Responses of Rat Maxillary Incisors to Loads

¹ Columbia University, New York City

In order to study the effect of blood flow in the periodontium on the dissipation of forces acting on a tooth, loads were suspended from a knife edge on rat maxillary central incisors. Observations were made of the period and the amplitude of the oscillation of the right incisor in its socket, relative to the left incisor which was used as a control. The pressure exerted on the periodontium exceeded capillary blood pressure. [see figure in the PDF file] Upon sacrifice of the animal, the experiment was repeated.

We found that the amplitude and the period of the vertical oscillation of the tooth in its socket was increased significantly after the sacrifice of the animal. We found also that in the dead animal the tooth remained further intruded in its socket after the removal of the loads from the incisal edges. In certain of the dead animals the tooth approached or reached the control level after thoracic massage. In no case did this octur in the living animal.

We observed in the living animal that the oscillatory action of a rat maxillary central incisor in its socket when a load was placed on the incisal edge and then withdrawn showed the characteristics of a hydraulic damper. We suggested, therefore, that blood flow gives the periodontal membrane the charatcteristics of a hydraulic damper.

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