(a) Custodial care institutions (either public or private or which qualify as a "hospital" or "school") may be allowed to employ a dental hygienist when a licensed dentist in on the staff of such institution and after approval by the state board. Any hygienist employed by such institution is subject to the same laws and rules pertaining to supervision and responsibility as a hygienist in the employ of a dentist in private practice.(b) A licensed hygienist may perform duties in certain custodial care facilities as provided in §115.5 of this chapter.(c) Locations for the performance of a dental procedure other than those named in the Dental Practice Act must be approved by the SBDE by rule or written authorization as a proper location prior to commencing a dental procedure at the location.