Carlos Álvarez Gayosso

Resistencia a fuerzas de tracción de miniimplantes usados en ortodoncia dependiendo del ángulo de inserción

For maximum anchorage in orthodontics, mini-implants have been used for various tooth movements without causing unwanted reactive forces on the teeth. The purpose of this study was to evaluate the mechanical resistance to traction of mini-implants to be evicted from bone and assess whether they can increase their tensile strength depending on its insertion angle (60 and 90 o ). Pig hip cuts were used for the placement of 5 mini-implants which were inserted with a 60 o angulation and a 90 o angulation. Ten new 2.5 mm (neck) x 1.6 (diameter) x 8 mm (length) with fl at head self- drilling mini-implants were used (MOSAS Dewimed. Germany). They were subjected to perpendicular tensile forces, using a universal mechanical testing machine (Instron) with a loading rate of 1 mm/min. The results were analyzed using Students t test. It was observed that 90 o angulation

Resistencia al desprendimiento de brackets adheridos con resina en contacto con una bebida alcohólica

The aim of this study was to determine the effect of an alcoholic drink (rum) in the adhesion of Transbond (3M) and Enlight (ORMCO) resins. Eighty brackets (0 o ) were bonded with Transbond and Enlight to healthy human teeth previously etched with phosphoric acid (37%). Each resin used its own adhesive. After bonding all teeth were immersed in physiologic serum at 7 oC for 24 hours and then thermocycled for 500 cycles; (5-55 o C). Forty samples were immersed in physiologic solution and the rest in the alcoholic drink for 12 days. At the end of 12 days, the force was measured in order to remove the bracket of each resin using a universal mechanical testing machine and the bond strength was calculated. The adhesion areas were observed in order to determine the failure site. The values were analyzed with ANOVA. The Enlight resin proved to have better bond strength than Transbond when both were immersed in serum but rum increased Transbond bond strength signifi cantly. It was concluded that the medium changes the bond strength signifi cantly. It was concluded that environment has an influence over bracket bond strength which could be an advantage for treatment since brackets have better adhesion but a disadvantage for the patients overall health. RESUMEN El proposito de este estudio fue determinar si las resinas Transbond (3M) y Enlight (ORMCO) sufren cambios en su adhesion al diente cuando estan en contacto con una bebida alcoholica (ron). Ochenta brackets (0o) fueron adheridos a dientes premolares humanos sin caries usando Transbond y Enlight, previamente grabados con acido fosforico al 37%. Cada resina uso su propio adhesivo. Despues de estar sumergidos en suero fi siologico a 7 o C durante 24 horas, se sometieron a un termociclado de 500 ciclos (5-55 o C). Se sumergieron cuarenta muestras en solucion fi siologica y el resto en la bebida alcoholica durante 12 dias; transcurrido este tiempo se midio la fuerza para desprender el bracket de cada resina usando una maquina universal de pruebas mecanicas y se calculo la resistencia al desprendimiento en MPa. Se observaron las zonas de desprendimiento para determinar el sitio de falla. Los valores fueron analizados con ANOVA. Se encontro que Enlight presento mayor resistencia al desprendimiento que Transbond cuando ambos estuvieron sumergidos en el suero, pero el ron incremento considerablemente la resistencia al desalojo de Transbond. Se concluyo que el medio infl uye en la resistencia al desprendimiento de los brackets, siendo una ventaja para la estabilidad de la aparatologia, ya que se adhiere mas el bracket, pero una desventaja para la salud.

Bond strength of brackets bonded with resin in contact with an alcoholic beverage

The aim of this study was to determine the effect of an alcoholic drink (rum) in the adhesion of Transbond (3M) and Enlight (ORMCO) resins. Eighty brackets (0 o ) were bonded with Transbond and Enlight to healthy human teeth previously etched with phosphoric acid (37%). Each resin used its own adhesive. After bonding all teeth were immersed in physiologic serum at 7 o C for 24 hours and then thermocycled for 500 cycles; (5-55 o C). Forty samples were immersed in physiologic solution and the rest in the alcoholic drink for 12 days. At the end of 12 days, the force was measured in order to remove the bracket of each resin using a universal mechanical testing machine and the bond strength was calculated. The adhesion areas were observed in order to determine the failure site. The values were analyzed with ANOVA. The Enlight resin proved to have better bond strength than Transbond when both were immersed in serum but rum increased Transbond bond strength signifi cantly. It was concluded that the medium changes the bond strength signifi cantly. It was concluded that environment has an influence over bracket bond strength which could be an advantage for treatment since brackets have better adhesion but a disadvantage for the patients overall health.

Estudio comparativo de resistencia a la fatiga de arcos de níquel-titanio de tres marcas

Los alambres de niquel-titanio han sido los arcos de eleccion para la nivelacion dental lo que provoca fuerzas ligeras para crear movimientos sin dano al periodonto. El objetivo de este estudio fue determinar el numero de ciclos que soporto un alambre de niqueltitanio a la fatiga en un ensayo de fl exion. Se probaron 60 arcos redondos de 0.016” de ORMCO (20), GAC (20) y 3M (20) a 37 o C. Se usaron brackets Roth (0.022x0.025”) adheridos a dientes de acrilico de un tipodonto para sujetar los arcos. Una maquina universal de pruebas mecanicas fue usada para hacer la prueba de fatiga hasta obtener la fractura del arco. Se reportan los ciclos que cada muestra soporto. Los resultados requirieron de un analisis de varianza (ANOVA) de una via con prueba de Tukey (p < 0.001). Las superfi cies fracturadas fueron examinadas en un microscopio metalografi co a 125X para observar el patron de fractura. Se encontro que los arcos ORMCO presentan mayor elasticidad que los arcos de 3M y GAC. Palabras clave: Arcos de NiTi, superelasticidad, fractura, fatiga.

Resistance to traction forces in mini-implants used in Ortohodontics depending on the insertion angle

For maximum anchorage in orthodontics, mini-implants have been used for various tooth movements without causing unwanted reactive forces on the teeth. The purpose of this study was to evaluate the mechanical resistance to traction of mini-implants to be evicted from bone and assess whether they can increase their tensile strength depending on its insertion angle (60 and 90o). Pig hip cuts were used for the placement of 5 mini-implants which were inserted with a 60o angulation and a 90o angulation. Ten new 2.5 mm (neck) x 1.6 (diameter) x 8 mm (length) with fl at head self- drilling mini-implants were used (MOSAS Dewimed. Germany). They were subjected to perpendicular tensile forces, using a universal mechanical testing machine (Instron) with a loading rate of 1 mm/min. The results were analyzed using Student’s t test. It was observed that 90o angulation mini-implants had better resistance (7.40 ± 2.68 Mpa) than 60o angulation ones (4.21 ± 0.58 Mpa). 90o angulation mini-implants could be a better option for orthodontic treatment due to their higher resistance to traction forces thus improving stability. Key words: Anchorage, miniscrews, tensile strenght.