Maximum voluntary lip force For the lip force measurements an oral screen (Dentaurum " Ulmer Modell " maxi, DENTAURUM GmbH&Co.KG, Ispringen, Germany) was connected to a Dynamometer (ZP50-N, IMADA, Toyohashi, Japan). It was placed in the anterior oral vestibule and a horizontal pulling force was applied whilst the participant tried to withstand the force as long as possible. Per size, three peak recordings were averaged for analysis.