Graft Volume Maintenance Research Articles

Comparative Analysis of Bone Regeneration According to Particle Type and Barrier Membrane for Octacalcium Phosphate Grafted into Rabbit Calvarial Defects.

This animal study was aimed to evaluate the efficacy of new bone formation and volume maintenance according to the particle type and the collagen membrane function for grafted octacalcium phosphate (OCP) in rabbit calvarial defects. The synthetic bone substitutes were prepared in powder form with 90% OCP and granular form with 76% OCP, respectively. The calvarial defects were divided into four groups according to the particle type and the membrane application. All specimens were acquired 2 weeks (n = 5) and 8 weeks (n = 5) after surgery. According to the micro-CT results, the new bone volume increased at 2 weeks in the 76% OCP groups compared to the 90% OCP groups, and the bone volume ratio was significantly lower in the 90% OCP group after 2 weeks. The histomorphometric analysis results indicated that the new bone area and its ratio in all experimental groups were increased at 8 weeks except for the group with 90% OCP without a membrane. Furthermore, the residual bone graft area and its ratio in the 90% OCP groups were decreased at 8 weeks. In conclusion, all types of OCP could be applied as biocompatible bone graft materials regardless of its density and membrane application. Neither the OCP concentration nor the membrane application had a significant effect on new bone formation in the defect area, but the higher the OCP concentration, the less graft volume maintenance was needed.

Injectable Prevascularized Mature Adipose Tissues (iPAT) to Achieve Long-Term Survival in Soft Tissue Regeneration.

Soft tissue regeneration remains a challenge in reconstructive surgery. So far, both autologous fat implantations and artificial implants methods used in clinical applications lead to various disadvantages and limited lifespan. To overcome these limitations and improve the graft volume maintenance, reproducing a mature adipose tissue already including vasculature structure before implantation can be the solution. Therefore, injectable prevascularized adipose tissues (iPAT) are made from physiological collagen microfibers mixed with human mature adipocytes, adipose-derived stem cells, and human umbilical vein endothelial cells, embedded in fibrin gel. Following murine subcutaneous implantation, the iPAT show a higher cell survival (84% ± 6% viability) and volume maintenance after 3 months (up to twice heavier) when compared to non-prevascularized balls and liposuctioned fat implanted controls. This higher survival can be explained by the greater amount of blood vessels found (up to 1.6-fold increase), with balanced host anastomosis (51% ± 1% of human/mouse lumens), also involving infiltration by the lymphatic and neural vasculature networks. Furthermore, with the cryopreservation possibility enabling their later reinjection, the iPAT technology has the merit to allow noninvasive soft tissue regeneration for long-term outcomes.

Effect of amount of biomaterial used for maxillary sinus lift on volume maintenance of grafts.

BackgroundRegardless of the kind of biomaterial used for the graft, it is clear that, over time, the graft undergoes dimensional changes that could influence the final bone volume obtained, which could alter the stability of the installed implants. The aim of the present study was to compared and correlated the graft behavior with the amount (in grams) of xenogeneic and alloplastic biomaterials used in grafts for maxillary sinus lift. Material and MethodsThis retrospective cohort study used 148 CBCT images of 74 grafts from 68 maxillary sinuses lift patients in a university, post-graduate clinic. The weights of biomaterials, categorized in intervals according to amount used, were correlated with the graft volumes at V1 (10 days) and V2 (180 days). Kruskal-Wallis test was used to evaluate the possible bias effect of weight on graft maintenance. ResultsMean weights of biomaterials used were: Bio-Oss Small® (1.58g); Bio-Oss Large® (1.35g); Endobon® (0.72g); BoneCeramic®+Emdogaim® (0.96g); Cerasorb® (1.13g) and Osteogen® (2.70g). No significant differences (p>0.05). Were found for the influence of these mean amounts in graft maintenance: Bio-Oss Small® (18); Bio-Oss Large® (10); Endobon® (17); BoneCeramic®+Emdogaim® (10); Cerasorb® (11); and Osteogen® (08) at V1 and V2. However, when biomaterials were categorized by intervals, all Cerasorb® interval groups showed statistically significant differences (p<0.001) in graft volume at V2. ConclusionsThe amounts of the biomaterials used could influence the final volume; depending on the biomaterial characteristics. Implant installation was possible with all studied grafts, although graft volume shrinkage should be considered when selecting biomaterial for sinus lift. Key words:Biocompatible materials; cone beam computed tomography; maxillary sinus; hydroxyapatites.

Effect of biomaterial weight on volume maintenance of grafts used for maxillary sinus lift

Effect of biomaterial weight on volume maintenance of grafts used for maxillary sinus lift

The Addition of Platelet-Rich Plasma to Facial Lipofilling: A Double-Blind, Placebo-Controlled, Randomized Trial.

