Analysis of peri-implant bone tissue between hydrophilic and rough implant surfaces in spontaneously hypertensive rats treated with losartan

Abstract Hypertensive individuals present alterations in their calcium metabolism that consequently decrease the concentration of this mineral in the bone tissue. Objectives to evaluate the morphological and functional characteristics of the peri-implant bone tissue that was formed during the healing process by the placement implants using two different surface treatments: hydrophilic Acqua™ (ACQ) and rough NeoPoros™ (NEO), in spontaneously hypertensive (SHR) and normotensive rats (Wistar) whether or not treated with losartan. Methodology In total, 96 male rats (48 Wistar and 48 SHR) were divided into eight subgroups: absolute control rough (COA NEO), absolute control hydrophilic (COA ACQ), losartan control rough (COL NEO), losartan control hydrophilic (COL ACQ), SHR absolute rough (SHR NEO), SHR absolute hydrophilic (SHR ACQ), SHR losartan rough (SHRL NEO), and SHR losartan hydrophilic (SHRL ACQ). The rats medicated with losartan received daily doses of the medication. NeoPoros™ and Acqua™ implants were installed in the tibiae of the rats. After 14 and 42 days of the surgery, the fluorochromes calcein and alizarin were injected in the rats. The animals were euthanized 67 days after treatment. The collected samples were analyzed by immunohistochemistry, biomechanics, microcomputerized tomography, and laser confocal scanning microscopy analysis. Results The osteocalcin (OC) and vascular endothelium growth factor (VEGF) proteins had moderate expression in the SHRL ACQ subgroup. The same subgroup also had the highest implant removal torque. Regarding microarchitectural characteristics, a greater number of trabeculae was noted in the control animals that were treated with losartan. In the bone mineralization activity, it was observed that the Acqua™ surface triggered higher values of MAR (mineral apposition rate) in the COA, COL, and SHRL groups (p<0.05). Conclusion the two implant surface types showed similar responses regarding the characteristics of the peri-implant bone tissue, even though the ACQ surface seems to improve the early stages of osseointegration.

Reparo periimplantar em ratos diabéticos tipo 2, tratados pela combinação da terapia fotodinâmica antimicrobiana e compostos polifenóis: caracterização biomecânica, histométrica, microtomográfica e molecular / Periimplant bone repair in type 2 diabetics rats treated with the combination of antimicrobial photodynamic therapy and polyphenol compounds: biomechanical, histometric, microtomographic and molecular characterization

