Ozone did not improve the bond of bioactive restoratives to enamel and dentine (n = 96)

Three ozone formulations, no difference in shear strength

Ozone is offered in paediatric dentistry as a cavity pre-treatment: antimicrobial action without preparation sounds attractive when working with an uncooperative child. The team around Federica Veneri asked the narrower question, the one clinicians care about most, namely whether the restoration will hold after such treatment.

Ninety-six standardised enamel and dentine surfaces were prepared from extracted human teeth and randomised into eight groups. Four treatment protocols (no treatment, gaseous ozone, ozonated water, ozonated gel) were combined with two bioactive restorative materials, Fuji II LC and ACTIVA Bioactive Restorative. After seven days in HBSS at 37 °C, shear bond strength was measured and failure mode analysed, surface roughness assessed by optical profilometry, and the interface composition by Raman spectroscopy and SEM-EDX.

The result is unambiguous and negative. Mean shear strength was 3.59 ± 3.23 MPa, ranging from 0.05 to 11.69 MPa, with no statistically significant difference between groups (p > 0.05) in strength, in failure mode or in roughness. The chemical analyses found no appreciable differences at the interface; the only hint was minimal fluoride release. In other words, ozone neither harmed nor improved the bond.

Limitations

This is a preliminary in vitro study on extracted teeth with storage of only seven days, so the finding does not transfer directly to how a restoration behaves in the mouth over years. The range of measured values was very wide, which points to marked variability between specimens.

For the practice

• If you already use ozone as an antimicrobial pre-treatment, these data give no reason to abandon it for fear of a weaker bond, but no reason to introduce it expecting better adhesion either.
• The standard conditioning protocol remains what carries bond quality; ozone does not replace it.
• The lower end of the measured values, 0.05 MPa, is a reminder that with bioactive materials a clean technique matters more than extra steps.