Lipofilling is a treatment modality to restore tissue volume, but it may also rejuvenate the aging skin. Platelet-rich plasma has been reported to augment the efficacy of lipofilling, both on graft take and rejuvenation, by altering the adipose-derived stem cells. The authors hypothesized that addition of platelet-rich plasma would increase the rejuvenating effect and shorten recovery time. The study conducted was a single-center, double-blind, placebo-controlled, randomized trial (2012 to 2015). In total, a well-defined cohort of 32 healthy female patients enrolled in the study, with 25 completing the follow-up. All patients underwent aesthetic facial lipofilling with either saline or platelet-rich plasma added. Outcome was determined by changes in skin elasticity, volumetric changes of the nasolabial fold, recovery time, and patient satisfaction during follow-up (1 year). Platelet-rich plasma did not improve the outcome of facial lipofilling when looking at skin elasticity improvement, graft volume maintenance in the nasolabial fold. Reversal of the correlation between age and elasticity, however, might suggest a small effect size, and thus might not be significant with our small study population. This randomized, double-blind, placebo-controlled study clearly has shown that platelet-rich plasma significantly reduces postoperative recovery time but does not improve patient outcome when looking at skin elasticity, improvement of the nasolabial fold, or patient satisfaction. The reversal of the correlation between age and elasticity might indicate some effect on skin but requires more power in future studies. Therapeutic, II.

Use of autogenous bone and beta-tricalcium phosphate in maxillary sinus lifting: a prospective, randomized, volumetric computed tomography study

The correction of bone defects can be performed using autogenous or alloplastic materials, such as beta-tricalcium phosphate (β-TCP). This study compared the changes in bone volume (CBV) after maxillary sinus lifting using autogenous bone (n=12), autogenous bone associated with β-TCP 1:1 (ChronOS; DePuy Synthes, Paoli, CA, USA) (n=9), and β-TCP alone (n=11) as grafting material, by means of cone beam computed tomography (CBCT). CBV was evaluated by comparing CBCT scans obtained in the immediate postoperative period (5–7 days) and at 6 months postoperative in each group using OsiriX software (OsiriX Foundation, Geneva, Switzerland). The results showed an average resorption of 45.7±18.6% for the autogenous bone group, 43.8±18.4% for the autogenous bone+β-TCP group, and 38.3±16.6% for the β-TCP group. All bone substitute materials tested in this study presented satisfactory results for maxillary sinus lifting procedures regarding the maintenance of graft volume during the healing phase before the insertion of implants, as assessed by means of CBCT.

Morphological Features of Cell Death and Tissue Remolding of Fat Grafts

Fat tissue graft has been commonly used for soft tissue augmentation. However, the mechanisms underlying the maintenance of graft volume and weight are still unclear. As morphological features provide direct evidences for cell death and survival, we aimed to investigate the fate of grafted adipocytes and the dynamic changes in the remodeling of adipose tissues by transmission electron microscopy technique. The unilateral inguinal fat pad of C57BL/6J mice was autografted to the dorsa of the mice. Perilipin expression and morphological changes were investigated by immunohistochemistry staining and transmission electron microscopy, respectively, in grafted tissues collected at posttransplantation days 0, 1, 3, 5, 7, 14, and 30. Transmission electron microscopy analysis revealed that most adipocytes in grafts showed traits of cell death on postgrafting day 3. Multilocular adipocytes with naive nuclei were observed as early as day 5 and a larger number of multilocular adipocytes were found on day 14. Perilipin immunostaining revealed that only some adipocytes located in the margin of grafts survived through the ischemic injury. New adipocytes were visualized at the periphery of the grafts, although the scope of viable adipocyte zonal areas increased from day 5 to day 30. The results provide ultrastructural evidences associated with the remodeling dynamics of adipose tissue grafts. It is suggested that maximized volume of graft should be obtained through promoting regeneration other than improving survival of grafted adipose tissues.

Platelet-Rich Plasma Greatly Potentiates Insulin-Induced Adipogenic Differentiation of Human Adipose-Derived Stem Cells Through a Serine/Threonine Kinase Akt-Dependent Mechanism and Promotes Clinical Fat Graft Maintenance

