Comparative osteogenesis of maxilla and iliac crest human bone marrow stromal cells attached to oxidized titanium: a pilot study

Objectives: Severe alveolar bone loss affects dental implant placement. Bone augmentation by grafting iliac crest bone rich in osteoprogenitor cells such as bone marrow stromal cells (BMSCs) requires a second surgical procedure in non‐orofacial bone. Skeletal site‐specific osteogenesis indicates maxilla and mandible BMSCs are highly proliferative and exhibit osteogenic properties superior to iliac crest BMSCs. Alveolar bone can be easily obtained during routine dental surgery, but it is unclear if titanium‐attached alveolar BMSCs will retain their superior osteogenic properties. This study evaluated and compared in vitro osteogenic properties of titanium‐attached maxilla and iliac crest BMSCs in same individuals. Material and methods: Primary culture of maxilla and iliac crest BMSCs from four normal healthy volunteers was expanded in culture. In 24‐well plates, first passage BMSCs were seeded directly (1 × 10⁴ cells/well) on oxidized titanium disks (1.27 cm diameter and 2 mm thickness) or tissue culture plate. Each cell type was assessed for affinity for titanium, post‐attachment survival and osteogenic differentiation based on alkaline phosphatase and osteopontin expressions. Results: There was no difference in the affinity of maxilla and iliac crest BMSCs to titanium. However, titanium‐attached maxilla BMSCs were apparently more osteogenically responsive than iliac crest cells based on calcium accumulation and gene expression of alkaline phosphatase and osteopontin. But these differences were not statistically significant in this small patient sample. Conclusion: Maxilla and iliac crest BMSCs have similar attachment affinity for titanium. This pilot study indicates that titanium‐attached maxilla BMSCs are more osteogenically responsive and may be a viable and more readily available donor graft material in implant dentistry.     

Immunohistochemical characterization of guided bone regeneration at a dehiscence-type defect using different barrier membranes: an experimental study in dogs

Objectives: The aim of the present study was to evaluate immunohistochemically the pattern of guided bone regeneration (GBR) using different types of barrier membranes. Material and methods: Standardized buccal dehiscence defects were surgically created following implant bed preparation in 12 beagle dogs. Defects were randomly assigned to six different GBR procedures: a collagen‐coated bone grafting material (BOC) in combination with either a native, three cross‐linked, a titanium‐reinforced collagen membrane, or expanded polytetrafluorethylene (ePTFE), or BOC alone. After 1, 2, 4, 6, 9, and 12 weeks of submerged healing, dissected blocks were processed for immunohistochemical (osteocalcin – OC, transglutaminase II – angiogenesis) and histomorphometrical analysis [e.g., bone‐to‐implant contact (BIC), area of new bone fill (BF)]. Results: In general, angiogenesis, OC antigen reactivity, and new bone formation mainly arose from open bone marrow spaces at the bottom of the defect and invaded the dehiscence areas along the implant surface and BOC. At 4 weeks, membranes supporting an early transmembraneous angiogenesis also exhibited some localized peripheral areas of new bone formation. However, significantly increasing BIC and BF values over time were observed in all groups. Membrane exposure after 10–12 weeks was associated with a loss of the supporting alveolar bone in the ePTFE group. Conclusion: Within the limits of the present study, it was concluded that (i) angiogenesis plays a crucial role in GBR and (ii) all membranes investigated supported bone regeneration on an equivalent level.     

Acellular dermal matrix as a barrier in guided bone regeneration: a clinical, radiographic and histomorphometric study in dogs

Objectives: The purpose of this study was to evaluate the effectiveness of the acellular dermal matrix (ADM) as a membrane for guided bone regeneration (GBR), in comparison with a bioabsorbable membrane.
Material and methods: In seven dogs, the mandibular pre-molars were extracted. After 8 weeks, one bone defect was surgically created bilaterally and the GBR was performed. Each side was randomly assigned to the control group (CG: bioabsorbable membrane made of glycolide and lactide copolymer) or the test group (TG: ADM as a membrane). Immediately following GBR, standardized digital X-ray radiographs were taken, and were repeated at 8 and 16 weeks post-operatively. Before the GBR and euthanasia, clinical measurements of the width and thickness of the keratinized tissue (WKT and TKT, respectively) were performed. One animal was excluded from the study due to complications in the TG during wound healing; therefore, six dogs remained in the sample. The dogs were sacrificed 16 weeks following GBR, and a histomorphometric analysis was performed. Area measurements of new tissue and new bone, and linear measurements of bone height were performed.
Results: Post-operative healing of the CG was uneventful. In the TG membrane was exposed in two animals, and one of them was excluded from the sample. There were no statistically significant differences between the groups for any histomorphometric measurement. Clinically, both groups showed an increase in the TKT and a reduction in the WKT. Radiographically, an image suggestive of new bone formation could be observed in both groups at 8 and 16 weeks following GBR.
Conclusion: ADM acted as a barrier in GBR, with clinical, radiographic and histomorphometric results similar to those obtained with the bioabsorbable membrane.     

