Comparação de diferentes metodologias para análise histométrica de implantes: estudo em ratos / Comparison of different methodologies for histometric analysis of implant. Study in rat

Introdução: Diferentes metodologias tem sido utilizadas para avaliação histológica da osseointegração, levando a diferentes resultados. Objetivo: O objetivo é comparar diferentes metodologias de análise histomorfométrica da osseointegração de implantes com diferentes superfícies, instalados em tíbias de ratos. Material e método: 24 ratos foram aleatoriamente divididos em 3 grupos (n = 8) para a instalação dos implantes. Esses grupos foram divididos de acordo com o tipo de implante instalado na tíbia: Grupo Hidrofílico - HFL (instalação de implante com superfície modificada por jateamento de óxidos e ataque ácido e mantida em solução de cloreto de sódio), Grupo Hidrofóbico - HFB (instalação de implante com superfície modificada por jateamento de óxidos e ataque ácido) e Grupo Usinado - U (instalação de implante com superfície usinada). No período de 45 dias após os procedimentos cirúrgicos de instalação dos implantes, os animais foram submetidos à eutanásia, e as tíbias foram removidas, sendo realizado o processamento histológico para amostras não descalcificadas. Após a obtenção das lâminas, foi realizada a análise histomorfométrica para avaliar as porcentagens de contato osso-implante (% BIC) e da área óssea entre as espiras (% BBT). As mensurações foram realizadas em duas diferentes regiões: 1) as roscas do implante na região do osso cortical e 2) todas as roscas do implante inseridas no osso (cortical e medular). A análise estatística foi feita por meio de ANOVA One-Way, seguida pelo teste de Tukey para análise inferencial dos dados. Resultado: Quando o BIC e o BBT foram analisados de forma independente nas regiões cortical e trabecular/total, observou-se uma diferença no comportamento histológico dos implantes de acordo com o tratamento de superfície. Os implantes HFL apresentaram BIC (%) trabecular 16,85% maior (p = 0,02) do que os implantes HFB e 26,12% maior (p ≤ 0,0001) do que os implantes usinados. Contudo, a região cortical de todos os grupos apresentou valores de BIC cortical significativamente maiores ao redor dos implantes, independentemente da superfície. Conclusão: Os resultados obtidos demonstraram que a formação óssea peri-implantar foi superior nas análises realizadas apenas em osso cortical, se comparados aos valores obtidos na mensuração total (osso cortical somado ao medular). Também foi possível observar que, dentro da mesma superfície, os valores de BIC (%) foram superiores em osso cortical. Em relação às limitações do estudo, pode-se concluir que diferentes metodologias de análise histométrica da osseointegração ao redor de diferentes superfícies de implantes instalados em tíbias de ratos podem interferir nos resultados de osseointegração, independentemente da superfície analisada.

Introduction: Different methodologies were used for histological evaluation of osseointegration, leading to different results. Objective: The objective is to compare different methodologies for histomorphometric analysis of the osseointegration of implants with different surfaces, installed in rat tibias. Material and method: Twenty-four rats were randomly divided into 3 groups (n=8) for implant installation. These groups were divided according to the type of implant that will be installed in the tibia: Hydrophilic Group (installation of an implant with a surface modified by oxide blasting and acid attack and maintained in a sodium chloride solution), Hydrophobic Group (installation of an implant with surface modified by oxide blasting and acid attack) and Machined Group (implant installation with machined surface). Within 45 days after the surgical procedures to install the implants, the animals were euthanized and the tibias were removed, and histological processing was carried out for non-decalcified samples. After obtaining the slides, histomorphometric analysis was performed to evaluate the percentages of bone-implant contact (%BIC) and the bone area between the turns (%BBT). Measurements were carried out in two different regions: 1) the implant threads in the cortical bone region and 2) all implant threads inserted into the bone (cortical and medullary). Statistical analysis was performed using One-Way ANOVA followed by Tukey's test for inferential data analysis. Result: The BIC and BBT were analyzed independently in the cortical and trabecular/total regions, a difference was observed in the histological behavior of the implants according to the surface treatment. HFL implants showed trabecular BIC (%) 16.85% higher (p=0.02) than HFB implants and 26.12% higher (p≤0.0001) than machined implants. However, the cortical region of all groups showed significantly higher cortical BIC values around the implants, regardless of the surface. Conclusion: the results obtained demonstrated that peri-implant bone formation was superior in analyzes carried out only on cortical bone, compared to the values obtained in the total measurement (cortical bone plus medullary bone). It was also possible to observe that, even within the same surface, the BIC(%) values were higher in cortical bone. Within the limitations of the study, it can be concluded that different methodologies for histometric analysis of osseointegration around different surfaces of implants installed in rat tibias can interfere with the results of osseointegration regardless of the surface analyzed

Influence of bone defect position and span in 3-point bending tests: experimental and finite element analysis

Abstract: Three-point bending test is the most common mechanical test used for quantifying the biomechanical quality of bone tissue and bone healing in small animals. However, there is a lack of standardization for evaluation of bone repair by cortical perforation. The aim of this study was to determine the influence of bone defect position in the proximal metaphysis of rat tibias during load application and different span configuration on the three-point bending test outcomes. Cortical defects with 1.6 mm diameter were created at a standardized location on the medial surface of 60 tibias of male Wistar rats. The animals were euthanized 7 days after surgery. Five specimens were used to create 3D models for finite element analysis using high-resolution micro-CT images. Two spans (6 and 10mm) and three positions of the bone defect in relation to the load application (upward, frontal and downward) were evaluated experimentally (n = 10) and in finite element analysis (n = 5). Maximum load (N) and stiffness (N/mm) were statistically analyzed with 2-way ANOVA and Tukey test (α = 0.05). The results demonstrated that span and orientation of the bone defect significantly influenced the fracture pattern, stress distribution and force versus displacement relation. Therefore, reliable outcome can be achieved creating the bone defect at 8 mm from the extremity of the proximal epiphysis; placing a 10 mm distance span and downward facing defect position to allow a better distribution of stress and more fracture patterns that reached the bone defect target area with less intra-group variability.

