Chlorhexidine diminishes the loss of bond strength over time under simulated pulpal pressure and thermo-mechanical stressing.
OBJECTIVE
The purpose of this study was to investigate the effects of chlorhexidine (CHX) digluconate at 0.2% and 2% on dentin bonding durability of etch-and-rinse and self-etch adhesive systems.


METHODS
In this study were used 24 extracted non-carious human third-molars. The occlusal surfaces of the molar crowns were removed with a low-speed diamond saw to expose flat dentin surfaces. The tested materials were Single-Bond (SB) (two-step etch-and-rinse adhesive) and Clearfil Tri S Bond (CTSB) (all-in-one self-etch adhesive) used in association or not with CHX at 0.2% and 2%. The bonding systems were applied according to manufacturer's instructions and followed by composite application (Z250). For each condition, half of the specimens was immediately submitted to microtensile test and half of them was submitted to long-term storage of 6 months under simulated pulpal pressure and thermo-mechanical stressing before testing. The data were analyzed using Two-Way ANOVA and Tukey post hoc test (alpha=0.05). Failure patterns of the specimens were observed using scanning electron microscopy.


RESULTS
The falling % in bond strength over the 6-month period was: SB control-43.64%; SB/0.2%CHX-23.79%; SB/2%CHX-26.42%; CTSB control-40.94%; CTSB/0.2%CHX-37.07%; CTSB/2%CHX-22.14%. The fracture modes were predominantly adhesive, mainly in the specimens of terminal groups.


CONCLUSIONS
CXH digluconate at 2% was able to diminish loss of microtensile bond strength over time associated to both etch-and-rinse and self-etch adhesives. Lower concentration of CHX (0.2%) was not able to diminish the loss of bond strength over time when associated to the self-etch adhesive CTSB.
Campos
Edson Alves
EA
Master of Science Program, Positivo University, Brazil. edson.campos@up.edu.br
Correr
Gisele Maria
GM
Leonardi
Denise Piotto
DP
Barato-Filho
Flares
F
Gonzaga
Carla Castiglia
CC
Zielak
João César
JC
D000268:Adhesiveness; D000891:Anti-Infective Agents, Local / Q000737:chemistry*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003782:Dental Pulp / Q000502:physiology*; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011312:Pressure; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors
D000891:Anti-Infective Agents, Local; C515604:Clearfil Tri-S Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; C010882:chlorhexidine gluconate; D002710:Chlorhexidine