Effect of nanotechnology in self-etch bonding systems on the shear bond strength of stainless steel orthodontic brackets

ABSTRACT Objective: To evaluate the effect of silica dioxide (SiO2) nanofillers in different bonding systems on shear bond strength (SBS) and mode of failure of orthodontic brackets at two experimental times. Methods: Ninety-six intact premolars were divided into four groups: A) Conventional acid-etch and primer Transbond XT; B) Transbond Plus self-etch primer; and two self-etch bonding systems reinforced with silica dioxide nanofiller at different concentrations: C) Futurabond DC at 1%; D) Optibond All-in-One at 7%. Each group was allocated into two subgroups (n = 12) according to experimental time (12 and 24 hours). SBS test was performed using a universal testing machine. ARI scores were determined under a stereomicroscope. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to determine the size and distribution of nanofillers. One-way ANOVA was used to compare SBS followed by the post-hoc Tukey test. The chi-square test was used to evaluate ARI scores. Results: Mean SBS of Futurabond DC and Optibond All-in-One were significantly lower than conventional system, and there were no significant differences between means SBS obtained with all self-etch bonding systems used in the study. Lower ARI scores were found for Futurabond DC and Optibond All-in-One. There was no significant difference of SBS and ARI obtained at either time points for all bonding systems. Relative homogeneous distribution of the fillers was observed with the bonding systems. Conclusion: Two nanofilled systems revealed the lowest bond strengths, but still clinically acceptable and less adhesive was left on enamel. It is advisable not to load the brackets immediately to the maximum.

RESUMO Objetivo: avaliar o efeito das nanopartículas de dióxido de silício (SiO2), presentes em diferentes sistemas adesivos, na resistência ao cisalhamento da colagem (RAC) e no modo de fratura de braquetes ortodônticos avaliados em dois momentos. Métodos: noventa e seis pré-molares intactos foram divididos em quatro grupos: A) condicionador ácido convencional e primer Transbond XT; B) primer autocondicionador Transbond Plus; e dois sistemas adesivos autocondicionantes reforçados com nanopartículas de dióxido de silício em diferentes concentrações, C) DC Futurabond a 1%; D) Optibond All-In-One a 7%. Cada grupo foi dividido em dois subgrupos (n = 12), de acordo com o tempo para realização do teste (12 e 24 horas). O teste da RAC foi realizado em uma máquina universal de ensaios. Os resultados do índice de adesivo remanescente foram determinados com um estereomicroscópio. Para determinar o tamanho e a distribuição das nanopartículas, utilizou-se microscopia eletrônica de varredura (MEV) e microscopia eletrônica de transmissão (MET). O ANOVA a um critério foi usado para comparar a RAC, seguido pelo teste post-hoc de Tukey. O teste qui-quadrado foi usado para avaliar os índices de adesivo remanescente. Resultados: a RAC média do Futurabond DC e do Optibond All-In-One foi menor do que a do sistema convencional, de forma estatisticamente significativa; e não houve diferença estatisticamente significativa entre os níveis médios de RAC obtidos nos sistemas adesivos autocondicionantes avaliados nesse estudo. Os menores índices de adesivo remanescente foram observados com o Futurabond DC e o Optibond All-In-One. Não houve, entre os sistemas adesivos, diferença significativa na RAC e nos índices de adesivo remanescente obtidos nos dois tempos de aplicação. Foi observada uma distribuição relativamente homogênea das partículas nos sistemas adesivos. Conclusão: os dois sistemas com nanopartículas demonstraram menor RAC, mas ainda aceitável e com o menor índice de adesivo remanescente no esmalte. É, assim, aconselhável não submeter os braquetes à carga máxima logo após a colagem.

Pulmonary dysfunctions in end stage chronic renal failure children on regular hemodialysis; possible risk factors