The use of a new bioresorbable barrier for guided bone regeneration in connection with implant installation. Case reports.

This report presents 4 cases with 6 implant exposures after the installation of Bråemark System® implants which called for treatment applying the guided bone regeneration technique. A bioresorbable barrier (GUIDOR® Matrix Barrier) was used to cover the defects, 4 defects with and 2 without the support of autologous bone chips. Complete bone filling was found in 4 (2 without and 2 with bone chips) and partial filling in 2 (with bone chips) of the treated defects, as registered at the abutment connection 6–7 months after surgery. Besides its ability to serve as a barrier for guided bone regeneration, it was found that the matrix barrier had the following properties; biocompatibility observed as uneventful tissue healing, malleability facilitating the clinical handling and ability to be resorbed within 6 to 7 months, as evaluated by clinical inspection. The observations of the present case reports indicate that the tested barrier may be used for guided bone regeneration in connection with implant installation. It is advisable, however, to use a supporting material to prevent barrier collapse, although bone regeneration can be achieved in certain situations without such material if the defect morphology is favourable.     

Role of periosteum in the formation of jaw bone

Abstract The aim of the present investigation was to evaluate the bone-forming capacity of the outer (fibrous) and inner (cambium) layer of the mandibular periosteum in skeletally mature rats. The experiment was carried out in 25 rats. The mandibular ramus was exposed on one side (experimental side) after elevation of a muscle-periosteal flap. A teflon capsule was placed with its opening facing the periosteum at the subsurface of the raised muscle-periosteal flap after suturing. In the contralateral side serving as control, the periosteum of the lateral aspect of the mandibular ramus was left intact. This time the teflon capsule was placed with its opening facing the periosteum left behind at the ramus. The histological analysis demonstrated that in all experimental and control specimens, some bone was produced at 7 days after operation. In the experimental specimens, however, both the incidence and the amount of newly-formed bone in the teflon capsules gradually decreased from 7 to 120 days, while increasing in the control capsules placed over the periosteum. At 120 days, the mean amount of new bone produced in the experimental capsules was 3% (range 0–15%) of the total space created by the capsule, while it was 68% (range 41–85%) for the control capsules. The results demonstrated that substantial amounts of bone can be produced predictably by the placement of an occlusive teflon capsule facing mandibular covered with periosteum. Bone produced from the periosteum and without continuity with existing bone becomes resorbed with time.     

A comparative study of barrier membranes as graft protectors in the treatment of localized bone defects. An experimental study in a canine model

Guided bone regeneration is a predictable and well-documented surgical approach for the treatment of deficient alveolar ridges prior to endosseous implant placement. The purpose of this study was to compare a new resorbable membrane (GORE RESOLUT ADAPT Regenerative Membrane, i.e. 67% glycolide (PGA) : 33% trimethyline carbonate (TMC)) with Bio-Gide, a resorbable collagen membrane. Five canines were used in the study. Three saddle-type osseous defects were created bilaterally in edentulous areas of the mandible. The defects were filled with assayed, canine demineralized freeze-dried bone (DFDB) in a thermoplastic gelatin matrix. Using a randomized block design, four sites were covered with PGA : TMC membranes of four different porosities, one site was covered with a collagen membrane and one site consisted of DFDB alone (control). At 3 months, the animals were euthanized and the mandibles were removed en bloc for laboratory processing. A total of 30 sites were reviewed microradiographically and underwent histomorphometric analysis for bone regeneration, soft tissue presence and remaining graft material. All sites exhibited uneventful healing. A significantly higher percentage of bone regeneration was seen in the sites protected by the PGA : TMC membrane. A higher component of soft tissue was visible beneath the collagen membrane as compared with the PGA : TMC membrane. The control sites exhibited noticeable deformation of the regenerated bone secondary to collapse of the overlying periosteum. The authors conclude that the PGA : TMC membrane protected the DFDB-filled defect and allowed a greater amount of bone regeneration than the defect protected by the collagen membrane or the control.     

