Effect of hyperbaric oxygen and low-level laser therapy on bone repair and biomechanics in type I diabetes mellitus rats

Chronic hyperglycemia due to type 1 diabetes mellitus affects multiple organs interfering in the quality of patients’ life with the disease. In bone, this condition changes bone metabolism, compromising regeneration and bone biomechanical properties. Supporting therapies, such as Low-Level Light (LLLT) and hyperbaric oxygen therapy (HBO) have been proposed to promote bone regeneration or improve tissue conditions. The aim of the present study was to evaluate the effect of LLLT and HBO on microarchitecture and biomechanics bone of rats with type 1 diabetes mellitus (T1DM). Analyzes were performed using computerized micro-tomography (MicroCT), histological and histomorphometric, biomechanical and Fourier transform infrared spectroscopy (FTIR). The results showed that diabetes significantly compromised the bone regeneration, with reduction bone neoformation, trabeculae number and bone volume. T1DM also change the organic and inorganic matrix compounds and mechanical bone properties (maximum strength, energy and stiffness). The therapies used, LLLT and HBO reduced the deleterious effects of diabetes, especially those related to bone neoformation, mechanical properties and ratio between organic and inorganic material. It is concluded that type 1 diabetes mellitus compromises bone regeneration and biomechanical properties; and LLLT and HBO reduce the deleterious effects of T1DM.FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas GeraisTese (Doutorado)A hiperglicemia crônica decorrente do diabetes mellitus tipo 1 afeta múltiplos órgãos interferindo na qualidade de vida dos portadores da doença. No osso, esse quadro altera o metabolismo ósseo, comprometendo o reparo e as propriedades biomecânicas ósseas. Terapias coadjuvantes como laserterapia (LT) e oxigenação hiperbárica (OH) têm sido propostas para favorecer o reparo ósseo ou melhorar as condições teciduais. O objetivo geral deste estudo foi avaliar o efeito da oxigenação hiperbárica e do laser de baixa potência no reparo, na microarquitetura e biomecânica em osso de ratos com diabetes mellitus tipo I (DMTI). Foram utilizadas análises por meio de micro-tomografia computadorizada (MicroCT), avaliação histológica qualitativa e histomorfométrica, análise biomecânica e espectroscopia no infravermelho transformada de Fourier (FTIR). Os resultados mostraram que o diabetes comprometeu significativamente o reparo ósseo, com redução de neoformação, número de trabéculas e volume ósseo. O DMTI também alterou os compostos orgânicos e inorgânicos da matriz e as propriedades mecânicas ósseas (força máxima, energia e rigidez). As terapias utilizadas, OH e LT reduziram os efeitos deletérios do diabetes, principalmente, os relativos à neoformação óssea, propriedades mecânicas e razão entre os componentes orgânico e inorgânico. Conclui-se que o diabetes mellitus tipo 1 compromete o reparo e as propriedades biomecânicas ósseas, e a oxigenação hiperbárica e a laserterapia de baixa potência reduzem os efeitos deletérios do diabete

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, mm3), 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/mm2) 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