The potential plasticity and therapeutic utility in tissue regeneration of human adipose-derived stem cells (ASCs) isolated from adult adipose tissue have recently been highlighted. The use of autologous platelet-rich plasma (PRP) represents an alternative strategy in regenerative medicine for the local release of multiple endogenous growth factors. Here we investigated the signaling pathways and effects of PRP and human recombinant insulin on proliferation and adipogenic differentiation of ASCs in vitro. PRP stimulated proliferation (EC(50) = 15.3 ± 1.3% vol/vol), whereas insulin's effect was the opposite (IC(50) = 3.0 ± 0.5 μM). Although PRP alone did not increase adipogenesis, in association with insulin it prevented ASC proliferative arrest, greatly enhanced intracytoplasmic lipid accumulation, strongly increased serine/threonine kinase Akt phosphorylation and mouse monoclonal anti-sterol regulatory element binding protein-1 accumulation, and downregulated Erk-1 activity; adipogenic effects were markedly prevented by the Akt inhibitor wortmannin. PRP with insulin synergistically upregulated fibroblast growth factor receptor (FGFR) and downregulated epidermal growth factor receptor (ErbB) expression; moreover, PRP in association prevented insulin-induced insulin-like growth factor-1 receptor and insulin receptor downregulation. The inhibition of FGFR-1, epidermal growth factor receptor (EGFR), and epidermal growth factor receptor-2 (ErbB2) activity reduced ASC proliferation, but only that of FGFR-1 reduced adipogenesis and Akt phosphorylation, whereas the ErbB2 inhibition effects were the opposite. However, EGFR activity was needed for ErbB2-mediated inhibition of ASC adipogenesis. Clinically, the injection of insulin further ameliorated patients' 1-year PRP-induced fat graft volume maintenance and contour restoring. Our results ascertain that PRP in association with insulin greatly potentiates adipogenesis in human ASCs through a FGFR-1 and ErbB2-regulated Akt mechanism. The ameliorated clinical fat graft maintenance suggests additional useful translational applications of combined PRP-insulin treatment in regenerative medicine.

Healing of onlay mandibular bone grafts covered with collagen membrane or bovine bone substitutes: A microscopical and immunohistochemical study in the sheep

The objective of this study was to evaluate the role of collagen membrane and Bio-Oss ® coverage in healing of an onlay graft to the mandible. Twelve adult sheep each received an onlay bone graft (experiment 1), bone graft + Bio-Gide ® (experiment 2), and bone graft + Bio-Oss ®/Bio-Gide ® (experiment 3) on the lateral surface of the mandible. The animals were euthanized at 4, 8, 12 or 16 weeks after surgery, and findings were analysed by routine microscopy and immunohistochemistry for proliferation (Ki67) and apoptotic (Caspase-3) markers. Grafts were fully incorporated in all specimens. Pronounced resorption was observed in experiment 1. Minimal loss of graft volume was seen in experiment 2 specimens without membrane displacement. A remarkable increase in the augmented region of the mandible was observed in experiment 3. A high number of osteoclasts were expressed within the grafts during the early healing period, and thereafter declined markedly. Osteoblasts within the grafts expressed a moderate level of Ki67 at 8 weeks, which thereafter declined markedly. The strongest expression of Caspase-3 on the bone surface was observed after 16 weeks. In conclusion, the effect of collagen membrane coverage on bone graft volume maintenance was dependent on membrane stability during healing. An autogenous bone graft covered with Bio-Oss ® particles resulted in a remarkable increase in augmented lateral surface of the mandible. The late stage of bone graft healing was associated with a high apoptotic induction pathway of osteoblasts lining the surfaces of the new bone, demonstrated by strong positive Caspase-3 immunoreactivity.

S212: Bone Grafting for Implant Site Preparation

The survival of implants depends on the quantity and quality of bone around the implant. This lecture describes harvesting techniques and the effective use of ramus, tibia and iliac crest bones to increase the quality and quantity of bone for implant site preparation in an office setting. Case selection will be discussed to improve success rate of the grafts and minimize morbidity of the donor sites. This lecture presents four key points for more predictable and successful bone grafting. A review of bone healing physiology will enable the clinician use autogenous bone more effective and maximize the graft volume maintenance. This lecture discusses when, where and how to use cancellous, cortical and corticocancellous bones. Instruments requirement and techniques of harvesting ramus, tibia and iliac crest will be discussed in details. Technology that makes harvesting bone simpler will be discussed. Anesthetic techniques which make these procedures feasible for the office will be emphasized.

Bone Grafting for Implant Site Preparation

The survival of implants depends on the quantity and quality of bone around the implant. This lecture describes harvesting techniques and the effective use of ramus, tibia and iliac crest bones to increase the quality and quantity bone for implant site preparation in an office setting. Case selection will be discussed to improve success rate of the grafts and minimize morbidity of the donor sites. This lecture presents four key points for more predictable and successful bone grafting. A review of bone healing physiology will enable the clinician use autogenous bone more effective and maximize the graft volume maintenance. This lecture discusses when, where and how to use cancellous, cortical and corticocancellous bones. Instruments requirement and techniques of harvesting ramus, tibia and iliac crest will be discussed in details. Technology that makes harvesting bone simpler will be discussed.

