A comparison of shear-peel band strengths of 5 orthodontic cements

The objective of this study was to compare the shear-peel band strength of 5 orthodontic cements using both factory and in-office micro-etched bands. The 5 orthodontic cements evaluated were a zinc phosphate (Fleck's Cement), 2 resin-modified glass ionomer cements (RMGI)(3M Multicure glass ionomer a nd Optiband), and 2 polyacid-modified composite resin cements (PMCR)(Transb ond Plus and Ultra Band Lok). Salivary contamination was examined with a po lyacid-modified composite resin (Transbond Plus). Two hundred and eighty ex tracted human molar teeth were embedded in resin blocks and each was random ly assigned to the following 7 groups: 6 groups with factory etched bands, 5 cement groups and salivary contaminated group, and 1 in-office micro-etch ed group. The cemented teeth were put in deionized water at 37 degrees C fo r 30 days and thermocycled for 24 hours. The force required to break the ce ment bond was used as a measure of shear-peel band retention. With the use of an Instron testing machine, a shear-peel load was applied to each cement ed band. Data were analyzed with a one-way analysis of variance (ANOVA) wit h a Tukey test for the multiple comparisons. The RMGIs and PMCRs demonstrat ed significantly greater shear-peel band strengths compared to the zinc pho sphate cement. No statistically significant differences were noted between the RMGI cement and PMCR cements and within the RMGI groups, however, there was a statistically significant difference within the PMCR groups. Signifi cantly lower band strengths were noted with the saliva contaminated PMCR ce ment group (Transbond Plus) and the inpractice sandblasted PMCR group. Both RMGIs and PMCRs were found to demonstrate favorable banding qualities. The lower band strength with saliva-contaminated bands suggests that moisture control is critical when using a PMCR. The variability noted in the in-offi ce micro-etched bands might be technique related.