Efeito local da associação de doxiciclina e alendronato no reparo ósseo

The aim of the present study was to investigate the local effect of 10% doxycycline and 1% alendronate combined with poly(lactic-co-glycolic acid (PLGA) on bone repair. Thirty rats were divided into three groups, as follow: Control Group (CG), Drug Group (DG) and Vehicle-PLGA Group (VG). Bone defect was created in the right femur and filled with: blood clot (CG); PLGA gel, 10% doxycycline and 1% alendronate (DG); or vehicle-PLGA (VG). The animals were euthanized seven or fifteen days after surgery. Bone radiodensity, bone matrix and number of osteoclasts were quantified. At seven days, the findings showed increased density in DG (177.75 ± 76.5) compared with CG (80.37 ± 27.4), but no difference compared with VG (147.1 ± 41.5); no statistical difference in bone neoformation CG (25.6 ± 4.8), VG (27.8 ± 4) and DG (18.9 ± 7.8); and decrease osteoclasts in DG (4.6 ± 1.9) compared with CG (26.7 ± 7.4) and VG (17.3 ± 2.7). At fifteen days, DG (405.1 ± 63.1) presented higher density than CG (213.2 ± 60.9) and VG (283.4 ± 85.8); there was a significant increase in bone neoformation in DG (31.5 ± 4.2) compared with CG (23 ± 4), but no difference compared with VG (25.1 ± 2.9). There was decrease number of osteoclasts in DG (20.7 ± 4.7) and VG (29.5 ± 5.4) compared with CG (40 ± 9.4). The results suggest that the 10% doxycycline combination with 1% alendronate in PLGA accelerated bone repair.Mestre em OdontologiaO objetivo do presente estudo foi investigar o efeito local de doxiciclina 10% e alendronato 1% associado ao poli (ácido láctico-co-glicólico) (PLGA) no reparo ósseo. Trinta ratos foram divididos em três grupos, como se segue: Grupo controle (GC), Grupo Droga (GD) e Grupo Veículo-PLGA (GV). Em todos os animais, foram criados defeitos ósseos nos fêmures direitos preenchidos com: apenas coágulo de sangue (GC); gel PLGA, doxiciclina 10% e alendronato 1% (GD); ou veículo-PLGA (GV). Os animais foram sacrificados sete ou 15 dias após a cirurgia e foram analisados os seguintes parâmetros: radiodensidade óssea (HU), porcentagem de matriz óssea e o número de osteoclastos. Aos sete dias, os resultados mostraram maior radiodensidade em GD (177,75 ± 76,5) comparando ao GC (80,37 ± 27,4), mas não houve diferença em comparação com GV (147,1 ± 41,5); não houve diferença estatística na porcentagem de matriz óssea em GC (25,6 ± 4,8), VG (27,8 ± 4) e GD (18,9 ± 7,8); e ocorreu decréscimo na quantidade de osteoclastos em GD (4,6 ± 1,9) comparando com GC (26,7 ± 7,4) e GV (17,3 ± 2,7). Em 15 dias, GD (405,1 ± 63,1) apresentou maior radiodensidade em relação ao GC (213,2 ± 60,9) e GV (283,4 ± 85,8); houve aumento significativo na porcentagem de matriz óssea em GD (31,5 ± 4,2) comparando com GC (23 ± 4), mas nenhuma diferença em comparação com GV (25,1 ± 2,9). Houve decréscimo na quantidade de osteoclastos em GD (20,7 ± 4,7) e GV (29,5 ± 5,4) comparando com GC (40 ± 9,4). Os resultados sugerem que a associação de doxiciclina 10% e alendronato 1% com PLGA acelera a reparação óssea

Implant site preparation-related bone microdamage: An alternative ex vivo analysis of drilling speed protocols

ABSTRACT Objective: The aim of this study was to evaluate bone microdamage in sites prepared for implant placement by using an ex vivo model with three drilling rotation speeds. Methods: Bovine bone ribs were used for the creation of 18 osteotomy sites at different rotation speeds: 1200 rpm, 800 rpm, and 400 rpm. Specimens were stained with xylenol orange and prepared for histological analysis by using fluorescence and polarized light microscopies. Bone microdamage was evaluated by number and based on total bone area, as follows: microfracture density (Fr.D = n/mm2), microcrack morphology (diffuse or linear), and density (Cr.D = n/mm2), and presence of bone chips. To complement the analysis, linear microcracks were assessed by using confocal microscopy for three-dimensional visualization. Results: Bone microdamage on the osteotomy sites included microcracks, diffuse damages, microfracture, and bone chip formation. There was an association between bone microdamage and cancellous bone (p 0.0016), as well as a positive correlation between Fr.D and Cr.D (p 0.05, r 0.54). BM occurrence was not different between the three rotation speeds. In 3D, the height of the microcrack depth was 60.81 µm. Conclusion: Bone microdamage occurs during osteotomy, and the ex vivo model used was effective for the assessment of these biomechanical parameters. In addition, microdamage was not influenced by the drilling rotation speed in this experimental condition

Influence of hyperbaric oxygen on biomechanics and structural bone matrix in type 1 diabetes mellitus rats.

