Efectos del entrenamiento muscular inspiratorio/espiratorio sobre función respiratoria de pacientes tetrapléjicos / Effects of inspiratory/expiratory muscular training on respiratory function in quadriplegic patients

Introduction: Functional impairment in patients with high spinal cord injuries is associated to ventilatory dysfunction due to paretic respiratory muscles, which causes alterations in the ventilatory and in the cough mechanisms. Respiratory muscle training has been studied as a therapeutic alternative for this group of patients with no conclusive results, whereas a mixed protocol, which stimulates both inspiratory and expiratory muscles, had not been previously investigated. Objective: To evaluate the effects of systematic respiratory muscle training during four months, on pulmonary function, respiratory muscles strength and effort tolerance, cough efficacy and dyspnea perception, in a group of quadriplegic patients with at least one year of evolution post injury. Method: A quasi-experimental design was used. Six adults with cervical spinal cord injuries were enlisted and incorporated in a mixed respiratory muscles training for four months. Pulmonary function, respiratory muscles strength and resistance, cough efficacy and dyspnea perception were assessed pre and post training. Results: The application of the mixed training protocol significantly improved inspiratory muscle strength (p = 0,028),respiratory muscles effort tolerance (p = 0,028) and cough efficacy (p = 0,034).The other measures did not reach statistical significance. Conclusion: Mixed(inspiratory/expiratory) muscular training, shows partially favorable results in the improvement of pulmonary function. Studies using greater numbers of patients are necessary to achieve more categorical results.

Introducción: El compromiso funcional en pacientes con lesiones medulares altas se asocia a disfunción ventilatoria por paresia de musculatura respiratoria y provoca alteraciones ventilatorias y en el mecanismo de la tos. El entrenamiento de la musculatura respiratoria ha sido analizado como alternativa terapéutica para neumo este grupo de pacientes sin resultados concluyentes, mientras que un protocolo mixto, que estimule músculos inspiratorios y espiratorios no ha sido estudiado con anterioridad. Objetivo: Evaluar la respuesta del sistema respiratorio al entrenamiento sistemático de la musculatura respiratoria durante cuatro meses, sobre la función pulmonar, fuerza y tolerancia al esfuerzo de la musculatura respiratoria, eficacia de la tos y percepción de disnea de un grupo de pacientes tetrapléjicos. Materiales y Métodos: Se aplicó un diseño cuasi-experimental. Seis pacientes con lesiones medulares cervicales de al menos un año de evolución fueron reclutados e incluidos en un programa de entrenamiento mixto de la musculatura respiratoria durante 4 meses. Se evaluó la función pulmonar, fuerza y resistencia de la musculatura respiratoria, eficacia de la tos y percepción de disnea antes y después del período de entrenamiento. Resultados: El protocolo de entrenamiento mixto aplicado incrementó significativamente la fuerza muscular inspiratoria (p= 0,028), la tolerancia al esfuerzo de los músculos respiratorios (p = 0,028) y la eficacia de la tos (p = 0,034). El incremento en todas las otras variables medidas no alcanzó significancia estadística. Conclusión: El entrenamiento muscular mixto(inspiratorio/espiratorio) muestra resultados parcialmente favorables en la mejoría de indicadores de función pulmonar. Estudios de mayor número de pacientes son necesarios para acceder a resultados más categóricos.

The effect of prophylaxis method on microtensile bond strength of indirect restorations to dentin.

The aim of this study was to evaluate the effect of different materials used for dentin prophylaxis on the microtensile bond strengths (µTBS) of adhesively cemented indirect composite restorations. Sixty bovine incisors had the buccal surface ground with wet #600-grit silicon carbide abrasive paper to obtain a flat exposed superficial dentin and were submitted to different prophylaxis protocols, as follows: 3% hydrogen peroxide (HydP); 0.12% chlorhexidine (Chlo); sodium bicarbonate jet (SodB); 50-µm aluminum oxide air abrasion (AirA); pumice paste (PumP), and control group-water spray (Cont). After prophylaxis protocols a resin composite block (3.0 mm × 5.0 mm × 5.0 mm) was adhesively cemented using dual resin cement (Rely X ARC). After 24 hours of water storage, specimens were serially sectioned perpendicular to the bonded interface into 1-mm-thick slices. Each specimen was trimmed with a diamond bur to an hourglass shape with a cross-sectional area of approximately 1.0 mm(2) at the bonded area. Specimens were tested (µTBS) at 0.5 mm/min using a universal testing machine. Scanning electron microscopy was used to examine the effects of prophylaxis techniques on dentin. Bond strength data (MPa) were analyzed by one-way analysis of variance and failure mode by Fisher test (α=0.05). µTBS data, means (SD), were (different superscripted letters indicate statistically significant differences): AirA, 25.2 (7.2)(a); PumP, 24.1 (7.8)(a); Chlo, 21.5 (5.6)(a); Cont, 20.6 (8.1)(a); HydP(,) 15.5 (7.6)(b); and SodB(,) 11.5 (4.4)(c). The use of aluminum oxide air abrasion, pumice paste, and chlorhexidine before acid etching did not significantly affect µTBS to dentin; however, the use of hydrogen peroxide and sodium bicarbonate jet significantly reduced µTBS.

Microtensile specimen attachment and shape--finite element analysis.

Microtensile bond strength values are influenced by specimen shape and attachment method to the gripping device during testing. We hypothesized that stress distribution inside the testing specimen is affected by microtensile specimen shape and attachment method. Rectangular, hourglass-, and dumbbell-shaped specimens, all with a 1 mm(2) cross-sectional testing region, were modeled as indirect ceramic restorations luted to dentin. Three specimen attachments were investigated: (1) posterior surface; (2) posterior, superior, and lateral surfaces; and (3) all surfaces. Qualitative and quantitative analyses were carried out according to von Mises' criteria. Stress analysis showed a direct correlation between attachment modes and stress distribution, with shear stresses observed in models with less surface attachment. Increasing the number of faces for specimen attachment to the metallic gripping device resulted in a more homogeneous and regular distribution of stress, with tensile stress concentrated at the adhesive interface. Dumbbell-shaped specimens showed improved stress distribution compared with rectangular and hourglass-shaped specimens.