Effect of Blood Decontamination Procedures on the Microshear Bond Strength of Resin-modified Glass Ionomer Cement to Resin Composite
To investigate the effect of decontamination procedures on the microshear bond strength (μSBS) of blood-contaminated resin-modified glass ionomer cement (RMGIC) bonded to resin composite (RC). Eighty RMGIC disc specimens were allocated into 5 groups (n=16). All groups except Group 2 were contaminated with blood. Group 1 had no decontamination procedure, Group 3 was decontaminated by rinsing, Group 4 was decontaminated by 34% phosphoric acid etching, and Group 5 was decontaminated by 5% sodium hypochlorite application. RMGIC specimens were subsequently bonded with RC using a universal adhesive in self-etch mode. μSBS tests were conducted using a universal testing machine at a crosshead speed of 1 mm/min. Failure mode analysis was conducted on RMGIC fracture surfaces under a scanning electron microscope. μSBS results indicated that Group 4 had the highest mean μSBS value of 6.22 ± 2.14 MPa, while Group 1 had the lowest mean μSBS value of 3.53 ±1.67 MPa. Significant differences were observed in the μSBS of Group 2 with no contamination (p=0.023) and Group 4 with decontamination by phosphoric acid-etching (p=0.003) when compared to Group 1 with blood contamination. No statistically significant differences (p>0.05) were observed between all other groups’ μSBS. For all groups, the predominant mode of failure was adhesive failure between the RMGIC-RC interface, with a few mixed failures in RMGIC for Groups 2-5. Blood contamination before adhesive application significantly reduced the μSBS between RMGIC and RC. Phosphoric acid etching was the most effective blood decontamination procedure to improve the μSBS.SUMMARY
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Flowchart summary of the experimental groups used.
Steps involved with bonding and bond strength testing. (a) Universal dental adhesive applied in self-etch mode and light cured for 20 seconds; (b) hollow brass tube stabilized on RMGIC specimen with resin composite packed into it; (c) resin composite light cured for 40 seconds; (d) specimens stored in distilled water for 24 hours; (e) μSBS tests conducted using a universal testing machine at a crosshead speed of 1 mm/min.
Mean microshear bond strength (μSBS) ± standard deviation measured in MPa of all experimental groups. *Indicates a statistically significant difference at a significance level of a=0.05.
Mean surface roughness (Ra) measured in μm for all experimental groups. No significant difference between the groups (p>0.05).
Representative SEM micrographs demonstrating different failure modes observed for the de-bonded specimens after μSBS testing. (a) Adhesive failure and (b) mixed failure — with cohesive RMGIC and adhesive failures. (Scale bars are shown.)
Representative SEM micrographs of specimens from each group. (a) Blood contamination control G1; (b) no blood contamination control G2; (c) experimental G3 decontaminated by water rinsing; (d) experimental G4 decontaminated by acid etching; (e) experimental G5 decontaminated by NaOCl rinsing. (Scale bars are shown.)
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