Computer-aided design and manufacturing of removable partial denture frameworks with enhanced biomechanical properties

A method for improving an initial digital model of a removable partial denture (RPD) framework obtained based on patient image data of at least part of an oral cavity of the patient, the method comprising:

• providing the initial digital model of the RPD framework, the RPD framework comprising a plurality of clasp retainers, each clasp retainer being configured for removable engagement with a corresponding one of a number of abutment teeth of a patient and characterized by a set of relevant geometric parameters, each relevant geometric parameter being provided with a nominal value in the initial digital model;
• providing, for each clasp retainer, a target value of a dislodging force for disengaging the clasp retainer from the corresponding abutment tooth with which the clasp retainer is configured for engagement;
• performing a force analysis on the initial digital model, the force analysis comprising, for each clasp retainer:
• simulating the application of the dislodging force on the initial digital model of the clasp retainer while varying the relevant geometric parameters of the clasp retainer around the nominal values thereof;
• and
• determining, from said simulating and varying, corrected values for the relevant geometric parameters of the clasp retainer, such that when the corrected values are assigned to the relevant geometric parameters, the dislodging force associated to the clasp retainer matches the target value thereof;
• and
• correcting the initial digital model by replacing, for each clasp retainer, the nominal values of the relevant geometric parameters by the corresponding corrected values, thereby obtaining a corrected digital model of the RPD framework.

A non-transitory computer readable memory storing computer executable instructions thereon that, when executed by a computer, perform steps of:

• receiving patient image data of at least part of an oral cavity of a patient;
• obtaining an initial digital model of a removable partial denture (RPD) framework based on patient image data, the RPD framework comprising a plurality of clasp retainers, each clasp retainer being configured for removable engagement with a corresponding one of a number of abutment teeth of the patient;
• for each clasp retainer, identifying a set of relevant geometric parameters and providing each relevant geometric parameter with a nominal value in the initial digital model;
• providing, for each clasp retainer, a target value of a dislodging force for disengaging the clasp retainer from the corresponding abutment tooth with which the clasp retainer is configured for engagement;
• performing a force analysis on the initial digital model, the force analysis comprising, for each clasp retainer:
• providing one or more force equations relating the dislodging force of the clasp retainer to the set of relevant geometric parameters of the clasp retainer;
• performing a parametric study on the one or more force equations, the parametric study comprising varying the relevant geometric parameters of the clasp retainer while simulating the application of the dislodging force on the initial digital model of the clasp retainer;
• and
• determining, from the parametric study, corrected values for the relevant geometric parameters of the clasp retainer, such that when the corrected values are assigned to the relevant geometric parameters in the one or more force equations, the dislodging force associated to the clasp retainer matches the target value thereof;
• and
• correcting the initial digital model by replacing, for each clasp retainer, the nominal values of the relevant geometric parameters by the corresponding corrected values, thereby obtaining a corrected digital model of the RPD framework.