Girts Salms

Volumetric analysis of implanted biphasic calcium phosphate/collagen composite by three-dimensional cone beam computed tomography head model superimposition.

Facial onlay augmentation is often performed as an ancillary procedure simultaneously with orthognathic surgery to improve facial appearance, with hydroxyapatite (HAp) and HAp-based composites often used as the materials of choice. The ability to apply HAp in a granular rather than solid shape form may be responsible for its comparatively reduced rate of complications. However, a known complication of HAp and HAp composites is reduction of implant volume over time associated with resorption of the material. Evaluation of the volumetric changes of implanted biphasic calcium phosphate (HAp/β-TCP)/collagen composite in the malar areas from baseline to 4 months, 9-12 months, and 18-24 months after surgery using cone beam computed tomography (CBCT) surface superimposition and volumetric subtraction was done. The average decrease of volume of implanted HAp/β-TCP 4 months after surgery was 18.6%. Further volumetric decreases were negligible and a mean total volume loss of 21.65% was found at 18-24 months postoperatively.

3D Cone Beam Radiodensitometry in Evaluation of Hydroxyapatite (HAP)/Tissue Hybrid after Maxillary Sinus Floor Elevation

Clinical and radiological outcomes of one and two stage maxillary sinus floor augmentation with HAP granules and dental implant insertion, degree of mineralization of residual bone and augmented sinus part were evaluated. 180 dental implant insertions in 84 patients in the age from 32-68 years were included in this study. Patient clinical and CBCT (Cone Beam Computer Tomography) were analyzed by quantitative radiodensitometry using HU (Hounsfield units) after 1 to 5 years after functional loading. Four implants were lost during osseointegration phase the 176 implants survived. We found 2.5 times denser synthetic HAP/bone area comparing with residual bone. With time there was a decrease in radiodensity in HAP augmented maxillary sinus area and an increase of radiodensity in the area of residual alveolar bone.

Change of Biomechanical Parameters in the Lower Jaws of Rabbits with Experimental Osteoporosis after Implantation of Calcium-Phosphate Bioceramic Material in the Greater Trochanter Region

Investigation of biomechanical properties of the rabbit bone tissue from a corner of the lower jaw was done. Experimental osteoporosis was induced by ovariectomy and following injections of methylprednisolone. The defects in the greater trochanter region was created and filled with granules of a hydroxyapatite and tricalcium phosphate (HAP/TCP 30/70) or HAP/TCP 30/70 together with 5% strontium ranelate. After 3 month animals were euthanased, squared samples have been cut out from a corner of the lower jaw and tested on a bend. Results of research show, that the corner of a lower jaw in rabbit becomes more rigid after filling of defects in the greater trochanter region with granules of a hydroxyapatite and tricalcium phosphate (HAP/TCP 30/70) or granules together with strontium ranelate. The ultimate strain for the bone tissue in the 2nd and 3rd group is less, than for control group. Thus, local uses calcium – phosphatic bioceramic material around the greater trochanter region improves biomechanical parameters of a bone tissue in the lower jaw of animals.

Autologous Fibrin Mixed with Biphasic Calcium Phosphate Bioceramic Granules Activates Encapsulation in Soft Tissue Environment

The physical, chemical and biological properties of both biphasic calcium phosphate (BCP) bioceramics and fibrin scaffolds may be cumulated for preparing advanced bone substitutes. Aim of experimental study was to evaluate histological response on implantation of synthetic biphasic HAp/TCP bioceramic granules mixed with autologous plasma derived fibrin scaffold in subcutaneous tissue of rabbits.

