Block Allograft Research Articles

"Calcaneogenesis" with secondary Achilles tendon-bone allograft for repair of the loss of hindfoot function : A12-year case report

Calcanectomy and Achilles tendon resection are very hard to repair. Ilizarov's "calcaneogenesis" is possible with ankle joint preservation. Even after 3.5years of functio laesa of the triceps surae muscle it can be rebuilt. A25-year-old motorcyclist suffered a3rd degree open calcaneal dislocation fracture (type5). Osteitis and necrosis required calcanectomy, resection of the Achilles tendon and alatissimus dorsi muscle transfer. Atalus corpus osteotomy with Ilizarov distraction created in the 1st step a"neo-calcaneus". In adelayed 2nd step afresh-frozen Achilles tendon-bone block allograft was transplanted to regain active plantar flexion. The initial AOFAS score of 35points was significantly improved to 70points 12years after step1. After both operations the patient could walk without an orthosis and regained 88% of normal plantar flexion strength. Quantitative measure of health outcome according to EQ-5D-5L was marked by the patient with 80out of 100points. "Calcaneogenesis" with preservation of the ankle joint is possible and innovative. Despite 3.5years of disconnection of the triceps surae muscle, an Achilles tendon-bone block allograft could restore 88% of the push-off force even attached to aneo-calcaneus that is 1/3 smaller than normal, which is also new.

Assessment of Autogenous Tooth Dentin Graft with Allogenic Bone Graft in the Preservation of Alveolar Ridge: A Clinicoradiographic Study

Abstract Background: Alveolar ridge is dynamic in nature. Preservation of residual alveolar ridge is always desirable. Bone grafts and platelet concentrates can be used for socket preservation. Maintenance of bone volume is essential and various ridge augmentation techniques are used for desirable functional and esthetic outcomes. Aim: Evaluation and comparison of the efficacy of autogenous dentin block versus allograft block in preserving alveolar ridge dimension with 6-month follow-up. Materials and Methods: Twenty subjects indicated for tooth extraction were randomly divided into three groups. In Group I, autogenous dentin graft with platelet-rich fibrin (PRF) membrane was used as socket filling material, Group II: allogenic bone graft with PRF membrane, or Group III: control group (socket left ungrafted). Clinical and radiographic examinations were done using periodontal probe and cone-beam computed tomography. Results: On intragroup comparison of socket size, the mean for Group I was found to be 33.270 mm2 at baseline and 25.358 mm after 12 months for Group II was found to be 53.250 mm2 at baseline and socket fill was 41.875 mm2 at 12 months. Group III was found to be 43.483 mm2 at baseline, and socket fill was 15.063 mm2 at 12 months. On intergroup comparison, the values were found to be statistically nonsignificant both at baseline (12 months postoperatively. The crestal bone loss was 0.975 for Group I, 1.075 for Group II, and 2.925 mm for Group III. Crestal bone loss was seen highest in Group III and lowest for Group I. The mean percentage of socket fill was found to be 80.01% for Group I, 76.13% for Group II, and 34.03% for Group I. Conclusion: A significant amount of radiographic socket fill was appreciated over 12 months in all the three groups. The percentage of socket fill in Group I was 80.01% and in Group II was 76.13% and the difference between them was statistically nonsignificant. Statistically significant socket fill was seen for both Group 1 and Group 2.

Salvage Reconstruction of a 12-cm Tendon Defect Following Chronic Achilles Rerupture-15-Year Follow-Up: A Case Report.

A 39-year-old man with a chronic Achilles rupture status post (1) failed primary repair and (2) secondary xenograft repair with graft rejection, resulting in a 12-cm Achilles tendon defect, which was reconstructed utilizing an Achilles bone block allograft and flexor hallucis longus (FHL) tendon transfer. At 15-year follow-up, the patient reported good functionality and satisfaction with the repair, with positive patient-reported outcome measures. Physical examination revealed excellent strength and range of motion. Magnetic resonance imaging confirmed the integrity and incorporation of the Achilles/FHL graft composite. This case study provides valuable insight into successful long-term management of complex chronic Achilles ruptures with large defects.

