The key of “Old Construction” had a straight shaft. A lateral extraction was less hazardous than a medial extraction using this key.
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Key in Lateral Position Illustration
Placed lateral to the dental arch, the claw rests parallel to the tooth and perpendicular to the axis of force. Courtesy of Martino Publishing, Eastford, CT — Colyer, 2006
Key in Medial Position Illustration
However, when placed medial to the dental arch, the claw rests in an oblique position relative to the tooth, and the torque applied during extraction could damage the adjacent posterior tooth. Additional damage could be done during a posterior extraction as the straight shaft did not provide clearance for the anterior teeth. Courtesy of Martino Publishing, Eastford, CT — Colyer, 2006
Straight Shaft Key
This straight shaft key (A147.183), circa 1760, is typical of the “Old Construction” type. University of the Pacific Permanent Collection,
Donor: Maurice J. Owens, DDS
Oval Bolster
It has an oval bolster...
Worn Claw Tip
It has an oval booster... and a well-worn claw attached to the shaft by a removable screw.
Deer Horn Handle
The plain deer horn handle is asymmetric and unfinished suggesting either its style’s antiquity or that the owner made a new handle to replace a fancier damaged original.
