Efetividade dos adesivos autocondicionantes na resistência da união em dentina tratada com clorexidina

Abstract

Chlorhexidine (CHX) is an antimicrobial agent with ability to slow down the action of metalloproteinases in dentin tissue conditioning with phosphoric acid. But, it is speculated that the products of their reaction may interfere chemically and physically on the immediate values of bond strength (TBS) of self-etching universal adhesives. The objective was to analyze the influence of treatment designed with CHX solution 2% prior to application of self-etch and universal adhesives on TBS. Occlusal surfaces of 20 sound human molars were removed to expose middle dentin surface. These were divided into 8 groups according to the type of treatment submitted: SEself- application of Clearfil SE Bond adhesive system according to the manufacturer's instructions; SEself + CHX: prior use of chlorhexidine for 20 s followed by washing; SBself: applying Scotchbond Universal according to the manufacturer's instructions in self-etching mode; SBself + CHX: previous application of CHX for 20 s followed by drying; SEtotal: phosphoric acid etching to 35% for 15 sec followed by washing, drying, primer acid for 10 seconds, adhesive and curing this for 10 seconds; SEtotal + CHX: Technical sequence similar to the above, but with application of CHX after acid etching; SBtotal: applying the adhesive according to the manufacturer's instructions in order condiciomento Total acid; SBtotal + CHX: after phosphoric acid etching, CHX was applied for 20 s followed by drying and application of the adhesive. Composite resin blocks with 5mm were built on the hybridized surfaces, cut into sticks of 1 mm2 and stored in deionized water at 37 °C for 24 hours. Afterwards, the samples were submitted to microtensile test speed of 1 mm/min until failure. The averages were submitted to two factors ANOVA and Tukey test (p = 0.05). In the self-etching mode, the SEself groups (39.77 ± 11,56MPa) and SBself (40.84 ± 12.49) did not differ statistically and were superior to SEself + CHX groups (22.86 ± 5,18MPa) and SBself + CHX (27.02 ± 5,58MPa), which have no statistical difference between them. On the total etching mode, SBU + CHX group had the highest average (37.81 ± 11,69MPa), followed by SBtotal groups (31.53 ± 9,22MPa) and SEtotal + CHX (28.09 ± 4, 2 MPa). Already SEtotal group (25.95 ± 5.43MPa) had the lowest average and was statistically lower to the other groups. It was concluded that the prior application of CHX on dentine interfered in the effectiveness of bond strength values of self-etching dentin and universal systems.