Reaction of Subcutaneous Connective Tissue of Experimental Animals on Bone Marrow Mesenchymal Stromal Cell Coated Hydroxyapatite

Summary Introduction. Hydroxyapatite (HAp) scaffolds have become an alternative to autologous bone grafts in orthopedic surgery, because it is possible to fill larger scale bone defects and of the decreased operation time and complication risks at the graft donor site, a promising method in bone regeneration is to load bone marrow - mesenchymal stromal cells (BM-MSCs) on to a HAp scaffold. Aim of the Study. The aim of our study is to compare subcutaneous tissue reaction of experimental animals to implantation of HAp and HAp that is coated with BM-MSCs. Materials and Methods. Autologous BM-MSCs were cultivated from crista iliaca dextra biopsy, 4 HAp ceramic implants were coated with BM-MSC and implanted in subcutaneous tissue on one side and non-coated HAp implants on the other side of the spine of 4 rabbits. Immunohistochemical staining of BM-MSC and connective tissue included TUNEL assay, NFkBp105, HSP 70k, Wnt1, TNF-α, VEGF, MMP-2 antibodies, microscoped at 400X magnification and analyzed semiquantitatively. Results. Routine staining with haemotoxilin and eosin demonstrated formation of granulation tissue around the HAp implant, which was more distinct on the control side. There was an increased number of NFκB p105 positive cells (fibroblasts, myocytes, endotheliocytes) on the experimental side (+++), in comparison to the control side (++). HSP70 and apoptosis index was decreased on the experimental side (++ and 60%), in comparison to the control side (+++ and 70%). Number of MMP2 positive structures was increased on the control side in the fibrous capsule (++), in comparison to the experimental side, where the result varied (0 - +) Conclusions. Cultured BM-MSC activity is partly limited due to the apoptosis, which is probably induced by environmental factors. BM-MSC coated HAp implant stimulates secretion of proliferation marker NFkBp105 in subcutaneous tissue, decreases cell stress, apoptosis and tissue degradation (decreased HSP 70, apoptotic cell count and MMP 2) to improve the local tissue quality and proving BM-MSC tissue protective effect

Radiodensitometric Analysis of Maxillary Sinus-Lift Areas Enforced with Bone Substitute Materials Containing Calcium Phophate

Summary Introduction. An enforcement of atrophic maxilla with biomaterials during sinus-lift surgery improves size and quality of alveolar bone. Radiological densitometric analysis can prove it. Within the study a density of bone was investigated and findings were compared with natural bone around the implants. Aim of the Study. Was to determine if density around the implant inserted with one stage sinus-lift operation using bone substitute materials increase and if that can be detected radiologically. Materials and Methods. Totally there were examined 22 patients where 64 implants were inserted in maxilla: 48 implants were inserted with one stage sinus-lift operation using bone substitute materials; represented study group. Sixteen implants were inserted in natural maxillary alveolar bone of the same patients, representing control group. The density of implant supporting tissue was measured with cone beam computed tomography and expressed in Hounsfield units (HU). The measurements were performed according to standardized pattern. Results. Densitometric measurements were higher in the study group than in the control group in all points, but statistically significant difference was observed in two measurement sites: buccally in sinus elevation area (BSM) (p=0.005) and palatinally in sinus elevation area (PSM) (p=0.0012), and corresponding areas in control group. Conclusions. Surgical elevation of maxillary sinus floor using calcium phosphate bone substitute materials resulted in higher optical density compared to natural bone. Mineralization of the bone, induced by the bone substitute materials, can be detected radiologically

Time-dependent cytokine expression in bone of experimental animals after hydroxyapatite (Hap) implantation

Proinflammatory cytokines mediate bone loss around the implants in patients with peri-implant disease. However, there is no complete data about the expression of cytokines into the bone around the implants. The aim of this work was to investigate the distribution and appearance of inflammatory cytokines and anti-inflammatory proteins in the bone of jaw of experimental rabbits in different time periods after HAp implantation. Material was obtained from 8 rabbits in lower jaw 6 and 8 months after HAp implants were placed. Tissues were processed for immunohistochemical detection of tumor necrosis factor alfa (TNFα), Interleukin 1, 6, 8, 10 (IL-1, IL-6, IL-8, IL-10) and defensin 2. Results demonstrated practically unchanged expression of IL-6 and IL-10 between both – experimental and control side 6 months after implantation, while IL-1 and IL-8 notably increased in control side. IL-1 and IL-10 expression did not change in either the experimental side nor the controle side after 8 months HAP implantation, but IL-6 and IL-8 demonstrated a decrease in the control sites. Only IL-8 was elevated with time in experimental sites, while IL-10 showed individual variations in 2 cases.

