Effect of total body irradiation on peri-implant tissue reaction: an experimental study (original) (raw)
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Analysis of the effects of irradiation in osseointegrated dental implants
2012
Objective: The purpose of the present study was to evaluate the influence of radiation in osseointegrated dental implants installed in tibiae of rats. Material and methods: Screw-shaped implants (2.5 mm diameter by 3.5 mm length) were custom made from commercially pure titanium bars. Titanium implants were blasted and sterilized before
Systemic and local effects of radiotherapy: an experimental study on implants placed in rats
Clinical Oral Investigations, 2019
Objectives Evaluate the modulating effect of ionizing radiation, blood cytokine levels, and bone remodeling of the interface around the implant to understand the radiation mechanisms which can impair the implants receptor site. Material and methods Sixty rats were submitted to grade V titanium implants in the femurs and were divided into the following groups: no-irradiation (N-Ir): control group with implant only; early-irradiation (E-Ir): implant + irradiation after 24 h; lateirradiation (L-Ir): implant + irradiation after 4 weeks; and previous-irradiation (P-Ir): irradiation + implant after 4 weeks. The animals in the E-Ir, L-Ir, and P-Ir groups were irradiated in two fractional stages of 15 Gy. At 3 days, 2 weeks, and 7 weeks after the final procedure, five animals were randomly euthanized per group. Serum levels of TNF-ɑ, IL-1β, TGF-β, IL-6, M-CSF, and IL-10 were measured from blood collected prior to euthanasia using the ELISA test. The pieces containing the implants were subjected to immunohistochemical labeling using the tartrate acid resistant to phosphatase, osteocalcin, and caspase-3 markers and mCT. The ANOVA test was used for statistical analysis, and the Tukey multiple comparison test (p < 0.05) was applied. Results The results indicated that ionizing radiation modifies the production of pro-and anti-inflammatory serum cytokines, the expression of proteins involved in bone remodeling and cellular apoptosis, as well as changes in bone formation. Conclusions The results suggests that a longer period between radiotherapy and implant placement surgery when irradiation occurs prior to implant installation would allow the recovery and renewal of bone cells and avoid future failures in osseointegration. Clinical relevance The search for modifications caused by ionizing irradiation in bone tissue can indicate the ideal period for implant placement without affecting the osseointegration process.
Journal of Applied Oral Science, 2020
Biomechanical and morphological changes produced by ionizing radiation on bone tissue surrounding dental implant Objective: This study analyzed the effect of ionizing radiation on bone microarchitecture and biomechanical properties in the bone tissue surrounding a dental implant. Methodology: Twenty rabbits received three dental morse taper junction implants: one in the left tibia and two in the right tibia. The animals were randomized into two groups: the nonirradiated group (control group) and the irradiated group, which received 30 Gy in a single dose 2 weeks after the implant procedure. Four weeks after the implant procedure, the animals were sacrificed, and the implant/bone specimens were used for each experiment. The specimens (n=10) of the right tibia were examined by microcomputed tomography to measure the cortical volume (CtV, mm 3), cortical thickness (CtTh, mm) and porosity (CtPo, %). The other specimens (n=10) were examined by dynamic indentation to measure the elastic modulus (E, GPa) and Vickers hardness (VHN, N/mm 2) in the bone. The specimens of the left tibia (n=10) were subjected to pull-out tests to calculate the failure load (N), displacement (mm) up to the failure point and interface stiffness (N/mm). In the irradiated group, two measurements were performed: close, at 1 mm surrounding the implant surface, and distant, at 2.5 mm from the external limit of the first measurement. Data were analyzed using one-way ANOVA, Tukey's test and Student's t-test (α=0.05). Results: The irradiated bone closer to the implant surface had lower elastic modulus (E), Vickers hardness (VHN), Ct.Th, and Ct.V values and a higher Ct.Po value than the bone distant to the implant (P<0.04). The irradiated bone that was distant from the implant surface had lower E, VHN, and Ct.Th values and a higher Ct.Po value than the nonirradiated bone (P<0.04). The nonirradiated bone had higher failure loads, displacements and stiffness values than the irradiated bone (P<0.02). Conclusion: Ionizing radiation in dental implants resulted in negative effects on the microarchitecture and biomechanical properties of bone tissue, mainly near the surface of the implant.
