Method of manufacturing a recess wall lined with bristles for a mouthpiece for simultaneously brushing at a plurality of dental positions, and a recess wall and mouthpiece obtained with the method; and dental cleaning device; and mouthpiece for brushing at a plurality of dental positions, brushing device comprising such mouthpiece, and method of operating such a mouthpiece or brushing device

A method of manufacturing a continuous recess wall lined with bristles for a mouthpiece for simultaneously brushing at a plurality of dental positions, the continuous recess wall having an arch-shaped length axis and, viewed transverse to the length axis, a U-shaped cross-section configured for encompassing said plurality of dental positions, and the arch-shaped length axis having a length which spans a distance at least equal to the distance from the left second pre-molar to the right second premolar;

• wherein the method comprises a providing step, in which an elongate, continuous, bristled sheet part having a first side lined with a plurality of bristles is provided, the elongate, bristled sheet part defining a length axis extending parallel to the bristled sheet part and, viewed transverse to the length axis, a cross-sectional shape, and wherein the elongate, continuous, bristled sheet part obtained in the providing step has an initial condition in which:
• the cross-sectional shape has an initial shape;
• and
• the length axis is arch-shaped;
• wherein the method further comprises a transforming step, in which the elongate, continuous, bristled sheet part obtained in the providing step is transformed to a said continuous recess wall having a final condition;
• wherein in the final condition:
• the cross-sectional shape has a final U-shape;
• the length axis is arch shaped;
• the first side is a concave inner side of the final U-shape;
• and
• wherein the first side is in the final condition more concave than in the initial condition.