Extensor Mechanism Reconstruction Using Achilles Tendon Allograft With Suture Tape Augmentation

The management of chronic extensor mechanism injuries represents a significant challenge for orthopaedic surgeons, with numerous options for graft choice and fixation construct, but no clear consensus on which technique achieves optimal outcomes. Although there is little published data regarding outcomes of different fixation methods, small case series have demonstrated modest success using Achilles tendon bone block allografts and transverse patellar screw fixation. In this technical note, we describe a surgical technique for the treatment of a chronic inferior pole patella fracture, with extensor mechanism reconstruction using an Achilles tendon allograft with suture tape augmentation. Our technique describes the use of vertical cannulated screws in the patella for passing tape augmentation sutures, increased construct security by suturing of the Achilles graft directly to the quadriceps tendon, and the use of a post screw in the proximal tibia for suture tape augmentation.

Alveolar ridge reconstruction with a digitally customized bone block allograft

AbstractBackgroundReduced alveolar ridge volume is an often consequence after tooth loss, compromising implant placement and prosthetic rehabilitation. The digital customization of bone block allografts (BBA) is an alternative that incorporates advantages such as intimate contact with the recipient bed, increasing graft stability and reduced surgical time. In addition, enamel matrix derivate (EMD) has attracted interest for its effect on osteogenic gene expression and cell adhesion; few studies have focused on the benefits of bone regeneration with EMD. The aim of this case report is to present the reconstruction of a severely atrophic alveolar ridge defect with a digitally customized bone block allograft (CBBA) in combination with EMD as an adjuvant for bone regeneration and soft tissue healing.MethodsInitially, the digital planning and manufacture of the BBA was performed based on an initial cone beam computed tomography (CBCT) scan. EMD was applied to the recipient site and to the CBBA before graft fixation. After 6 months, bone biopsies were obtained on re‐entry surgery for prosthetically guided implant placement.ResultsClinically, bone block showed good integration with the adjacent tissue and no signs of rejection or necrosis were found. On the histological evaluation, new bone was observed in intimate contact with the allograft and showed viable osteocytes and osteoblasts along its entire length. Residual allograft particles were observed to be highly osteoconductive.ConclusionAccording to the clinical and histological results presented, the digital customization of the BBA allows an ideal graft fit to the recipient bed with excellent results in bone regeneration.

Salvage First Metatarsophalangeal Joint Fusion with a Three-Dimensional-Printed Implant for Osseous Defects: A Case Series.

In this study, we aimed to describe a case series of revision first metatarsophalangeal joint fusion with a three-dimensional (3-D)-printed implant for osseous deficits of the first metatarsophalangeal joint. Bone defects of the first ray are a common problem in foot and ankle surgery. Etiologies include nonunion, avascular necrosis, osteomyelitis, failed first metatarsophalangeal joint implant arthroplasty, and failed hemijoint resection arthroplasty. Treatment options include acute shortening, block allograft, block autograft, distraction osteogenesis, vascularized free fibula, Masquelet technique, and partial first-ray amputation. Three-dimensional printing provides an opportunity to improve outcomes, with less donor site morbidity and less extensive recovery time than an external fixation device. It has been used in other facets of foot and ankle surgery with encouraging results. Three patients (four feet) underwent revision first metatarsophalangeal joint fusion with a 3-D-printed implant. Reasons for revision included avascular necrosis after distal metatarsal osteotomy in one patient and bone deficit after failed first metatarsophalangeal joint implant in two patients. All patients had a minimum follow up of 12 months. Two patients had painful hardware and had to undergo revision due to implant design. At most recent follow up all patients were pain free with improved pain scores. In revisional first metatarsophalangeal joint surgery with osseous deficits, the goal is to restore length and alignment, which improves function of the medial column. Custom 3-D-printed implants for first metatarsophalangeal joint revision can provide an opportunity for improved outcomes and healing.

