Transalveolar maxillary sinus floor elevation using osteotomes with or without grafting material. Part II: Radiographic tissue remodeling

OBJECTIVES: To evaluate the pattern of tissue remodeling after maxillary sinus floor elevation using the transalveolar osteotome technique with or without utilizing grafting materials. METHODS: During the period of 2000-2005, 252 Straumann dental implants were inserted using the transalveolar sinus floor elevation technique in a group of 181 patients. For 88 or 35% of those implants, deproteinized bovine bone mineral with a particle size of 0.25-1 mm was used as the grafting material, but for the remaining 164 implants, no grafting material was utilized. Periapical radiographs were obtained with a paralleling technique and digitized. Two investigators, who were blinded to whether grafting material was used or not, subsequently evaluated the pattern of tissue remodeling. RESULTS: The mean residual bone height was 7.5 mm (SD 2.2 mm), ranging from 2 to 12.7 mm. The mean residual bone height for implants placed with grafting material (6.4 mm) was significantly less compared with the implants installed without grafting material (8.1 mm). The implants penetrated on average 3.1 mm (SD 1.7 mm) into the sinus cavity. The measured mean radiographic bone gain using the transalveolar technique without grafting material was significantly less, 1.7 mm (SD 2 mm) compared with a mean bone gain of 4.1 mm (SD 2.4 mm), when grafting material was used. Furthermore, the probability of gaining 2 mm or more of new bone was 39.1% when no grafting material was used. The probability increased to 77.9% when the implants were installed with grafting material. CONCLUSION: When the transalveolar sinus floor elevation was performed without utilizing grafting material, only a moderate gain of new bone could be detected mesial and distal to the implants. On the other hand, when grafting material was used, a substantial gain of new bone was usually seen on the radiographs.

Wound models for periodontal and bone regeneration: the role of biologic research

The ultimate goals of periodontal therapy remain the complete regeneration of those periodontal tissues lost to the destructive inflammatory-immune response, or to trauma, with tissues that possess the same structure and function, and the re-establishment of a sustainable health-promoting biofilm from one characterized by dysbiosis. This volume of Periodontology 2000 discusses the multiple facets of a transition from therapeutic empiricism during the late 1960s, toward regenerative therapies, which is founded on a clearer understanding of the biophysiology of normal structure and function. This introductory article provides an overview on the requirements of appropriate in vitro laboratory models (e.g. cell culture), of preclinical (i.e. animal) models and of human studies for periodontal wound and bone repair. Laboratory studies may provide valuable fundamental insights into basic mechanisms involved in wound repair and regeneration but also suffer from a unidimensional and simplistic approach that does not account for the complexities of the in vivo situation, in which multiple cell types and interactions all contribute to definitive outcomes. Therefore, such laboratory studies require validatory research, employing preclinical models specifically designed to demonstrate proof-of-concept efficacy, preliminary safety and adaptation to human disease scenarios. Small animal models provide the most economic and logistically feasible preliminary approaches but the outcomes do not necessarily translate to larger animal or human models. The advantages and limitations of all periodontal-regeneration models need to be carefully considered when planning investigations to ensure that the optimal design is adopted to answer the specific research question posed. Future challenges lie in the areas of stem cell research, scaffold designs, cell delivery and choice of growth factors, along with research to ensure appropriate gingival coverage in order to prevent gingival recession during the healing phase.

Conditioned medium from fresh and demineralized bone enhances osteoclastogenesis in murine bone marrow cultures

OBJECTIVES Osteoclasts rapidly form on the surface of bone chips at augmentation sites. The underlying molecular mechanism, however, is unclear. Soluble factors released from bone chips in vitro have a robust impact on mesenchymal cell differentiation. Whether these soluble factors change the differentiation of hematopoietic cells into osteoclasts remains unknown. METHODS Osteoclastogenesis, the formation of tartrate-resistant acid phosphatase-positive multinucleated cells, was studied with murine bone marrow cultures exposed to RANKL and M-CSF, and conditioned medium from fresh (BCM) and demineralized bone matrix (DCM). Histochemical staining, gene and protein expression, as well as viability assays were performed. RESULTS This study shows that BCM had no impact on osteoclastogenesis. However, when BCM was heated to 85°C (BCMh), the number of tartrate-resistant acid phosphatase-positive multinucleated cells that developed in the presence of RANKL and M-CSF approximately doubled. In line with the histochemical observations, there was a trend that BCMh increased expression of osteoclast marker genes, in particular the transcription factor c-fos. The expression of c-fos was significantly reduced by the TGF-β receptor I antagonist SB431542. DCM significantly stimulated osteoclastogenesis, independent of thermal processing. CONCLUSIONS These data demonstrate that activated BCM by heat and DBM are able to stimulate osteoclastogenesis in vitro. These in vitro results support the notion that the resorption of autografts may be supported by as yet less defined paracrine mechanisms.