Effect of topical Insulin administration on bone defect healing in diabetic rats / Efeito da administração tópica de insulina na cicatrização de defeitos ósseos em ratos diabéticos

Objective: insulin has been reported to possess anabolic effect on bone. Topical application of insulin in bone defects in diabetic rats has not been investigated. The objective of this study was to evaluate histologically the effect of topical administration of insulin for the restoration of tibial bone defects in diabetic rats. Materials and Methods: Sixteen adult male albino diabetic rats were grouped into two equal groups, group I (diabetic control) which had not received any graft, group II (experimental) which was diabetic and had received topical insulin loaded on PVP (Polyvinylpyrrolidone). Specimens were harvested on days seven and twenty eight days after surgical procedures, prepared and examined histologically by H&E (haematoxylin and eosin) stain, there were wide histological differences between the groups of this study along the different intervals of the study.Results:The histological results demonstrated that there was obvious retardation in resolving the inflammatory phase, organization of the blood clot and bone formation in the diabetic control group I than the experimental group II along the different intervals of this study. Moreover, there was great acceleration in granulation tissue formation, organization and bone formation in experimental group II which received the insulin PVP. Discussion: The enhancement in bone healing process was due to the effect of insulin which accelerates the bone regeneration by means of inflammation resolve, angiogenesis, proliferation and successive differentiation of mesenchymal cells. Conclusion: Topical applications of insulin in bone defects enhance new bone formation in diabetic rats. (AU)

Objetivo: Foi relatado que a insulina possui efeito anabólico no osso. A aplicação tópica de insulina em defeitos ósseos em ratos diabéticos não foi investigada. O objetivo deste estudo foi avaliar histologicamente o efeito da administração tópica de insulina na restauração de defeitos ósseos tibiais em ratos diabéticos. Material e Métodos: dezesseis ratos albinos machos adultos diabéticos foram agrupados em dois grupos iguais, grupo I (controle diabético) que não recebeu qualquer enxerto, grupo II (experimental) diabético e recebeu insulina tópica carregada em PVP (polivinilpirrolidona). As amostras foram colhidas nos dias sete e vinte e oito dias após os procedimentos cirúrgicos, preparadas e examinadas histologicamente pela coloração H&E (hematoxilina e eosina); houve grandes diferenças histológicas entre os grupos deste estudo ao longo dos diferentes intervalos do estudo. Resultados: os resultados histológicos demonstraram que houve retardo óbvio na resolução da fase inflamatória, organização do coágulo sanguíneo e formação óssea no grupo controle diabético I do que no grupo experimental II ao longo dos diferentes intervalos deste estudo. Além disso, houve grande aceleração na formação de tecido de granulação, organização e formação óssea no grupo experimental II o qual recebeu a insulina PVP. Discussão: a melhora do processo de cicatrização óssea deveu-se ao efeito da insulina, que acelera a regeneração óssea por meio da resolução da inflamação, angiogênese, proliferação e sucessiva diferenciação das células mesenquimais. Conclusão: aplicações tópicas de insulina em defeitos ósseos melhoram a formação óssea em ratos diabéticos (AU)

The influence of Aloe vera with mesenchymal stem cells from dental pulp on bone regeneration: characterization and treatment of non-critical defects of the tibia in rats

Abstract Objective This study aimed to evaluate the inflammatory effect and bone formation in sterile surgical failures after implantation of a collagen sponge with mesenchymal stem cells from human dental pulp (hDPSCs) and Aloe vera. Material and Methods Rattus norvegicus (n=75) were divided into five experimental groups according to treatment: G1) control (blood clot); G2) Hemospon®; G3) Hemospon® in a culture medium enriched with 8% Aloe vera; G4) Hemospon® in a culture medium containing hDPSCs and G5) Hemospon® in a culture medium enriched with 8% Aloe vera and hDPSCs. On days 7, 15 and 30, the animals were euthanized, and the tibia was dissected for histological, immunohistochemistry and immunofluorescence analyses. The results were analyzed using nonparametric Kruskal-Wallis test and Dunn's post-test. Results On days 7 and 15, the groups with Aloe vera had less average acute inflammatory infiltrate compared to the control group and the group with Hemospon® (p<0.05). No statistically significant difference was found between the groups regarding bone formation at the three experimental points in time. Osteopontin expression corroborated the intensity of bone formation. Fluorescence microscopy revealed positive labeling with Q-Tracker® in hDPSCs before transplantation and tissue repair. Conclusion The results suggest that the combination of Hemospon®, Aloe vera and hDPSCs is a form of clinical treatment for the repair of non-critical bone defects that reduces the inflammatory cascade's effects.

Efeitos da sitagliptina no tecido ósseo em ratos diabéticos e não diabéticos / Effects of sitagliptin on bone tissue in diabetic and non-diabetic rats

A diabetes mellitus, doença caracterizada pelo aumento da glicemia no sangue, é um dos mais importantes problemas de saúde pública do mundo, com incidência crescente, sobretudo em países em desenvolvimento. Novas terapias medicamentosas para controlar os níveis de glicose no sangue têm sido desenvolvidas, entre elas, os inibidores da enzima dipeptidil peptidase-4 (DPP-4) como a sitagliptina. Pesquisas atuais mostram que este medicamento, além do controle da glicemia, contribui na estimulação da formação e inibição da reabsorção óssea e possui ação anti-inflamatória. O objetivo deste trabalho foi avaliar os efeitos da sitagliptina no tecido ósseo em ratos diabéticos e não diabéticos. Foram utilizados 38 ratos machos, divididos em 4 grupos: Grupo diabético tratado com sitagliptina (GDS- 10 mg/Kg/dia); Grupo diabético (GD); Grupo normoglicêmico tratado sitagliptina (GNS-10 mg/Kg/dia); Grupo normoglicêmico (GN). Para indução da diabetes os animais receberam solução 10% de frutose na água de beber por 14 dias, após o quê receberam 40 mg/Kg de estreptozotocina via intraperitoneal. Quatro semanas depois, avaliou-se a glicemia e iniciou-se o tratamento com sitagliptina nos grupos GDS e GNS, que continuou por mais 4 semanas, quando ocorreu a eutanásia. A glicemia e a resistência à insulina (HOMA-IR) foram avaliadas também no dia da eutanásia. As tíbias foram removidas e avaliadas a porcentagem de volume ósseo (BV/TV), espessura trabecular (Tb.Th), número de trabéculas (Tb.N) e a separação de trabéculas (Tb Sp) da metáfise tibiana por microtomografia computadorizada. Os dados foram submetidos à análise estatística, ao nível de 0,05. Os animais dos grupos GD e GDS apresentaram maior glicemia que os animais dos demais grupos, mas não houve diferença entre os grupos com relação aos dados de HOMA-IR, evidenciando a indução de diabetes do tipo I. Os animais diabéticos apresentaram menor BV/TV e Tb.N, e maior Tb.Sp. Não houve diferença com relação à Tb.Th. O modelo experimental foi eficaz para a indução da diabetes, mas o tratamento com sitagliptina não foi suficiente para reverter os efeitos da diabetes no tecido ósseo(AU)