The potential of the mineralized bone allograft block as an appropriate candidate for bone tissue engineering in periodontology

The potential of the mineralized bone allograft block as an appropriate candidate for bone tissue engineering in periodontology

Revision Rates After Primary Allograft ACL Reconstruction by Allograft Tissue Type in Older Patients.

While there is extensive literature on the use of allograft versus autograft in anterior cruciate ligament (ACL) reconstruction, there is limited clinical evidence to guide the surgeon in choice of allograft tissue type. To assess the revision rate after primary ACL reconstruction with allograft and to compare revision rates based on allograft tissue type and characteristics. Cohort study; Level of evidence, 3. Patients who underwent primary allograft ACL reconstructions at a single academic institution between 2015 and 2019 and who had minimum 2-year follow-up were included. Exclusion criteria were missing surgical or allograft tissue type data. Demographics, operative details, and subsequent surgical procedures were collected. Allograft details included graft tissue type (Achilles, bone-patellar tendon-bone [BTB], tibialis anterior or posterior, semitendinosus, unspecified soft tissue), allograft category (all-soft tissue vs bone block), donor age, irradiation duration and intensity, and chemical cleansing process. Revision rates were calculated and compared by allograft characteristics. Included were 418 patients (age, 39 ± 12 years; body mass index, 30 ± 9 kg/m2). The revision rate was 3% (11/418) at a mean follow-up of 4.9 ± 1.4 years. There were no differences in revision rate according to allograft tissue type across Achilles tendon (3%; 3/95), BTB (5%; 3/58), tibialis anterior or posterior (3%; 5/162), semitendinosus (0%; 0/46), or unspecified soft tissue (0%; 0/57) (P = .35). There was no difference in revision rate between all-soft tissue versus bone block allograft (6/283 [2%] vs 5/135 [4%], respectively; P = .34). Of the 51% of grafts with irradiation data, all grafts were irradiated, with levels varying from 1.5 to 2.7 Mrad and 82% of grafts having levels of <2.0 Mrad. There was no difference in revision rate between the low-dose and medium-to high-dose irradiation cohorts (4% vs 6%, respectively; P = .64). Similarly low (0%-6%) revision rates after primary ACL reconstruction were seen regardless of allograft tissue type, bone block versus all-soft tissue allograft, and sterilization technique in 418 patients with mean age of 39 years. Surgeons may consider appropriately processed allograft tissue with or without bone block when indicating ACL reconstruction in older patients.

The Use of Cancellous Block Allografts for Reconstruction and Following Implant Failure Associated with Severe Bone Loss: A Prospective Survival and Histomorphometric Study.

A failed implant site is prone to reduced alveolar bone volume, both horizontally and vertically. The present study assessed the outcome of using cancellous bone block allografts for ridge reconstruction following the removal of failed implants associated with severe bone loss. Individuals presenting with failed implants and massive bone loss were included. Cancellous bone block allografts were used for reconstruction of the atrophic alveolar ridge. Radiographic evaluation at 6 months postgrafting revealed favorable bone healing, allowing implant placement. Bone biopsy samples were taken during implant placement. Twenty-four blocks and 58 implants were placed in 16 patients. Over a mean follow-up time of 40 ± 15 months, the mean bone gain was 5 ± 0.5 mm horizontally and 7 ± 0.5 mm vertically. Block and implant survival rates were 96% (1 block failed) and 95% (3 implants failed), respectively. Histomorphometrically, the mean percentage of newly formed bone was 40%, with 20% residual cancellous block allograft and 40% marrow and connective tissue. Cancellous bone block allograft is a viable treatment alternative for reconstructing the alveolar ridge to achieve a successful second reimplantation, even in the presence of initial severe bone loss.

Quadriceps Tendon Reconstruction With Achilles Tendon Bone Block Allograft

Chronic quadriceps tendon ruptures are relatively uncommon albeit debilitating injuries to the knee extensor mechanism. Previous literature demonstrates worse reported outcomes with delayed surgical intervention, and no gold-standard technique currently exists for managing chronic quadriceps tendon ruptures. The goal of this technique is to provide orthopaedic surgeons an additional option that may provide a greater mechanical load to failure and greater allograft acceptance for cases with large tendon gapping or poor tissue quality that may not be viable to other lengthening techniques. We describe the repair of a chronic quadriceps tendon rupture using an Achilles tendon bone block allograft.

