Like the incline barbell bench press also the incline dumbbell bench press is a compound exercise for your upper chest that works anterior deltoids and triceps as well.
All you need is a 45 degrees incline bench and two dumbbells. Keep in mind that the more you raise the back support the more you work your shoulders, the more you lower it the more you work your chest.
PRIMARY MUSCLE: Upper Chest
SECONDARY MUSCLES: Triceps, Shoulders
EQUIPMENT: Incline Bench, Dumbbells
Compared to barbell exercises, more auxiliary muscles are involved in dumbbell exercises because they force you to maintain a certain degree of stability.
INITIAL POSITION: Sit on a 45 degree incline bench with your feet stable on the ground and your back in full contact with the back support. Grab two dumbbells and extend your arms shoulder width above your head. Your elbows should be slightly bent.
MOVEMENT: Slowly lower the weights till you feel the stretch in your chest and then push up with force on a vertical line (watch for balance and stability). Feel the squeeze in your chest and then repeat.
BREATHING: Exhale when you push and inhale when you lower the weights.
TIPS and ERRORS: Some benches allow you to incline the seat part too, which should avoid "sliding" down during the execution of the exercise. Dumbbells allow you to lower your arms more than a barbell because your chest is not going to block the movement. This will allow you to work on a wider range of motion. Don't lower your arms too much to avoid dangerous and unnecessary stretches. Don't arch your back.
Using dumbbells is generally speaking more dangerous than using a barbell because they force you to work on balance too. Especially on an incline bench it's easy to lose control if you don't focus and concentrate on what you're doing.
I've seen people injuring their shoulder or elbow when doing this exercise.
If you lose control (maybe because your muscles are starting to get tired) you really risk to hurt yourself, especially if your arm bends backwards.
You may want to have a spotter behind you that can follow the movement with his hands just below your elbows, ready to grab you in time before you get hurt.