Wound stimulation by growth-arrested human keratinocytes and fibroblasts: HP802-247, a new-generation allogeneic tissue engineering product

HP802-247 is a new-generation, allogeneic tissue engineering product consisting of growth-arrested, human keratinocytes (K) and fibroblasts (F) delivered in a fibrin matrix by a spray device.

Improving chondrogenesis: potential and limitations of SOX9 gene transfer and mechanical stimulation for cartilage tissue engineering

Articular cartilage injuries and degeneration affect a large proportion of the population in developed countries world wide. Stem cells can be differentiated into chondrocytes by adding transforming growth factor-beta1 and dexamethasone to a pellet culture, which are unfeasible for tissue engineering purposes. We attempted to achieve stable chondrogenesis without any requirement for exogenous growth factors. Human mesenchymal stem cells were transduced with an adenoviral vector containing the SRY-related HMG-box gene 9 (SOX9), and were cultured in a three-dimensional (3D) hydrogel scaffold composite. As an additional treatment, mechanical stimulation was applied in a custom-made bioreactor. SOX9 increased the expression level of its known target genes, as well as its cofactors: the long form of SOX5 and SOX6. However, it was unable to increase the synthesis of sulfated glycosaminoglycans (GAGs). Mechanical stimulation slightly enhanced collagen type X and increased lubricin expression. The combination of SOX9 and mechanical load boosted GAG synthesis as shown by (35)S incorporation. GAG production rate corresponded well with the amount of (endogenous) transforming growth factor-beta1. Finally, cartilage oligomeric matrix protein expression was increased by both treatments. These findings provide insight into the mechanotransduction of mesenchymal stem cells and demonstrate the potential of a transcription factor in stem cell therapy.

Neocartilage formation in 1 g, simulated, and microgravity environments: implications for tissue engineering

The aim of this study was to analyze and compare the deposition of cartilage-specific extracellular matrix components and cellular organization in scaffold-free neocartilage produced in microgravity and simulated microgravity.

Sleep quality, the neglected outcome variable in clinical studies focusing on locomotor system; a construct validation study

In addition to general health and pain, sleep is highly relevant to judging the well-being of an individual. Of these three important outcome variables, however, sleep is neglected in most outcome studies.Sleep is a very important resource for recovery from daily stresses and strains, and any alteration of sleep will likely affect mental and physical health, especially during disease. Sleep assessment therefore should be standard in all population-based or clinical studies focusing on the locomotor system. Yet current sleep assessment tools are either too long or too specific for general use.

Proliferation, differentiation and gene expression of osteoblasts in boron-containing associated with dexamethasone deliver from mesoporous bioactive glass scaffolds

Boron is one of the trace elements in the human body which plays an important role in bone growth. Porous mesopore bioactive glass (MBG) scaffolds are proposed as potential bone regeneration materials due to their excellent bioactivity and drug-delivery ability. The aims of the present study were to develop boron-containing MBG (B-MBG) scaffolds by sol-gel method and to evaluate the effect of boron on the physiochemistry of B-MBG scaffolds and the response of osteoblasts to these scaffolds. Furthermore, the effect of dexamethasone (DEX) delivery in B-MBG scaffold system was investigated on the proliferation, differentiation and bone-related gene expression of osteoblasts. The composition, microstructure and mesopore properties (specific surface area, nano-pore volume and nano-pore distribution) of B-MBG scaffolds have been characterized. The effect of boron contents and large-pore porosity on the loading and release of DEX in B-MBG scaffolds were also investigated. The results have shown that the incorporation of boron into MBG scaffolds slightly decreases the specific surface area and pore volume, but maintains well-ordered mesopore structure and high surface area and nano-pore volume compared to non-mesopore bioactive glass. Boron contents in MBG scaffolds did not influence the nano-pore size distribution or the loading and release of DEX. B-MBG scaffolds have the ability to maintain a sustained release of DEX in a long-term span. Incorporating boron into MBG glass scaffolds led to a controllable release of boron ions and significantly improved the proliferation and bone-related gene expression (Col I and Runx2) of osteoblasts. Furthermore, the sustained release of DEX from B-MBG scaffolds significantly enhanced alkaline phosphatase (ALP) activity and gene expressions (Col I, Runx2, ALP and BSP) of osteoblasts. These results suggest that boron plays an important role in enhancing osteoblast proliferation in B-MBG scaffold system and DEX-loaded B-MBG scaffolds show great potential as a release system to enhance osteogenic property for bone tissue engineering application.

