March 1, 2024

Removable Partial Denture Using Implant-Supported Loc-In Attachments

Implant-supported Locator-type attachments have been used for many years to stabilise complete dentures. They offer an affordable option for denture-wearing patients to improve their quality of life and chewing. However, they can also stabilize removable partial dentures (RPDs), which is often overlooked. The use of Loc-in attachments can improve retention and esthetics and can be used to salvage a comfortable RPD when an abutment tooth is lost.

There are many uses for Loc-in attachments with RPDs, including stabilising distal extensions, hiding unsightly clasps, customising retention to the patient's desire, and creating a retention system where retention can be easily regained when it lessens (by replacing the worn retentive nylon). An additional benefit is that a choice of thinner implants is possible, as the load is comfortably spread between the implants/attachments.

In this case, DSI Premium Slim 3.0x11.5 (right) and two 3.5x11.5 (left side) were used.

It is important to remember that the implant and attachment are there to retain the RPD, not support it. Forces during compression should be distributed over the soft tissue and bone and any remaining supporting teeth.

With complete dentures, a minimum of two implants is recommended in the mandible and a minimum of four in the maxilla to minimize stress on the implants. However, in the case of RPDs, like the one we review, the number of implants is less since the remaining teeth can minimize rotation forces on the implants.

Additional considerations include ensuring that 1.5 mm of the abutment is above soft tissue level for proper engagement of the Loc-in retentive soft cap and torquing the abutment to 30 Ncm (per DSI recommendation). We used 4mm g/h DSI loc-in abutments for the patient.

A minimum of 10 mm from the implant platform to the opposing dentition is ideal to prevent fractures of the RPD over the Loc-in housing.

At recall visits, it is important to confirm that the RPD doesn't need a reline, as a tissue misfit may result in increased forces on the implant. This can be done by feeling for a soft tissue "squish" when applying finger pressure. If tooth support prevents this, a small amount of bite registration material or soft liner can be placed on the soft tissue-borne portion of the RPD and fully seated the prosthesis, making sure to engage the Locator. Once set, remove the RPD and measure the material with a probe to see if a reline is indicated.

Using implant-supported Locators to retain RPDs is a great service in your practice. It can result in more patient referrals and, more importantly, more happy patients!