Bond strength to primary tooth dentin following disinfection with a chlorhexidine solution: an in vitro study

The aim of this study was to determine the effect on shear bond strength of chlorhexidine used as a cavity disinfectant on primary tooth dentin.

Thirty specimens were randomly divided into 3 groups (N = 10) and treated as follows: (1) in Group I, the dentin was acid etched with a 37% phosphoric acid for 15 seconds, washed and dried; (2) in Group II, a 2% commercial chlorhexidine solution (Cav Clean) was applied for 40 seconds, washed and dried following acid etching for 15 seconds; and (3) in Group III, dentin was treated with a 37% phosphoric acid gel containing 2% digluconate of chlorhexidine (Cond AC) for 15 seconds. In all specimens, the adhesive Single Bond (3M) was applied, and composite cylinders (Filtek Z 250) were built. The specimens were sheared with a universal testing machine (Instron) running at a crosshead speed of 0.5 mm/min, and the results calculated in MPa. The specimens were also observed to record the failure mode.

ANOVA analysis revealed that the shear bond strength of Group II (17.99+1.15 MPa) was significantly lower than Group I (19.88+1.02 MPa) and Group III (19.57+1.02 MPa). After debonding, 63% of the specimens presented cohesive failure of the material, 24% adhesive failure and 10% cohesive failure of dentin.

The commercial cavity disinfectant containing 2% chlorhexidine had an adverse effect on Single Bond and produced significantly lower shear bond strength than the etch gel with chlorhexidine and the acid etch alone.