A Mathematical method for Calculating the Retentive Force of Ring Clasps when Designing the Removable Partial Denture Metal Frame

Practically, calculating the retentive force of the clasps used as a part of removable partial dentures testing of general retention. This test is done using a universal testing machine or a pull test kit. However, these techniques aren't feasible until after designing and fabricating the framework. Therefore, a calculating method or formula based on the variables affecting the retentive force of any clasp seems necessary while developing the framework and before the final casting of the partial denture. The objective of this experiment is to determine the formula that mathematically estimates the pulling force of four-ring clasps in vitro. The experiment included the fabrication and recording of pullout forces for four types of ring clasps; then, the variables were identified and related to the retentive force mathematically. An equation was generated to count the retentive force for the four clasps and assess the precision of the results. In addition, the retentive arm sizes were correlated to the pulling forces using the Pearson coefficient. In conclusion, a new mathematical method was presented to the profession using simple math. The method is a practical and simple way to enhance the selection of clasps concerning their retentive force in addition to the other design factors. Therefore, additional tools for creating the removable partial denture with a bio-protective concept were displayed, and further research should be done to analyze the force generated by other clasps to make a global system to be added to the software for designing the partial dental framework.