Effects of different doses of ionizing radiation on alveolar bone repair in post-extraction tooth socket: an experimental study in rats.

OBJECTIVE: This study aimed to evaluate the dose-response effects of ionizing radiation (IR) on alveolar bone repair and bone strength after tooth extraction. MATERIALS AND METHODS: A total of 32 male Wistar rats were used in the study, 28 animals were included in the final analysis, and n = 7 for each experimental group. Mandibular first molars were extracted. After 7 days, the animals were randomly divided into four groups according to single-dose irradiation: NIr, control group; Ir15, irradiated at 15 Gy; Ir20, irradiated at 20 Gy; and Ir30, irradiated at 30 Gy. The tooth extraction sites were subjected to micro-computed tomography (micro-CT), histological, histomorphometric, and biomechanical analyses 14 days after extraction. Data were analyzed using one-way ANOVA followed by Tukey's post hoc test (α = 0.05). RESULTS: Micro-CT analysis revealed that IR led to lower values of bone volume (BV, in mm3) (0.68 ± 0.08, P < 0.001) and bone volume fraction, ratio of the segmented bone volume to the total volume of the region of interest (BV/TV, in %) (44.1 ± 8.3, P < 0.001) for the Ir30 group compared to the control group. A significantly lower amount of newly formed bone was observed in the Ir30 (P = 0.005) than in the Ir15 group. The histomorphometric results of quantification of bone matrix neoformation and the micro-CT were in agreement, demonstrating greater damage to the Ir30 group. IR30 cells showed a lower percentage of densely packed collagen than control cells. No significant differences were found in the biomechanical parameters. CONCLUSION: IR affects alveolar bone repair. A dose of 30 Gy reduced the bone healing process owing to a smaller amount of newly formed bone and a lower percentage of densely packed collagen. Therefore, a dose of 30 Gy can be used to successfully establish an animal model of an irradiated mandible that mimics the irradiated clinical conditions. CLINICAL RELEVANCE: Radiotherapy can lead to severe side effects and tooth extraction is a major risk factor. A proper understanding of the pathological mechanisms of radiation in alveolar bone repair requires the establishment of a suitable animal model of clinical conditions.

Effects of periodontal therapy on GCF cytokines in generalized aggressive periodontitis subjects.

AIM: To examine changes in levels of gingival crevicular fluid (GCF) cytokines, after periodontal therapy of generalized aggressive periodontitis (GAgP). MATERIALS AND METHODS: Twenty-five periodontally healthy and 24 GAgP subjects had periodontal clinical parameters measured and gingival crevicular fluid (GCF) samples collected from up to 14 sites/subject. GCF samples were analysed using multiplex bead immunoassay for: GM-CSF, IFN-γ, IL-10, IL-1ß, IL-2, IL-6 and TNF-α. Aggressive periodontitis subjects were randomly assigned to either scaling and root planing (SRP) alone or SRP plus systemic amoxicillin (500 mg) and metronidazole (400 mg) 3 times a day for 14 days. Clinical parameters and GCF cytokines were re-measured 6 months after treatment. Differences over time were analysed using the Wilcoxon test and between groups using the Mann-Whitney test. RESULTS: Significant reductions in GCF GM-CSF, IL-1ß and the ratio IL-1ß/IL-10 and increases in GCF IL-6 were detected after therapy. The mean change in GCF cytokines did not differ significantly between groups. CONCLUSIONS: Periodontal therapy improved GCF cytokine profiles by lowering IL-1ß and increasing IL-10 levels. The reduction in GCF GM-CSF after therapy implicates this cytokine in the pathogenesis of GAgP. There was no difference between therapies in changes of GCF cytokines.

Periodontal risk assessment model in a sample of regular and irregular compliers under maintenance therapy: a 3-year prospective study.

BACKGROUND: The purpose of this study is to investigate the association of the periodontal risk assessment (PRA) model with the recurrence of periodontitis and tooth loss during periodontal maintenance therapy (PMT). METHODS: In a prospective PMT program, 75 regular complier (RC) and 89 erratic complier (EC) patients were selected. A periodontal examination and PRA were performed after active periodontal therapy and after 3 years of PMT. Risk profiles (low, moderate, or high) of participants were evaluated, and the recurrence of periodontitis and tooth loss were analyzed using univariate and multivariate analyses. RESULTS: RCs showed less recurrence of periodontitis and tooth loss than ECs (P <0.05). Rates of periodontitis recurrence in RCs and ECs were 2.7% and 3.4%, respectively, for the moderate-risk profile and 6.7% and 11.2%, respectively, for the high-risk profile. During PMT, 49 teeth (0.65 ± 1.4 teeth per participant) were lost in the RC group, and 70 teeth (0.78 ± 2.1 teeth per participant) were lost in the EC group. High-risk profile participants showed more recurrence of periodontitis and lost significantly more teeth than did participants with moderate- or low-risk profiles in RC and EC groups (P <0.05). CONCLUSION: The risk profile influenced the recurrence of periodontitis and tooth loss. RCs had less recurrence of periodontitis and less tooth loss. The PRA model can be useful in particularizing the risk of patients and adjusting recall intervals.

