adding non-titanium pieces to titanium jewellery?

is there a reason why you can't add things like charms or other decorations to titanium jewellery (for healed piercings)? I was just wondering due to the lack in interesting designs for full titanium pieces. if the non titanium parts didn't touch your flesh, would that still be an issue? I know that it's probably not recommended as the non titanium parts might still touch you when youre sleeping or lying down but I figured I'd ask anyway. ty!