title: Influence of peripheral enamel bonding and chlorhexidine pretreatment on resin bonding to dentin.
abstract: OBJECTIVE
  To evaluate the influence of peripheral enamel bonding, chlorhexidine digluconate (CHX) pretreatment, and storage time on resin-dentin microtensile bond strength (µTBS) of a self-etching adhesive system and selfetching cement.
  
  
  METHODS
  Fifty-six noncarious human third molars were coronally sectioned to provide a flat dentin surface; the circumferential enamel was removed from half of these and the other half was left intact. Pretreatment with 0.2% or 2% CHX or none (control) was performed before bonding composite blocks with Panavia F2.0 or RelyX Unicem to dentin. Specimens were stored in 0.5% chloramine for 3 days (control) or 6 months. Bonded specimens were sectioned into 1-mm2 dentin-only beams and a tensile load was applied until failure. The resulting 14 test groups, defined by control group/storage time/cement/CHX application mode/enamel bonding, were analyzed using two-way and three-way ANOVA, as well as Tukey's HSD post-hoc test (α = 0.05). Failure patterns of the specimens were observed and measured using scanning electron microscopy.
  
  
  RESULTS
  The comparison of the control vs experimental subgroups with peripheral enamel bonding and without CHX pretreatment after six months found no significant differences regarding the µTBS between the cements (p > 0.05) but did for the storage time (p <= 0.05). When storing the specimens for six months, the absence of peripheral enamel bonding significantly decreased the µTBS (p <= 0.05). Panavia F2.0 specimens showed significantly higher µTBS values than RelyX Unicem specimens (p <= 0.05). CHX pretreatment, regardless the concentration, showed a significant influence on the µTBS (p <= 0.05). SEM revealed that peripheral enamel bonding reduced failures at the resin/dentin interface.
  
  
  CONCLUSIONS
  The absence of peripheral enamel bonding and a longer storage time decrease the µTBS of twostep self-etching adhesive system and a one-step self-etching cement. CHX pretreatment of the dentinal surfaces seems to improve the durability of the bond to dentin.
authors.affiliation: Department of Stomatology, Zhejiang University, Hangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Lin
authors.forename: Matthias
authors.initials: M
authors.lastname: Kern
authors.forename: Jing
authors.initials: J
authors.lastname: Ge
authors.forename: Jiajun
authors.initials: J
authors.lastname: Zhu
authors.forename: Huiming
authors.initials: H
authors.lastname: Wang
authors.forename: Oliver
authors.initials: O
authors.lastname: Vollrath
authors.forename: Christian
authors.initials: C
authors.lastname: Mehl
mesh_terms: D000704:Analysis of Variance; D002710:Chlorhexidine / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel; D045662:Dental Etching; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents; D006801:Humans; D008964:Molar, Third; D019279:Resin Cements; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D017220:Dentin-Bonding Agents; C438843:Panavia-Fluoro; C483701:Rely X Unicem; D019279:Resin Cements; D002710:Chlorhexidine