Osseointegration and Remodeling of Mineralized Bone Graft Are Negatively Impacted by Prior Treatment with Bisphosphonates.

Bisphosphonates limit resorption by inhibiting osteoclast formation and activation. They are removed during preparation of demineralized bone matrix (DBM) particles, but it is not known if osteogenesis and incorporation of mineralized bone allografts from patients treated with oral bisphosphonates are affected in vivo. Human block allografts from 3 bisphosphonate-treated donors and 3 age and sex-matched control donors who had not received bisphosphonates were obtained (Musculoskeletal Transplant Foundation); one-half from each donor was demineralized. In the first study, 3 × 2-mm mineralized and demineralized cylindrical grafts were implanted bilaterally in the femoral metaphysis of 56 rats. In the second study, samples from each group were pooled, prepared as particles, and implanted bilaterally in the femoral marrow canal of 24 rats. Osseointegration, defined as native bone in contact with allograft, was assessed at 10 weeks by micro-computed tomography (CT) and histomorphometry. Micro-CT showed greater bone volume in sites treated with demineralized samples compared with the control mineralized and bisphosphonate-exposed mineralized samples. More new bone was generated along the cortical-endosteal interface compared with mineralized samples. Histology showed significantly less new bone in contact with the mineralized bisphosphonate-exposed allograft (10.4%) compared with mineralized samples that did not receive bisphosphonates (22.8%) and demineralized samples (31.7% and 42.8%). A gap was observed between native bone and allograft in the bisphosphonate-exposed mineralized samples (0.50 mm 2 ). The gap area was significantly greater compared with mineralized samples that did not receive bisphosphonates (0.16 mm 2 ) and demineralized samples (0.10 and 0.03 mm 2 ). Mineralized allografts were osseointegrated, but not remodeled or replaced by living bone, preventing full regeneration of the bone defect. Prior treatment of the donor with bisphosphonates affected osteogenesis, preventing osteointegration and remodeling of the allograft into the regenerating bone. Clinical use of mineralized allografts from patients who had received bisphosphonate therapy needs to be evaluated; in this animal model, such grafts were not integrated into the host bone or remodeled, and full regeneration of the bone defects was prevented.

Bone allograft block using demineralized freeze-dried bone ring technique in Indian patients.

Our study aimed to evaluate the effectiveness of the bone ring technique for ridge augmentation using Demineralized Freeze - Dried Bone Allograft block in Siebert's class II/class III defects along with simultaneous implant placement. A total of 15 partially edentulous patients (16 surgical sites) with Siebert's class II and/or class III defects in the anterior region of both jaws requiring ridge augmentation along with implant placement were selected. Starting from the first stage, surgery (Ridge augmentation+ implant placement) was done in the first month. Then, with continuous follow-ups and radiographic assessment, after 6 months of 2nd stage surgery was done, the implant was loaded with the final restoration. Significant results were revealed with all the parameters other than keratinized gingival and peri-implant mucosa thickness. With the mean bone resorption of 1.22 mm and 1.17 mm at the mesial and distal site at a 6-month interval, the success rate of the bone ring technique was 93.75%. The allograft bone ring technique showed a favorable outcome for the reconstruction of large vertical defects.

Achilles Tendon-Bone Block Allograft for Massive Rotator Cuff Tears With Bony Deficiency of the Greater Tuberosity: A Minimum 2-Year Follow-up Study.