Influence of irradiation on the osteoinductive potential of demineralized bone matrix
Calcified Tissue International, 1988
Samples of demineralized bone matrix (DBM) were exposed to graduated doses of radiation (1-15 Megarad) (Mrad) utilizing a linear accelerator and then implanted into the thoracic region of Long-Evans rats. Subcutaneous implantation of DBM into allogenic rats induces endochondral bone. In response to matrix implantation, a cascade of events ensues; mesenchymal cell proliferation on day 3 postimplantation, chondrogenesis on day 7, calcification of the cartilagenous matrix and chondrolysis on day 9, and osteogenesis on day 11 resulting in formation of an ossicle containing active hemopoietic tissue. Bone formation was assessed by measuring alkaline phosphatase activity, the rate of mineralization was determined by measuring 45Ca incorporation to bone mineral, and 4~ content measured the extent of mineralization; acid phosphatase activity was used as a parameter for bone resorption. The dose of radiation (2.5 Mrad) currently used by bone banks for sterilization of bone tissue did not destroy the bone induction properties of DBM. Furthermore, radiation of 3-5 Mrad even enhanced bone induction, insofar as it produced more bone at the same interval of time than was obtained from unirradiated control samples. None of the radiation doses used in these experiments abolished bone induction, although the response induced by matrix irradiated with doses higher than 5 Mrad was delayed.
Clinical Oral Implants Research, 2002
This research focuses on the effects of radiotherapy on the osseointegration of dental implants placed before or after radiotherapy in 11 male beagles. After the extraction of all mandibular premolars 1st and 2nd molars, three dogs were implanted without radiotherapy (Control group), four dogs were irradiated 4 weeks after implantation (IrA group) and four dogs were irradiated 8 weeks before implantation (IrB group). Eight implants were placed in each dog, in an alternating pattern: four nonsubmerged ITI Bonefit A titanium plasma spray-coated and four submerged Steri-Oss A hydroxyapatite-coated. The irradiated dogs received 4.3 Gy daily for 10 days. Two different fluorescent markers were administered at the time of implantation and of irradiation. The dogs were sacrificed 6 months after implantation, i.e. 5 months after radiotherapy for the IrA group and 8 months for the IrB group. Each mandible was submitted to histological and microradiographic analysis. Bone formation occurred around 85 of the 88 implants and consisted mostly of the successive deposit of woven and lamellar bone. Both irradiated groups showed obvious bone remodeling in alveolar bone as well as in the basilar part of the mandible. Nevertheless, in the IrA group, the resorption phenomena predominated over osteogenesis. The balance between these two opposite processes seemed to be restored 8 months after the end of radiotherapy (IrB group). In spite of focal lesions of radiation-specific bone destruction emphasized in some irradiated dogs, we conclude from our results that osseointegration of dental implants is possible in irradiated bone tissue.
Therapeutic doses of radiation alter proliferation and attachment of osteoblasts to implant surfaces
Journal of Biomedical Materials Research Part A, 2008
Osseointegration of implants in irradiated bone is inadequate. The effect of radiation on cell-implant material interaction has not been adequately studied. The goal of this study was to investigate the effects of ionizing radiation on the proliferation, differentiation, and attachment of osteoblasts to commercially pure titanium (cpTi). Human fetal osteoblasts (hFOB) were irradiated either before or after plating in tissue culture (TC) dishes with or without cpTi disks. Radiation was single dose of 10 cGy, 25 cGy, 50 cGy, 1 Gy, 2 Gy, 4 Gy or 8 Gy. Cell proliferation was determined by counting trypsinized cells on 7 days after irradiation. Attachment of irradiated hFOB was measured indirectly by counting cells 2 and 6 h after plating. Differentiation was evaluated by alkaline phosphatase activity. Compared with nonirradiated sham controls, higher doses of radiation significantly reduced cell attachment and proliferation. Both proliferation and attachment were significantly lower on cpTi compared with TC. Attachment decreased based on the length of postirradiation period. Although differentiation was significantly enhanced by a dose of 8 Gy, proliferation was lowest. These initial studies show that effects of therapeutic doses of radiation on osteoblasts varied depending on the surface, time-elapsed, and amount of radiation.
Effects of irradiation on bone remodelling around mandibular implants: an experimental study in dogs
International journal of oral and maxillofacial surgery, 2006
This research focuses on the effects of radiotherapy on bone remodelling around mandibular implants in dogs. After bilateral extraction of the mandibular premolars and first 2 molars, each of 11 beagles received 8 mandibular implants. Four animals were irradiated 4 weeks after implantation and 4 others 8 weeks before implantation; the remaining 3 did not receive radiotherapy. Irradiation consisted of 10 daily fractions of 4.3Gy (60)Co. Fluorochromes were given at implantation and irradiation to allow the measurement of bone apposition. The dogs were killed 6 months after implantation. Each hemi-mandible was processed according to bone-specific histological techniques. New bone formation was visible around 85 of the 88 implants. Stimulated mandibular remodelling was attested in both irradiated groups by increased porosity and numerous labelled osteons. Resorption was more pronounced in the group irradiated after implantation, but osteon formation appeared unvarying. Osseointegration ...