[Effect of flowablenano-composite on the bonding strength of tooth reattachment on fractured crowns].

PURPOSE: To study the effect of flowable nano-composite and different resin adhesives on reattachment of fractured crowns. METHODS: Thirty four fractured human maxillary incisors were obtained and randomly assigned into 4 groups and reattached using two types of adhesives: Easy one (EO) and Single bond 2(SB2), with or without Filtek Z350 flowable nano-composite. Four days after reattaching, the teeth were tested to achieve the shear bonding strength (SBS) and the recovery rate of fracture resistance after reattachment (R) were calculated. Statistical analysis was performed by use of SPSS 20.0 software package. RESULTS: Using flowable nano-composite failed to increase the SBS and R.The recovery rates of the specimens using EO without flowable composite achieved the highest value and they were significantly higher than those of the specimens using SB2 without flowable composite (P=0.046). CONCLUSIONS: If the fragment matches the fractured tooth perfectly, the tooth reattached using EO without composite will achieve higher bonding strength. However, not all the adhesives can be used to reattach without composite. Clinical decisions should be made on two aspects: whether the selected adhesive has sufficient mechanical strength and if there is any loss of tooth tissue after fracture.