Quality of reporting of clinical studies to assess and compare performance of implant-supported restorations

The objective of this analysis was to assess and compare the 5- and 10-year survival of different types of tooth-supported and implant-supported fixed dental prostheses (FDPs) and single crowns (SCs), and to describe the incidence of biological and technical complications with emphasis on quality of reporting.

Cartilage tissue engineering for degenerative joint disease

Pain in the joint is often due to cartilage degeneration and represents a serious medical problem affecting people of all ages. Although many, mostly surgical techniques, are currently employed to treat cartilage lesions, none has given satisfactory results in the long term. Recent advances in biology and material science have brought tissue engineering to the forefront of new cartilage repair techniques. The combination of autologous cells, specifically designed scaffolds, bioreactors, mechanical stimulations and growth factors together with the knowledge that underlies the principles of cell biology offers promising avenues for cartilage tissue regeneration. The present review explores basic biology mechanisms for cartilage reconstruction and summarizes the advances in the tissue engineering approaches. Furthermore, the limits of the new methods and their potential application in the osteoarthritic conditions are discussed.

Vertebroplasty and kyphoplasty: a systematic review of 69 clinical studies

STUDY DESIGN: Systematic literature review. OBJECTIVE: To evaluate the safety and efficacy of vertebroplasty and kyphoplasty using the data presented in published clinical studies, with respect to patient pain relief, restoration of mobility and vertebral body height, complication rate, and incidence of new adjacent vertebral fractures. SUMMARY OF BACKGROUND DATA: Vertebroplasty and kyphoplasty have been gaining popularity for treating vertebral fractures. Current reviews provide an overview of the procedures but are not comprehensive and tend to rely heavily on personal experience. This article aimed to compile all available data and evaluate the clinical outcome of the 2 procedures. METHODS: This is a systematic review of all the available data presented in peer-reviewed published clinical trials. The methodological quality of included studies was evaluated, and data were collected targeting specific standard measurements. Where possible, a quantitative aggregation of the data was performed. RESULTS: A large proportion of subjects had some pain relief, including 87% with vertebroplasty and 92% with kyphoplasty. Vertebral height restoration was possible using kyphoplasty (average 6.6 degrees ) and for a subset of patients using vertebroplasty (average 6.6 degrees ). Cement leaks occurred for 41% and 9% of treated vertebrae for vertebroplasty and kyphoplasty, respectively. New fractures of adjacent vertebrae occurred for both procedures at rates that are higher than the general osteoporotic population but approximately equivalent to the general osteoporotic population that had a previous vertebral fracture. CONCLUSIONS: The problem with stating definitely that vertebroplasty and kyphoplasty are safe and effective procedures is the lack of comparative, blinded, randomized clinical trials. Standardized evaluative methods should be adopted.

Enzymatic formation of modular cell-instructive fibrin analogs for tissue engineering

The molecular engineering of cell-instructive artificial extracellular matrices is a powerful means to control cell behavior and enable complex processes of tissue formation and regeneration. This work reports on a novel method to produce such smart biomaterials by recapitulating the crosslinking chemistry and the biomolecular characteristics of the biopolymer fibrin in a synthetic analog. We use activated coagulation transglutaminase factor XIIIa for site-specific coupling of cell adhesion ligands and engineered growth factor proteins to multiarm poly(ethylene glycol) macromers that simultaneously form proteolytically sensitive hydrogel networks in the same enzyme-catalyzed reaction. Growth factor proteins are quantitatively incorporated and released upon cell-derived proteolytic degradation of the gels. Primary stromal cells can invade and proteolytically remodel these networks both in an in vitro and in vivo setting. The synthetic ease and potential to engineer their physicochemical and bioactive characteristics makes these hybrid networks true alternatives for fibrin as provisional drug delivery platforms in tissue engineering.