Background:Massive rotator cuff tears associated with greater tuberosity bone loss are challenging to treat. Repairing the rotator cuff without addressing the greater tuberosity deficiency may result in poorer clinical outcomes.Hypothesis:Utilizing an Achilles tendon–bone block allograft to address both the massive rotator cuff tear and greater tuberosity bone loss concurrently can result in improved clinical outcomes.Study Design:Case series; Level of evidence, 4.Methods:The authors performed a retrospective study of patients treated between January 2011 and December 2018 with Achilles tendon–bone block allograft for massive rotator cuff tears associated with greater tuberosity bone loss. The inclusion criteria were massive rotator cuff tear and bony deficiency of the greater tuberosity; patients with a history of bony metabolism disease, connective tissue disease, and previous surgery to the wrist or elbow of the affected limb were excluded. Range of motion, visual analog scale for pain, Constant score, and Single Numeric Assessment Evaluation score were assessed preoperatively and at a minimum of 2 years postoperatively. Radiographs and ultrasound images were evaluated to assess allograft union and rotator cuff integrity.Results:Five patients (3 male and 2 female; mean age, 54.0 ± 12.2 years) were included in the study. The mean follow-up was 80.6 ± 33.7 months. Preoperative to postoperative values improved significantly on the visual analog scale (from 45.8 ± 25.5 to 14.5 ± 14.1; P = .04), Constant score (from 36.8 ± 7.9 to 73.5 ± 3.1; P < .001), and Single Numeric Assessment Evaluation score (from 42.5 ± 26.3 to 82.5 ± 10.4; P = .04). Forward flexion improved significantly from 53° ± 47° to 149° ± 17° (P = .03). Four of the 5 patients achieved bony union. One patient required removal of symptomatic hardware at 6 months postoperatively, and 1 patient required revision surgery at 1 year postoperatively because of progressive osteonecrosis of the humeral head.Conclusion:In patients with massive rotator cuff tears and a greater tuberosity bony deficiency, utilizing an Achilles tendon–bone block allograft to restore the bony defect and reinforce the rotator cuff repair was safe and effective. At a minimum of 2 years postoperatively, most patients demonstrated improved clinical outcomes, tendon healing, and graft incorporation.

The Use of Bone Block Allografts for Vertical Augmentation of the Extremely Atrophic Mandible.

Treatment alternatives based on implant-supported prostheses (ISPs) may be almost impossible in cases with extremely atrophic mandibles. Vertical bone augmentation is then the only possibility to achieve an ISP. The consequences of vertical augmentation in extremely atrophic mandibles (≤ 10-mm bone height) of edentulous patients using allogeneic block grafts via a submental approach were assessed. The recorded parameters were sex, age, physical status, hospitalization duration, postoperative complications, implant characteristics (length, diameter), early and late implant failure (yes/no; primary outcome variable). Bone height was measured at three points using the pre-grafting and pre-implant placement CBCT imaging. The difference between the measurements was defined as bone gain (primary outcome variable). Sixteen patients (2 men, 14 women) were included. The preoperative bone height ranged from 4 to 10 mm. A mean of 5.3 ± 1 months was allowed for graft consolidation. The average bone height gain was 11.2 ± 3.1 mm. Two to six dental implants were placed in the grafted bone. Early implant failure occurred in 4 out of 73 (5.5%). Follow-up ranged from 12 to 92 (mean: 48 ± 30) months. All patients were followed for more than a year, and two additional late implant failures were recorded, rendering a 92% cumulative survival rate. Bone grafting using allogeneic bone blocks via a submental approach seems to be a promising solution for reconstruction of the extremely atrophic mandible.

Ridge Augmentation Comparing a Cancellous Block Allograft to an Osteoinductive Demineralized Bone Matrix Allograft: A Randomized, Controlled, Blinded Clinical Trial.

Twenty-six patients with a horizontal ridge defect were entered into this 4-month randomized, controlled, blinded clinical trial to compare a cancellous block allograft to a demineralized bone matrix (DBM) allograft for ridge augmentation. Six patients were excluded from the study, leaving 20 for data interpretation. Both groups had a xenograft overlay and a collagen membrane. For the Block group there was a significant gain of 4.8 ± 1.9 mm (P = .00002; 95% confidence interval [CI]: 3.49 to 6.21), while the DBM group gained 4.6 ± 2.4 mm (P = .0002; 95% CI: 2.88 to 6.36). Vertical change was minimal for both groups (P > .05). The Block group had a mean of 40% vital bone while the DBM group had 35%.

