Adhesion of an RMGI Protective Coating With Orthodontic Primer

Objectives: Resin-modified glass ionomer (RMGI) coatings have demonstrated clinical success in preventing demineralization around orthodontic brackets (1). For workflow efficiency, many orthodontists apply these coatings during or immediately after bracket bonding. Additionally, high-intensity LED curing lights enable much faster light cure. Study objectives are (a) to measure bond strength of an RMGI protective coating applied over an orthodontic primer, and (b) to compare bond strengths of the coating cured 3s with a 1600 mW/cm2 LED curing light compared to 20s with a 1200 mW/cm2 light.
(1) Anurag et al., Am J Orthod Dentofacial Orthop, 2015.
Methods: Materials used are shown in Table 1, sample preparation details in Table 2, curing lights in Table 3. 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. All samples were then primed with SU, cured 10s with 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 37°C. Data were analyzed via one-way ANOVA and compared with Tukey’s t-test (p<0.05); results and analysis in Table 3.
Results: Results are shown in Table 3. Groups A-D were statistically not different.
Conclusions: Shear bond strength of VXT applied directly over SEP, 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. Shear bond strength of VXT cured 3s with 1600 mW/cm2 curing light is statistically not different from 20s with a 1200 mW/cm2 light.