This book describes an in-vitro study that investigates different methods of repairing a fractured nano-filled resin-based fissure Sealant, and the effect of different curing time on microleakage of a repaired fissure sealant. This study attempts to increase the retention of sealants and eliminate microleakage, by the usage of recent nano-adhesive systems with the innovative light-emitting diode (LED) curing units to establish the next step in sealant improvement for children and young adults.