Complex sentence: The American or Canadian dental associations have not been invited to participate in the development of this device as it does not affect teeth or occlusion; although the device is fit within the mouth, the Angellift devices affect the skin surface and not the perioral cavity.
Split into simpler sentences: The American or Canadian dental associations have not been invited to participate in the development of this device as it does not affect teeth or occlusion. Although the device is fit within the mouth, the Angellift devices affect the skin surface and not the perioral cavity.