1. you listen, touch and look. listen at the nose for breath, touch for a pulse and look for the chest moving. if none of that is there.......there are no vital signs. tilt the jaw back and up and give two quick breaths.......then start the compressions and the breaths.
2. do not remove dentures. dentures keep the mouth in shape and enable you to achieve a seal for the breaths. and yes, you can use a mouth guard. i don't use one. i don't feel comfortable with it.
i left the above out and i might as well lay it all out in the order of how it goes down.
i've seen people react/respond differently in all kinds of situations.....i think my upbringing is responsible for my attitude about emergencies. my mom was a midwife and we lived on a ranch. with daily animal emergencies......you couldn't just stand around and gawk......

it's due to my mom and dad.