RESUMEN
The aim of this study was to evaluate the effects of bleaching and delayed bonding on the shear bond strengths of metal and ceramic brackets bonded with light and chemically cure composite resin to human enamel. One hundred and twenty extracted human premolar teeth were randomly divided into three groups of 40 each. The first two groups were bleached with 20 per cent carbamide peroxide (CP) at-home bleaching agent. No bleaching procedures were applied to the third group and served as control. The first two and control groups were divided into equal subgroups according to different adhesive-bracket combinations. Specimens in group 1 (n = 40) were bonded 24 hours after bleaching process was completed while the specimens in group 2 (n = 40) were bonded 14 days after. The specimens in all groups were debonded with a Universal testing machine while the modified adhesive remnant index was used to evaluate fracture properties. No statistically significant differences were found between the shear bond strengths of metal and ceramic brackets bonded to bleached enamel after 24 hours, 14 days, and unbleached enamel with light or chemical cure adhesives (P > 0.05). The mode of failure was mostly at the bracket/adhesive interface and cohesive failures within the resin were also observed. Our findings indicated that at-home bleaching agents that contain 20 per cent CP did not significantly affect the shear bond strength of metal and ceramic orthodontic brackets to enamel when bonding is performed 24 hours or 14 days after bleaching.
Asunto(s)
Cerámica/química , Aleaciones Dentales/química , Recubrimiento Dental Adhesivo , Esmalte Dental/ultraestructura , Soportes Ortodóncicos , Blanqueadores Dentales/química , Blanqueamiento de Dientes/métodos , Grabado Ácido Dental/métodos , Adhesividad , Óxido de Aluminio/química , Bisfenol A Glicidil Metacrilato/química , Peróxido de Carbamida , Esmalte Dental/efectos de los fármacos , Análisis del Estrés Dental/instrumentación , Humanos , Curación por Luz de Adhesivos Dentales , Ensayo de Materiales , Peróxidos/química , Peróxidos/farmacología , Cementos de Resina/química , Auto-Curación de Resinas Dentales , Resistencia al Corte , Dióxido de Silicio/química , Acero Inoxidable/química , Estrés Mecánico , Propiedades de Superficie , Temperatura , Factores de Tiempo , Blanqueadores Dentales/farmacología , Urea/análogos & derivados , Urea/química , Urea/farmacologíaRESUMEN
The aim of this study was to evaluate the prophylactic potential of hyperbaric oxygenation treatment and the timing of hyperbaric oxygen (HBO2) therapy for cyclophosphamide-(CYP) induced cystitis in rats. Forty male Sprague-Dawley rats were divided into 5 groups. Four groups received a single dose of CYP (100 mg/kg.) intraperitoneally (i.p.) at the same time (group 1 served as the control). Group 2 received CYP only; group 3 received HBO2 treatment (2.8 atmospheres absolute, 90 minutes, twice daily) before and the day after CYP. Group 4 received HBO2 before and on the day of CYP administration. Group 5 received HBO2 on the day of and the day after CYP. CYP injection resulted in severe cystitis. Prophylactic HBO2 treatment did not prevent the severe cystitis. After CYP injection, however, HBO2 treatment attenuated CYP-induced hemorrhagic cystitis in rats. Hyperbaric oxygen has a beneficial effect on repairing and healing bladder damage, though it does not function to prevent CYP-induced hemorrhagic cystitis.
Asunto(s)
Antineoplásicos Alquilantes/efectos adversos , Ciclofosfamida/efectos adversos , Cistitis/terapia , Oxigenoterapia Hiperbárica , Animales , Cistitis/inducido químicamente , Cistitis/patología , Masculino , Ratas , Ratas Sprague-Dawley , Vejiga Urinaria/efectos de los fármacos , Vejiga Urinaria/patologíaRESUMEN
We investigated the effect of hyperbaric oxygen (HBO2) and penicillin therapy in a murine model of group A streptococcal myositis. The thighs of mice were inoculated with Streptococcus pyogenes. Four groups were evaluated: 1) control (n = 13), 2) HBO2 treatment (n = 15), 3) penicillin treatment (n = 12), and 4) penicillin and HBO2 treatment (n = 13). Histologic methods were utilized to prove the existence of myositis and histologic changes in tissues following experimental intramuscular inoculation of mice with Streptococcus pyogenes. Mortality (day of death) and the number of colony forming units (cfu) were measured. Microscopic sections of the left thighs revealed extensive necrosis of muscle with acute inflammatory infiltrate in all groups. Penicillin significantly lowered cfu count in comparison to the control (P < 0.01). Cfu's in group 4 were significantly lower than in group 3 (P < 0.01). Survival was significantly longer in the penicillin group compared to the control (P < 0.01). Survival in the combined treatment group was significantly longer than penicillin alone (P < 0.01). These results suggest that 1) HBO2 treatment alone does not decrease mortality significantly in vivo, 2) penicillin therapy alone improves outcome significantly, and 3) the combined treatment of penicillin and HBO2 exerts synergistic effects in both decreasing bacterial counts in vivo and increasing survival in this model.