Diabetes mellitus, a disease characterized by increased blood glucose levels, is one of the most important public health problems in the world, with a growing incidence, especially in developing countries. New drug therapies to control blood glucose levels have been developed, including dipeptidyl peptidase-4 (DPP-4) inhibitors such as sitagliptin. Current research shows that this drug, in addition to glycemic control, contributes to stimulate the formation and inhibition of bone resorption and has an anti-inflammatory action. The aim of this study was to evaluate the effects of sitagliptin on bone tissue in diabetic and non-diabetic rats. Thirty-eight male rats were divided into four groups: Diabetic group treated with sitagliptin (GDS-10 mg / kg / day); Diabetic group (GD); normoglycemic group treated with sitagliptin (GNS-10 mg / kg / day); normoglycemic group (GN). For induction of diabetes the animals received 10% solution of fructose in the drinking water for 14 days, after which they received 40 mg / kg streptozotocin intraperitoneally. Four weeks later, glycemia was evaluated and sitagliptin treatment was started in the GDS and GNS groups, which continued for another 4 weeks, when euthanasia occurred. Blood glucose and insulin resistance (HOMA-IR) were also evaluated on the day of sacrifice. Bone volume (BV/TV), trabecular thickness (Tb.Th), number of trabeculae (Tb.N) and trabeculae separation (Tb.Sp) of the tibial metaphysis were evaluated by computerized microtomography. Data were submitted to statistical analysis at the 0.05 level. The animals of groups GD and GDS presented higher glycemia, but there was no difference regarding HOMA-IR, evidencing diabetes type I induction. The animals in which diabetes was induced presented lower BV/TV and Tb.N, and higher Tb.Sp. There was no difference among groups in TB.Th. The experimental model was sufficient for the induction of diabetes, but treatment with sitagliptin was not enough to reverse the effects of diabetes on bone tissue(AU)

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.

Effects of hyperbaric oxygen treatment on implant osseointegration in experimental diabetes mellitus

Abstract Objective To evaluate whether hyperbaric oxygen (HBO) treatment has a favorable effect on implant osseointegration in diabetic rabbits. Material and Methods An experimental diabetes model was induced in 32 New Zealand rabbits through IV injection of alloxan. After the state of diabetes had been confirmed, one dental implant was placed in the metaphysical region of each animal's tibia. After the implants' placements, the animals were divided into two groups. Half of the animals underwent HBO treatment, while the other group did not receive HBO treatment and served as the control group. The animals were euthanized at the 4th and 8th weeks. The osseointegration of the implants were compared by histomorphometry and resonance frequency analysis (RFA). Results The Bone Implant Contact (BIC) values were significantly higher in the HBO group than in the control group at the 4th week. There was no difference in the BIC values between the groups at the 8th week. There was no significant difference in the RFA scores between the groups both at the 4th and 8th weeks after the operation. Conclusion Histomorphometry findings suggest that HBO has positive effect on implant osseointegration in the early healing period in diabetic rabbits. However, implant stability is not affected by HBO treatment.

Short term sodium alendronate administration improves the peri-implant bone quality in osteoporotic animals

Abstract Sodium alendronate is a bisphosphonate drug that exerts antiresorptive action and is used to treat osteoporosis. Objective The aim of this study was to evaluate the bone repair process at the bone/implant interface of osteoporotic rats treated with sodium alendronate through the analysis of microtomography, real time polymerase chain reactions and immunohistochemistry (RUNX2 protein, bone sialoprotein (BSP), alkaline phosphatase, osteopontin and osteocalcin). Material and Methods A total of 42 rats were used and divided in to the following experimental groups: CTL: control group (rats submitted to fictitious surgery and fed with a balanced diet), OST: osteoporosis group (rats submitted to a bilateral ovariectomy and fed with a low calcium diet) and ALE: alendronate group (rats submitted to a bilateral ovariectomy, fed with a low calcium diet and treated with sodium alendronate). A surface treated implant was installed in both tibial metaphyses of each rat. Euthanasia of the animals was conducted at 14 (immunhostochemistry) and 42 days (immunohistochemistry, micro CT and PCR). Data were subjected to statistical analysis with a 5% significance level. Results Bone volume (BV) and total pore volume were higher for ALE group (P<0.05). Molecular data for RUNX2 and BSP proteins were significantly expressed in the ALE group (P<0.05), in comparison with the other groups. ALP expression was higher in the CTL group (P<0.05). The immunostaining for RUNX2 and osteopontin was positive in the osteoblastic lineage cells of neoformed bone for the CTL and ALE groups in both periods (14 and 42 days). Alkaline phosphatase presented a lower staining area in the OST group compared to the CTL in both periods and the ALE at 42 days. Conclusion There was a decrease of osteocalcin precipitation at 42 days for the ALE and OST groups. Therefore, treatment with short-term sodium alendronate improved bone repair around the implants installed in the tibia of osteoporotic rats.

The effects of supplemental melatonin administration on the healing of bone defects in streptozotocin-induced diabetic rats

ABSTRACT Diabetes mellitus (DM) causes an increased production of free radicals that can impair bone healing. Melatonin is a hormone secreted mainly by the pineal gland, which participates in the neutralization process of free radicals. Objective The aim of this study was to investigate histologic and biochemical effects of supplemental melatonin administration on bone healing and antioxidant defense mechanism in diabetic rats. Material and Methods Eighty-six Sprague-Dawley male rats were used in this study. Diabetes mellitus was induced by intraperitoneal (i.p.) administration of 65 mg/kg streptozotocin (STZ). Surgical bone defects were prepared in the tibia of each animal. Diabetic animals and those in control groups were treated either with daily melatonin (250 μg/animal/day/i.p.) diluted in ethanol, only ethanol, or sterile saline solution. Rats were humanely killed at the 10th and 30th postoperative days. Plasma levels of Advanced Oxidation Protein Products (AOPP), Malondialdehyde (MDA), and Superoxide Dismutase (SOD) were measured. The number of osteoblasts, blood vessels and the area of new mineralized tissue formation were calculated in histologic sections. Results At the 10th day, DM+MEL (rats receiving both STZ and melatonin) group had significantly higher number of osteoblasts and blood vessels as well as larger new mineralized tissue surfaces (p<0.05 for each) when compared with DM group. At the 30th day, DM group treated with melatonin had significantly lower levels of AOPP and MDA than those of DM group (p<0.05). Conclusion Melatonin administration in STZ induced diabetic rats reduced oxidative stress related biomarkers and showed beneficial effects on bone healing at short term.

