California Code, Corporations Code - CORP § 13407

Shares in a professional corporation or a foreign professional corporation qualified to render professional services in this state may be transferred only to a licensed person, to a shareholder of the same corporation, to a person licensed to practice the same profession in the jurisdiction or jurisdictions in which the person practices, or to a professional corporation, and any transfer in violation of this restriction shall be void, except as provided herein.

A professional corporation may purchase its own shares without regard to any restrictions provided by law upon the repurchase of shares, if at least one share remains issued and outstanding.

If a professional corporation or a foreign professional corporation qualified to render professional services in this state shall fail to acquire all of the shares of a shareholder who is disqualified from rendering professional services in this state or of a deceased shareholder who was, on his or her date of death, licensed to render professional services in this state, or if such a disqualified shareholder or the representative of such a deceased shareholder shall fail to transfer said shares to the corporation, to another shareholder of the corporation, to a person licensed to practice the same profession in the jurisdiction or jurisdictions in which the person practices, or to a licensed person, within 90 days following the date of disqualification, or within six months following the date of death of the shareholder, as the case may be, then the certificate of registration of the corporation may be suspended or revoked by the governmental agency regulating the profession in which the corporation is engaged. In the event of such a suspension or revocation, the corporation shall cease to render professional services in this state.

Notwithstanding any provision in this part, upon the death or incapacity of a dentist, any individual named in subdivision (a) of Section 1625.3 of the Business and Professions Code may employ licensed dentists and dental assistants and charge for their professional services for a period not to exceed 12 months from the date of death or incapacity of the dentist. The employment of licensed dentists and dental assistants shall not be deemed the practice of dentistry within the meaning of Section 1625 of the Business and Professions Code, provided that all of the requirements of Section 1625.4 of the Business and Professions Code are met. If an individual listed in Section 1625.3 of the Business and Professions Code is employing licensed persons and dental assistants, then the shares of a deceased or incapacitated dentist shall be transferred as provided in this section no later than 12 months from the date of death or incapacity of the dentist.