Introduction

The rehabilitation of the partially edentulous patient involves the creation of prosthetic products including the Partial Removable Prosthesis (PPR) whose peculiar characteristic is that it can be inserted and removed by the patient. The PPR hook has the function of providing support, retention, stabilization and balancing of the prosthesis. Clasps lead to long-term problems on the abutment tooth. The new designed hook would make it possible to overcome the critical issues associated with the use of hooks in PPR.

Technical features

The innovation consists of 2 components: the pin which is an integral part of the prosthesis and the hook which is produced separately. The pin has an oval section: the hook fits around this. When the patient wants to remove the prosthesis, he applies a force on the hook, which rotates around the pin and widens slightly, detaching itself from the tooth. When you stop applying force, the hook, thanks to the oval section of the pin, will return to its original position with ease. The force required to mobilize the hook, in addition to depending on the material and thicknesses, also depends on the section of the pin. In fact, the more the oval will be stretched, therefore with a large difference between the long axis and the short axis, the more force will be needed to move the hook. Conversely, the more rounded the section of the pin is, the less force will be required.

Possible Applications

– This type of clasp can be used in all Removable Partial Prosthesis and all types of clasp (subequatorial and supraequatorial)
– The use of the prosthesis in case of different insertion axes between abutment teeth or an insertion too difficult for the patient to perform

Advantages

– Clasp mobility avoids negative effects on abutment teeth
– Possibility of adjusting the clasp retention by changing the pin size
– Overcoming undercuts (which also provide better retention);
– Use of inclined abutment teeth
– Versatility of production, design and/or repair materials