| 摘要 |
<p>The electrical tooth pulp testing unit has a battery in the handpiece, on which the testing head with active electrode is movably mounted the movement opening and closing the circuit. Contacts (8, 11) working together are mounted on opposite parts of head (2) and handpiece, and spring-loaded (9) so that when there is no load on the head the circuit is broken. The circuit is closed when the head is tilted, or slid towards the handpiece. The contacts can be ring-shaped, mounted on the end faces of head and handpiece. Alternatively one can comprise a set of tongues in a star pattern, and the other a ring.</p> |
