Copper rings came to prominence in the later nineteenth and early twentieth centuries when more sophisticated tooth preparations were being undertaken with the ‘new' treadle drills. Accurate impressions proved difficult with the dental materials available at the time, but the problem was overcome with the introduction of the copper ring.

Until the middle of the nineteenth century softened beeswax was the only impression material available. Then in 1847 Edwin Truman introduced gutta-percha as an improvement to the beeswax. Even so, it tended to distort when removed from the patient's mouth and shrank on cooling. In 1857 the London dentist Charles Stent (1807-1885) improved the properties of gutta-percha by adding stearin and talc to produce the compound still known today as Stent.

Even with Stent, it was impossible to take an accurate full arch impression, as the material wasn't elastic enough to reproduce undercuts and would break on removal from the mouth.

It was at this stage the humble copper ring came into its own. A suitably sized ring (there were at least 24 sizes) was trimmed to fit snuggly over the prepared tooth, for example, a crown preparation. With the ring securely in position over the preparation, softened Stent would be pressed into the ring. Once set, an overall impression would be taken with beeswax in an impression tray which had recently become popular. On removing the tray from the mouth, the copper ring with its one tooth accurate impression was secure within the full-arch impression, ready for an accurate stone model to be poured.

The copper ring impression technique remained popular until the arrival of elastomeric materials between the 1950s and the 1970s, with the likes of the polysulfides followed by condensation silicones, polyethers and addition silicones - many still in use today.

The copper ring now took on a new role as the ideal matrix ‘band' for very broken-down teeth requiring a core build-up where there was insufficient tooth tissue available to secure a conventional matrix band. When amalgam was used the band would be left in place with the patient returning another day for its removal. But today with the ‘snap-set' light cured core materials the ring is removed immediately leaving the tooth ready for its final preparation.

No other dental material can claim to have been in continuous use for over 150 years, so perhaps, the humble copper ring is not so humble after all.