Microleakage of the prosthetic abutment/implant interface with internal and external connection: in vitro study.

OBJECTIVE: This study determined the degree of marginal microleakage of the abutment-implant interface on platforms with Morse taper connection and external connection. MATERIALS AND METHODS: For this in vitro study, 42 implants, 21 with external connection and 21 with Morse taper connection, were used, immersed in acrylic resin cylinders. Each implant was joined by a prosthetic abutment screw tightened at different degrees, forming the six study groups: (1) External connection, manual tightening (2) External connection, 20 Newton (N) tightening (3) External connection, 30 N tightening (4) Morse taper connection, manual tightening (5) Morse taper connection, 20 N tightening (6) orse taper connection, 30 N tightening. All samples were subjected to load cycling and thermocycling. Then, they were submerged in a solution of 0.2% methylene blue for 24 h. Finally, the microleakage was measured via 20× optical microscopy in each study group, average was obtained, and Mann-Whitney test was applied. RESULTS: Statistically significant differences (P < 0.001) were found between the levels of microleakage presented in the Morse taper connection implants (1.48) and external connection implants (2.8) in all three types of tightening. Microleakage levels decreases when increasing torque is applied to the screws. CONCLUSION: Morse taper connection implants showed lower levels of microleakage than external connection implants; also, it was observed that microleakage decreases in the way torque increases.

Recidiva del grado de clareamiento dental por té: in vitro / Relapse of dental bleaching after the consumption of tea: in vitro study

INTRODUCCION: El referente estético en nuestra sociedad viene determinado por varios factores, el que más insatisfacción produce es un color anómalo del diente, por eso que al mejorar su color dental, los pacientes esperan buenos resultados y duraderos. OBJETIVO: Determinar la recidiva de color experimentado por piezas dentarias clareadas y posteriormente sumergidas en solución de té. METODOLOGIA: Utilizamos 42 incisivos centrales sanos de bovinos de 3 y 4 años, preparados en probetas cilíndricas acrílicas, mantenidos en saliva artificial a 37ºC, a 100% de humedad, divididas en: grupo experimental (GC), tratado con peróxido de carbamida al 35% gel por 30 minutos y Grupo Control (GNC) no tratado. A ambos medimos color inicial con espectrofómetro Vita Easyshade® y sumergieron en solución de Té por 10 minutos. Medimos el nuevo color, realizando este procedimiento 50 veces. RESULTADOS: Analizados con, Pruebas T y Análisis de Regresión Lineal, tanto el GC como el GNC presentan el primer cambio de color con la primera inmersión en té. El segundo cambio para el GE (p < 0,029) es en la segunda inmersión y para el GC entre la tercera y cuarta. El cambio de color máximo fue alcanzado por el GNC entre las 20 a 30 inmersiones, sin embargo, el GC lo hace entre la 10 y 20 inmersión. CONCLUSIONES: Las piezas clareadas presentan mayor regresión del color que las piezas no tratadas. Además un color inicial claro determina cambios de más intensidad en menor tiempo y sin un patrón definido de progresión.

INTRODUCTION: Esthetic model in our society comes determined by several factors, one of the more important dissatisfaction is an anomalous color of the tooth for that reason patients are wating for good and long lasting results when improving the color of their teeth. OBJETIVE: To determine the color regression experienced by bleached teeth that were later plunged in a solution of tea. METHODOLOGY: 42 central permanent healthy incisor teeth from 3-4 year old bovine, supported in cylindrical acrylic and maintain in artificial saliva at 37ºC for 100% of humidity, were divided in: experimental group (CG), treated with Carbamide Peroxide 35% gel for 30 minutes and Control Group (NCG) not treated. In both, the initial color was measured with Vita Easyshade® Instruments and then plunged into Tea solution for 10 minutes. The new color was measured, and the procedure was repeated 50 times. RESULTS: Analyzed with, T tests and Analysis of Lineal Regression, both the GG and the NCG present the first change of color with the first dip in Tea. The second change for the CG (p < 0.029) is in the second dip and for the CG between the third and fourth dip. The change of maximum color was reached by the NCG between 20 to 30 dips, nevertheless, the CG dip does it between the 10 to 20 immersions. CONCLUSIONS: Bleached teeth present the highest return regression of the color that the not treated. In addition an initial clear color determines changes of more intensity in less time and without a definite form of progression.