[Myocardial protection to the hypertrophied heart: the eternal challenge]. / Proteção miocárdica ao coração hipertrofiado: o eterno desafio.

The myocardial protection allowed great advance in cardiac surgery, decreasing the mortality and making more feasible complex surgeries. Lately, the patient population elected for cardiac procedures has been changing towards elderly patients with ventricular function depressed and myocardial hypertrophy. The myocardial hypertrophy condition represents a great challenge since the beginning of the cardiac surgery. Several techniques have been described to protect the myocardial hypertrophy, however with no satisfactory results. In this manuscript we present the state of the art technique of myocardial protection.

Proteção miocárdica ao coração hipertrofiado: o eterno desafio: [revisão] / Myocardial protection to the hypertrophied heart: the eternal challenge: [review]

A proteção miocárdica permitiu enorme avanço na moderna cirurgia cardíaca, reduzindo a mortalidade e permitindo que operações cada vez mais complexas pudessem ser realizadas. A alteração na população eleita para procedimentos cirúrgicos cardiológicos mudou significativamente nas últimas décadas, com o aumento de pacientes mais idosos, com função ventricular deprimida e miocárdio hipertrofiado. Essa última condição, desde os primórdios da cirurgia cardíaca, constituiu-se em grande desafio. Diversas técnicas de proteção ao miocárdio hipertrofiado foram descritas, porém com resultados não alentadores. As características da hipertrofia miocárdica no adulto com cardiopatia cirúrgica apresentam particularidades desafiadoras. Nesse artigo, procuramos atualizar o estado da arte sobre a proteção miocárdica ao coração hipertrofiado.

The myocardial protection allowed great advance in cardiac surgery, decreasing the mortality and making more feasible complex surgeries. Latterly, the patient population elected for cardiac procedures has been changing towards elderly patients with ventricular function depressed and myocardial hypertrophy. The myocardial hypertrophy condition represents a great challenge since the beginning of the cardiac surgery. Several techniques have been described to protect the myocardial hypertrophy, however with no satisfactory results. In this manuscript we present the state of the art technique of myocardial protection.

Effects of myocardial protection in hypertrophic rabbit hearts: structural and ultra structural analysis.

OBJECTIVE: To experimentally compare the structural and ultrastructural changes in isolated hypertrophied rabbits' hearts submitted to cardiac arrest protected using sanguineous and crystalloid cardioplegia solutions. METHOD: The study comprised two experimental groups and one control group. In Experimental Group I, cardiac arrest was achieved by the continuous infusion of tepid sanguineous cardioplegia solution. In Experimental Group II, cardiac arrest was obtained by an intermittent infusion of a cold crystalloid cardioplegia solution. In the Control Group the hearts were submitted to normothermic anoxic arrest for 45 minutes. After the procedures, eight samples of the left ventricle lateral wall were collected and fixed in 10% formaldehyde and 2.5% glutaraldehyde for structural and ultrastructural analysis. RESULTS: The structural and ultrastructural results demonstrated that the hearts submitted to cardiac arrest protected by continuous tepid sanguineous cardioplegia, Group I, were better preserved and with less accentuated cellular alterations compared to those submitted to cardiac arrest protected using intermittent cold crystalloid cardioplegia and the Control Group. CONCLUSION: Continuous tepid sanguineous cardioplegia was more efficient in the preservation of the structural and ultrastructural integrity of the myocardium when compared to intermittent cold crystalloid cardioplegia.

Efeitos das cardioplegias sangüínea e cristalóide no miocárdio hipertrófico de coelho: avaliação estrutural e ultra-estrutural / Effects of myocardial protection in hypertrophic rabbit hearts: structural and ultra structural analysis

OBJETIVO: Comparar e avaliar experimentalmente as alterações estruturais e ultra-estruturais em corações hipertrofiados isolados de coelhos submetidos à parada protegida pela solução de cardioplegia sangüínea e cardioplegia cristalóide. MÉTODO: O estudo compreendeu um grupo controle e dois grupos experimentais. No grupo I, a parada cardíaca foi obtida pela infusão da solução de cardioplegia sangüínea contínua e tépida. No grupo II, a parada cardíaca foi conseguida pela infusão da solução de cardioplegia cristalóide intermitente e fria. No grupo controle, os corações foram submetidos à parada anóxia normotérmica por 45 minutos. Após experimentos, oito amostras da parede lateral do ventrículo esquerdo foram coletadas e fixadas em formaldeído 10 por cento e glutaraldeído 2,5 por cento para análises estrutural e ultra-estrutural. RESULTADOS: Os resultados estruturais e as descrições ultra-estruturais mostraram que os corações submetidos à parada protegida pela cardioplegia sangüínea contínua e tépida (grupo I) estavam mais preservados com alterações celulares menos acentuadas se comparados aos submetidos à parada protegida pela cardioplegia cristalóide intermitente e fria (grupo II) e ao grupo controle. CONCLUSÃO: A cardioplegia sangüínea contínua e tépida (Grupo I) foi mais eficiente na preservação da integridade estrutural e ultra-estrutural do miocárdio, quando comparada à cardioplegia cristalóide intermitente e fria (Grupo II).