Impact of micronutrients supplementation on bone repair around implants: microCT and counter-torque analysis in rats

ABSTRACT The use of natural substances and micronutritional approaches has been suggested as a therapeutic alternative to benefit the bone healing associated with no side effects. Nevertheless, the influence of micronutritional interventions with therapeutic proprieties on the bone repair has yet to be intensely evaluated, and no evidence is available exploring the impact of micronutrient supplementation on the peri-implant bone healing. Objective This study investigated the effect of micronutrients supplementation on the bone repair around implants. Material and Methods One screw-shaped titanium implant was inserted in each tibia of each rat, which were assigned to: daily administration, for 30 d, of the placebo solution (Placebo group-n:18) or micronutrients supplementation (Micronutrients group-n:18), based on calcium, magnesium, zinc, and vitamin D3 intake. After, the animals were sacrificed. One of the implants was removed by applying a counter-torque force to evaluate the force to rupture the bone-implant interface. The other implant was evaluated by microcomputed tomography (CT) examination to determine the bone-to-implant contact (BIC) and the bone volume (BV/TV). Results No statistically significant differences were observed between the groups for both counter-torque values and microCT parameters (p>0.05). Conclusion Within the limits of this study, micronutrients supplementation did not provide additional benefits to the bone healing around dental implants.

Avaliação do reparo ósseo na interface osso/implante em ratos pinealectomizados: análise histológica, imunoistoquimica, histométrica, biomecânica e por microct / Bone repair evaluation in bone/implant interface in pinealectomized rats: histological, immunohistochemistry, histometric, biomechanics and microCT analysis

O presente estudo teve como objetivo investigar a interface osso / implante em ratos pinealectomizados tratados com melatonina. Métodos: 30 ratos, machos, adultos foram divididos em 3 grupos: controle (CO), pinealectomizados (PnX) e pinealectomizado com melatonina (PNXm). Após 30 dias da Pinealectomia, um implante foi instalado em cada tíbia e a eutanásia foi realizada aos 42 dias. As amostras foram submetidas a histomorfométrica (ELCOI e AON), biomecânica (de torque reverso), microtomografia e análise imunoistoquímica. Os dados quantitativos foram submetidos à análise estatística (P <0,05). Para os resultados histométricos, valores ELCOI para PNX foram menores quando comparados com PNXm (P = 0,0393), enquanto AON não mostrou diferença entre os grupos (P = 0,761). Os valores de torque reverso não mostraram diferença entre os grupos PNX e PNXm (P = 0,5000), e as interações CO vs PNXm, e CO vs PNX mostraram diferença significativa (P <0,05). Os parâmetros volumétricas BV/TV (P = 0,933); Tr.N (P = 0,933); Tb.Th (P = 0,933), Tb.Sp (P = 0,200) não apresentaram diferença estatística. A imunomarcação para OPG, RANKL, TRAP e osteocalcina mostrou similaridade entre os grupos, apesar da PNXm parece assemelhar-se às condições fisiológicas (CO). Portanto, a melatonina melhorou a remodelação óssea na região peri-implante em ratos pinealectomizados

This study aimed to investigate the interface bone/implant in pinealectomized rats treated with melatonin. 30 rats, male, adults were divided into 3 groups: control (CO), pinealectomized (PNX) and pinealectomized with melatonin (PNXm). After 30 days of the pinealectomy, one implant was installed on each tibia and euthanasia was performed at 42 days. The samples were submitted to histometric (BIC and NB), biomechanical (reverse torque), microtomography and immunohistochemical analysis. The quantitative data were subjected to statistical analysis (P<0.05). For the histometric results, BIC values to PNX were lower when compared to PNXm (P=0.0393), whereas NB did not showed difference among the groups (P=0.761). Reverse torque did not show difference between the groups PNX and PNXm (P=0,5000), and the interactions CO vs PNXm, and CO vs PNX showed significantly difference (P<0.05). The volumetric parameters BV/TV (P=0.933); Tr.N (P=0.933); Tb.Th (P=0.933), Tb.Sp (P=0.200) did not present statistical difference. The immunolabeling for OPG, RANKL, TRAP and osteocalcin showed similarity among the groups, despite the PNXm it seems to resemble to physiological conditions (CO). Therefore, melatonin improved the bone turnover in peri-implant region in pinealectomized rats

Avaliação histológica e histomorfométrica da energia superficial e molhabilidade em implantes de titânio grau IV e grau V: estudo experimental em coelhos / Histologic and histomorphometric evaluation of surface energy and wettability in dental implants of titanium grade IV and V: experimental study in rabbits

O presente estudo teve como objetivo avaliar a resposta biológica ao redor de implantes de titânio grau IV (titânio comercialmente puro) e grau V (Ti6Al4V), com diferentes tipos de tratamentos de superfície através da análise do contato ossoimplante (bone implant contact - BIC) e da área de neoformação óssea com e sem fluorocromo (bone area BA e BAfluo) das 3 primeiras roscas em contato ósseo de cada implante. Para isso, utilizou-se um total de 90 implantes Cone Morse de titânio grau IV (Drive 45 implantes) e titânio grau V (Facility 45 implantes), com dimensões de 3.5x8mm e 2.9x7mm, respectivamente. Estes dois tipos de implantes foram avaliados em três tratamentos de superfícies diferentes: a) superfície com jateamento com partículas abrasivas seguido de tratamento ácido - NeoPoros (NP) - em embalagem seca (Grupo Controle); b) superfície jateada seguido de tratamento ácido e energia de superfície, armazenado em líquido (ESm); c) superfície jateada seguido de tratamento ácido com energia de superfície e embalado a seco (ESs); totalizando 6 grupos, distribuídos em 15 coelhos New Zealand, em cada um foram instalados 6 implantes, sendo 3 em cada tíbia. Após 15 dias de osseointegração, os coelhos passaram por eutanásia e as tíbias seccionadas, fixadas e incluídas para a avaliação histológica e histomorfométrica. Mensurações no analisador de imagens ImageJ foram realizadas e a análise dos dados estatísticos, de todos os grupos foram avaliados através da análise de variância a dois critérios e do teste de Tukey para comparações múltiplas grupo a grupo, adotando o nível de significância de 5% (p<0,05). Os resultados mostraram que não houve diferença estatisticamente significante entre os dois tipos de titânio, porém houve diferença estatisticamente significante entre os tipos de superfície em relação ao BIC, BA e BAfluo; também, não houve interação entre titânio e superfície. Na análise do contato osso-implante (BIC) a superfície ESm teve melhor desempenho em relação ao NP, que por sua vez foi semelhante ao ESs. Quanto à área óssea (BA), a superfície NP teve menor desempenho em relação à ESs, este obteve semelhante desempenho a ESm. Quanto a área ósseo neoformada com presença de fluorocromo (BAfluo), NP teve menor desempenho em relação ao ESs, o qual obteve semelhante comportamento a ESm. Com isso, concluiu-se que implantes de titânio de gau IV e grau V obtiveram respostas biológicas equivalentes, enquanto que a energia de superfície com a molhabilidade podem ser consideradas como vantagem, uma vez que otimizam o processo de osseointegração.(AU)