Clinical, Radiographic and Pathohistological Outcomes of Hydroxyapatite (HAp) Ceramics and Dental Implants in Atrophic Posterior Maxilla

Clinical, Radiographic and Pathohistological Outcomes of Hydroxyapatite (HAp) Ceramics and Dental Implants in Atrophic Posterior Maxilla Introduction. Implant based prosthodontic rehabilitation of patients with atrophic edentulous posterior maxilla has necessity in reinforcement of alveolar bone using different bone substitutes. It is important to evaluate late outcomes in integration of synthetic HAp as biomaterial in chemical composition close to main natural bone mineral component in elevated maxillary sinus floor and osseointegration of dental implants. Aim of the study. To evaluate clinical and radiological outcomes of one stage maxillary sinus floor augmentation with synthetic HAp granules and dental implant insertion, mineralization degree of residual bone and augmented sinus part, morphological analysis of biopsies from HAp/host tissue hybrid and residual alveolar bone was performed. Materials and methods. One stage maxillary sinus floor elevation with synthetic HAp granules and 147 SEMADOS (BEGO) dental implant insertions in 70 patients were included in this study. Clinical and radiograph analyzes by dental X-rays, digital orthopantomogramms, quantitative radiodensitometry after 3 and 5 years was done. Trephine biopsies of residual alveolar bone and elevated part of maxillary sinus 6 months after implantation was done in 30 cases. Results. During this period 6 implants (4.2%) were lost. We found the decrease of radiodensity in HAp augmentated maxillary sinus area and increase of radiodensity in the area of residual alveolar bone. In biopsies after 6 months biomaterial/host tissue hybrid consisted of small bone trabecules, fibrous tissue and granules of irregular shape without inflammatory cells. Slow degradation of HAp granules by activity of osteoclast like macrophages was observed. Conclusions. Osseointegration was lost in 4.2% of inserted in augmented maxillary sinus implants. Radiodensitometry showed decrease of optical density in augmented sinus part and increase in residual alveolar bone. In biopsies of host tissue/biomaterial hybrid was bone newformation, connective tissue and biodegradation of HAp granules by osteoclast like cells.

Reactogenicity of Synthetic Hydroxyapatite (HAp) Ceramic Materials Implanted in Rabbits Jaws

Experimental comparing of morphofunctional changes in implant contact tissue with same tissue involved in surgical intervention of same manner without insertion of artificial materials can clarify specific reactogenicity of implant and/or material. To evaluate early reactogenicity of porous synthetic HAp ceramic implants inserted in holes of rabbit upper jaw assessment of inflammatory response and regeneration in contact bone and soft tissue using histological and immunohistochemical methods was done. Our results demonstrated stimulation of TGFs and FGFR1 in bone after HAp implantation indicating possible osseoinductive role for the same Hap implants. Also moderate apoptosis and rich expression of FGFR1 in connective tissue around HAp implants commonly indicated intensive regeneration ability of the soft tissue with such cell death type that does not cause the fibrotic changes. Neuropeptide-containing innervation was not involved in healing processes after HAp implantation.

DRUG INFILTRATION IN POROUS HYDROXYAPATITE CERAMIC AND TISSUE RESPONSE

ABSTRACT Sintered porous hydroxyapatite (HAp) ceramics were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), optical and scanning electron microscopy (SEM). The samples were saturated with dexamethasone solution (1 mg/ml) or lidocaine solution (5 mg/ml) using vacuum method. To evaluate early reactogenity of porous synthetic impregnated HAp ceramic implants were inserted in holes of rabbits lower jaws for 2 weeks, 1 month and 3 months. Immunohistochemical methods for evaluation of growth factors and apoptosis were applied. This study aims to further comprehension of reactogenicity of HAp bioceramic implants as bone substitutes in subperiostal environment.