Speaking as someone who tore my shoulder a few years ago, I can only conclude that while one-rep max sets are great for the ego, they can be disastrous to your overall training progress. However, I realize it's futile to preach against this time-honored part of with iron game. Instead, I'll tell you what you can do to improve your benching as safely as possible, and hopefully you'll be wise enough to apply common sense to your training.
The basic problem is simple enough: you have a sticking point a few inches above your chest because you are Biomechanically at your weakest right there. There's not much you can do about that, except applying special training focused on that particular part of the exercise. I recommend a two-sided approach, where you alternate partial reps and static training.
Like always, make sure to get a good warm-up and some light stretching before you hit the weights. For added safety and intensity, have a spotter standing by to give you helping hand when you need it.
Use a bench where you can adjust the stops. Set them so that in case you drop the bar, the stops will catch it just above your chest. The closer to your chest you get the stops, the fuller range of motion you will have when working out. A Smith-machine can also work. Next you load on the amount of weight you'd normally use for a 6-8 rep set, and add another 20% on top of that. Grasp the bar with a shoulder-wide grip as usual, and push the bar up about 6 inches, or just beyond your normal sticking point.
In other words, when it starts getting easy, you stop and turn back down all the way to the stops above your chest. Don't bounce, just let it barely touch the stops, and push it back up 6 inches again. This is intense, and will get you exhausted in a hurry. When you've done as many reps as you can by yourself, have your spotter give you a hand on the way up, but make sure he or she lets go immediately at the top.
Once your spotter lets go, focus on resisting the weight all the way down. Try to make the descent last as long as possible (2-3 seconds) and enjoy the burn. When you can't take it anymore, rack the weight and stretch. Grabbing a pair of light dumbbells to do some presses can also help you flush out the lactic acid out of the muscles. As opposed to the normal good habit of keeping the rest-pause short, you can allow yourself a few minutes of rest. After all, today you're training for strength, not size.
Load on another 10% weight for your second set. Also double-check that the stops on the rack is secure. You WILL drop the bar at the end of the set, and you want to be sure you don't get trapped! This is the static part of the workout, so let your partner help you get in place. Hold the bar 2-3 inches above your chest, where you're at your very weakest. Just HOLD it there for as long as you can. Have your partner count the seconds out loud so that you get a benchmark for how your strength improves from workout to workout. The set isn't over until the bar has sunk all the way down to the stops.
Now rest and stretch while waiting for the next set, which will be another round of partial reps (with lesser weight.) Then repeat the process two more times so that you will have done 3 sets of partials and 3 sets of statics.
This should get you off the plateau and help you get past your sticking point. Keep in mind, however, that this is just a short fix for a specific problem, not a way to train. You can do this for a few weeks, but I would not recommend this kind of extreme, targeted training for more than a month.