Histomorphometrical Assessment of Sinus Augmentation Using Allograft (Particles or Block) and Simultaneous Implant Placement

The aim of the present study was to compare the clinical, radiological and histomorphometrical outcome of simultaneous implant placement following augmentation of atrophic maxillary sinuses using allograft (block or particles). Consecutive patients with maxillary residual alveolar ridge height ≤3 mm, scheduled for sinus floor augmentation with simultaneous implant placement, were randomly included. Allograft bone-block or bone-particles served as grafting material. Simultaneously, dental implants were inserted. Biopsies were taken at second stage surgery (after 9 months) for histomorphometric evaluation. Initially 38 sinus augmentations (29 individuals) were allocated for the study. In 4 out of 21(19%) sinuses using particles it was impossible to stabilize the implants and a second stage insertion was preferred, leaving 34 sinuses for histomorphometric evaluation. The difference in the ability to perform simultaneous implant placement was statistically significant (p < 0.05). Ninety implants were inserted simultaneously. All implants osseointegrated. None of the implants was lost up to the end of follow-up time (Range 50–120 months, Mean 74.5 ± 13.5 months). Bone gain radiographically 12.3 ± 1 mm vs. 11.2 ± 1 mm (block vs. particles respectively) and new bone formation histomorphometrically 27.7 ± 15% vs. 32.1 ± 19% (block vs. particles respectively) showed no statistically significant differences between the two groups. Sinus augmentation using allograft (particles or block) and simultaneous implant placement is predictable. All outcome parameters are similar when sinus bone-blocks augmentation is compared to bone-particles augmentation (radiological new bone gain, implant survival, hisomorphometricly new bone formation) despite the ability to stabilize implants, when placed simultaneously with sinus augmentation. Blocks may be advisable when simultaneous implant placement is imperative in cases with residual alveolar bone height ≤3 mm.

How to Prevent Mandibular Lower Border Notching After Bilateral Sagittal Split Osteotomies for Major Advancements: Analysis of 168 Osteotomies

Mandibular ramus bilateral sagittal split osteotomy (BSSO) has been the most commonly used technique in orthognathic surgery for mandibular advancement. However, a common complication of BSSO has been the occurrence of visible and palpable osseous defects at the inferior border of the mandible. The aim of the present study was to determine whether bone grafting of the osseous defect at surgery would reduce the defect at 1year postoperatively compared with no bone grafting. The present retrospective cohort study evaluated patients who had undergone mandibular ramus BSSO for 10mm or more of advancement. The primary predictor variable was BSSO surgery with bone grafting of the defect (graft group [GG]) versus no bone graft (no graft group [NGG]). The size of the mandibular ramus inferior border defect was the outcome variable considered within the framework of a 1-year postoperative cone beam computed tomography (CBCT) analysis. Gender, age, and the amount of advancement were also considered in the multilevel regression analyses. From January 2012 to November 2016, 84 patients (168 osteotomies) had undergone BSSO surgery with 10mm or more of mandibular advancement at the Facesurgery Center (Parma, Italy). Their mean age was 27.4years (range, 17 to 44years). Of the 84 patients, 40 had undergone BSSO with bilateral bone grafts (GG). The monocortical block of the iliac crest bone was used as the bone homograft. The final residual defect was measured at 1year postoperatively on CBCT scans. The GG and NGG had presented with a mean final defect of 0.7mm (range, 0 to 4.5mm) and 3.0mm (range, 0 to 5.5mm), respectively. Complete absence of the defect was achieved in 72% of the osteotomies in the GG and 9% of the osteotomies in the NGG. The use of an iliac crest bone allograft block in the gap between 2 segments during mandibular advancement of 10mm or more substantially reduced the size and incidence of inferior border defects.