This study aimed to evaluate the biological response around grade IV (commercially pure titanium) and grade V (Ti6Al4V) titanium implants with different types of surface treatments by analyzing bone-implant contact (BIC) and the bone formation area with and without fluorochrome (BA and BAfluo) of the 3 first threads on bone contact of each implant. To this end, this study used 90 Morse Taper grade IV (Drive - 45 implants) and grade V (Facility - 45 implants) titanium implants, measuring 3.5x8mm and 2.9x7mm, respectively. Both types of implants were evaluated in three different surface treatments: a) blasted/acid-etched implant surface - NeoPoros (NP) - dry pack (control group); b) blasted/acid-etched implant surface and surface energy, stored in liquid (ESm); c) blasted/acid-etched implant surface with surface energy and dry packed (ESs); totalizing 6 groups, distributed in 15 New Zealand rabbits. Six implants were placed in each rabbit, 3 in each tibia. After 15 days of osseointegration, the rabbits were euthanized and the tibias sectioned, fixed and embedded for histologic and histomorphometric evaluation. Measurements were carried out using the image analysis program ImageJ and the assessment of statistical data concerning all groups was done through the two-way analysis of variance and the Tukey test for multiple comparisons group to group, adopting the significance level of 5% ( p <0.05). The results showed no statistically significant difference between the types of titanium used. However, there were statistically significant differences between the types of surface in relation to the BIC, BA and BAfluo. In addition, there was no interaction between titanium and the surface. Concerning the analysis of bone-implant contact (BIC), the ESm surface had better performance compared to the NP, which, in turn, was similar to the ESs. As for bone area (BA), the NP surface had lower performance in relation to the ESs surface, as the latter had a similar performance to the ESm surface. Concerning the newly formed bone area with presence of fluorochrome (BAfluo), the NP had lower performance if compared to the ESs, which behaved similarly to that of the ESm surface. Thus, this study concluded that grade IV and grade V titanium implants showed equivalent biological responses, while the surface energy, together with its wettability, can be considered an advantage, enhancing the osseointegration process.(AU)

Avaliação do reparo ósseo na interface osso/implante em ratos pinealectomizados: análise histológica, imunoistoquimica, histométrica, biomecânica e por microct / Bone repair evaluation in bone/implant interface in pinealectomized rats: histological, immunohistochemistry, histometric, biomechanics and microCT analysis

O presente estudo teve como objetivo investigar a interface osso / implante em ratos pinealectomizados tratados com melatonina. Métodos: 30 ratos, machos, adultos foram divididos em 3 grupos: controle (CO), pinealectomizados (PnX) e pinealectomizado com melatonina (PNXm). Após 30 dias da Pinealectomia, um implante foi instalado em cada tíbia e a eutanásia foi realizada aos 42 dias. As amostras foram submetidas a histomorfométrica (ELCOI e AON), biomecânica (de torque reverso), microtomografia e análise imunoistoquímica. Os dados quantitativos foram submetidos à análise estatística (P <0,05). Para os resultados histométricos, valores ELCOI para PNX foram menores quando comparados com PNXm (P = 0,0393), enquanto AON não mostrou diferença entre os grupos (P = 0,761). Os valores de torque reverso não mostraram diferença entre os grupos PNX e PNXm (P = 0,5000), e as interações CO vs PNXm, e CO vs PNX mostraram diferença significativa (P <0,05). Os parâmetros volumétricas BV/TV (P = 0,933); Tr.N (P = 0,933); Tb.Th (P = 0,933), Tb.Sp (P = 0,200) não apresentaram diferença estatística. A imunomarcação para OPG, RANKL, TRAP e osteocalcina mostrou similaridade entre os grupos, apesar da PNXm parece assemelhar-se às condições fisiológicas (CO). Portanto, a melatonina melhorou a remodelação óssea na região peri-implante em ratos pinealectomizados.

This study aimed to investigate the interface bone/implant in pinealectomized rats treated with melatonin. 30 rats, male, adults were divided into 3 groups: control (CO), pinealectomized (PNX) and pinealectomized with melatonin (PNXm). After 30 days of the pinealectomy, one implant was installed on each tibia and euthanasia was performed at 42 days. The samples were submitted to histometric (BIC and NB), biomechanical (reverse torque), microtomography and immunohistochemical analysis. The quantitative data were subjected to statistical analysis (P<0.05). For the histometric results, BIC values to PNX were lower when compared to PNXm (P=0.0393), whereas NB did not showed difference among the groups (P=0.761). Reverse torque did not show difference between the groups PNX and PNXm (P=0,5000), and the interactions CO vs PNXm, and CO vs PNX showed significantly difference (P<0.05). The volumetric parameters BV/TV (P=0.933); Tr.N (P=0.933); Tb.Th (P=0.933), Tb.Sp (P=0.200) did not present statistical difference. The immunolabeling for OPG, RANKL, TRAP and osteocalcin showed similarity among the groups, despite the PNXm it seems to resemble to physiological conditions (CO). Therefore, melatonin improved the bone turnover in peri-implant region in pinealectomized rats.

