Stress distribution within circumferential clasp arms.

An analysis of stress distributions within circumferential clasp arms with various tapers, was undertaken in an effort to (1) determine the area of maximum stress concentration in both tapered and non-tapered clasps, and (2) to compare this point of maximum stress concentration with the area of frequent clasp breakage. The non-tapered clasp showed better distribution of stresses than the tapered clasps. The less favourable stress concentrations could result in eventual failure of the clasp when coupled with other factors such as porosities.

Modulus of elasticity and strength properties of dental cements.

The modulus of elasticity of commercial dental cements was determined by an optical strain gauge method. Values of compressive and tensile strengths also were measured. Of the cements of primary consistency tested, a noneugenol zinc oxide cement had the lowest mechanical properties.

Effects of cement bases on the stresses and deflections in composite restorations.

A model was used to investigate stresses and deflections in cement bases and in a composite restorative material induced in a posterior Class I restoration. Deflections in the composite were highest when it was supported by a base with a low modulus; however, the maximum tensile stress (12 MN/meter2) occurring in the composite restoration at the interface with the base was well below the maximum tensile strength of most composite materials (30 to 40 MN/ meter2). Tensile and shear stresses occurring in the cement bases were of sufficient magnitude to exceed the strength of the cement when a 1.

Modification of stresses in alveolar bone induced by a tilted molar.

Stresses induced in the supporting bone by a tilted molar tooth under load have been investigated by both the photoelastic and the finite element model systems. The following conclusions were reached. 1.

Distribution of stresses in porcelain-fused-to-metal and porcelain jacket crowns.

An idealized porcelain jacket and porcelain-fused-to-metal crown model was prepared, loaded, and analyzed to establish the trends and distributions of the internal and external stresses. Loads at 30 degrees to the vertical axis created adverse tensile stresses at the level of the gingiva and specifically at the gold-dentin-cement interface.

Effects of cement bases on the stresses in amalgam restorations.

A computerized dental model was used to study the stress induced in a Class 1 amalgam restoration when supported by bases of varying materials and thickness. Under the same load, the maximum tensile stresses and deflections in the amalgam restoration increased at least threefold with a zinc oxide-eugenol base as compared with a ZnPO4 cement base.