The Gates-Bonwill and Howland-Perry crowns.

Fig. 7. The Gates-Bonwill crown, patented in 1875. The crown was made of porcelain, and was secured by a metal dowel which was threaded and screwed into the crown, and anchored with amalgam. Fig. 8. The Howland-Perry crown, where the dowel was confined to the body of the porcelain. Page 5, 'Principles and practice of crowning teeth : a practical, systematic and modern treatise upon the requirements and technique of artificial crown work, including some incidental reference to bridgework' byHart John Goslee, 1903.