Caracterizar as respostas reparacionais do tecido ósseo após a instalação de implantes em ratos diabéticos tipo 2 tratados sistemicamente com resveratrol e com o uso local da aPDT, por meio das análises biomecânica e molecular. Foram utilizados 128 ratos divididos em quatro grandes grupos: 1- NG: ratos normoglicêmicos; 2- NGrvt: ratos normoglicêmicos tratados com resveratrol oral; 3- T2D: ratos diabéticos tipo 2; e 4- T2Drvt: ratos diabéticos tipo 2 tratados com resveratrol oral. Dentro de cada grupo existem quatro subgrupos: ST- Sem terapia local (n=8), a loja cirúrgica não recebeu terapia local adicional; AM- Azul de metileno (n=8), aplicação tópica de azul de metileno por 60 segundos; FBM- fotobiomodulação (n=8), irradiação com laser em baixa intensidade por 60 segundos; aPDT- Terapia fotodinâmica antimicrobiana (n=8), associação da aplicação de azul de metileno com irradiação com laser em baixa intensidade. A indução do T2D foi feita pela associação de dieta de cafeteria com uma única aplicação de Estreptozotocina (35mg.kg). Após a comprovação do diabetes tipo 2, foi dado início ao tratamento com resveratrol e passadas duas semanas os animais foram submetidos à cirurgia de exodontia dos primeiros molares superiores e instalação dos implantes. Neste momento foram realizadas as terapias locais de acordo com os grupos. Passados 28 dias, foi realizada a eutanasiados animais e realizadas as análises biomecânica (torque de remoção) e molecular de RT-PCR (IBSP, OCN, TRAP OPG e RANK-L). Os dados quantitativos foram submetidos ao teste de normalidade Shapiro Wilk para confirmar a distribuição normal das amostras. Na sequência, foram aplicados os testes de ANOVA um fator ou dois fatores, seguidos de pós teste de Tukey, com nível de significância de 5%. Os resultados da análise biomecânica revelaram que em animais normoglicêmicos tratados ou não por resveratrol tiveram uma diminuição do torque de remoção dos implantes quando empregado o uso de terapias locais. A presença da interferência sistêmica e o uso de terapias locais auxiliaram no aumento nos valores de contra-torque, especialmente no grupo T2Drvt com o uso da aPDT. A análise molecular de RT-PCT aos 28 dias sugere que no grupo NG a expressão de IBSP foi semelhante com a presença ou não das terapias locais, entretanto houve uma diminuição dos genes de OCN e um aumento de TRAP com o uso das terapias. Em NGrvt, houve um aumento na expressão de IBSP na ausência de terapias locais, uma diminuição de OCN e TRAP quando utilizadas as terapias e um aumento expressivo de OPG com ausência de RANK-L com o uso sistêmico de resveratrol sem tratamentos locais. O grupo T2D expressou um aumento de IBSP com o uso da terapia de FBM e a terapia com aPDT elevou a expressão de OCN e diminuiu TRAP e RANK-L. O uso de resveratrol em T2Drvt e sua associação com a aPDT aumentaram a expressão de IBSP e OCN, e além disso diminuíram a expressão de TRAP e RANK-L. A análise conjunta dos resultados permite-nos concluir que o uso sistêmico de resveratrol e a sua associação com a aPDT promoveram uma melhora no reparo periimplantar de ratos diabéticos tipo 2, aumentando a expressão de genes relacionados a mineralização da matriz óssea e diminuindo a expressão de genes relacionados a reabsorção óssea que resultaram em uma melhora da biomecânica óssea(AU)

The aim of this study is to characterize bone tissue repair responses after the installation of implants in type 2 diabetic rats treated systemically with resveratrol and with local use of aPDT, through biomechanical and molecular analysis. One hundred and twenty-eight rats were used, divided into four groups: 1- NG: normoglycemic rats; 2- NGrvt: normoglycemic rats treated with oral resveratrol; 3- T2D: type 2 diabetic rats; and 4- T2Drvt: type 2 diabetic rats treated with oral resveratrol. Within each group, are four subgroups: ST- No local therapy (n=8), the surgical store received no additional local therapy; MB- Methylene blue (n=8), topical application of methylene blue for 60 seconds; FBM- Photobiomodulation (n=8), low intensity laser irradiation for 60 seconds; aPDT- Antimicrobial photodynamic therapy (n=8), association of methylene blue application with low intensity laser irradiation. T2D induction was made by the association of cafeteria diet with a single application of Streptozotocin (35mg.kg). After type 2 diabetes confirmation, resveratrol treatment was started and after two weeks the animals were submitted to upper first molars extraction and implants installation. At this moment the local therapies were performed according to the groups. After 28 days, the animals were euthanized and the biomechanical (removal torque) and molecular analysis of RT-PCR (IBSP, OCN, TRAP OPG and RANK-L) were performed. The quantitative data were submitted to the Shapiro Wilk normality test to confirm the normal distribution of the samples. In the sequence, the ANOVA tests were applied one or two factors, followed by Tukey's post-test, with a significance level of 5%. The results of biomechanical analysis showed that in normoglycemic animals treated or not by resveratrol had a decrease in the implants removal torque when local therapies were applied. The presence of systemic interference and the use of local therapies helped to increase biomechanical values, especially in the T2Drvt group with the use of aPDT. The molecular analysis of RT-PCT at 28 days suggests that in the NG group the expression of IBSP was similar with the presence or not of local therapies, however there was a decrease in OCN genes and an increase in TRAP with the use of therapies. In NGrvt, there was an increase in IBSP expression in the absence of local therapies, a decrease in OCN and TRAP when using therapies and a significant increase in OPG without RANK-L with the systemic use of resveratrol without local treatments. T2D group expressed an increase of IBSP with the use of PBM therapy, aPDT raised the expression of OCN and decreased TRAP and RANKL. The use of resveratrol on T2Drvt and its association with aPDT increased the expression of IBSP and OCN, and also decreased TRAP and RANK-L expression. The overall analysis of the results allows us to conclude that the systemic use of resveratrol and its association with aPDT promoted an improvement in periimplant repair of type 2 diabetic rats, increasing the expression of genes related to bone matrix mineralization and decreasing the expression of genes related to bone resorption that resulted in an improvement of bone biomechanics(AU)

