Film Thickness of Bioactive Glass-Containing Resin-Modified Glass Ionomer Orthodontic Cement

Use of bioactive orthodontic cements would be beneficial in preventing tooth decalcification by inducing the formation of mineralized apatitic phases in and on the enamel adjacent to the brackets.

Objectives: This study assessed novel resin-modified glass bioactive glass-containing ionomer cement (RM-BGIC) film thickness and compared these to commercially available RMGICs.

Methods: GC Fuji Ortho LC served as a control group. Sol-gel synthesized bioactive glass was mixed with control powder in 1:3 and 1:1 volume fractions. Film thickness was tested as described in ISO 9917. Mean and standard deviations for individual groups were calculated, as were procedural run standard deviations of group averages. Acceptability was determined using the ISO requirements.

Results: Both experimental and control groups failed to pass the ISO requirement on procedural run one. Control and 1:3 RM-BGIC groups failed in five measurements, while 1:1 RM-BGIC failed in ten measurements. All groups passed second and third procedural runs in five measurements. For procedural run one, group means and standard deviations for the control, 1:1 RM-BGIC, and 1:3 RM-BGIC were 27.8±3.7µm, 25.7±3.2µm, and 26.2±2.3µm, respectively, while procedural run standard deviation was 1.1µm. In procedural run two, group means and standard deviations for the control, 1:1 RM-BGIC, and 1:3 RM-BGIC were 22.0±3.7µm, 21.6±4.0µm, and 22.6±3.3µm, respectively, while procedural run standard deviation was .5µm. During procedural run three, means and standard deviations for the control, 1:1 RM-BGIC, and 1:3 RM-BGIC were 23.4±2.5µm, 24±2.2µm, and 23.2±2.9µm, respectively, while procedural run standard deviation was .4µm.

Conclusion: Powder and liquid mixing technique sensitivities are likely to account for procedural run one results. Smaller individual group and run standard deviations during subsequent runs support this. Compositions passing two ISO 9917 procedural runs were considered passed. Therefore, novel 1:3 and 1:1 RM-BGIC compositions show acceptable film thickness properties.

Acknowledgement: Funded by A.D. Williams Trust.