Retention of Approximal Guiding Plane Surfaces in Removable Partial Skeletal Prosthesis

Abstract

Background: The morphology of the retention tooth often does not correspond with the required design; hence there is often an indication for enamel recontouring or other restorative procedures.

Aim: The study aimed to determine the impact of changing the path of insertion of the prosthesis by reshaping the anatomical and morphological structures of the natural teeth predetermined for the retention of the prosthesis.

Material and methods: The group of 40 patients with Class II, Subclass 1 according to Kennedy was formed, and 120 approximal surfaces of retention teeth were obtained. Two different types of prostheses were made on the models: one group in the zero point position of the model, and another group in the zero position of the model, with changing of the direction of input at an angle of 2°.

Results: The difference between the established and theoretical normal distribution of frequencies was tested with the Kolmogorov-Smirnov and Lilliefors tests (r < 0.10; r < 0.01). The first group showed a retention force of 0.08 N. In the second group the retention force was 0.94 N.

Conclusion: It could be concluded that the change in the path of insertion of the dental prosthesis with conservative restorations as composite inlays, as well as the accurate extension of the prosthesis onto guiding plane surfaces, will undoubtedly increase the retention force of the prosthesis.

Keywords: Clasp; Guiding surface; Partial dentures; Retention; Retention force.

Figure 1

Formation of guiding surfaces

Figure 2

The framework with three rings

Figure 3

Measurement of retention force

Figure 4

Moving the carrying table downwards for tension force

Figure 5

Histogram of the distribution of the variable retention force in unprepared retention teeth

Figure 6

Histogram of the distribution normality of the retention variable strength in prostheses with prepared guiding surfaces