Losartan improves alveolar bone dynamics in normotensive rats but not in hypertensive rats

Abstract Hypertension is one of the main causes of premature death in the world; also, it is associated with several bone alterations. Preclinical studies have demonstrated delayed alveolar bone healing in hypertensive rats. However, losartan has been favorable for consolidation of bone grafts and reduction in active periodontitis. Therefore, losartan is suggested to be effective in bone formation stages, as well as in the synthesis of matrix proteins and mineralization. Objectives: To evaluate the alveolar bone dynamics in hypertensive rats treated with losartan by laser confocal microscopy and histological analysis. Methodology: Thirty-two rats, 16 spontaneously hypertensive rats (SHR) and 16 Wistar albinus rats, treated or not with losartan (30 mg/kg/day) were used. Calcein fluorochrome at 21 days and alizarin red fluorochrome at 49 days were injected in rats (both 20 mg/kg). The animals were submitted to euthanasia 67 days after treatment, and then the right maxilla was removed for laser confocal microscopy analysis and the left maxilla for histological analysis. Results: This study showed a greater calcium marking in normotensive animals treated with losartan in relation to the other groups. Laser confocal microscopy parameters showed higher values of bone volume formed, mineralized surface, active surface of mineralization and bone formation rate in normotensive animals treated with losartan. However, a smaller mineralized surface was observed in all hypertensive animals. Conclusion: Losartan can improve bone mineralization parameters under normal physiological conditions, but the same anabolic effect does not occur under hypertension.

Daily melatonin administration improves osseointegration in pinealectomized rats

Abstract The hypothesis of this study was that the peri-implant bone healing of the group of pinealectomized rats would differ from the control group. The samples were subjected to immunohistochemical, microtomographic (total porosity and connectivity density), and fluorochrome (mineralized surface) analyses. Objectives The goal of this study was to investigate the cellular changes and bone remodeling dynamics along the bone/implant interface in pinealectomized rats. Material and Methods The total of 18 adult male rats (Rattus norvegicus albinus, Wistar) was divided into three groups (n=6): control (CO), pinealectomized without melatonin (PNX) and pinealectomized with melatonin (PNXm). All animals were submitted to the first surgery (pinealectomy), except the CO group. Thirty days after the pinealectomy without melatonin, the second surgery was conducted, in which all animals received an implant in each tibia (36 titanium implants with surface treatment were installed - Implalife® São Paulo, SP, Brazil). By gavage, the rats of the PNX group received the vehicle solution, and the procedure. Results Immunohistochemical analysis for runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteopontin (OP) and osteocalcin (OC) showed that the bone repair process in the PNXm group was similar to that of the CO group, whereas the PNX group showed a delay. The microtomographic parameters of total porosity [Po(tot)] and bone surface (BS) showed no statistically significant differences, whereas for the connective density (Conn.Dn) a statistical difference was found between the CO and PNXm groups. Fluorochrome analysis of the active mineralized surface showed statistically significant difference between the CO and PNX and between the CO and PNXm groups. Conclusion The absence of the pineal gland impaired the bone repair process during osseointegration, however the daily melatonin replacement was able to restore this response.