Influence of a resorbable collagen membrane for alveolar bone graft on clinical outcomes and ridge volume stability in cleft alveolus.

This study compared the clinical outcomes, graft quality, and graft quantity after alveolar bone grafting with and without a resorbable collagen membrane. Twenty unilateral cleft patients undergoing defect repair with cancellous iliac bone were assigned to either the collagen membrane group (Mb group) or standard group without a membrane (St group). Postoperative pain and swelling, bone density, and bone volume and quality were assessed. The Mb group showed significantly lower postoperative pain than the St group (P < 0.001) and significantly less swelling (P < 0.01) on day 3 postoperative. The reduction in bone density was significantly greater in the St group than in the Mb group at 1 and 3 months postoperative (P ≤ 0.001), but not at 6 months. The reduction in bone volume in the St group was significantly greater than that in the Mb group at 3 months (29.11 ± 6.26% vs 17.67 ± 11.89%, P = 0.016) and 6 months postoperative (40.95 ± 6.81% vs 25.67 ± 11.51%, P = 0.002). Nine cases in the Mb group versus six in the St group showed good bone quality. In conclusion, the collagen membrane facilitated predictable clinical outcomes in bone maturation, bone volume preservation, and bone bridging in the alveolar bone graft.

Effect of osteogenic periosteal distraction by a modified Hyrax device with and without platelet-rich fibrin on bone formation in a rabbit model: a pilot study.

This study evaluated the effect of a modified Hyrax device and platelet-rich fibrin (PRF) on osteogenic periosteal distraction (OPD). Twelve adult male New Zealand white rabbits were separated into two main groups (six in each) according to the duration of the consolidation period (4 or 8 weeks). In each main group, the animals underwent OPD of the left and right sides of the mandible and were divided into four subgroups (three animals per group): device vs. device+PRF, and PRF vs. sham. Radiographic, histological, histomorphometric, and micro-computed tomography (micro-CT) analyses were performed. New bone formation was observed on the lateral and vertical sides of the mandible of all groups. Micro-CT and histomorphometry showed that the device+PRF group presented the highest percentages of bone volume and bone area at 4 weeks (56.67 ± 12.67%, 41.37 ± 7.57%) and at 8 weeks (49.67 ± 8.33%, 55.46 ± 10.67%; significantly higher than the other groups, P<0.001), followed by the device group at 4 weeks (33.00 ± 1.73%, 33.21 ± 11.00%) and at 8 weeks (30.00 ± 3.00%, 23.25 ± 5.46%). In conclusion, the modified Hyrax device was used successfully for OPD in a rabbit model to gain vertical ridge augmentation, and greater bone maturation was achieved with the addition of PRF.

A comparison of autogenous bone graft combined with deproteinized bovine bone and autogenous bone graft alone for treatment of alveolar cleft.

This study assessed the use of composite autogenous bone and deproteinized bovine bone (DBB) for repairing alveolar cleft compared with autogenous bone alone in terms of clinical outcomes and patient morbidity. 30 patients with a mean age of 10.2±1.7 years were randomly divided into two groups. Group I used autogenous cancellous bone graft harvested from the anterior iliac crests by the conventional trapdoor approach. Group II used a composite of DBB and autogenous cancellous bone harvested by a trephine bone collector; the proportion of 1:1 by volume was used. The bone graft quantities of both groups decreased with time. Their average changes were not statistically different over 24 months after grafting. The canines of both groups could spontaneously or orthodontically erupt through the grafting areas. Patients in group II recovered from uncomfortable walking significantly faster than those in group I (p<0.05) and their duration of hospital stay was significantly shorter than those in group I (p<0.05). The average operation time, intra-operative blood loss and postoperative pain were less in group II than in group I (p>0.05).

Proportion of deproteinized bovine bone and autogenous bone affects bone formation in the treatment of calvarial defects in rabbits.

This study assessed new bone formation generated using three different proportions of autogenous bone (AB) and deproteinized bovine bone (DBB). Thirty bicortical skull defects were prepared in 15 rabbits, divided into 3 groups: Group 1, critical size defect (CSD) versus AB as controls; Group 2, DBB versus a composite of AB and DBB using a proportion of 1:1; and Group 3, a composite of AB and DBB using a proportion of 1:2 versus a proportion of 1:4. After 8 weeks, radiographic evaluation was assessed using densitometry and new bone formation by histomorphometry. The mean optical density of the CSD (0.108+/-0.238) and AB (0.352+/-0.161) groups differed significantly from the DBB group (1.044+/-0.093) and the groups using a proportion of 1:1 (0.905+/-0.078), 1:2 (0.865+/-0.294) and 1:4 (0.867+/-0.304). Histomorphometry revealed a higher percentage of new bone in the AB group (30.223+/-16.722) than in the groups using proportions of 1:2 (22.639+/-5.659), 1:1 (20.929+/-6.169), 1:4 (9.621+/-2.400), DBB (14.441+/-2.742) and CSD (10.645+/-8.868), respectively. The 1:2 group had significantly higher bone content than the 1:4 group. The proportions of 1:1 and 1:2 resulted in greater bone formation than the proportion of 1:4, DBB and CSD.

Properties of chitosan-collagen sponges and osteogenic differentiation of rat-bone-marrow stromal cells.

