Deciduous teeth first teeth seen in the mouth are the mandibular centrals and the last are the maxillary second molars. The primary teeth are made up of central incisors, lateral incisors, canines, first molars, and secondary molars; there is one in each quadrant, making a total of four of each tooth. All of these are gradually replaced with a permanent counterpart except for the primary first and second molars; they are replaced by premolars. The replacement of primary teeth begins around age six, when the permanent teeth start to appear in the mouth, resulting in mixed dentition. The erupting permanent teeth cause
U Should've Known Better successful on "Billboard"´s component charts. It reached number 6 on the Hot R&B/Hip-Hop Singles & Tracks—Monica's tenth non-consecutive top ten entry on that particular chart—as well as the top ten on the Hot R&B/Hip-Hop Airplay and the top twenty on the Hot 100 Airplay chart. It also appeared on the Rhythmic Top 40 at number 20. The song was ranked 72nd on the Hot R&B/Hip-Hop Singles 2004 year-end chart. The music video for "U Should've Known Better" was shot by director Benny Boom, and produced by Joyce Washington for FM Rocks. It was filmed in various locations throughout Mexico, in