I found this answer about the benefits of electric toothbrushes with tons of sources. It only mentions the positive impacts on plaque removal and gingival inflammation (i.e. efficiency of the cleaning)
But the main argument I heard against the electric toothbrushes is that they are not as sensitive to the gingiva and, therefore, can be harmful to it while cleaning.
Also, I heard from two dentistry students two different opinions about the difference between the sonic and oscillating. Each of them was said at their university that one of the types is harmful and the other is ok.
Is there any study proving this negative effect on the gingiva?
Which of the types is better?