Jorge Guerrero Ibarra

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

Efecto del eugenol residual en los conductos radiculares sobre la adhesión de endopostes lumínicos prefabricados, cementados con resina compuesta

It has been reported in scientific literature, that eugenol inhibits polymerization of resin-based cements; this fact can influence retention of posts cemented upon this material. Recently, prefabricated resin posts reinforced with clear fibers have been introduced in the dental environment. The target of these new posts is twofold: the light used for polymerization can be transmitted to the resin cementing medium through the aforementioned posts, contributing thus to esthetic reconstruction and incidence decrease of endodontically treated teeth fractures. It has been shown that the use of a comprehensive acid-etch technique for extended time periods cancels residual eugenol effects in root canals on the lighttransmitting posts and the resin used to cement them. In the present study 10 extracted teeth were subjected to root canal treatment. These teeth were sealed with gutta-percha points (cones) and zinc oxide-eugenol cement. For this endeavor, lateral condensation technique was used. Root canals were prepared with low speed burrs (as found in the endodontic-post system), to be then cemented with resin following the technique recommended by the manufacturer. Traction forces were applied until achieving dislodgement, at which point retention was assessed. Results: Retention of all samples was refl ected into graphs. It could be appreciated that retention values among groups were unequal; it can therefore be established that no statistically signifi cant difference was encountered. Conclusion: Residual eugenol did not interfere in post adhesion when an extended time acid etch technique was followed. RESUMEN Se afi rma en la literatura que el eugenol inhibe la polimerizacion de los cementos a base de resina, esto puede infl uir en la retencion de los postes cementados con este material. Recientemente los postes prefabricados de resina, reforzados con fi bras transparentes, fueron introducidos a la odontologia con el proposito de que la luz para la fotopolimerizacion se transmita al medio cementante de resina a traves de ellos, contribuyendo asi a la reconstruccion estetica y disminuyendo la incidencia de fracturas de dientes tratados endodoticamente. Demostrando que empleando una tecnica de grabado de acido total por tiempos prolongados elimina los efectos del eugenol residual en los conductos radiculares sobre la retencion de los postes transluminicos y la resina utilizada para cementar los mismos. Se realizaron tratamientos de conductos en 10 dientes extraidos, obturandose con puntas de gutapercha y cemento de oxido de zinc y eugenol, con la tecnica de condensacion lateral. Se prepararon los conductos con fresas de desobturacion a baja velocidad, que se incluyen en el sistema de endopostes y se cementaron con la tecnica descrita por el fabricante, utilizando resina de cementacion. Se les aplico fuerza traccional hasta lograr su desalojo y se midio la retencion. Resultados: La retencion de cada una de las muestras fueron grafi cadas, demostrando que los valores de retencion entre cada grupo no eran iguales; por lo que se establecio que no existe diferencia estadisticamente signifi cativa. Conclusion: El eugenol residual no interfi ere en la adhesion de postes cuando se emplea una tecnica de grabado acido en tiempos prolongados.

Influencia de los cambios térmicos en la deflexión transversa de acrílicos para la base de dentaduras con y sin insertos metálicos

El proposito de este estudio in vitro fue determinar si los cambios termicos infl uyen en la defl exion transversa de dos diferentes marcas de acrilico para la base de dentaduras con y sin insertos metalicos, despues de ser sometidos a un periodo de termociclado con cambios de temperatura. Se elaboraron 40 muestras de acrilico de acuerdo con la especifi cacion no. 12 de la ADA; y se conformaron cuatro grupos, dos de Lucitone 199 y dos de ProBase Hot. Los resultados se sometieron al analisis estadistico ANOVA de una via y comparacion de grupos Tukey con un valor de p < .001. Conclusion: Ambos acrilicos para la base de dentadura cumplen con las especifi caciones de la norma no. 12 de la ADA. Los insertos metalicos permiten disminuir la defl exion de los acrilicos y los cambios termicos afectan de manera considerable las propiedades fisicas.

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.