Volumetric Stability of Fresh Frozen Bone Blocks in Atrophic Posterior Mandible Augmentation
Fresh frozen bone allografts (FFB) have become an alternative for bone augmentation in the past decades, especially because of the absence of recent reports of disease transmission or immunologic reactions when it is used. The aim of this prospective controlled study is to evaluate volumetric changes of newly created bone following reconstruction of the atrophic posterior mandible. Twenty consecutive patients presenting for reconstruction of posterior mandibular alveolar bone ridge width ≤6.0 mm and/or height ≤6.0 who met all inclusion and exclusion criteria were included. FFB blocks were used. The main outcome variable investigated was bone volume dynamics. Vertical, horizontal, and 3-dimensional bone gain data were measured from computerized tomography scans. The main predictor variable was time evaluated at 3 points: immediately after surgery (T1), at implant placement (T2), and 1 year after functional loading (T3). Secondary outcome parameters evaluated were implant survival, histologic findings, and microtomographic morphometry. The study included 28 hemi-mandibles, 50 FFB bone blocks, and 15 female and 5 male patients (mean age, 51.8 years). Block and implant survival rates were 100% and 96%, respectively, after 31.75 months of follow-up. Vertical and horizontal bone gain at T2 was 5.15 and 6.42 mm, respectively. Volumetric resorption was 31% at T2, followed by an additional 10% reduction at T3. Histologic evaluation showed newly formed vital bone in intimate contact with the remaining FFB. Microtomography revealed 31.8% newly formed bone, 14.5% remaining grafted bone, and 53.7% connective tissue and bone marrow. Thus, FFB blocks may lead to new bone formation and consolidation, with satisfactory volumetric bone maintenance, allowing implant-supported rehabilitation with high success rates.
(a) Clinical intraoral view of the atrophied posterior mandible alveolar ridge. (b) A full-thickness flap was made to gain access to the surgical site. (c) Recipient bone bed showing the perforations for improving graft vascularization. (d) Final aspect of the block after shaping and fixation. (e) Bovine bone mineral granules were used for covering the block. (f) A resorbable collagenous membrane was positioned over the graft before wound closure.
Mimics output showing the methodology used for volumetric measurements of the grafts.
Figure 3. Box plot of the vertical bone gain. T1: immediately after bone grafting; T2: 6 months postoperatively at implant placement; T3: 1 year after functional loading. Median, minimum, maximum, and standard deviation (*eg, analysis of variance [ANOVA], H = 42.905, df = 2, P < .05). Figure 4. Box plot of horizontal bone gain. T1: immediately after bone grafting; T2: 6 months postoperatively at implant placement; T3: 1 year after functional loading. Median, minimum, maximum, and standard deviation (*eg, ANOVA, H = 68.843, df = 2, P < .05). Figure 5. Box plot of the volumetric bone gain. T1: immediately after bone grafting; T2: 6 months postoperatively at implant placement; T3: 1 year after functional loading. Median, minimum, maximum, and standard deviation (*eg, ANOVA, H = 66.139, df = 2, P < .05). Figure 6. Box plot of the volumetric bone resorption. T2: 6 months postoperatively at implant placement; T3: 1 year after functional loading. Median, minimum, maximum, and standard deviation (*eg, Mann-Whitney U test, U = 712.500, P < .05).
Microtomography views and 3-dimensional reconstruction of a bone sample at 6 months postoperatively. Newly formed bone (blue arrows) and remaining grafted bone (yellow arrows).
Histologic findings (hematoxylin and eosin). Newly formed vital bone (blue arrows) in close contact with the remaining grafted bone (yellow arrows) surrounded by connective tissue containing vessels (black arrows) (original magnification ×10).
Contributor Notes