California Code, Health and Safety Code - HSC § 104855

The governing board of each school district and the governing authority of each private school shall distribute to each pupil's parent or guardian or responsible relative or adult who has assumed responsibility for his or her care and custody (in the case of a minor), or the pupil (if an adult), a letter which may be returned to such district or authority in which the person to receive the letter may indicate that the treatment is desired and the pupil is to receive the treatment or that the pupil is not to receive the treatment for one of the following reasons: (i) the pupil has received the treatment from a dentist, or (ii) the treatment is not desired.