Crown fractures: effectiveness of current enamel-dentin adhesives in reattachment of fractured fragments.

OBJECTIVE: The introduction of the current enamel-dentin adhesives has simplified the reattachment of fractured dentinal fragments. The objective of this study was to determine the strength needed to detach coronal fragments reattached with the most recent adhesives. METHOD AND MATERIALS: A complete coronal fracture was caused on the incisal one third of 40 noncarious maxillary and mandibular lateral and central incisors. Each fractured coronal fragment was reattached to its tooth with the enamel-dentin adhesive Scotchbond MP, All-Bond 2, Dentastic, or One-Step (10 specimens each). RESULTS: There was no statistically significant difference between 2 similar fourth-generation adhesives that use orthophosphoric acid as etchant (Dentastic and All-Bond 2) and a fourth-generation adhesive that uses maleic acid as etchant (Scotchbond MP). The values obtained with the fifth-generation adhesive (One-Step) were significantly inferior to those obtained with the other 3 enamel-dentin adhesives. CONCLUSION: In the reattachment of fractured tooth fragments, fourth-generation adhesives can guarantee a bonding force stronger than fifth-generation adhesives.