Osteo-Odonto Keratoprosthesis: Titanium Analogue

Osteo-odonto-keratoprosthesis (OOKP) is successful when using highly mineralised dentine (canine tooth root), living bone (surrounding jawbone) and overlying buccal mucous membrane allografts. However, OOKP laminae present challenges. Primary disease affects dentition and oral hygiene is a low priority for blind patients. Age and smoking can also result in edentulous patients or unsuitable dentition.

There are other drawbacks. Anatomical asymmetry of bone caused by tapering root, thus optical cylinders are closer to the crown. Dentine size limits optical cylinder diameter. Even with successful cases, OOKP laminae are subject to resorption over time.

Design concept in the setting of the National OOKP Service in the United Kingdom (1996 to 2022). Synthetic grafts are difficult to create. Alternatives, such as OOKP allograft, tibial KPro, Pintucci and Boston KPro2 have not yielded equal results. An OOKP analogue may be the solution.

Titanium proves to be the choice material, being light, biocompatible and bio-integrable. The analogue would retain the bilayer structure to mimic the OOKP lamina. It would have a porous anterior layer for soft tissue to invest and a solid posterior layer with sharp edges to press against cornea, thus providing a good seal. This model would retain its rectangular shape to facilitate pointing the optical cylinder to the fovea and to centralise the optic cylinder opening. However, it would be thinner to reduce weight. The optical cylinder diameter will no longer be constrained by small tooth diameters.

This new lamina would retain its epicorneal position for shrink wrapping under buccal mucosal graft and would provide an alternative when there is no suitable tooth. Benefits include reduced oral damage, surgical time and skill, and improved oral cosmesis.

OOKP is successful in its current design but has limitations which could be addressed by our proposed bi-layer titanium analogue.