Section 14. Every dental service corporation is hereby declared to be a charitable corporation. No such corporation shall be liable for injuries resulting from negligence or malpractice on the part of any participating dentist, nor shall it be liable for the cost of dental services to which the subscriber or covered dependent may be entitled under the provisions of chapter 152, but said corporation shall be liable for injuries resulting from negligence or malpractice on the part of any dentist employed by it or of its agents, servants or employees. Every such corporation shall be exempt from all provisions of the insurance laws of the commonwealth, except as otherwise provided in this chapter. The property of every such corporation shall, except as hereinafter provided, be exempt from all state and local taxes.