Bands and orthodontic cements: glass ionomer releases fluoride exactly where it is needed

The molar band has been partly replaced by the bonded tube, which is quicker and more comfortable. It nonetheless remains indicated in specific situations, and choosing it is not a return to the past.

The strongest indication concerns teeth receiving high forces or carrying appliances: a palatal expander, a lingual arch, headgear. The band encircles the tooth and distributes force over the whole crown.

It is also indicated where bondable surface is insufficient: partially erupted molars, extensive prosthetic crowns, surfaces with large amalgam restorations where adhesion would be unreliable.

Preliminary separation is the step that determines fit. Elastic separators are placed a few days beforehand and create the interproximal space needed to seat the band without forcing it.

Forcing a band into insufficient space causes two kinds of damage: injury to the periodontal ligament, and distortion of the band itself, which then no longer seats uniformly.

Fit is checked at the gingival margin and at the occlusal one. A band extending beyond the gingival margin traumatises the tissue chronically; one that is too short lacks retention.

Glass ionomer cement is the prevailing choice for a reason beyond adhesion: it releases fluoride over time, and releases it precisely in the area most at risk of demineralisation.

The margin of a band is a plaque stagnation point for the whole of treatment, and the ability of glass ionomer to recharge with fluoride from toothpaste makes it particularly suitable.

Resin-modified glass ionomers add light curing and improve initial strength while retaining fluoride release. They are today the most balanced choice for band cementation.

Pure resin cements have higher adhesion but no fluoride release, and on a band that will remain in the mouth for two years that characteristic outweighs the difference in bond strength.

Partial decementation is the specific risk of bands and the most insidious. The band stays in place because it is mechanically retained, but the cement beneath has dissolved.

Beneath that apparently intact band a carious lesion forms that nobody sees until removal. The check is made with a probe at the margin and by looking for a white halo or localised malodour.

In summary: bands remain indicated where forces are high or surfaces unbondable, preliminary separation prevents periodontal damage, resin-modified glass ionomer is the reference cement, and decementation must be sought actively because it is symptomless.