Oral care implement and refill head thereof

An oral care implement comprising:

• a gripping portion having a distal end surface;
• and
• a stem extending from the distal end surface of the gripping portion, the stem extending along a stem axis from the distal end surface to a distal end of the stem, the stem comprising:
• a base stem section adjacent the distal end surface of the gripping portion and comprising a locking depression;
• and
• a distal stem section comprising a first planar surface and a second planar surface opposite the first planar surface, the first and second planar surfaces being substantially parallel to one another and to the stem axis, the distal stem section further comprising a first radial planar shoulder and a second radial planar shoulder, the first radial planar shoulder located closer to the distal end surface of the gripping portion than the second radial planar shoulder;
• and
• an oral care refill head detachably coupled to the stem, the oral care refill head comprising:
• a head portion comprising an oral care treatment tool;
• and
• an attachment portion extending along a longitudinal axis from a proximal end to a distal end, the head portion located at the distal end of the attachment portion, the attachment portion comprising:
• a connection cavity defined by an inner sidewall and an inner end wall of the attachment portion, the connection cavity extending along a cavity axis from an opening in the proximal end of the attachment portion to the inner end wall of the attachment portion, the connection cavity configured to receive the stem;
• a locking protuberance located at a first axial distance from the proximal end of the attachment portion, the locking protuberance protruding from the inner sidewall into the connection cavity and configured to engage the locking depression of the stem;
• a first radial shoulder formed in the inner sidewall and located a second axial distance from the proximal end of the attachment portion, the first radial shoulder circumferentially aligned with the locking protuberance and the second axial distance being greater than the first axial distance;
• a second radial shoulder formed in the inner sidewall and located on an opposite side of the inner sidewall than the first radial shoulder, the second radial shoulder located a third axial distance from the proximal end of the attachment portion that is greater than the second axial distance;
• and
• a third radial shoulder circumferentially aligned with the first radial shoulder and located a fourth axial distance from the proximal end of the attachment portion that is greater than the third axial distance;
• wherein the inner sidewall further comprises:
• a first planar section located between the first radial shoulder and the inner end wall;
• a second planar section located between the second radial shoulder and the inner end wall;
• and
• a third planar section extending from the third radial shoulder to the inner end wall, the third planar section configured to contact a distal stem section of the stem;
• and
• wherein, when the stem is received within the connection cavity, a gap exists between a first portion of the first planar surface of the stem and the first planar section of the inner sidewall, and a second portion of the first planar surface of the stem is in contact with the third planar section of the inner sidewall.