Temperature-Responsive Clips for Removable Dental Prostheses

ABSTRACT The American Academy of Implant Dentistry reports that about 70% of Americans between the ages of 35-44 have at least one missing tooth, and that one in four over the age of 74 lose all their natural teeth. The first choice treatment for patients with multiple or all of their teeth missing are overdentures, which are removable replacement teeth retained by dental implants. The main reasons overdentures are more effective than conventional dentures are the superior retention and stability provided by the attachment system. Retention is in fact one of the most important indicators of patient satisfaction with removable overdentures. Ideally, patients with overdentures would be able to enjoy all foods, including hard and chewy foods that are usually too difficult to eat with dentures. This requires strong retention force. However, it can be difficult for patients, especially elderly patients, to remove their dentures when the retention force is too strong. Consequently, manufactures of overdenture retention systems encounter competing design variables: maximize retention force at the expense of retrievability or vice versa, and patients and their dentists are expected to choose between tight fit or easy removal. Clearly, improvements to the design of retention systems are needed for optimal treatment with overdentures. To overcome these limitations, RODO Medical has developed Smileclip, a temperature-responsive nitinol clip that rapidly engage/disengage dentures from implant- supported bars. Specifically, Smileclip has been engineered to have a phase transformation temperature well below body temperature so that when dentures with Smileclip are rinsed with cool water, the clip’s retention force drops to allow for easy denture seating onto the retention bar. Once the temperature equilibrates to the oral environment, the retention force increases and the clip tightly grips the retention bar and provides the tight fit patients need. To remove their dentures, patients only need to rinse with cool water again and apply a gently force to unclip them from the retention bar. The overall goal of this Phase 1 project is to characterize the mechanical and electrochemical performance of these retention clips in order to optimize retrieval and retention forces, and ensure a long service life for the retention system as reflected by the following aims: Aim 1 – Determine the mechanical retention and fatigue resistance of Smileclip on implant-supported bar. Aim 2 – Determine the corrosion resistance of Smileclip. Aim 3 – Determine the retention force between Smileclip and dental resin it is embedded in. Successful completion of Phase 1 will establish the design parameters that can withstand physiological loading for at least 1,000,000 cycles while maintaining a strong retention force and still easily retrieved.PROJECT NARRATIVE Nearly one in four Americans over the age of 74 lose all their natural teeth, and require complete or partial dentures. RODO Medical has developed Smileclip, a temperature- responsive metal clip for implant-supported dentures that provides the strong retention forces patients need to enjoy the hard and chewy foods that would otherwise be too difficult to eat and still allows for easy denture removal. The goal of this Phase 1 project is to characterize the mechanical and electrochemical performance of these retention clips in order to optimize retrieval and retention forces, and ensure a long service life for the retention system.