A Novel Approach to Assess and Measure Resorption of Allograft Cancellous Blocks. A Clinical Pilot Study

Aim The aim of this pilot study was to evaluate the feasibility of a novel method in assessing the volumetric changes in block alveolar bone grafts following augmentation

Methods The study utilised information from pre-surgical cone beam CTs, post-surgical cone beam CTs, and milled allograft blocks to evaluate the volumetric differences in ridge volume, and thus the volumetric resorption of the augmentation block. This process involved reformatting DICOM data to obtain STL files, and 3-dimensional voxel analysis of the aligned STL files. In addition the study undertook surface mapping to obtain colorimetric maps depicting hotspots with increased resorption.

Results Four cases were assessed in total (with six block grafts). Block volume sizes varied between 614mm3 and 1674mm3. The results obtained suggest a mean block resorption at 4-months post- augmentation of 19.5%. This is comparable to existing published literature which has involved calculation of block resorption using analog means. In addition, the method described was able to consistently show areas with increased resorption within the block volume at the 4-month timepoint.

Conclusion This novel method may be beneficial to investigate the treatment outcomes from alveolar block grafting with greater accuracy than previous methods, whilst also providing new information on the patterns of resorption within blocks.