Comparative in vitro study of four commercial biomaterials used for bone grafting.

PURPOSE: This work aimed to study and compare the behavior of macrophages and human osteoclast-like cells cultured in contact with four commercial bone substitute materials used as graft for ridge augmentation techniques. Two materials are of natural origin and two are synthetic bone substitutes. METHODS: Macrophage activation and cytokine release were assessed using SEM analysis and a sandwich ELISA kit while the activity of human osteoclast-like cells was studied quantifying calcium released from the substrata studied together with SEM analysis of cell morphology and pit formation on the bone substitutes. RESULTS: Hydroxyapatite proved to be the greatest macrophage activator, while the bovine derived material turned out to be the only bone substitute that does not induce macrophages to release IFNγ. No material had direct induction of osteoclast precursor differentiation even if mature osteoclasts showed the highest activity on the human derived material followed by bone ceramic, while the bovine derived material was the substrate with the least osteoclast activity. CONCLUSIONS: The four materials reacted differently with the cells tested and between them, the bovine derived bone, being the lowest macrophage and osteoclast activator may be considered a good bone substitute for clinical situations requiring greater time of permanence of the material at the site of implantation, while human derived bone will be more suitable for clinical applications that require lower time of permanence.

Chondrogenic induction of human mesenchymal stem cells using combined growth factors for cartilage tissue engineering.

The objective of this study was to evaluate whether growth factors (FGF-2, FGF-4 and FGF-6) used alone or in combination with TGFß2 are able to increase the proliferation and induce the differentiation of human bone marrow mesenchymal stem cells (hMSCs) to chondrocytes, with a view to using them in cartilage tissue engineering. Cells cultured in monolayer, used to test the activity of the growth factors on cell proliferation, showed that a combination of FGFs with TGFß2 increases cell proliferation compared to cells cultured in control medium or in the presence of growth factors alone. The chondrogenic potential, evaluated in three-dimensional (3D) cell aggregates, showed that FGF-2 and FGF-6, when used in combination with TGFß2 increased the size and glycosaminoglycan content of the cell aggregates without increasing cell number. Extracellular matrix (ECM) also showed higher collagen type II immunoreactivity, which was particularly evident in an area similar to a germinative pole that was observed only in pellets cultured with FGF-2 and FGF-6 combined with TGFß2, or in pellets cultured with FGF-2 alone. Moreover, the RT-PCR assay has highlighted an increased expression of collagen type II and Sox9, used as gene markers for chondrogenesis. We can conclude that combinations of FGF-2 or FGF-6 with TGFß2 may provide a novel tool to induce the differentiation of adult human mesenchymal stem cells for applications in cartilage tissue engineering.

Flap design for guided tissue regeneration surgery in the esthetic zone: the "whale's tail" technique.

The aim of this paper was to describe a new surgical technique designed to preserve interdental tissue in guided tissue regeneration. This procedure was created to specifically regenerate wide intrabony defects in the esthetic zone. Fourteen subjects with an intraosseous defect in the maxillary incisor region took part in this clinical study. The defects were treated with bioresorbable membranes in combination with a bovine bone mineral graft. At baseline and at 12 months after surgery, the following clinical parameters were measured: full-mouth plaque scores, full-mouth bleeding scores, probing pocket depths, clinical attachment levels, and gingival recession. A significant gain in clinical attachment level (4.57 +/- 0.65 mm) and a reduction in probing depths (5.14 +/- 0.95 mm) were reported 12 months after surgery. The surgical technique allowed complete flap closure in every treated site, resulting in significant improvement of the clinical parameters; thus, it appeared especially appropriate for the treatment of wide defects in the esthetic zone.

A novel multiphase anodic spark deposition coating for the improvement of orthopedic implant osseointegration: an experimental study in cortical bone of sheep.

The effect of a new three-step anodic spark deposition process, labeled TiSpark, including two consecutive treatments performed first in a P solution and second in Ca solution, followed by an additional alkali etching step, was investigated for the improvement of osseointegration of commercial grade 2 titanium, machined (Ti) or Al(2)O(3) sandblasted (Ti-SA), cylindrical implants (12 mm in length and 4 mm in diameter) in cortical bone of 12 adult sheep. Histomorphometric and microhardness measurements were carried out at each experimental time (4, 8, and 12 weeks) to quantify the bone-to-implant contact around the implants as well as the newly bone hardness and bone maturation index. TiSpark treated surfaces were covered by a thick layer of crystalline anatase TiO(2) and by a further Ca/P layer. Bone tissue extends and grows on the surface of the TiSpark treated implants without any fibrous tissue, enhancing the short-term osseointegration properties of implant. Bone mineralization rate was also influenced by the chemical composition of implants and sandblasted materials presented the lowest bone maturation rate at the interface. Data suggests that the TiSpark treatment produces a modification of the Ti surface, which presents good bioactivity and may be suitable for achieving a stable implant osseointegration.

