Adhesion of an RMGI Protective Coating With Orthodontic Primer

Objectives: Resin-modified glass ionomer (RMGI) coatings are used to prevent demineralization around orthodontic brackets, exhibiting clinical success. For practice efficiency, many orthodontists apply these coatings during or immediately after bracket bonding. Study objective is to measure bond strength of an RMGI protective coating applied over orthodontic primers.
Methods: Materials used are shown in Table 1; sample preparation details in Table 2. 3M™ Vanish™ XT Extended Contact Varnish (VXT) and primers were light-cured with 3M™ Ortholux™ Luminous Curing Light for 3 s (OL); 3M™ Scotchbond™ Universal Adhesive (SU) and 3M™ Filtek™ Z250 Universal Restorative (Z250) for 10s or 20s, respectively, with 3M™ Elipar™ S10 LED Curing Light (ES). Pumiced, potted bovine teeth (obtained from a packing plant) were etched, then primed or left intact; the primer was either light-cured 3s via OL or left uncured before application of VXT; then cured 3s via OL. All samples were then primed with SU, cured 10s via ES, before applying & curing a Z250 cylinder (2.38mm diameter, 2mm height). Group A is considered the positive control. Notched edge shear bond strength was measured in an Instron at 1mm/min after 24hr in deionized water at 37C. Data were analyzed via one-way ANOVA and compared with Tukey’s t-test (p<0.05); results and analysis in Table 2.
Results: Results are shown in Table 3. Groups A-E were statistically not different.
Conclusions: Shear bond strength of VXT applied directly over MIP or XTP, where primer is either cured or uncured, is statistically not different from VXT applied directly to etched enamel. VXT may be applied directly over cured or uncured orthodontic primers.