Effects of chlorhexidine/solvent solutions on bond strength stability to dentin

Objectives: Resin/dentin bonds deteriorate via hydrolytic-enzymatic activity. The adjunctive use of ethanol-wet bonding with chlorhexidine-diacetate(CHX) could improve infiltration of hydrophobic resins and add benefits from CHX to preserve collagen fibrils. We evaluated the effects of the adjunctive use of CHX and storage time with both water- and ethanol-wet bonding on the bond strength of All Bond 3 (AB3, Bisco) and Excite (EX, Ivoclar) to dentin.

Methods: Flat dentin surfaces were etched (32% PA), rinsed (30s) and blot-dried with absorbent paper. The surfaces were re-wetted with either water (Water); 1% chlorhexidine diacetate in water (CHX/Water); ethanol (Ethanol); and 1% chlorhexidine diacetate in ethanol (CHX/Ethanol) solutions for 30s. They were then bonded with AB3 or EX using a smooth, continuous rubbing application (15s), followed by 15s gentle air stream. The adhesives were light-cured (20s) and resin build-ups constructed for the microtensile method. Bonded beams were obtained and tested after 24 h and 6 months water storage@37^oC. Storage water was changed every month. Effects of treatment and testing periods were analyzed (ANOVA, Tukey's, p<0.05) for each adhesive.

Results: There were no interactions between factors for both adhesives. Different superscript letters indicate significant differences (p<0.05). Lowercases compare columns and capital letters compare rows/adhesive.  

Rewetting solutions	Microtensile bond strengths(MPa). Means±S.D.(n).
	ALL BOND 3		EXCITE
	24-hours	6-months	24-hours	6-months
Water	49.41±10.7(19)aA	57.32±10.6(23)aA	36.00 ± 14.0(19)(a,b)A	33.58±19.2(17)(a,b)A
1% CHX in water	51.27±17.2(16)aA	55.13±15.8(16)aA	31.38 ± 9.1(20)(b,c)B	22.38±10.3(18)(b,c)B
Ethanol	58.27±10.4(20)aA	57.31±10.1(21)aA	20.82 ± 8.6(19)cC	12.09±9.0(16)cC
1% CHX in ethanol	53.08±15.8(21)aA	59.71±12.9(19)aA	46.26 ± 7.0(18)aD	44.16±13.9(14)aD

Conclusions:  AB3 bonds were not affected by any of the rewetting solutions, regardless of the time.  EX bonds were lower when ethanol was used but higher using 1%CHX in ethanol; however they were not significantly affected over time. Future experiments will examine bond strengths after 1, 2 and 3 years.

Support: Bisco, CNPq.