Bone Incorporation of a Poly (L-Lactide-Co-D, L-Lactide) Internal Fixation Device in a Rat's Tibia: Microtomographic, Confocal LASER, and Histomorphometric Analysis.

This study evaluated the bone incorporation process of a screw-shaped internal fixation device made of poly (L-lactide-co-D, L-lactide) (PLDLLA). Thirty-two male Wistar rats received 32 fixation devices (2 mm × 6 mm) randomly assigned to either the right or left tibia and one implant in each animal. After 7, 14, 28, and 42 days, the rats were euthanized and the specimens were subjected to microtomographic computed tomography (microCT) and histomorphometric analyses to evaluate bone interface contact (BIC%) and new bone formation (NBF%) in cortical and cancellous bone areas. The animals euthanized on days 28 and 42 were treated with calcein and alizarin red, and confocal LASER microscopy was performed to determine the mineral apposition rate (MAR). Micro-CT revealed a higher percentage of bone volume (p < 0.006), trabecular separation (p < 0.001), and BIC in the cortical (p < 0.001) and cancellous (p = 0.003) areas at 28 and 42 days than at 7 and 14 days. The cortical NBF at 42 days was greater than that at 7 and 14 days (p = 0.022). No statistically significant differences were observed in cancellous NBF or MAR at 28 and 42 days. Based on these results, it can be seen that the PLDLLA internal fixation device is biocompatible and allows new bone formation around the screw thread.

Early Peri-Implant Bone Healing on Laser-Modified Surfaces with and without Hydroxyapatite Coating: An In Vivo Study.

(1) Objective: The aim of this study was to assess the biological behavior of bone tissue on a machined surface (MS) and modifications made by a laser beam (LS) and by a laser beam incorporated with hydroxyapatite (HA) using a biomimetic method without thermic treatment (LHS). (2) Methods: Scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM/EDX) was performed before and after installation in the rabbit tibiae. A total of 20 Albinus rabbits randomly received 30 implants of 3.75 × 10 mm in the right and left tibias, with two implants on each surface in each tibia. In the animals belonging to the 4-week euthanasia period group, intramuscular application of the fluorochromes calcein and alizarin was performed. In implants placed mesially in the tibiofemoral joint, biomechanical analysis was performed by means of a removal torque (N/cm). The tibias with the implants located distally to the joint were submitted for analysis by confocal laser microscopy (mineral apposition rate) and for histometric analysis by bone contact implant (%BIC) and newly formed bone area (%NBA). (3) Results: The SEM showed differences between the surfaces. The biomechanical analysis revealed significant differences in removal torque values between the MSs and LHSs over a 2-week period. Over a 4-week period, both the LSs and LHSs demonstrated removal torque values statistically higher than the MSs. BIC of the LHS implants were statistically superior to MS at the 2-week period and LHS and LS surfaces were statistically superior to MS at the 4-week period. Statistical analysis of the NBA of the implants showed difference between the LHS and MS in the period of 2 weeks. (4) Conclusions: The modifications of the LSs and LHSs provided important physicochemical modifications that favored the deposition of bone tissue on the surface of the implants.

Avaliação do processo de reparo alveolar em ratos utilizando ß- tricálcio-fosfato associado ou não ao laser de baixa potência / Evaluation of the alveolar repair process in rats using ß-Tricalcium Phosphate associated or not with low power laser

O uso de biomateriais em substituição ao enxerto autógeno tem sido objeto de estudo, e apresentando resultados promissores. Deste modo, o objetivo desse estudo foi verificar os efeitos do ß-tricálcio-fosfato e do LASER de baixa potência no processo de reparo alveolar. Foram utilizados 96 ratos (Rattus novergicus albinus Wistar), sendo 24 ratos para análise dos cortes calcificados e 72 ratos para análise dos cortes descalcificados. Os animais foram submetidos a exodontia do incisivo superior direito e em seguida foi feita a separação por grupo e por tempo. Para os cortes calcificados, foi feita a divisão em 4 grupos de 6 animais cada: Grupo CO (Controle), Grupo BTF (Biomaterial), Grupo LS (LASER de baixa potência), Grupo BTFL (biomaterial LASER de baixa potência), eutanasiados no período de 28 dias. Para análise dos cortes descalcificados foram utilizados os mesmos grupos em tempos de eutanasia de 7,14 e 28 dias. As maxilas foram removidas e submetidas às análises histológica e histométrica nos cortes descalcificados e análise tomográfica microcomputadorizada (Micro-Ct) nos cortes calcificados. A análise por micro-Ct evidenciou formação de tecido ósseo em todos os grupos, porém não houve diferença entre os grupos experimentais e o controle. A análise histométrica evidenciou maior presença de tecido ósseo neoformado estatististicamente significante em LS aos 7 dias quando comparados aos demais grupos. Desta forma, concluiu-se que o LASER de baixa potência acelerou as fases inicias do processo de reparo alveolar(AU)

The use of biomaterials to replace autogenous grafts has been the subject of study, and has shown promising results. Thus, the objective of this study was to verify the effects of ß-tricalcium-phosphate and low-power LASER on the alveolar repair process. 96 rats (Rattus novergicus albinus Wistar) were used, being 24 rats for analysis of calcified cuts and 72 rats for analysis of decalcified cuts. The animals underwent extraction of the upper right incisor and then the separation was made by group and by time. For the calcified cuts, the division was made into 4 groups of 6 animals each: Group CO (Control), Group BTF (Biomaterial), Group LS (low power LASER), Group BTFL (low power LASER biomaterial), euthanized in the 28-day period. For the analysis of decalcified cuts, the same groups were used at times of euthanasia of 7.14 and 28 days. The jaws were removed and subjected to histological and histometric analysis in the decalcified sections and microcomputerized tomographic analysis (Micro-Ct) in the calcified sections. Micro-Ct analysis showed bone tissue formation in all groups, but there was no difference between experimental and control groups. Histometric analysis showed a greater presence of statistically significant neoformed bone tissue in LS at 7 days when compared to the other groups. Thus, it was concluded that the low-power LASER accelerated the early stages of the alveolar repair process(AU)

Critical Defect Healing Assessment in Rat Calvaria Filled with Injectable Calcium Phosphate Cement.

(1) Background: The tissue engineering field has been working to find biomaterials that mimic the biological properties of autogenous bone grafts. (2) Aim: To evaluate the osteoconduction potential of injectable calcium phosphate cement implanted in critical defects in rat calvaria. (3) Methods: In the calvarial bone of 36 rats, 7-mm diameter critical size defects were performed. Afterwards, the animals were randomly divided into three groups according to filler material: a blood clot group (BC), blood clot membrane group (BCM), and an injectable ß-tricalcium phosphate group (HBS) cement group. After periods of 30 and 60 days, the animals were euthanized, the calvaria was isolated, and submitted to a decalcification process for later blades confection. Qualitative and quantitative analysis of the neoformed bone tissue were conducted, and histometric data were statistically analyzed. (4) Results: Sixty days post-surgery, the percentages of neoformed bone were 10.67 ± 5.57 in group BC, 16.71 ± 5.0 in group BCM, and 55.11 ± 13.20 in group HBS. The bone formation values in group HBS were significantly higher (p < 0.05) than in groups BC and BCM. (5) Conclusions: Based on these results, it can be concluded that injectable calcium phosphate cement is an osteoconductive material that can be used to fill bone cavities.