Background To evaluate the antibacterial property of a modified orthodontic resin with different concentrations of silver-nanoparticles (AgNPs), and quantify its preventive effect on the formation of white spot lesions (WSLs). Material and Methods An orthodontic resin (Transbond XT) was modified with four concentrations of AgNPs (1%, 0.5%, 0.1%, and 0.05%), the orthodontic resin without AgNPs was used as control. Polymerized resin discs (n=80) were submitted to Agar diffusion test on Petri dishes inoculated with Streptococcus mutans and Lactobacillus acidophilus . In addition, resin discs of each group (n=40) were placed in 96-well plates with bacterial suspensions to evaluate the colony-forming-units (CFU). For the WSLs prevention test, brackets were bonded with the experimental orthodontic resins on 45 premolars (n=5), and were subjected to a microbiological caries induction method for 9 days. Photographs were taken before and after the test, and the images were evaluated with the Image J software to calculate the area of WSLs. The data were analyzed using ANOVA and Tukey-HSD test, Student´s t-test and Kruskal-Wallis test (α=0.05). Results The 0.5% and 1% AgNPs modified resin inhibit the growth of S. mutans and L. acidophilus . All the modified resins showed significantly less CFU, when compared to the control ( p <0.05). 1% AgNPs resin promote the higher prevention of WSLs formation. There was no significant difference between the control group and the 0.1% and 0.05% groups. Conclusions 0.5% and 1% of AgNPs modified orthodontic resin exhibit an important antibacterial activity against S. mutans and L. acidophilus , and prevent the formation of WSLs. Key words: White spot lesions, antibacterial, orthodontics, adhesive, Silver-nanoparticles.

Objetivo: Determinar la asociación entre el biotipo facial y el nivel de sobremordida. Material y métodos: La muestra estuvo constituida por 152 estudiantes entre 12 y 17 años con dentición permanente. Se tomaron registros fotográficos en norma frontal con los estudiantes en posición natural de la cabeza. Sobre las fotografías impresas se determinó el ángulo de apertura facial para establecer el biotipo facial. El registro de la sobremordida vertical se realizó de forma clínica con la ayuda de un calibrador Vernier y un lápiz dermatográfico Resultados: La distribución del biotipo facial en la muestra fue de 80,3% para los dolicofaciales, seguido por los mesofaciales con 19,7%, no se encontró pacientes de biotipo braquifacial. En el grupo de dolicofaciales hubo una predominancia de sobremordida normal (55,7%), seguido por la mordida profunda (36,9%) y mordida abierta (7,4%). El grupo de mesofaciales presentó mayor frecuencia de sobremordida normal (63,3%), seguido por la mordida profunda (33,3%) y la mordida abierta (3,3%). No se encontró asociación estadísticamente significativa (P> 0,05). Conclusiones: Debido a que no se encontraron resultados que respondan a un patrón específico, podemos concluir que los biotipos faciales no están asociados al grado de sobremordida vertical.

Background To evaluate the marginal microleakage in single metal copings cemented with zinc phosphate, glass ionomer, and resin-modified ionomer. Material and Methods An experimental in vitro study was carried out. The calculation of the sample was determined using the G*Power software; 15 premolars were considered per group. The teeth were carved considering a preparation with a chamfer-type shoulder with an angulation of 6°. Working models were obtained, where the metallic copings were made. Cementation was carried out with zinc phosphate (Prothoplast), glass ionomer (Ketac-Cem Easymix), and resin-modified ionomer (Relyx™ Luting 2) cements. The samples were immersed in 2% methylene blue solution for 24 hours. The microleakage measurement was carried out with a 40x stereo microscope at four measurement points (vestibular, lingual, mesial, and distal). In order to compare the microleakage values, the ANOVA test was carried out, followed by the Scheffé test. A significance level of 5% was adopted. Results The zinc phosphate cement showed the highest values of marginal microfiltration (109.28 ± 51.27 µm) followed by the resin-modified ionomer cement (102.63 ± 45.07 µm) and the ionomer of glass (98.64 ± 39.18 µm), although these differences were not statistically significant ( p >0.05). Conclusions Zinc phosphate, glass ionomer, and resin-modified ionomer cements exhibited similar properties to prevent marginal microfiltration in unitary metal copings. Key words: Cementation, dental leakage, dental restoration failure.

Las lesiones de mancha blanca son efectos adversos frecuentes en los pacientes con tratamiento de ortodoncia. Son producto del ataque de ácidos orgánicos capaces de desorganizar la estructura del esmalte y su formación está asociados a la presencia de factores de riesgo como el tiempo prolongado de tratamiento ortodóntico, la mala higiene bucal y edades tempranas de inicio de tratamiento. En la literatura existen diversos métodos de diagnóstico para este tipo de lesiones, así como diversas propuestas para su prevención y/o tratamiento. El objetivo de esta revisión de literatura es presentar la evidencia científica relacionada a la formación de las lesiones de mancha blanca, su prevalencia, factores de riesgo asociados a su formación, así como describir los métodos de diagnóstico más frecuentes y los mecanismos de prevención y de tratamiento.

Background To evaluate the effect of an orthodontic resin modified with various concentrations of silver-nanoparticles (AgNPs) on enamel color. Material and Methods Twenty lower premolars were collected and divided into four groups (n = 5) according to the concentration of AgNPs (0.05%, 0.1%, 0.5%, and 1% wt/wt). Additionally, a group bonded with a conventional resin was used as control (n=5). Previous to the bracket bonding, enamel color was measuring with a spectrophotometer. Specimens were stored for 6 months in deionized water. Brackets were debonded and color changes of enamel were calculated with the CIEDE 2000 formula (∆E00). One-way ANOVA and Tukey test were used to assess the color change (α = .05). Results The control group showed the lowest ∆E00 values, and no significant difference was observed when compared to the group with 0.05% of AgNPs ( P > .05). The highest color change was observed in the group with 1% of AgNPs (∆E00 = 8.04±1.48), however no significant difference was observed between groups with 0.1% and 0.5% AgNPs. Conclusions The incorporation of AgNPs into orthodontic resin result in tooth color alteration. Lower concentrations of AgNPs should be considered to minimize negative changes in enamel color. Key words: White spot lesions, antibacterial, orthodontics, adhesive, Silver-nanoparticles.