An Evaluation of the Repetitive Tooth Bleaching with Nonthermal Atmospheric Pressure Plasma

This study was undertaken to achieve a high bleaching efficacy with plasma, through longer application and reparative bleaching processes, by different shade evaluation methods. Extracted human teeth were divided into 6 groups (n=10). All teeth were treated in pairs. Low concentration of 15% carbamide peroxide (CP) was applied, with and without plasma, for 10, 20, and 30-min tooth bleaching, respectively. The bleaching procedure was repeated once daily for four days. The teeth were maintained in a moist environment provided by artificial saliva. The Vitapan Classical shade guide and Commission Internationale de L'Eclairage (CIELAB) color system were collectively used to measure the bleaching efficacy. Color evaluation was statistically analyzed using Student t-test and one-way analysis of variance (ANOVA) complemented by Tukey's test. Combining the plasma with 15% CP showed significantly greater color changes compared to bleaching without plasma (p<0.05). A high bleaching efficacy with plasma is proportional to the repetitive application and the treatment time. A 30-min application with plasma provided the best bleaching. Repetitive bleaching showed lower probability of color relapse of the bleached tooth. The color change by shade guide correlated with the changes in CIELAB color system. A value of 1 color change units (CCU) conversion factor for overall color change (ΔE) values comparisons was 3.724 values. The two measuring methods provide a more accurate correspondence of color change. The repetitive and longer application for tooth bleaching, combined with plasma, has a strong bleaching effect and produces whiter teeth.

Recidiva del color dentario por té, café y vino: in vitro / Dental bleaching regression caused by chromogenic beverages: in vitro

Este estudio, in vitro, determinó si los dientes con clareamiento presentan mayor cambio de color en el tiempo que los no tratados, al someterse a tinción con bebidas cromógenas, café, té y vino. Se utilizaron 45 incisivos sanos de bovino conservados en suero a 37ºC. Cada espécimen se dividió en dos mitades, una sometida a clareamiento con peróxido de hidrógeno al 35 por ciento y otra control. Se midió color con Espectrofotómetro Vita EasyShade. Se dividieron los especímenes al azar en grupos de 15 y fueron sumergidos en café, té y vino, durante 10 minutos, 20 veces, registrando color después de cada inmersión. Los datos fueron analizados con ANOVA y Test de Tukey, con 95 por ciento de intervalo de confianza. Los resultados mostraron que, el clareamiento modifica significativamente (p=0.05) el color en los tres grupos (GC=85.8 a 95.1; GT=87.4 a 97.3 y GV=90.8 a 99.3), la recidiva de color se observa a lo largo de las 20 inmersiones, siendo significativa la diferencia de valores ΔE iniciales (GC=18.89; GT=22.97; GV=56.46) y finales (GC=5.56; GT=5.38; GV=12.49). El grupo tratado presenta mayor descenso de unidades ΔE a lo largo de las inmersiones, por lo que es el más teñido (GCcontrol=20.98-5.01; GTcontrol=17.11-3.66; GVcontrol=54.62-11.49). Las tres bebidas cromógenas causan recidiva de color en los dientes clareados, siendo el vino el que causa mayor tinción. Se concluyó que las piezas tratadas, sometidas a los tres tipos de cromógenos, tienen mayor cambio de color que las que no lo son, pero finalmente no se oscurecen más que las no tratadas.

This in vitro study established if teeth treated with dental bleaching have a higher change of color over time than those that aren’t treated, when subjected to three chromogenic beverages (coffee, tea and red wine). 45 healthy bovine incisors were used, maintained in 0.9 percent sodium chloride, at 37ºC. Every specimen was divided into 2 half; one half was subjected to dental bleaching with 35 percent hydrogen peroxide and the other was taken as control. The color was measured with the Vita EasyShade Spectrophotometer. The specimens were randomly divided in groups of 15, and were immersed in coffee, tea and red wine for 10 minutes, 20 times, the value being recorded after each immersion. The data was analyzed with ANOVA and Tukey test, using 95 percent of confidence interval. Results show that bleaching significantly modifies (p=0.05) the color in the three groups (GC=85.8 to 95.1; GT=87.4 to 97.3 y GV=90.8 to 99.3). Color relapse in the three groups was observed along the 20 immersions. Initial ΔE values (GC=18.89; GT=22.97; GV=56.46) were significantly different than final ΔE values (GC=5.56; GT=5.38; GV=12.49). The chromogenic beverages stained more the treated group because a higher ΔE units decrease was observed in this group (GCcontrol=20.98-5.01; GTcontrol=17.11-3.66; GV control=54.62-11.49). The three chromogenic beverages produced color relapse in the bleaching teeth, being red wine the one causing more staining. It was concluded that the specimens treated subjected to three kinds of chromogenic, had higher change of color than control group, but at the end the treated group doesn’t get more stained than the control group.