Effects of a cold atmospheric plasma device utilizing ambient air on bracket bonding to human enamel and surface...

Evaluating a cold atmospheric plasma (CAP) device using ambient air for enamel pretreatment before bracket bonding and the impact on surface roughness.

180 human third molars were assigned to 12 groups. After pretreatment with a) phosphoric acid+Transbond XT Primer (TXP), H₃PO₄, b) CAP (30 s)+TXP, CAP-30, c) CAP (60 s)+TXP, CAP-60, d) CAP+Transbond Plus self-etching primer (SEP-CAP) a metal bracket was bonded (Transbond XT adhesive). Shear bond strength (SBS) was tested after 1) 24 hours wet storage, 2) 500 thermal cycles (5°/55°C), 3) 90 days of wet storage with a universal testing machine. The adhesive remnant index (ARI) was determined. Additional specimens were fabricated, pretreated as groups a),b),d) before application of Transbond XT adhesive, removal with a tungsten bur and surface measurements before and after polishing with a profilometer.

After 24 hours, SBS in the H₃PO₄ and SEP-CAP group was higher than in both CAP groups (p<0.001). 500 thermal cycles reduced SBS in both CAP groups compared to 24 hours (p<0.001) and 90 days (CAP-30 p=0.001; CAP-60 p=0.008). In both CAP groups, an ARI of 0 was predominant. Surface roughness before polishing was higher in the CAP group.

The use of CAP with air as working gas does not ensure sufficient SBS for clinical use, but in combination with SEP. Surface roughness was more impacted by CAP than H₃PO₄.

H₃PO₄ etching is still considered the gold standard for bracket bonding. Further research is required to understand the effect of CAP to enamel.