Do universal adhesives promote bonding to dentin? A systematic review and meta-analysis

OBJECTIVES: The aims of this study were to conduct a systematic review of the microtensile bond strength (µTBS) of multi-mode adhesives to dentin and to perform a meta-analysis to assess the significance of differences in the µTBS of one of the most commonly used universal adhesives (Scotchbond Universal, 3M ESPE) depending on whether the etch-and-rinse or self-etch mode was used. MATERIALS AND METHODS: An electronic search was performed of MEDLINE/PubMed, ScienceDirect, and EBSCOhost. Laboratory studies that evaluated the µTBS of multi-mode adhesives to dentin using either the etch-and-rinse or self-etch mode were selected. A meta-analysis was conducted of the reviewed studies to quantify the differences in the µTBS of Scotchbond Universal adhesive. RESULTS: Only 10 studies fulfilled the inclusion criteria for the systematic review. Extensive variation was found in the restorative materials, testing methodologies, and failure mode in the reviewed articles. Furthermore, variation was also observed in the dimensions of the microtensile testing beams. The meta-analysis showed no statistically significant difference between the etch-and-rinse and self-etch modes for Scotchbond Universal adhesive (p > 0.05). CONCLUSIONS: Multi-mode ‘universal’ adhesives can achieve substantial bonding to dentin, regardless of the used modes (either etch-and-rinse or self-etch).

Effect of Different Silane Treatments on Long-Term Bonding Between Non-Etched Glass-Ceramic and Resin Cement

he present study evaluated the bond strength between glass-ceramic and resin cement, using different silane treatments, performing no previous hydrofluoric acid (HF) etching on ceramic surface, after short- and long- term storage. One hundred and eighty glass-ceramic plaques (IPS e.max CAD®) were polished and divided into six groups (n=30) to receive different silane treatments: (1) RCP-RelyX Ceramic Primer® (one-bottle silane), (2) RCP+SB-RelyX Ceramic Primer and Adper Singlebond2® (silane plus separated adhesive), (3) SBU-Scotchbond Universal® (silane-containing universal adhesive), (4) CP-Clearfil Ceramic Primer® (silane/MDP primer), (5) NC-no-silane (negative control) and (6) PC-Previous HF etching (5%, 20s) plus RelyX Ceramic Primer® (positive control). Two resin cement cylinders (Rely X Ultimate®) were built on each plaque. Each group was divided into two sub-groups to be stored for 24 hours (24h) or 6 months (6mo) in distilled water at 37°C (n=15). Then microshear (µSBS) testing was performed. Failure mode was analyzed using scanning electron microscopy (SEM). Data were statistically analyzed by two-way ANOVA and Tukey´s test (α=0.05). Both factors and their interaction resulted statistically significant (p≤0.05). PC obtained the highest µSBS values (in MPa) at both storage times (24h: 28.11±2.44; 6mo: 19.10±3.85). After 24h storage, groups RCP+SB (10.86±3.62), SBU (8.37±4.33) and CP (8.05±3.62) were not statistically different from NC (8.00±2.51); only RCP (19.73±4.63) and PC obtained higher values. After 6 months, only PC showed higher values than NC (0.04±0.01). Cohesive failure in resin cement was more prevalent for RCP-24h and PC, while adhesive failure was more frequent among all other groups. Clinical relevance: None of the commercially available silane primers tested, improve long- term ceramic/cement bonding without performing HF etching on ceramic surface. Combination of HF acid and silane, remain as a gold standard treatment for glass-ceramic materials.

ste estudio evaluó la resistencia de unión entre cerámica vítrea y cemento resinoso, utilizando diferentes tratamientos de silano, sin realizar condicionamiento previo de la cerámica con ácido fluorhídrico (HF), después de almacenamiento en corto y largo plazo. Ciento ochenta placas de cerámica (IPS e.max CAD®) fueron pulidas y divididas en 6 grupos (n=30) para ser tratadas como sigue: (1) RCPRelyX Ceramic Primer® (silano de 1 frasco), (2) RCP+SB-RelyX Ceramic Primer y Adper Singlebond2® (silano más adhesivo separado), (3) SBU-Scotchbond Universal® (adhesivo universal conteniendo silano), (4) CP-Clearfil Ceramic Primer® (primer cerámico conteniendo silano y MDP), (5) NC-ningún silano (control negativo) y (6) PC-Condicionamiento con HF previo (5%, 20s) y silano (RelyX Ceramic Primer®) (control positivo). Dos cilindros de cemento resinoso (Rely X Ultimate®) fueron construidos en cada placa. Cada grupo fue dividido en 2 sub-grupos para ser almacenados por 24 horas (24h) y 6 meses (6mo) en agua destilada a 37°C (n=15). Luego fue realizada la prueba de microcizallamiento (µSBS). El tipo de fractura fue analizado con microscopio electrónico de barrido (SEM) y los datos analizados con las pruebas estadísticas ANOVA de dos factores y Tukey (α=0.05). Ambos factores y su interacción resultaron estadísticamente significativos (p≤0.05). PC presentó los valores más altos de µSBS (MPa) para ambos tiempos de almacenamiento (24h: 28.11±2.44; 6mo: 19.10±3.85). Luego de 24h, los grupos RCP+SB (10.86±3.62), SBU (8.37±4.33) y CP (8.05±3.62) no fueron estadísticamente diferentes del grupo control negativo (NC: 8.00±2.51); sólo RCP (19.73±4.63) y PC obtuvieron resultados mayores. Después de 6 meses de almacenaje, sólo el grupo PC obtuvo valores estadísticamente mayores que NC (0.04±0.01). Fractura cohesiva en el cemento fue más prevalente para RCP-24h y PC, mientras que el tipo adhesivo fue el más frecuente para todos los demás grupos. Relevancia Clínica: Ninguno de los tratamientos de silano evaluados, mejoró significativamente la adhesión a largo plazo entre cerámica vítrea no condicionada y cemento resinoso. La combinación de HF y silano, continúa siendo el tratamiento de preferencia para cerámica vítrea durante el proceso de cementación.