Tooth whitening apparatus

A tooth whitening apparatus comprising:

• a container comprising a first engagement feature and a cavity containing a tooth whitening composition;
• an applicator assembly comprising:
• a cap comprising a second engagement feature;
• a rod member coupled to the cap and protruding from a bottom end of the cap, the rod member comprising a longitudinal axis, an outer surface, and a distal portion;
• and
• an applicator tip coupled to the distal portion of the rod member;
• wherein the applicator assembly is alterable between:
• (1) an attached state whereby at least a portion of the rod member and the applicator tip are located within the cavity of the container and the second engagement feature of the cap engages with the first engagement feature of the container to couple the applicator assembly to the container and seal the cavity;
• and (2) a detached state whereby the applicator assembly is separated from the container and the applicator tip is configured to apply the tooth whitening composition onto a user's teeth;
• and
• wherein the outer surface of the rod member comprises at least one vent groove that is elongated in a direction of the longitudinal axis to reduce a pressure in the cavity of the container when altering the applicator assembly into the attached state.