Early osseointegration driven by the surface chemistry and wettability of dental implants

Objective The objective of this study was to investigate the impact of two different commercially available dental implants on osseointegration. The surfaces were sandblasting and acid etching (Group 1) and sandblasting and acid etching, then maintained in an isotonic solution of 0.9% sodium chloride (Group 2). Material and Methods X-ray photoelectron spectroscopy (XPS) was employed for surface chemistry analysis. Surface morphology and topography was investigated by scanning electron microscopy (SEM) and confocal microscopy (CM), respectively. Contact angle analysis (CAA) was employed for wetting evaluation. Bone-implant-contact (BIC) and bone area fraction occupied (BAFO) analysis were performed on thin sections (30 μm) 14 and 28 days after the installation of 10 implants from each group (n=20) in rabbits' tibias. Statistical analysis was performed by ANOVA at the 95% level of significance considering implantation time and implant surface as independent variables. Results Group 2 showed 3-fold less carbon on the surface and a markedly enhanced hydrophilicity compared to Group 1 but a similar surface roughness (p>0.05). BIC and BAFO levels in Group 2 at 14 days were similar to those in Group 1 at 28 days. After 28 days of installation, BIC and BAFO measurements of Group 2 were approximately 1.5-fold greater than in Group 1 (p<0.05). Conclusion The surface chemistry and wettability implants of Group 2 accelerate osseointegration and increase the area of the bone-to-implant interface when compared to those of Group 1. .

Bone tissue response to plasma-nitrided titanium implant surfaces

A current goal of dental implant research is the development of titanium (Ti) surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration. Objective The aim of this study was to evaluate the in vivo bone response to Ti surfaces modified by plasma-nitriding treatments. Material and Methods Surface treatments consisted of 20% N2 and 80% H2, 450°C and 1.5 mbar during 1 h for planar and 3 h for hollow cathode. Untreated surface was used as control. Ten implants of each surface were placed into rabbit tibiae and 6 weeks post-implantation they were harvested for histological and histomorphometric analyses. Results Bone formation was observed in contact with all implants without statistically significant differences among the evaluated surfaces in terms of bone-to-implant contact, bone area between threads, and bone area within the mirror area. Conclusion Our results indicate that plasma nitriding treatments generate Ti implants that induce similar bone response to the untreated ones. Thus, as these treatments improve the physico-chemical properties of Ti without affecting its biocompatibility, they could be combined with modifications that favor bone formation in order to develop new implant surfaces. .

Análise histomorfométrica de implantes hidrofóbicos e hidrofílicos: estudo experimental em coelhos / Comparative histomorphometric analysis of hydrophobic and hydrophilic implants: an experimental study in rabbits

O íntimo contato entre osso e implante é considerado um pré-requisito fundamental para o sucesso dos implantes dentários, condição esta conhecida como osseointegração. Devido a isto, um grande número de pesquisas com tratamentos de superfícies de implantes vem sendo desenvolvido por várias empresas nos últimos anos, visando acelerar esse fenômeno. O objetivo deste trabalho é avaliar histomorfometricamente o percentual de contato osso-implante (BIC) e área de osso novo (BA) entre implantes de tratamento de superfície Neoporos (GC - hidrofóbico) e implantes com energia de superfície molhada Acqua (GE - hidrofílicos). Foram utilizados 15 coelhos da raça new zealand, que receberam 30 implantes divididos em cada lado de suas tíbias direita e esquerda, ambos de titânio comercialmente puro grau IV com 3.5x8mm de dimensão, sendo ao final de 15 dias, a região dos implantes coletada e processada histologicamente para obtenção de cortes teciduais não desmineralizados, embora dois implantes do grupo Esm tenham sido excluídos da pesquisa devido à instalação ter ocorrido dentro do canal medular e terem obtido tecido necrosado, não cumprindo as características de osseointegração. Para análise dos dados estatísticos, utilizou-se o teste t de Students para amostras independents e teste Mann-Whitney Rank Sum com nível de significância de p<0.05. Os resultados mostraram que não houve diferença estatisticamente significante entre os grupos para a análise de BIC. O grupo GC apresentou a média de 42.9% de BIC, ligeiramente menor que o grupo GE, que apresentou 49.3% de média. Já para o teste BA houve diferenças de 15%, em que o grupo GC apresentou 58.6% e o grupo GE, 74.4%. A conclusão é que há, ainda, necessidade de maiores estudos a cerca do referido tema.

The near contact between bone and implant is considered an essential pre-requisite for the success of dental implants, a condition known as osseointegration. Due to it, a great amount of researches on implants surface treatments has been developed by several companies in recent years to accelerate the phenomenon of osseointegration. The aim of the present study is to evaluate histomorphometrically the percentage of bone-implants contact (BIC) and the area of new bone (BA) between implants with surfaces treatment Neoporos (GC - hydrophobic) and implants with wets surface energy Acqua (GE - hydrophilic). It was used fifteen (n=15) New Zealand rabbits, which received thirty implants installed dividing them between its right and left tibias. Implants were commercially pure titanium grade IV with 3.5x8mm dimension. After fifteen days, the implants area were collected and processed histologically in order to obtain not demineralized tissue sections. For statistical data analysis, it was used the t test for independents samples and Mann-Whitney Rank Sum test. The significance level was p<0.05. Results showed no statistical significant difference between groups for BIC analysis. The control group showed a mean of 42.9% of BIC, slightly lower than the GE group, which showed a mean of 49.3%. For BA test, there was a significant difference of more than 15% in the control group (58.6% for the GC group and 74.4% for GE group). It was concluded that futher studies is needed on this topic of osseointegration and hydrophobic /hydrophilic implants.

Aloe vera as vehicle to mineral trioxide aggregate: study in bone repair / Aloe vera como veículo ao mineral trióxido agregado: estudo em reparo ósseo

Aim: Mineral trioxide aggregate (MTA) was associated to Aloe vera to verify the coadjutant action of that medicinal plant in the bone neoformation process in tibia of rats. Material and Method: 36 male rats (Rattus norvegicus) were used, divided into two groups of 18 rats each. Two circumferential bone defects with approximately 5 mm in diameter were made on the right tibia of each animal: the upper defect was filled with blood coagulates in both groups to serve as experimental control and the lower defect was filled with MTA and Aloe vera in experimental (group E1) and MTA and distilled water in experimental (group E2). Seven, 15 and 30 days after surgery, six animals from each group were euthanized and the right tibia of each animal was removed for histological analysis. Result: Histologically, experimental group E1 presented better results for the two variables, inflammation [at seven days (p=0.045)] and bone formation [at seven days (p=0.018) and 30 days (p=0.034)], compared to the E2 group. Conclusion: The association of MTA and Aloe vera showed potential to reduce the effects of the inflammatory cascade and promote bone neoformation making it to a promising proposal for future use in endodontic therapy. .

