Bristles vs. Bristles
Lets get this straight. There is absolutely no research that proves that any type of angled bristles or rubber in the head would be more efficient than regular straight bristles.
A toothbrush is a essentially just a basic brush and it is HOW you use it that will make the difference.
Dentists recommend you not to use hard bristles. But people do it anyways... Why? Most of the time they feel like softer bristles don't clean/brush the teeth enough.. Often these types of people are also people who brush hard. It is kind of a bad circle here, since the combination of brushing hard with hard bristles is not good for either teeth or gums.
Toothbrush bristles should be gentle. You use the toothbrush to clean your teeth and tongue and mainly to take away the bacteria filled biofilm called Plaque. Plaque is soft.
Therefor there is no need to use hard bristles that could do damage over a longer period of time.