altman plot for the comparison of the two measurement techniques for assessing the graft volume. The differences between the two techniques were plotted against the averages of the two techniques. Horizontal lines were drawn at the mean difference, and at the limits of agreement, which were defined as the mean difference plus and minus 1.96 times the standard deviation of the differences

Figure 7

Comparison of defect heights before therapy, post augmentation, after 6 months and after 12 months

Figure 8

Comparison of horizontal defect depths before therapy, post augmentation, after 6 and 12 months at the apical level (a), in the middle of the vertical defect height (b), and at cervical level (c)

Figure 9

Comparison of the defect volumes before therapy, post augmentation, after 6 and 12 months