title: Interfacial nanoleakage and bonding of self-adhesive systems cured with a modified-layering technique to dentin of weakened roots.
abstract: OBJECTIVE
  The purpose of the study was to evaluate the nanoleakage and bond strength of different self adhesive systems cured with a modified-layering technique (MLT) to dentin of weakened roots.
  
  
  METHODS
  Twenty-one maxillary incisors were decoronated and then root canals were instrumented and obturated with the cold lateral compaction technique. Weakened roots were simulated by flaring root canals until only 1 mm dentin thickness remained. Teeth were distributed into three groups. The canals were backfilled with Vertise Flow (VF group), a self-adhering system, following a modified-layering technique using two light-transmitting posts, sizes 6 and 3. DT Light Post size 2 was cemented using the same material. Remaining roots were prepared and cured in the same way as the VF group. However, in the TS/MF group, Clearfil Tri-S Bond (TS) adhesive and Clearfil Majesty Flow (MF) composite were used, while in the ED/PF group, ED primer II (ED)/Panavia F2.0 (PF) were used. After one week of storage, each root was sectioned to obtain six slices (two slices from each root third: coronal, middle and apical) of 0.9 ± 0.1 mm thickness. Interfacial nanoleakage expression was analyzed using a field emission scanning electron microscope (FEG-SEM), and the micro push-out bond strength (μPOBS) was measured at different root regions. Modes of failure were also determined using SEM. Data were statistically analyzed using two-way analysis of variance with repeated measures and Tukey post hoc test (p≤0.05).
  
  
  RESULTS
  With MLT, all adhesive systems showed nanoleakage. For μPOBS, there was a statistically significant effect for adhesive systems (p<0.001) but not for root region (p<0.64) or for their interaction (p=0.99). Tukey post hoc test revealed that the bond strength of the VF group was significantly higher than the TS/MF and ED/PF groups for all root regions.
  
  
  CONCLUSIONS
  All of the tested self-adhesive systems cured using MLT had slight nanoleakage and were not sensitive to root regional differences. Self-adhering systems had higher bond strength than self-etch adhesives.
authors.forename: E
authors.initials: E
authors.lastname: Mobarak
authors.forename: R
authors.initials: R
authors.lastname: Seyam
mesh_terms: D001840:Dental Bonding / Q000379:methods*; D003763:Dental Leakage / Q000378:metabolism*; D003804:Dentin / Q000378:metabolism*; D017220:Dentin-Bonding Agents / Q000378:metabolism*; D006801:Humans; D007180:Incisor; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D055116:Self-Curing of Dental Resins / Q000379:methods; D014092:Tooth Root / Q000378:metabolism*
chemical_list: D017220:Dentin-Bonding Agents