Having a movable bolster reduced gum trauma throughout the extraction process by applying a more uniform pressure to the fulcrum as the shaft rotated.
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Movable Bolster Key Illustration
This innovative design first appeared in 1796 and was described in 1845 as "one of the most valuable improvements which this instrument has ever undergone."
Courtesy of Martino Publishing, Eastford, CT — Colyer, 2006
Enhanced Key
A circa-1800 key (A256.6) shows a number of new features, including...
University of the Pacific Permanent Collection,
Donor: Herbert J. Stuart, DDS ’37
Knurled Thumbscrew
A circa-1800 key (A256.6) shows a number of new features, including a hardwood handle with knurled thumbscrew.
Bolster Designed for Covering
A soft covering can be sewn to the thin movable bolster through its four holes.
Spring-Loaded Pin
Running inside the lower shaft, a spring-loaded pin allows quick reversal of the same claw, for left verses right extractions, or exchange of different-sized claws.
