A partial acrylic lingual plate is commonly used as a transitional / temporary denture connector. What are the main disadvantages of using this as a permanent connector?

Acrylic lingual plates are often prescribed as a temporary solution as a cheaper alternative where the dentures life is expected to be short or where alterations will occur. As a more permanent connector it has many disadvantages. A lingual plate is used when there is insufficient vertical space for a lingual bar.

This lack of space may be related to gingival recession, high muscle attachments, or high frenum attachments on the lingual aspect of the mandibular arch.

Often less scope is available when designing an acrylic partial denture as it is weak and less rigid than metal alloys. This means that they are often more bulky to prevent flexing or fracture and covers more of the gingival margins. Especially when designing a lower APD the surface area is much smaller and little relief is given to the gingival margins as the major connector must cover the abutment surfaces to provide additional strength to the acrylic. These design issues cause tissue damage over time and with little to no tooth support the denture is primarily tissue supported instead.

For the APD to be tooth-supported metal alloys in the form of rests and clasps are integrated into the acrylic major connector, however these connections are weak as there is no chemical bond present between stainless steel and acrylic.

Considering acrylics bio-compatibility, some people suffer with allergic reactions to acrylic and are not able to have an acrylic denture. It also is a porous material suffering with a higher accumulation of plaque. When comparing to a metal major connector, its thermal conductivity is inferior. This becomes important when registering different temperatures in the mouth.

Lastly acrylic resin is radiolucent, if accidentally swallowed the location of the prosthesis will not show up through x-rays making it more difficult to find its location.