The Influence of Structural Designs and Retainer Designs on the Fracture Resistance of Removable Partial Denture.

Abstract

The retainer with a framework is an important device for excellent function of the removable partial denture.However,prosthetic appliance fracture primarily occurs at the terminal abutment-cantilever junction.In this study,combinations of five structural designs(double structure consisting of six columns,or four columns,T-shapes,trusses and rectangular columns)and three retainer designs(full coverage,4/5 coverage and mesiodistal rest)were subjected to the statical bending test.The fracture resistance of these frameworks were evaluated to measure maximum stiffness,yield load and strain of the retainer.The obtained results were as follows:1.Maximum stiffness of the double structure consisting of six columns,trusses and T-shapes was approximately 10 times greater than that of rectangular columns.2.Ultimate strength of double structure consisting of six columns was the greatest,followed by that of four columns,trusses and T-shapes.3.Fracture resistance of full coverage and 4/5 coverage was about 4 times greater than that of mesiodistal rest.4.When 20 kgf load was applied,the strain of the marginal and occlusal regions tended to increase according to the strength of the framework,whereas that of the proximal region decreased.

Comparative study of maxillary complete dentures constructed of metal base and metal structure framework

“…From this viewpoint, the structural dentures have no physiological problems compared with the conventional dentures. Higher durability and ease of readjustment, as previously reported (Ohkubo, 1989; Ohkubo et al , 1992, 1994, 1996, 1997), plus the physiological findings in the present study, lead to the conclusion that the structurally designed dentures can be recommended for long‐term use.…”

“…We have reported on a new denture design based on the concept that one denture can provide long‐term clinical service without remaking and is much stronger than the conventional acrylic denture. A metal structure framework designed as a three‐dimensional framework, such as a double structure, a T‐shaped structure, or a trussed structure could resolve the strength problem as previously reported (Ohkubo, 1989; Ohkubo et al , 1992, 1994, 1996, 1997; Obana, 1994) (Fig. 1).…”

“…For ease of periodic relines and adjustment, the basal surface and muscle surface of this denture could be also made of acrylic resin materials. The higher durability of dentures, using the above‐mentioned structural designs, has been confirmed from clinical observation for a long‐term period exceeding 10 years (Obana, 1994) and from fundamental studies on their strength and stiffness compared with dentures with conventional designs (Ohkubo et al , 1992, 1994, 1996). Dentures require not only strength and stiffness.…”

“…These differences affect considerably the patients’ tolerance of the dentures (Farmy & Kharat, 1990; Hosman, 1991). Although a large number of our studies (Ohkubo, 1989; Ohkubo et al , 1992, 1994, 1996, 1997) have been performed on the strength and stiffness of the structurally designed dentures, little is known about the patients’ tolerance of them.…”