Lipotransfer as an adjunct in head and neck reconstruction.

To present our technique of lipotransfer and to evaluate a single center's experience in the use of lipotransfer as an adjunct to head and neck reconstruction. A retrospective review of all patients undergoing lipotransfer over a 5-year period by the senior author was undertaken. A total of 23 patients with a minimum follow-up of 1 year were available for analysis. Patient records were retrospectively reviewed to assess functional (in the case of palate augmentation) and esthetic outcomes. Twenty-three patients undergoing lipotransfer as part of their reconstructive effort included (1) eight patients undergoing temporal fossa augmentation following temporalis muscle flap reconstruction for extirpative skull base surgery, (2) six patients undergoing facial defect augmentation following traumatic atrophy, (3) three patients undergoing palatal augmentation for correction of velopharyngeal insufficiency, and (4) six patients undergoing soft tissue augmentation following flap reconstruction of the face. Twenty of the 23 patients had excellent maintenance of graft volume. An adequately vascularized recipient bed appears to be an important factor in determining ultimate graft survival using our technique. Lipotransfer of the head and neck represents a simple, effective adjunctive technique providing for large amounts of readily available, well-tolerated soft tissue filler material. Patient selection is important, specifically in regard to determining that there is adequate vascularity of the recipient bed.

The use of cancellous bone for frontal sinus obliteration and reconstruction of frontal bony defects.

The objective of this report is to review our experience and indications for the use of cancellous bone in frontal sinus obliteration and reconstruction of frontal defects. We also describe a method of minimizing iliac crest donor-site morbidity. Case series. Patients treated on the Facial Plastics and Trauma Service at the University of Cincinnati (Ohio) Medical Center. Ten patients were selected for frontal sinus obliteration and reconstruction of frontal defects with cancellous bone based on the following criteria: (1) complex frontal bony defects involving the frontal sinus; (2) acute trauma with loss or comminution of more than 40% of either anterior or posterior sinus wall; and (3) failure of previous frontal sinus obliteration for either chronic sinusitis or trauma. The use of cancellous bone grafts for frontal sinus obliteration and reconstruction of frontal defects. Success of cancellous bone grafts in frontal sinus obliteration and reconstruction of frontal defects. Follow-up averaged 26 months. Follow-up computed tomographic scans showed good maintenance of graft volume and complete frontal sinus obliteration in all patients. Seven of 10 patients reported minimal donor-site discomfort and three patients had moderate pain. Cancellous bone grafts are effective, with acceptable donor-site morbidity, for frontal sinus obliteration and frontal reconstruction in patients in whom adipose grafts would have a significant chance of complications or long-term failure.

Effects of nerve growth factor on craniofacial onlay bone graft survival: preliminary findings.

A study was undertaken to evaluate the effects of nerve growth factor (NGF), which had previously demonstrated bone formation around mandibular nerve regenerates, on resorption of onlay bone grafts to the rabbit skull. Iliac grafts were onlayed on the parietal bone bilaterally and immobilized with wire ligatures in 15 animals. NGF and a control solution were introduced into the grafts through subcutaneous osmotic pumps. After 60 days, graft survival was compared by weights, histology, and fluorochrome labels. NGF-treated grafts were characterized by an average of 88.4% weight retention, preservation of the outer cortical plate with firm fixation to the underlying calvarium, and fluorescent labels localized to the inner cortex. Conversely, control grafts had an average weight retention of 42.8% (p < 0.01), nearly complete outer cortical plate loss with increased mobility of the residual inner cortex, and a lack of fluorescence in any part of the grafts. Despite the incongruous name, NGF exhibited a beneficial effect on onlay bone graft volume maintenance in this study. Although the mechanism and the long-term effects are unknown, inhibition of graft resorption rather than enhancement of bone formation is suggested.

Fixation effects on membranous and endochondral onlay bone-graft resorption.

Difficulties arise in the prediction of maintenance of graft volume over time when bone grafts are used for facial contour reconstruction. We hypothesize that graft fixation will decrease movement and lead to decreased resorption. Fixed and nonfixed endochondral (rib) and membranous (skull) onlay bone grafts measuring 30 X 10 X 4 mm were grafted to the mandible bilaterally in 10 adult sheep. Fixation was achieved using the lag-screw technique. Volume measurements using caliper technique were made 20 weeks postoperatively. The volume of graft present at 20 weeks was significantly greater for the fixed bone grafts (p less than 0.001): fixed membranous, 85.9 percent; fixed endochondral, 76.2 percent; nonfixed membranous, 55 percent; and nonfixed endochondral, 16.6 percent. The results are explained using biomechanical theories related to the effects of strain. At present, it is suggested by this study that when onlay bone grafts are stabilized, improved results with respect to graft resorption can be expected.