Evaluation of smear layer and debris removal by stepwise intraoperative activation (SIA) of sodium hypochlorite.

OBJECTIVES: To evaluate the efficacy of a stepwise intraoperative activation (SIA) of irrigants during and after the instrumentation compared with that of a conventional activation (CA) performed only after the instrumentation to remove smear layer and debris using different activation devices. MATERIALS AND METHODS: A total of 70 single-rooted teeth were divided into a control group (no activation, n = 10) and two different experimental groups according to the irrigant activation protocol used: group 1 (CA), in which sodium hypochlorite was activated only after the use of the last mechanical file, and group 2 (SIA), in which activation was performed during and after the instrumentation. The two groups were divided into 3 subgroups according to the activation device used (n = 10): passive ultrasonic irrigation (PUI, subgroup a), EndoActivator (EA, subgroup b), and EDDY (subgroup c). The roots were split longitudinally and observed using scanning electron microscopy (SEM) to evaluate the presence of debris and smear layer, and the results were statistically analyzed. RESULTS: All activation protocols and devices were more effective than control group in removing smear layer and debris from all root canal thirds (P < 0.05), except for CA-EA (group 1b) in the apical third. In the apical third, SIA was found to be more effective than CA (P < 0.05) to remove smear layer and residual debris when PUI was used, to remove the smear layer when EA was used (P < 0.05), and to remove residual debris when EDDY was used (P < 0.05). PUI and EDDY removed statistically more smear layer and debris than EA in the apical third (P < 0.05). CONCLUSIONS: The SIA technique improved the smear layer and debris removal from the apical third and debris removal from the coronal third, and PUI and EDDY were more effective than EA in the apical third. CLINICAL RELEVANCE: The stepwise intraoperative activation (SIA) technique may increase smear layer and debris removal.

Expandable tumor prostheses in children.

Any surgical resection in the lower extremities in children will cause a leg length discrepancy from physeal resection. To avoid the resulting functional deficit, leg length discrepancy must be reconciled with surgical techniques to approximate equal leg lengths at skeletal maturity. Currently there are several manufacturers who offer options for prosthetic reconstruction with expandable implants. These implants can be expanded to a length projected on the basis of three factors: the length of bone resected, the anticipated future growth of the contralateral extremity, and the estimated discrepancy of limb length at skeletal maturity. In this article, we review the basic principles and guidelines for prediction of remaining bone growth and planning lengthening in children, and present the currently available expandable prostheses and the evolution performed over time.

Exact linear hydrodynamics from the Boltzmann equation.

Exact (to all orders in Knudsen number) equations of linear hydrodynamics are derived from the Boltzmann kinetic equation with the Bhatnagar-Gross-Krook collision integral. The exact hydrodynamic equations are cast in a form which allows us to immediately prove their hyperbolicity, stability, and existence of an H theorem.

Total knee replacement versus osteochondral allograft in proximal tibia bone tumours.

Total knee modular megaprosthesis or osteochondral allograft are used to preserve joint movement in bone tumours of the proximal tibia. The aim of this study was to compare two groups of patients with total knee modular megaprosthesis and osteochondral allograft through an objective analysis. Eighteen patients, ten treated with prosthesis (TKR group) and eight with osteochondral allografts (AL group), were included in the study. X-ray, muscular strength measurements, and studies of gait analysis including electromyography (EMG) were used to compare functional results of patients. In the TKR group a higher incidence of knee extension lag was found. While the TKR group had a prevalent knee stiff/hyperextension pattern with reduced rectus femoris activity, the AL group had a higher percentage of normal knee pattern. Knee extensor muscular strength was reduced in the TKR group. TKR functional performance during gait is in most cases abnormal, consistent with the weakness of the extensor apparatus and knee extension lag. Although a greater rate of normal walking was found in the AL group, problems related to a short patellar tendon, knee instability, and joint mismatching were considered to be responsible for abnormal knee kinematics. An allograft, when optimal reconstruction is performed, gives better functional results.

Spontaneous disappearance of intracranial arterio-venous malformations.

4 cases of spontaneous disappearance of intracranial arteriovenous malformations are reported. All the malformations were in the rolandic-parietal area, and fed in most cases by the MCA. In one case, the malformation was associated with a proximal aneurysm. One malformation was large, one medium-sized, and two small. Venous drainage was towards the longitudinal sinus in all cases. Presenting symptoms consisted of epilepsy in 2 cases, and intracerebral haemorrhage in 2 cases. Disappearance of the AVM was documented by angiography from 1 to 15 years after diagnosis, and was preceded by a new haemorrhage in 2 cases. Acute or gradual thrombosis of the AVM is suggested as the most likely cause of the disappearance of an AVM. Spontaneous thrombosis of an AVM should be considered as an aspect of the pathological entity known as "thrombosed AVM". Guidelines for the management of patients exhibiting spontaneous disappearance of an AVM are briefly discussed.