OBJECTIVE: To experimentally compare the structural and ultrastructural changes in isolated hypertrophied rabbits' hearts submitted to cardiac arrest protected using sanguineous and crystalloid cardioplegia solutions. METHOD: The study comprised two experimental groups and one control group. In Experimental Group I, cardiac arrest was achieved by the continuous infusion of tepid sanguineous cardioplegia solution. In Experimental Group II, cardiac arrest was obtained by an intermittent infusion of a cold crystalloid cardioplegia solution. In the Control Group the hearts were submitted to normothermic anoxic arrest for 45 minutes. After the procedures, eight samples of the left ventricle lateral wall were collected and fixed in 10 percent formaldehyde and 2.5 percent glutaraldehyde for structural and ultrastructural analysis. RESULTS: The structural and ultrastructural results demonstrated that the hearts submitted to cardiac arrest protected by continuous tepid sanguineous cardioplegia, Group I, were better preserved and with less accentuated cellular alterations compared to those submitted to cardiac arrest protected using intermittent cold crystalloid cardioplegia and the Control Group. CONCLUSION: Continuous tepid sanguineous cardioplegia was more efficient in the preservation of the structural and ultrastructural integrity of the myocardium when compared to intermittent cold crystalloid cardioplegia.

Solução cardioplégica polarizante: estado da arte / Polarizing cardioplegic solution: state of the art

A exegese do termo cardioplegia remete aos significados de lesão, golpe, ataque ou ferimento, bem diferente, portanto, do sentido em que o termo é empregado na maior parte dos centros de cirurgia cardíaca do Brasil e do mundo, ou seja, como correspondendo à proteção miocárdica. Daí a melhor denominação de solução cardioplégica, para caracterizar as soluções empregadas com finalidade de promover a parada cardíaca controlada do coração. A parada cardíaca induzida por solução cardioplégica pode acontecer por hiperpolarização, despolarização ou com bloqueadores da bomba de cálcio. No presente trabalho, discorreremos sobre os principais agentes que promovem a parada cardíaca por hiperpolarização da membrana miocárdica. Com a solução hiperpolarizante, o coração pára no perído diastólico, havendo uma redução ainda maior no seu gasto energético, o que propicia melhores condições ao coração quando este reinicia sua contração ao final do procedimento cirúrgico

Cardioplegia using low volumic cardioplegic agents: morphological study in isolated rabbit hearts

INTRODUÇAO: A soluçäo cardioplégica farmacológica busca eliminar as conseqüências do dano isquêmico, que é o resultado do desbalanço entre a oferta e o consumo de energia durante a parada dos batimentos cardíacos, nas cirurgias cardíacas com circulaçäo extracorpórea. OBJETIVO: Este trabalho avalia experimentalmente as alterações estruturais e ultra-estruturais em coraçäo isolado de coelhos submetidos à parada protegida pela Soluçäo para Cardioplegia de Baixo Volume (SCBV). MÉTODO: O estudo compreendeu um grupo controle e dois grupos experimentais. No grupo I, a parada cardíaca foi obtida pela infusäo da SCBV por 2 horas. No grupo II, o experimento foi conduzido da mesma forma até a parada protegida pela SCBV por duas horas, imediatamente procedeu-se à reperfusäo com soluçäo oxigenada de Ringer Locke (RL) por uma hora. No grupo controle os corações foram perfundidos com soluçäo oxigenada de RL por duas horas. Após os experimentos, oito amostras de parede lateral do ventrículo esquerdo foram fixadas em formaldeído 10 por cento e glutaraldeído 2,5 por cento para análises histológica e ultra-estrutural. RESULTADOS: As células do miocárdio, fibroblastos e células endoteliais, observadas nos grupos experimentais I e II, apresentaram marginalizaçäo da heterocromatina, compactaçäo do nucléolo, alteraçäo na forma das mitocôndrias, compactaçäo das cristas e aumento da densidade da matriz mitocondrial, indicando que tanto a estrutura nuclear quanto a das organelas citoplasmáticas foram alteradas em relaçäo às células do grupo controle. CONCLUSAO: As modificações estruturais foram decorrentes de uma adaptaçäo fisiológica da célula, näo sendo indicativas de oncose ou apoptose, sugerindo, portanto, que a soluçäo cardioplégica utilizada foi eficiente para a preservaçäo das células.