The aim of this study was to further investigate effects of a combined chitosan and collagen matrix on osteogenic differentiation of rat-bone-marrow stromal cells (BMSCs), including analysis of the physical and mechanical properties of the sponges. There were 4 study groups: collagen, chitosan, 1:1 chitosan-collagen and 1:2 chitosan-collagen sponges. Chitosan-collagen sponges were fabricated using the freeze-drying technique. BMSCs were seeded on the sponges and cultivated in mineralized culture medium for 27 days. Attachment and growth of cells on the sponges were examined under a scanning electron microscope. Alkaline phosphatase activity and levels of osteocalcin were monitored. Tests of swelling, collagenase and lysozyme enzymatic degradation, and mechanical strength were performed. The BMSCs attached successfully to the structure of the sponges, and expression of ALP and osteocalcin on collagen and chitosan-collagen composite sponges was greater than on chitosan sponges. All sponges showed a high degree of water uptake. Chitosan and chitosan-collagen sponges showed a higher resistance to enzymatic degradation than collagen sponges. A 1:1 chitosan-collagen sponge demonstrated the highest compressive strength. Combined chitosan-collagen matrixes promoted osteoblastic differentiation of BMSCs, and improved the mechanical and physical properties of the sponges.

Growth and differentiation of mouse osteoblasts on chitosan-collagen sponges.

The aim of this study was to investigate the effects of collagen on the microstructure and biocompatibility of chitosan-collagen composite sponges fabricated by a freezing and drying technique. The study was categorized into four groups: Group I: collagen; Group II: chitosan; Group III: 1:1 (by wt) chitosan-collagen and Group IV: 1:2 (by wt) chitosan-collagen sponges. A mouse osteoblast cell line, MC3T3-E1, was cultivated on the sponges in a mineralized culture medium for 21 days. Microstructure of scaffolds and growth of cells on the sponges were examined using scanning electron and confocal laser scanning electron microscopes. Pore size was analysed from scanning electron microscope images using Image-Pro Plus image analysis software. Cell viability (MTT assay), alkaline phosphatase activity and levels of osteocalcin and calcium were monitored every 3 days and on days 15 and 21, respectively. It was found that the sponges were porous with average pore sizes of 80-100 microm. A combination of chitosan and collagen matrixes created a well defined porous microstructure and biocompatible scaffolds. Chitosan-collagen composite sponges promoted growth and differentiation of osteoblasts into the mature stage. To optimize application of the composite sponges in bone regeneration, the fabrication process must be improved to increase the pore size of the scaffolds.

The use of SPECT to evaluate growth cessation of the mandible in unilateral condylar hyperplasia.

In unilateral condylar hyperplasia, for surgical intervention to be effective, the status of condylar bone growth has to be assessed correctly. Previously this assessment relied on serial clinical observations. This study aimed to evaluate the MDP-SPECT method of assessing condylar growth in unilateral condylar hyperplasia. Twenty-six MDP-SPECT of the mandible had been performed; 21 were diagnosed as condylar hyperplasia and five as non-mandibular disease. Three isotope parameters: isotope counts, pixel counts and counts per pixel were summed for each condyle per subject. The percentage difference in isotope uptake of the three parameters between the two condyles was calculated as the ratio of the combined counts of the two sides. These differences significantly correlated with each other (Pearson r=0.78-0.98) and with the clinical status of bone growth (Spearman rho=0.72-0.86). There was a significant difference for the count per pixel between the 'growing' condyle (transaxial, T: 15.05+/-7.14, coronal, C: 12.29+/-7.88), the 'no further growth' condyle (T: 5.22+/-4.08, C: 5.67+/-3.88) and the 'normal' condyle (T: 0.82+/-0.76, C: 1.34+/-0.66). This method was able to separate 'active growth' from 'growth cessation' of the condyle by a single MDP-SPECT of the mandible. However, further studies are needed to confirm this finding.

In situ hybridisation and immunocytochemical localisation of osteolytic cytokines and adhesion molecules in ameloblastomas.

Ameloblastomas produce interleukin-1-like activity that could explain some part of their osteolytic capability. However, the cellular source of this osteolytic activity is unknown. In the present study, cytokines with known inflammatory and osteolytic activity, i.e., interleukin-1 (IL-1), tumour necrosis factor (TNF), and interleukin-6 (IL-6), have been localised by immunocytochemistry and in situ hybridisation. The cellular adhesion receptors ICAM-1, E-selectin and VCAM-1 have also been immunolocalised. Immunocytochemistry demonstrated that all seven specimens showed positive staining for IL-1alpha and IL-6 with these cytokines being located in the stellate reticulum-like cells and vascular endothelium. Very faint staining for IL-1beta was seen in four of seven specimens. No reaction was seen for TNF-alpha. All specimens demonstrated E-selectin staining in the vascular endothelium and ICAM-1 and VCAM-1 staining in the stellate reticulum-like cells and the endothelium. In situ hybridisation for the cytokines showed the presence of mRNA of both IL-1alpha and IL-6 in the stellate reticulum-like cells. Faint staining for IL-1beta was also seen. No staining was seen for TNF. These findings show that ameloblastomas synthesize two bone-modulating cytokines, IL-1alpha and IL-6, and that these are synthesized mainly by the stellate reticulum-like cells. These tumours also contain a proportion of activated blood vessels in which endothelial cells express the cellular adhesion receptors ICAM-1, E-selectin and VCAM-1.