Objetivo: Mineral trióxido agregado (MTA) foi associado a Aloe vera para se verificar a ação coadjuvante desta planta medicinal no processo de neoformação óssea em tíbia de ratos. Material e Método: 36 ratos machos (Rattus norvegicus) foram utilizados, divididos em dois grupos com 18 animais em cada. Dois defeitos ósseos circunferenciais com aproximadamente 5 mm de diâmetro foram feitos na tíbia direita de cada animal: o defeito superior foi preenchido com coágulo sanguíneo em ambos os grupos para servir como controle e o defeito inferior foi preenchido com MTA e Aloe vera (grupo E1) e MTA e água destilada (grupo E2). Sete, 15 e 30 dias após a cirurgia, seis animais de cada grupo foram submetidos à eutanásia e a tíbia direita de cada animal foi retirada para análise histológica. Resultado: Histologicamente, o grupo experimental E1 apresentou melhores resultados para as duas variáveis, inflamação [em sete dias (p = 0,045)] e formação óssea [em sete dias (p = 0,018) e 30 dias (p = 0,034)], em comparação com os resultados do grupo E2. Conclusão: A associação entre o MTA e Aloe vera demonstrou potencial para reduzir os efeitos da cascata inflamatória e promover a neoformação óssea, tornando-a uma proposta promissora para uso futuro no tratamento endodôntico. .

Efeito da desmineralização ácida da interface enxerto-leito na consolidação de enxertos ósseos autógenos em bloco / Influence of acid demineralization of contacting osseous surfaces on the consolidation of autogenous onlay bone grafts

Para testar a hipótese de que a desmineralização in situ das superfícies de contato enxerto-leito, e a forma como o enxerto é estabilizado ao leito, podem influenciar os mecanismos envolvidos na consolidação do enxerto, fragmentos ósseos de 10 mm de diâmetro foram removidos das metáfises proximais tibiais de 36 coelhos (Oryctolagus Cuniculus) e transplantados para uma área adjacente. Na tíbia esquerda dos animais, as superfícies de contato do enxerto e do leito hospedeiro foram desmineralizadas com ácido cítrico pH 1,0 por 3 minutos antes dos enxertos serem fixados ao leito. Na tíbia direita, o transplante do bloco ósseo não foi precedido de desmineralização. Metade dos enxertos foi imobilizada sobre o leito pela superposição de uma membrana não reabsorvível de politetrafluoretileno colada com cianoacrilato ao leito à distância da interface enxerto-leito. A outra metade dos enxertos foi fixada por um parafuso de titânio no centro do enxerto. Assim, foram formados 4 grupos de estudo: membrana (M), membrana + ácido (MA), parafuso (P) e parafuso + ácido (PA). Três animais de cada grupo forneceram espécimes para análise microscópica quantitativa e qualitativa aos 15, 30 e 45 dias de pós-operatório. A análise qualitativa demonstrou que não houve formação óssea na interface em nenhum espécime aos 15 dias e que nos demais períodos, em todos os grupos, a quantidade de tecido ósseo neoformado na interface e seu estágio de maturação aumentaram com o tempo. Ambos os métodos de fixação empregados foram eficientes em manter os enxertos em posição, porém a membrana promoveu menor reabsorção da estrutura do enxerto. A análise quantitativa computadorizada revelou que, aos 30 dias, os grupos MA e PA apresentaram maior área de formação óssea na interface (71,34 ± 12,03%; 56,74 ± 2,15% respectivamente) em relação aos grupos M e P (51,75 ± 11,02%; 43,95 ± 4,05% respectivamente) e superfícies de consolidação óssea mais extensas (93,41 ± 5,95%; 93,73 ± 4,96%...

In order to test the hypothesis that the demineralization "in situ" of contacting surfaces of bone graft/bone bed and the fixation method used for graft stabilization can influence the mechanisms involved in the consolidation of the graft, bone fragments of 10 mm in diameter were removed from the proximal tibial metaphysis of thirty-six male rabbits (Oryctolagus Cuniculus) and transplanted to an adjacent area. In the left tibia of the animals, the contacting surfaces of the graft and host bed were demineralized with citric acid pH 1.0 for 3 minutes before the grafts were fixed to the receptor bed. In the right tibia, the bone block transplantation was not preceded by demineralization. Half of the grafts were immobilized on the bone bed by a nonresorbable polytetrafluoroethylene membrane glued with cyanoacrylate adhesive to the host bed distant from the bone graft-bone bed interface. The other half of the grafts were fixed by a titanium screw in the center of the graft. Thus, four groups were formed: membrane (M), membrane + acid (MA), screw (P) and screw + acid (PA). Three animals from each group provided specimens for quantitative and qualitative microscopic analysis at 15, 30 and 45 days postoperatively. Qualitative analysis showed no significant bone formation at the interface in any specimen of the groups at 15 days and on the other periods in all groups, the amount of newly formed bone at the interface as well as the stage of bone maturation increased with time. Both fixation methods were effective in maintaining the graft in position, but the membrane resulted in less resorption of the graft. Quantitative analysis, performed by means of a computer program for image analysis, showed that at day 30, groups MA and PA, showed greater area of bone formation at the interface (71.34 ± 12.03%; 56.74 ± 2 15%) than groups M and P (51.75 ± 11.02%, 43.95 ± 4.05%) and more osseointegrated bone surfaces (93.41 ± 5.95%, 93.73 ± 4.96%) than those...

Análise histomorfométrica dos implantes de titânio grau 4 e grau 5: estudo experimental em coelhos / Histomorphometric evaluation of titanium implants grade 4 and grade 5: experimental study in rabbits

Os implantes dentários de titânio comercialmente puro (Ticp) grau 4 e os de titânio-alumínio-vanádio (Ti6Al4V) grau 5, possuem boas propriedades mecânicas. No entanto, algumas situações clínicas com restrição de espessura óssea impedem a utilização dos implantes com 3.75mm de diâmetro tradicionalmente fabricados em titânio 4 e que apresentam resistência mecânica testada em profusão. Como a liga de grau 5 possui superior resistência à tração e à fadiga, este estudo objetiva analisar a resposta óssea do titânio grau 4 e grau 5 em implantes curtos e estreitos através da análise do contato osso-implante (BIC) e da área de neoformação óssea. Para este fim, o presente estudo utilizou 15 coelhos da raça New Zealand, que receberam um total de trinta implantes divididos em suas tíbias direita e esquerda. Os implantes de grau 4 e de grau 5, com dimensões de 3.5x8mm e 2.9x7mm, respectivamente, foram fornecidos pela empresa NEODENT® (Curitiba-Brasil). Neste estudo, dois grupos foram formados, um com implantes de titânio grau 4 e outro com implantes de titânio grau 5, ambos contendo quinze implantes curtos e estreitos. Cortes histológicos foram realizados após duas semanas de osseointegração. Mensurações no analisador de imagens ImageJ foram feitas para verificar o BIC e a área de osso neoformado. Para a análise dos dados estatísticos, utilizou-se o teste t de Student para amostras independentes com nível de significância de p<0.05. Os resultados mostraram que não houve diferença estatisticamente significante entre os grupos nos dois tipos de análises. A média dos valores de BIC do titânio grau 4 obteve o valor médio mais alto de 56,53%, variando de 95,74% a 9,4%. O grupo de titânio grau 5 apresentou média de 50,63%, variando entre 84,3% e 13,12%. Com base em imagens com fluorescência, realizou-se análise da área óssea. O grupo de titânio grau 5 apresentou valor de 46,3% (variando entre 79% a 14,21%) em fluorescência, número ligeiramente maior do que o verificado no...

