Measurement of Strains in Fixed Bridges with Electronic Strain Gauges

¹ University of Michigan, School of Dentistry, Ann Arbor, Michigan

Strains in fixed bridges cemented to models were measured with strain gauges. The position and the magnitude of the static load was varied, and strains were measured on the metal surface and on the porcelain facings.

Larger surface strains were observed when the load was applied directly on the pontic bearing the strain gauge. The strain decreased, depending on the distance from the load and the amount of support given by the abutment.

Under similar conditions, maxillary anterior bridges had more surface strain than mandibular anterior bridges, and the posterior bridge had low surface strains. These observations are explained on the basis of the length of span, balk of the restoration, and the presence of cantilever action.

The surfaces of the porcelain facings were under low strain, even when the bridges were loaded to the maximum of 60 lb.