[Experimental measurement of force exerted by palatal bars. 1]

The Authors have prepared a protocol of research to evaluate the forces of lateral expansion expressed by the palatal bar et different degrees of activation. A special instrument has been built to this purpose. The forces expressed at the different degrees of activation are then evaluated and confronted in relation to the following variables: --length of the bar;--the presence or the absence of a U loop; --the more or less bowed conformation given to the bar. It is shown how, on the same terms, the presence of the U loop reduces the force made by the bar by about the half and that the more or less bowed conformation of the bar influences the force in the same way.