To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
These brushes are great for cleaning between hard to get to teeth such as rear molars. I have found that eventually the head of the brush breaks off at the point it joins the plastic stem presumably due to being flexed repeatedly. This can leave the bristly bit stuck between your teeth and awkward to remove. I use another brush to gently push the broken head out, trying not to swallow it!