Reconstruction of Interimplant Papilla by Demineralized Freeze-dried Bone Allograft Block Fixed by Titanium Screw in Maxillary Esthetic Zone

To evaluate effectiveness of demineralized freeze-dried bone allograft (DFDBA) block fixed by titanium screw for reconstructing interimplant papilla in maxillary esthetic zone during one-stage early loading multiple implant procedure. A total of 20 implants were placed in 10 systemically healthy patients (2 implants per patient) for replacement of multiple teeth by early loading one-stage implants along with interimplant papilla reconstruction using DFDBA block fixed by titanium screw. At the baseline, 6 months, and at 1 year, clinical measurements (interimplant papillary height measurement, papilla contour) and radiographic measurements were recorded. At 1 year, mean gain in interimplant vertical crestal bone was 1.7 mm, and complete reconstruction of the papilla was observed in 90% cases. Demineralized freeze-dried bone allograft block fixed by titanium screw for reconstruction of interimplant papilla in maxillary esthetic zone during one-stage early loading multiple implant procedure is effective. Presence of interimplant papilla is of utmost importance for esthetically successful implant-supported restoration in the anterior region. This technique leads to reconstruction of interimplant papilla, thus providing esthetic appearance.

Acellular mineralized allogenic block bone graft does not remodel during the 10 weeks following concurrent implant placement in a rabbit femoral model.

Due to bone loss, endosseous implants often require addition of a bone graft to support adequate primary fixation, bone regeneration, and osseointegration. The aim of this study was to compare effectiveness of autogenic and allogenic bone grafts when used during simultaneous insertion of the implant. 4-mm-diameter rabbit diaphyseal bone autografts or allografts (n=16/group) with a 3.2-mm pre-drilled hole in the center were placed into a 4mm defect in the proximal femur of 3.5kg male New Zealand White rabbits. Machined 3.2×10mm grit-blasted, acid-etched titanium-aluminum-vanadium (Ti6Al4V) implants were placed. Control implants were placed into progressively drilled 3.2-mm holes in the contralateral limbs. Post-insertion day 70, samples were analyzed by micro-CT and calcified histology, or by mechanical torque and push-out testing followed by decalcified histology. Both grafts were integrated with the native bone. Micro-CT showed less bone volume (BV) and bone volume/total volume (BV/TV) in the allograft group, but histology showed no differences in BV or BV/TV between groups. Allograft lacked living cells, whereas autograft was cellularized. No difference was found in maximum removal torque between groups. Compressive loading at the graft-to-bone interface was significantly lower in allograft compared with autograft groups. There was less bone in contact with the implant and significantly less maximum compressive load in the allograft group compared with autograft. The allograft remained acellular as demonstrated by empty lacunae. Taken together, block allograft implanted simultaneously with an implant produces a poorer quality bone compared with autograft.

Anterior atrophic mandible restoration using cancellous bone block allograft.

Bone block grafting may be required to restore the alveolar process prior to implant placement in Kennedy Class IV partial edentulism of the anterior mandible. Evaluate the application of allograft cancellous bone blocks for the augmentation of the anterior atrophic mandible. Fourteen consecutive patients underwent augmentation with cancellous bone block allografts in the anterior mandible. A bony deficiency of at least 3 mm horizontally and up to 3 mm vertically according to computerized tomography para-axial reconstruction served as inclusion criteria. Following 6 months, 26 implants were placed and a cylindrical sample core was collected. All specimens were prepared for histological and histomorphometrical examination. The rehabilitation scheme was two dental implants, placed in the lateral incisor area, supporting a 4-unit implant-supported prosthesis. Twenty-four blocks were placed in 14 patients. Mean follow-up was 26 ± 17 months. Mean bone gain was 5 ± 0.5 mm horizontally, and 2 ± 0.5 mm vertically. Twenty-six implants were used. Marginal bone loss at last follow up did not extend beyond the first thread. Block and implant survival rates were 91.6% and 100%, respectively. All patients but one received a fixed implant-supported prosthesis. Histomorphometrically, the mean fraction of the newly formed bone was 42%, that of the residual cancellous block-allograft 17%, and of the marrow and connective tissue 41%. The potential of cancellous bone block allografts for reconstruction of Kennedy Class IV partial edentulism in the anterior mandible seems promising but still has to be evaluated scientifically in long-term observations.