Commercially pure titanium implants (Ticp) of degree IV and of titanium-aluminum-vanadium degree V have good mechanical properties. However some clinical situations with limited bone thickness preclude the use of traditionally implants with 3.75mm diameter made from titanium IV and present strength tested in profusion. In addition, degree V alloy shows higher resistance to traction and fatigue, this study aims to analyze the bone response to degree IV and degree V titanium in short and narrow implants with the same surface treatment through the analysis of the bone-to-implant contact (BIC) and the area of the new bone formation. For such purpose, this study used15 New Zealand white rabbits which had a total of thirty implants inserted in their right and left tibiae. Both degree IV and degree V implants, measuring 3.5x8mm and 2.9x7mm, respectively, were provided by dental implant manufacturer NEODENT® (Curitiba-Brazil). The implants were allocated into two distinct groups. Fifteen short and narrow implants of degree IV were utilized in a group, whereas fifteen short and narrow implants of degree V were employed in the other group. Histological sections samples were carried out after a two-week period of osseointegration. Subsequently, measurements were calculated using ImageJ software in order to verify the BIC and the area of the newly grown bone. Analysis of statistical data of independent samples with significance level p<0.05 was carried out via Student's t-test. Results showed no statistically substantial difference between both groups regarding both measurement activities. The media values BIC for the degree IV titanium group reached the highest average value of 56,53%, varying from 95,74% to 9,4%. The degree V titanium group averaged 50,63%, oscillating between 84,3% and 13,12%. The bone areas were analyzed based on images with fluorescence. The degree V titanium...

Efeito da desmineralização ácida da interface enxerto-leito na consolidação de enxertos ósseos autógenos em bloco / Influence of acid demineralization of contacting osseous surfaces on the consolidation of autogenous onlay bone grafts

Para testar a hipótese de que a desmineralização in situ das superfícies de contato enxerto-leito, e a forma como o enxerto é estabilizado ao leito, podem influenciar os mecanismos envolvidos na consolidação do enxerto, fragmentos ósseos de 10 mm de diâmetro foram removidos das metáfises proximais tibiais de 36 coelhos (Oryctolagus Cuniculus) e transplantados para uma área adjacente. Na tíbia esquerda dos animais, as superfícies de contato do enxerto e do leito hospedeiro foram desmineralizadas com ácido cítrico pH 1,0 por 3 minutos antes dos enxertos serem fixados ao leito. Na tíbia direita, o transplante do bloco ósseo não foi precedido de desmineralização. Metade dos enxertos foi imobilizada sobre o leito pela superposição de uma membrana não reabsorvível de politetrafluoretileno colada com cianoacrilato ao leito à distância da interface enxerto-leito. A outra metade dos enxertos foi fixada por um parafuso de titânio no centro do enxerto. Assim, foram formados 4 grupos de estudo: membrana (M), membrana + ácido (MA), parafuso (P) e parafuso + ácido (PA). Três animais de cada grupo forneceram espécimes para análise microscópica quantitativa e qualitativa aos 15, 30 e 45 dias de pós-operatório. A análise qualitativa demonstrou que não houve formação óssea na interface em nenhum espécime aos 15 dias e que nos demais períodos, em todos os grupos, a quantidade de tecido ósseo neoformado na interface e seu estágio de maturação aumentaram com o tempo. Ambos os métodos de fixação empregados foram eficientes em manter os enxertos em posição, porém a membrana promoveu menor reabsorção da estrutura do enxerto. A análise quantitativa computadorizada revelou que, aos 30 dias, os grupos MA e PA apresentaram maior área de formação óssea na interface (71,34 ± 12,03%; 56,74 ± 2,15% respectivamente) em relação aos grupos M e P (51,75 ± 11,02%; 43,95 ± 4,05% respectivamente) e superfícies de consolidação óssea mais extensas (93,41 ± 5,95%; 93,73 ± 4,96%...

In order to test the hypothesis that the demineralization "in situ" of contacting surfaces of bone graft/bone bed and the fixation method used for graft stabilization can influence the mechanisms involved in the consolidation of the graft, bone fragments of 10 mm in diameter were removed from the proximal tibial metaphysis of thirty-six male rabbits (Oryctolagus Cuniculus) and transplanted to an adjacent area. In the left tibia of the animals, the contacting surfaces of the graft and host bed were demineralized with citric acid pH 1.0 for 3 minutes before the grafts were fixed to the receptor bed. In the right tibia, the bone block transplantation was not preceded by demineralization. Half of the grafts were immobilized on the bone bed by a nonresorbable polytetrafluoroethylene membrane glued with cyanoacrylate adhesive to the host bed distant from the bone graft-bone bed interface. The other half of the grafts were fixed by a titanium screw in the center of the graft. Thus, four groups were formed: membrane (M), membrane + acid (MA), screw (P) and screw + acid (PA). Three animals from each group provided specimens for quantitative and qualitative microscopic analysis at 15, 30 and 45 days postoperatively. Qualitative analysis showed no significant bone formation at the interface in any specimen of the groups at 15 days and on the other periods in all groups, the amount of newly formed bone at the interface as well as the stage of bone maturation increased with time. Both fixation methods were effective in maintaining the graft in position, but the membrane resulted in less resorption of the graft. Quantitative analysis, performed by means of a computer program for image analysis, showed that at day 30, groups MA and PA, showed greater area of bone formation at the interface (71.34 ± 12.03%; 56.74 ± 2 15%) than groups M and P (51.75 ± 11.02%, 43.95 ± 4.05%) and more osseointegrated bone surfaces (93.41 ± 5.95%, 93.73 ± 4.96%) than those...