The robot venture company Genics from Waseda University developed a mouthpiece type fully automated toothbrush.

The brush moves up and down, left and right and ends in about 30 seconds.
The removal rate of dental plaque is similar to hand polish.
Aiming for trial sales during FY 2019. (Nikkei Sangyo Shimbun)

It seems that a patent application has been filed (Japanese Patent Application No. 2017-164328).
It is epochal if it reaches enough to the back teeth.

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