Atrophic mandible reconstruction using calvarial bone grafts and implant-supported overdentures: radiographic assessment of autograft healing and adaptation.

Bone grafting constitutes a vital surgical procedure in the management of severely atrophic mandibles. In this regard, calvarial bone autografts are applied in the reconstruction of wide mandibular defects caused by edentulousness and long-term denture-related resorption. Grafts are used as a framework to augment the residual ridge and provide implant stability for further prosthetic restoration. On the basis that radiographic evidence corresponds to biologic changes in bone response to transplantation and loading, the goal of this article is to document the radiographic assessment of calvarial autologous bone grafts in the recipient site. Panoramic radiographs were used to evaluate bone changes occurring during both the graft healing period and graft adaptation after implant loading. Emerging data show that conventional panoramic radiography may have an effect on the investigation of bone grafts and provide initial information about graft incorporation and adaptation.

Single-tooth replacement by immediate implant and connective tissue graft: a 1-9-year clinical evaluation.

OBJECTIVES: The aim of the present study was to evaluate the long-lasting efficacy of a combined surgical protocol, using immediate implant and subepithelial connective tissue graft for single-tooth replacement. The advantages of this single-center, longitudinal, randomized, blind examiner research were the following: preservation of both keratinized mucosa amount and bone tissue, optimal peri-implant marginal sealing, satisfactory aesthetic results, reduction in treatment time. MATERIALS AND METHODS: In the time period from 1990 to 1998, 116 patients were consecutively admitted for treatment with a total of 116 solid screw ITI-implants supporting single crowns. Ninety-six patients underwent the proposed combined treatment (test group), while 20 received only single immediate implants (control group). The observation time extended from 1 up to 9 years. RESULTS: The 9-year cumulative survival rate was 100% for both test and control groups. Comparative statistical analysis of soft and hard tissue peri-implant parameters demonstrated better results in the test group than in the control during every single 3-year analysis and especially in the last observation interval. The test group also showed very good results in terms of aesthetic parameters, which estimated the keratinized mucosa width, the alignment of crown emergence profile and the patient's satisfaction. CONCLUSION: Single-tooth replacement by immediate solid screw ITI implants in association with connective tissue autograft was demonstrated to be a predictable procedure. Moreover, this treatment can be considered as a sure system to reach an excellent functional and harmonious aesthetic restoration.

Osteoporosis: the effect on maxillary bone resorption and therapeutic possibilities by means of implant prostheses--a literature review and clinical considerations.

Osteoporosis is a systemic disease in which the skeletal condition is characterized by a decreased mass of normally mineralized bone. It is considered the most common metabolic bone disease, and it constitutes a major public health problem. Given the evidence that alveolar processes provide the bony framework for tooth support, the decline of skeletal mass has to be correlated with an increased risk of oral bone loss and has a negative consequence on tooth stability. Data from past research confirm that aging and estrogen depletion have a negative influence on both tooth retention and residual alveolar crest preservation. The goal of the present article is, however, to underline how the morphostructural evolution of the edentulous maxilla is mainly due to mechanical factors as the result of alterations in maxillary function. The advantages of prosthetic rehabilitation supported by osseointegrated implants are also considered, focusing the therapeutic role of this procedure on preserving the residual alveolar ridge from atrophy.

Histologic evaluation of autogenous calvarial bone in maxillary onlay bone grafts: a report of 2 cases.

Bone augmentation for implant dentistry has become a necessary procedure for a number of edentulous patients. Calvarial bone grafting constitutes an important tool in achieving maxillary augmentation and sinus elevation. Much effort has been directed toward improving graft survival and volumetric maintenance. The purpose of the present study was to evaluate the histologic results of the calvarial onlay graft for maxillary reconstruction before implant placement. Two patients underwent maxillary augmentation using autogenous calvarial onlay grafts. After a 4-month healing period, biopsies of the augmented regions were performed and implants were placed. The implants were loaded after 5 months and then clinically examined after 15 months of function. Biopsies showed that calvarial onlay grafts were well incorporated into the preexisting bone after a 4-month period. Histologic and histomorphometric findings demonstrated a living bone that showed features characteristic of mature and compact osseous tissue. The restored Implants were stable and osseointegrated after a 15-month period of follow-up. The use of calvarial onlay grafts can be a predictable and successful method to achieve maxillary augmentation, allowing appropriate placement of implants and stable prosthetic restorations.