Effectiveness of self-adhesive luting cements in bonding to chlorhexidine-treated dentin.
OBJECTIVE
The aim was to investigate the microtensile bond strength (μ-TBS) and failure pattern of self-adhesive luting cements (SLC) to dentin pre-treated with different concentrations of chlorhexidine (CHX) solutions.


METHODS
The occlusal enamel was removed from 30 extracted sound human molars in order to expose a flat dentin. Resin-composite (Filtek Z250, 3M ESPE) discs (12 mm in diameter, 6.0mm thickness) were cemented to the smear layer-covered dentin using the SLC [RelyX U100, 3M ESPE (U100); Multilink Sprint, Ivoclar Vivadent (MS)] with 0.2% or 2.0% CHX solutions. Results were compared with the control, untreated dentin. Six groups were then created based on the SLC and dentin pre-treatment (n=5). After 24h of water storage, restored teeth were serially sectioned into beams with a cross-sectional area of 0.8mm(2) at the bonded interface. Subsequently, specimens were tested in tension with a crosshead speed of 0.5mm/min in a universal testing machine, and the failure patterns were classified. Two-way ANOVA and Tukey's tests were performed (α=0.05). Additionally, 18 teeth were subjected to energy-dispersive X-ray spectroscopy (EDS) analysis and micromorphology characterization of the smear layer-covered dentin and 0.2% or 2.0% CHX-treated dentin surfaces.


RESULTS
The μ-TBS obtained for both control groups were significantly higher, regardless of the CHX concentration and/or the cement used. Bond strengths were significantly higher for U100 than for MS, except when 2.0% CHX was applied. Fractographic analysis indicated that most failures in the control groups occurred cohesively in the SLC. Pre-treated dentin with 0.2% and 2.0% CHX solutions presented higher incidences of adhesive failures. EDS/SEM analysis exhibited varied concentrations of chlorine ions and crystal-shaped precipitates, depending upon the CHX concentration.


CONCLUSIONS
Pre-treatment of dentin with 0.2% or 2.0% CHX adversely affects the bonding efficacy when associated with the SLCs tested.
Biomaterials Research Group, Anhanguera - Bandeirante University of São Paulo - UNIBAN, School of Dentistry, Brazil. vdhipolito@yahoo.com.br
Vinicius
V
Di Hipólito
Flávia Pires
FP
Rodrigues
Fabiana Bárbara
FB
Piveta
Lídia da Cunha
Lda C
Azevedo
Roberta Caroline
RC
Bruschi Alonso
Nick
N
Silikas
Ricardo Marins
RM
Carvalho
Mario Fernando
MF
De Goes
Paulo Henrique
PH
Perlatti D'Alpino
D000537:Aluminum Oxide / Q000737:chemistry; D000891:Anti-Infective Agents, Local / Q000737:chemistry*; D002710:Chlorhexidine / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D045662:Dental Etching / Q000379:methods; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry; D016369:Smear Layer; D013052:Spectrometry, X-Ray Emission; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000891:Anti-Infective Agents, Local; D003188:Composite Resins; C444701:Filtek Z250; D019279:Resin Cements; D012821:Silanes; C502351:multilink adhesive system; D014867:Water; D000537:Aluminum Oxide; D002710:Chlorhexidine