Varnish or polymeric coating for the prevention of demineralization? An ex vivo study

Objective: The ability of an experimental coating, Odyssey, to prevent demineralisation ex vivo was compared with that of a fluoride varnish, Duraphat ^® and a chlorhexidine-containing varnish, Cervitec. Design: an ex vivo single-blind study. Setting: Hard tissue research laboratory. Materials and methods: thirty bovine enamel blocks 0·5 cm X 1·5 cm were divided into 6 groups of 5 specimens. The enamel blocks were then allocated to one of 6 surface treatments. Interventions: (1) surface left unprepared (control), (2) Duraphat ^® application, (3) Cervitec application, (4) experimental polymer coating, (5) enamel conditioned with 10% citric acid and coated with the experimental polymer coating Odyssey (O + C), (6) enamel etched for 30 sec with 37% phosphoric acid and coated with the experimental coating (O + E). All specimens were cycled for 7 days through a daily procedure of demineralisation for 4 hours and remineralisation for 20 hours, and exposed to an equivalent of 2 months toothbrushing. A single operator blinded to the treatment allocation of each specimen carried artificial lesion depth assessment out using computer-assisted transverse microradiography. Results: The control group had the greatest mean lesion depth (97·16 + 29·8 μm) with the Duraphat ^® group exhibiting the lowest mean lesion depth (24·53 + 15·44 μm). The Duraphat ^®, Odyssey, O + C and O + E groups all had significantly less lesion depth when compared with no surface preparation (p < 0·05 for all comparisons). There were no significant differences between any of the Odyssey groups. Conclusions: The efficacy of Duraphat ^® application in preventing demineralisation ex vivo has been demonstrated in the present study, but clinical trials are required to assess its usefulness in orthodontic practice.