The aim of this study was to evaluate the biomechanics and structural bone matrix in diabetic rats subjected to hyperbaric oxygen therapy (HBO).Twenty-four male rats were divided into the following groups: Control; Control + HBO; Diabetic, and Diabetic + HBO. Diabetes was induced with streptozotocin (STZ) in the diabetic Groups. After 30 days, HBO was performed every 48h in HBO groups and all animals were euthanized 60 days after diabetic induction. The femur was submitted to a biomechanical (maximum strength, energy-to-failure and stiffness) and Attenuated Total Reflectance Fourier transform infrared (ATR-FTIR) analyses (crosslink ratio, crystallinity index, matrix-to-mineral ratio: Amide I + II/Hydroxyapatite (M:MI) and Amide III + Collagen/HA (M:MIII)).In biomechanical analysis, diabetic animals showed lower values of maximum strength, energy and stiffness than non-diabetic animals. However, structural strength and stiffness were increased in groups with HBO compared with non-HBO. ATR-FTIR analysis showed decreased collagen maturity in the ratio of crosslink peaks in diabetic compared with the other groups. The bone from the diabetic groups showed decreased crystallinity compared with non-diabetic groups. M:MI showed no statistical difference between groups. However, M:MIII showed an increased matrix mineral ratio in diabetic+HBO and control+HBO compared with control and diabetic groups. Correlations between mechanical and ATR-FTIR analyses showed significant positive correlation between collagen maturity and stiffness.Diabetes decreased collagen maturation and the mineral deposition process, thus reducing biomechanical properties. Moreover, the study showed that HBO improved crosslink maturation and increased maximum strength and stiffness in the femur of T1DM animals

Ionizing radiation and bone quality: time-dependent effects

Abstract Background The aim of this study was to evaluate the ionizing radiation (IR) effects on rat bone 30 and 60 days after irradiation. Methods Wistar rats were submitted to IR (30 Gy) on the left leg and were euthanized after 30 and 60 days. The legs were divided into four groups according to the treatment and euthanization time: C30 and C60 (right leg–without IR), IR30 and IR60 (left leg-with IR). Results CT analysis showed more radiodensity in C60 compared with other groups, and IR60 showed more radiodensity than IR30. In histomorphometric analysis, C30 showed lower bone matrix values compared with IR30 and C60. Lacunarity analyses showed more homogeneous bone channel distribution in C30 than IR30. ATR-FTIR showed decrease in ratio of mature and immature crosslinks in IR30 compared with C30. Crystallinity Index was decrease in IR60 compared with C60. The Amide III + Collagen/HA ratio was increased in C60 compared with C30; however this ratio decreased in IR60 compared with IR30. Biomechanical analysis showed lower values in IR groups in both time. Conclusions IR damaged bone quality and decreased stiffness. Moreover, the results suggested that the deleterious effects of IR increased in the late time points

Maximum strength of biomechanical analyses in different groups (*p<0.05).

<p>Maximum strength of biomechanical analyses in different groups (*p<0.05).</p

Energy of biomechanical analyses in different groups (*p<0.05).

<p>Energy of biomechanical analyses in different groups (*p<0.05).</p

Crystallinity index of ATR-FTIR analyses in different groups (*p<0.05).

<p>Crystallinity index of ATR-FTIR analyses in different groups (*p<0.05).</p

Matrix: Mineral ratio (Amide III+Collagen/Hydroxyapatite) of ATR-FTIR analyses in different groups (*p<0.05).

<p>Matrix: Mineral ratio (Amide III+Collagen/Hydroxyapatite) of ATR-FTIR analyses in different groups (*p<0.05).</p