Influence of tooth bleaching on the bonding strength of silorane-based restorative system / Influencia del aclaramiento dental en la fuerza de adhesion del sistema restaurativo a base de silorano

Bleaching procedures can interfere on adhesive bonding of methacrylate-based restorative materials. After introduction of silorane-based composites, little information is available about this interaction. The objective is evaluate the influence of bleaching on enamel shear bond strength of silorane-based restorative system. Forty sound incisive bovine teeth were randomly divided into 04 groups (n= 10), being: G1 (control) ­ not bleached + Clearfil SE Bond (CSEB)/Filtek Z250 (Z250), G2 (control) not bleached + Silorane Adhesive (SA)/Filtek P90 (P90), G3 ­ bleached + CSEB/Z250; G4 ­ bleached + SA/P90. The teeth were sectioned, had crowns included in a PVC rings, and the enamel surfaces gridded and polished with silicon carbide abrasive papers. G1 and G2 were stored in artificial saliva (37 C), daily renewed, for a period of 04 days. G3 and G4 were exposed to 02 sessions of 38% hydrogen peroxide (38HP), with 03 applications of 15 min in each session. Composite resin cylinders were built up on the enamel surfaces. Bonding procedures were performed according the manufacturer's instructions. After storage in distilled water for 24 h (37 C), the samples were submitted to shear bond test. Data were analyzed by two-way ANOVA and t (LSD) tests (5%). Intra group comparison showed significant difference for Z250 after bleaching, but not for P90. Shear strength was significant lower for P90, despite bleaching procedures. In conclusion, 38HP bleaching had no influence on the enamel bond strength of P90, even though presenting lower bond strength than Z250.

Los procedimientos de blanqueamiento dental pueden interferir en la unión adhesiva de los materiales de restauración a base de metacrilato. Después de la introducción de materiales compuestos a base de silorano, hay poca información disponible acerca de esta interacción. El objetivo fue evaluar la influencia del blanqueamiento en la cizalladura de la fuerza de adhesion sobre esmalte del sistema restaurativo a base de silorano. Cuarenta dientes incisivos bovinos fueron divididos aleatoriamente en 4 grupos (n= 10), siendo: G1 (control) - no aclarado + Clearfil SE Bond (CSEB)/Filtek Z250 (z250), G2 (control) - no aclarado + adhesivo de silorane (AS)/Filtek P90 (P90), G3 - aclarado + CSEB / Z250; g4 - aclarado + AS/P90. Los dientes fueron seccionados, tenían coronas incluidas en anillos de pvc, y las superficies de esmalte fueron molidas y pulidas con papeles abrasivos de silicona de silicio. G1 y G2 fueron almacenados en saliva artificial (37 °C), renovada diariamente, durante un período de 04 días. G3 y G4 se expusieron a 2 sesiones de peróxido de hidrógeno al 38% (38 HP) con 03 aplicaciones de 15 min en cada sesión. Los cilindros de resina compuesta fueron construidos en las superficies de esmalte. Los procedimientos de unión se realizaron según las instrucciones del fabricante. Después del almacenamiento en agua destilada durante 24 h (37 °C), las muestras fueron sometidas al ensayo de resistencia de adhesión al cizallamiento. Los datos fueron analizados por ANOVA de dos vías y prueba t (5%). La comparación intragrupo mostró diferencias significativas para Z250 después del aclaramiento, pero no para P90. La resistencia al corte fue significativamente menor para P90, a pesar de los procedimientos de blanqueamiento. En conclusión, el blanqueamiento con 38HP no tuvo influencia en la resistencia de la unión esmalte de P90, a pesar de presentar una fuerza de unión más baja que Z250.

Association between dentin thickness and presence of accessory foramina in human permanent mandibular molars

The roots and periodontal system in human dentition are closely correlated from the early stagesof dental formation, maintaining this connection after teeth are established in the oral cavitythrough the apical foramen or other communications. Aim: Therefore, the aim of this study was toevaluate the correlation between the presence of foramina on the pulp chamber floor surface andin the furcation region and the thickness of dentin in this area. Methods: Forty sound permanentmandibular molars were submitted to scanning electron microscopy (SEM) to determine thepresence of foramina on the pulp chamber floor and in the furcation region, and to correlate thepresence of foramina with the variation in wall thickness in these regions. Results: The resultsshowed a mean thickness of 2.16 mm for the teeth analyzed and a 25% frequency of foramina onthe pulp chamber floor and 92.5% in furcation area, with only 22.5% showing foramina on bothsides. The foramina found on both surfaces showed varied diameters and shapes and locationsdispersed throughout the area. Conclusions: There was no significant difference between themean thicknesses of teeth featuring foramina and those without foramina.