Lung and kidney functions are intimately related in both health and disease. In renal failure respiratory changes help to mitigate the systemic effects of renal acid-base disturbances. Changes in the function of the respiratory system are among the frequent complications of renal impairment. Alteration in the respiratory drive, mechanics, muscle function, lung volumes, gas exchange and hemodynamics are frequent and could occur in the lungs without obvious pulmonary symptoms. Their effects could be the way to pulmonary functional disorders. Patients with chronic renal failure treated with hemodialysis may exhibit various changes in ventilation and gas exchange. Moreover, hemodialysis and peritoneal dialysis may have their own impact on the respiratory functions. The main objectives of this work were to assess the pulmonary functions and arterial blood gases as well as assessment of echocardiographic changes in a group of children with chronic renal failure undergoing regular hemodialysis. We also aimed to explore possible risk factors that make these children more liable to disturbed pulmonary function. The study included 19 patients with CRF on regular hemodialysis during the period from January to March 2005. Their ages ranged from 8-17 years [mean 13.63 +/- 2.65]. They were 12 males and 7 females. These patients were attending the pediatric nephrology unit in Assiut University Hospital. The duration of dialysis varied from 1-5 years. Patients with known or recent cardiac, infectious, inflammatory or pulmonary diseases were excluded from the study, They were classified according to the duration of dialysis into two groups. Group [1]: 8 CRF children with duration of dialysis<3 years and Group [2]: 11 CRF children with duration of dialysis >/= 3 years, Fifteen apparently healthy children of matchable age, and sex were included as control group. All subjects had full clinical assessment including body weight, height, wt/ht ratio and full examination including: pulse, blood pressure measurement, chest and cardiac examination. The following investigations were also done: complete blood picture, total serum protein, albumin, urea, creatinine, calcium, phosphorus, and arterial blood gases [before and after a hemodialysis session]. Posteroanterior and lateral chest X-ray and echocardiographic examination. Spirometry was performed at the chest department of Assiut University hospital using sensor Medics [IBM] apparatus. The following parameters were obtained: Forced vital capacity [FVC]; Forced expiratory volume in one second [FEV1]; FEVI/FVC ratio; and Peak expiratory flow rate [PEFR]. Out of the studied patients, 15.79%had pulmonary venous congestion while 10.52%had pleural effusions. On the other hand 15.79%had pericardial effusion and a similar percent had cardiomegaly. Cases as a whole and also both subgroups [A and B] showed significantly lower mean levels of wt/ht ratio, Hb, albumin, Ca, and FS but significantly higher mean levels of systolic blood pressure, blood urea, creatinine, P, LVESD, LVEDD, and indexed LVM than controls. Cases as a whole showed significantly lower mean levels of FVC, FEV1 and PEFR than controls. Cases in group B showed significantly lower mean level of FVC and FEVI and PEFR than controls. Analysis of blood gases showed that cases as a whole and also both groups [A and B] had significantly lower mean levels of pH and HCO3 and base excess than controls. Furthermore both groups showed significantly lower PCO2 before and after a HD session. FVC, FEV1 and PEFR correlated positively with each of wt/ratio ratio, Hb, albumin, Ca and FS and negatively with the duration of the dialysis, creatinine, P, and indexed LVM. Restrictive pattern of pulmonary dysfunctions is frequent in ESCRF patients. Structural and functional cardiac abnormalities are very important among the many predisposing factors for pulmonary function disturbances. Other factors such as malnutrition, hypocalcemia, hyperphosphatemia and anemia may also affect the pulmonary functions indirectly through cardiac affection. Uremic toxins are important factors for both system dysfunctions and the longer the duration of the disease, the more are the disturbances of the pulmonary functions. Low PCO[2] in uremic patients may be a trial by the respiratory system to compensate for acidosis by CO[2] wash in order to elevate the pH to near normal. This is very important since the possible noxious effect of overcorrection of acidosis may lead to alkalosis in such patients who are liable to be alkalosis after dialysis. Although standard treatment of malnutrition in CRF, include measures such as early and adequate dialysis, nutritional counseling, oral protein and amino acid supplements, these interventions cannot restore the nutritional status in all malnourished uremic patients. Adequate management of anemia is critically needed for breaking the cycle connecting renal failure, anemia and cardiac disease [all are predisposing factors for pulmonary dysfunctions]. Adequate management of the cardiac problems as well as appropriate monitoring and follow up is necessary to ameliorate the effects on the lungs and may prevent or delay the occurrence of pulmonary dysfunctions. Hemodialysis itself has its own impact on various organs. This points to the importance of renal transplantation as a better therapeutic alternative particularly in children

Child abuse in urban and rural areas of Assiut.

The study aims to identify child abuse at home in Urban and rural areas of Assiut Governorate. The sample comprised 400 mothers; 200 mothers from Assuit City and 200 from three rural villages around Assuit. A questionnaire sheet was designed to collect the relevant information about child neglect [physical, medical, safety and educational] and child abuse [emotional and physical]. The study was carried out during the period from January, to the end of September 2003. The study revealed that children living within overcrowded families are liable to suffer from neglect either physical, safety, medical or educational than those living in small sized families. Family instability especially traveling of parents or parental separation are important factors leading to child abuse. Neglect [physical, safety and medical] decrease with increased level of education. Finally safety and medical neglect are higher in rural than in urban localities

Fecal occult blood and iron status in cow's milk- fed infants

The present study included fifty apparently healthy infants attending the outpatient pediatric clinic of Assiut University Hospital for preventive medicine. They were 25 breast-fed infants [15 males and 10 females], aged 6-12 months with mean age 9.1 +/- 1.73 months and 25 cow's milk-fed infants [12 males and 13 females], their age ranged from 6-12 months, mean age 8.46 +/- 1.76 months. Infants with protein energy malnutrition [PEM] and chronic diseases were excluded from the study. Peripheral hemogram, serum iron, serum ferritin, transferrin saturation percentage and fecal occult blood testing were done for all studied infants. The mean hemoglobin [Hb] and hematocrit [Hct] values were significantly lower in cow's milk-fed infants than in breast-fed ones. At a cut-off value of 11 gm/dl for Hb and 34% for Hct, significantly higher number of infants showed lower Hb [< 11 gm/dL] and lower Hct [<34%] in cow's milk- fed group than in breast-fed one. Furthermore, at a cut-off value of 70 fL [femtolitre] for mean corpuscular volume and 23 pg/cell for mean corpuscular hemoglobin [MCH], the number of infants with lower levels was significantly higher in the former than in the latter group. Serum iron, ferritin and transferrin saturation percentages were significantly lower in cow's milk feeders than in breast-fed ones. At a cut-off value of 22 micro g/dL for serum iron, 10 ng/ml for ferritin and 16% for transferrin saturation percentage, significantly larger number of cow's milk-fed infants showed lower values than breast-fed ones. On the other hand, high total iron binding capacity [> 400 micro g/dL] was more frequent in the former than in the latter group [P<0.1]. Occult blood in stools was detected with significantly higher frequency in cow's milk than in breast milk-fed group

Conclusion: iron deficiency is more common in cow's milk-fed infants than in breast-fed ones and it may be attributed to increased occult blood loss and decreased iron bioavailability in cow's milk group. If non-mother milk is mandatory to be given before 1 year of age for any reason, it is to be fortified with iron