Effect of barrier membranes and autologous bone grafts on ridge width preservation around implants

Background: The purpose of this study was to explore the effect of barrier membranes and autologous bone grafts on the preservation of ridge width around implants. Materials and Methods: Sixty‐one patients were chosen from a database of case series; treatment assignment was based on clinical judgment. The patients received a total of 76 implants:34 implants with guided tissue regeneration procedures, 27 with autologous bone grafts, and 15 without ridge preservation procedures (control group). Results: The ridge width around the 76 implants decreased an average of 1.4 mm (95% CI, ‐1.9 to‐1.1 mm). Implants placed with autologous bone grafts or membranes tended to have worse outcomes. When compared to the no augmentation group, implants placed with guided tissue regeneration and autologous bone grafts resulted in 0.1 mm of additional bone loss (95% CI, ‐1.7 to ‐1.5 mm; p <.93) and 0.8 mm of additional bone loss (95% CI, ‐2.3 to 0.7 mm; p <.28), respectively. Conclusions: Autologous graft procedures or barrier membranes do not appear to improve crestal ridge preservation around implants.     

Role of chitin beads in the formation of jaw bone by guided tissue regeneration. An experiment in the rat

It has been reported that local application of bone grafts or synthetic bone substitutes (filler materials) may favour bone formation when used in combination with guided tissue regeneration (GTR). Therefore, the aim of the present investigation was to evaluate the effect of application of chitin beads (a bioabsorbable natural polymer) as a bone substitute in bone formation by GTR. The experiment was carried out in 25 rats. The mandibular ramus was exposed on one side after elevation of a muscle-periosteal flap, and a teflon capsule filled with chitin beads (2.0 mm in diameter) was placed with its opening facing the lateral aspect of the ramus. On the contralateral side of the jaw, serving as control, an empty teflon capsule was placed in the same manner. Groups of 5 animals were sacrificed at 7, 15, 30, 60 and 120 days following capsule placement. Histological analysis demonstrated that the amount of newly formed bone was similar in both experimental and control specimens, amounting to approximately 3% of the central/largest, cross-sectional area created by the capsule at 15 days, and to approximately 9% of this area at 30 days following capsule placement. At 60 and 120 days, however, the amount of newly formed bone observed in the control specimens was twice as large as that observed in the test specimens, amounting to approximately 31% of the cross-sectional area created by the capsule at 60 days, and to approximately 45% at 120 days. It is concluded that, although chitin beads (2.0 mm in diameter) are biocompatible, their presence retards bone formation in the model system used.     

引导骨再生屏障膜改良的研究进展

引导骨再生术是解决骨组织缺损问题的重要技术,引导骨再生屏障膜在其中发挥着不可替代的作用。引导骨再生膜是防止成纤维细胞进入骨缺损部位的屏障,同时可促进成骨细胞的黏附、增殖和骨组织再生。由于目前广泛应用于引导骨再生的胶原膜尚存在一些缺陷,探索具有更优良性质的引导骨再生屏障膜成为一个重要的课题。因此出现了从抗菌性的改良、成骨性的改良和新材料的研发等多方面的努力以改良引导骨再生膜。本文回顾了近年来引导骨再生膜改进的研究成果和进展,展望了未来相关研究的发展方向,为进一步展开骨再生及修复的相关研究工作提供参考。     

引导骨再生屏障膜改良的研究进展

引导骨再生术是解决骨组织缺损问题的重要技术,引导骨再生屏障膜在其中发挥着不可替代的作用。引导骨再生膜是防止成纤维细胞进入骨缺损部位的屏障,同时可促进成骨细胞的黏附、增殖和骨组织再生。由于目前广泛应用于引导骨再生的胶原膜尚存在一些缺陷,探索具有更优良性质的引导骨再生屏障膜成为一个重要的课题。因此出现了从抗菌性的改良、成骨性的改良和新材料的研发等多方面的努力以改良引导骨再生膜。本文回顾了近年来引导骨再生膜改进的研究成果和进展,展望了未来相关研究的发展方向,为进一步展开骨再生及修复的相关研究工作提供参考。     

Bioactivation of alumina by surface modification: a possibility for improving the applicability of alumina in bone and oral repair

Objectives: In regenerative medicine, surface engineering of bioinert synthetic materials is often required in order to introduce bioactive species that can promote cell adhesion, proliferation, viability and enhanced ECM-secretion functions. The aim of this work is to study cell interaction with alumina-modified surfaces.
Material and methods: In this work, chemical properties of alumina surface were changed by a reaction at the surface of alumina with low molecular weight dicarboxylic acid, which produced carboxyl groups.
Results: These carboxyl groups were able to complex with Ca²⁺ on the surface, forming sites of precipitation for calcium phosphates that make alumina biocompatible, as indicated by cell culture of pre-osteoblasts (MC3T3-E1 cell line).
Conclusions: The procedure presented in this work shows that the insertion of specific functional groups on the surface of alumina increases cell interaction with the surface of alumina. This knowledge can be important in oral science and orthopedics, for the construction of prosthesis.