Identifying an ideal attachment layer for smile reanimation, using a model platform for biomechanical analysis of...

Various complications can be the reason for loosening from peri oral attachment after a functioning muscle transfer such as suture failure, tearing of the transplanted muscle at the attachment or a tear in the attachment itself. All these can lead to revisional surgery, which is reported as high as 39%. Although SMAS(superficial muscular aponeurotic system) is the most frequently used layer, the primary authors has encountered multiple unsatisfactory results using SMAS as the sole attachment layer. Main purpose of the study is to investigate biomechanical properties of distinct layers around the mouth by exposing various tissue blocks harvested from fresh cadaver heads to a load until failure system.

A total of 51 distinct 1 cm² tissue blocks, consisting of either submucosa, SMAS, SMAS-buccinator complex or a combination of all the mentioned layers (ergo full thickness) were taken from perioral region of 6 different fresh cadaver hemifaces and placed in a servo-hydraulic testing machine using a load-until-failure model. Vector of the applied load was similar to an in vivo scenario.

SMAS group had the least ultimate load capacity and worst stiffness among all groups. Full thickness group resisted higher ultimate loads and both full thickness and submucosa group had less extension at ultimate load compared to the remaining two.

Contrary to common practice, SMAS had the least favorable attributes for a stable attachment for muscle transfer; full thickness bite can a reliable option for secure attachment while accompanied by attachment to different layers for nuanced outcomes.