Patent Number: 042232295
Section: summary

BACKGROUND OF THE INVENTION The use of X-rays for diagnostic purposes, and radiotherapy, expecially as applicable for treatment of malignancies, has been found necessary and desireable in many phases of dentistry and medicine. Unnecessary and uncontrolled subjection of the human body, or portions thereof, to radiation, however, including X-rays for diagnostic purposes, or radiation exposure connected with radiotherapy treatment of malignancies, are increasingly recognized as being harmful. The medical and dental professions accordingly have taken steps attempting to reduce, in so far as possible, the subjection of patients to such harmful radiation, occuring either inadvertently or during intended treatment but perhaps to specifically different parts of the body, or resulting from stray, scattered and surplus rays. Recent studies have shown, for example, that oral complications occur in patients undergoing radiotherapy treatments for malignancies, even though the malignancies were not in the head and neck. An article in The Journal of the American Dental Association, September 1978, Volume 97, No. 3, pps. 468-472, by Stephen T. Sonis, Andrew L. Sonis and Alan Lieberman, entitled "Oral Complications in Patients Receiving Treatment for Malignancies Other Than of The Head and Neck" discusses the results of a recent study in this connection and reference is made therein to several additional publications & articles reporting the results of other studies. The following ones of the articles are pertinent in regard to the background of the present invention: Ref. 1. DelRegato, J.A. Dental lesions observed after roentgen therapy in cancer of the buccal cavity, pharynx, and larynx. American Journal of Roentgenology Radium Therapy and Nuclear Medicine, 42:404, Sept. 1939. Ref. 2 King, E.R., Elzay, R.P. and Dettman, P.M., Effects of ionizing radiation in the human oral cavity and oropharynx, results of a survey. Radiology, 91:990, November 1968. The use of X-rays for diagnostic purposes in dentistry has also recently been of some concern. Research has generally led the medical and dental professions to avoid unnecessary exposure of patients to X-rays. It has been found that even very limited amounts of exposure to radiation, especially in children, sometimes causes damage to such glands as the pituitary and thyroid. In efforts to avoid such problems, techniques and apparatus have been developed attempting to either absorb or otherwise shield body areas of a patient from undesired exposure or from stray, or scattered x-rays such as those which normally tend to scatter from the principal stream of X-rays. Preferably the only X-rays allowed to contact human tissue are those necessary in the procedure. Some apparatus of this type is disclosed, for example, in United States Patents Re. 25,773; 3,304,422 and 3,304,423. These patents disclose dental X-ray shields and X-ray aiming means, in conjunction with X-ray film holding devices used in the taking of X-rays of teeth. The stated purpose, and suggested result, is to greatly minimize possible injury to the patient from scattered and surplus X-rays contacting tissues other than those which are intended to be subjected to X-rays. It is also known to use protective garments or covers, in the nature of aprons and the like, to shield patients and/or certain body areas from stray X-rays during the course of X-ray examination or treatment. An example of an apron type of protective shield is shown in U.S. Pat. No. 3,233,248. Generally, however, such shields and/or protective covers are very heavy and uncomfortable, and varied sizes are required for efficient use with different individual patients. Another example of a protective shield is shown in U.S. Pat. No. 3,569,713. This patent discloses a shield used in dentistry which is adapted for positionment on, and partially around, the neck of a patient, and is a shield for the thyroid gland of the patient. There is additionally an increasing awareness in the medical and dental professions of possible serious damages which can be inflicted on teeth, gingiva, dentition, periodontal bone, parotid, sublingual, and salivary glands, and other related near body areas, by harmful side effects of radiation therapy, particularly when the patient receives large radiation doses in the head and neck regions for example. Research, resulting in part in the above noted articles, which while alluding generally to detrimental and dangerous conditions resulting from negligent use of radiation, fail to completely appreciate the problems, and the techniques and apparatus advanced in the articles, as also in the prior patents, have failed to solve some of the existing problems. A primary purpose of the present invention is to provide techniques and apparatus which help to overcome some of the existing problems, and to a very substantial extent fulfill a need in the medical and dental professions. SUMMARY OF THE INVENTION The present invention is primarily directed to an appliance devised to overcome some of the problems which are resulting effects of radiation, either directly or indirectly applied to teeth and surrounding patient areas and tissues, as also glands, in areas of a patient being treated. More specifically, the invention teaches a radiation shield intended to protect the teeth, gingiva (gums), periodontal bone and salivary glands against harmful side effects of radiation therapy. The shield, can consist of or include specifically different materials which are known to protect against radiation, such as lead in sheet form, or lead carried in or by another material, one known material for example consisting of multilayered plastic sheets, an intermediate one of the layers containing fine particles of lead. The shield can vary in thickness and other physical characteristics depending upon the intensity of radiation required for treatments, and also as equated to the patient being treated. In a preferred form of an appliance for practicing the invention, a composite or combined unit is used including an intraoral portion and an extraoral portion, selectively joinable. The intraoral portion is so designed as to substantially cover the teeth, gingiva, periodontal bone and related tissue to prevent impingement thereon of the radiation rays, and the extraoral portion, which in effect serves as a selectively usable attachment to the intraoral portion, provides a shield which covers the extraoral anatomy of the face and provides protection for the parotid and sublingual and salivary glands. The conditions among others which the oral radiation protector appliance is intended to protect against include: 1. Salivary gland atrophy and xerostomia (dry mouth). The salivary glands, when exposed to radiation atrophy (shrink) and their function markedly decreases or ceases altogether. This condition lasts from weeks to a permanent loss of function. The patient finds it difficult to chew, swallow and digest food. The food will also adhere to the dentition and periodontal areas increasing the liklihood of caries and periodontal disease. 2. The appliance is also intended to provide protection to the teeth. The dentition is very susceptible to the effects of radiation. Therapeutic radiation in the range of 2500 r to 5000 r causes great injury to teeth and bone. Most organs such as thyroid and brain radiation require over 5000 r. The oral radiation protector appliance will allow a patient to receive large doses in the head and neck region and yet preserve the integrity of the teeth. Should a patient fail to have protection, the dentition becomes susceptible to a condition known as "Radiation Caries." This condition is characterized by demineralization and breaking down of enamel. The teeth become brittle, usually getting cavities in the cervical region, and often breaking off at the gumline. 3. The appliance will also provide protection to children whose teeth are just erupting or are still unerupted. Children often require radiation treatment for head and neck tumors. Hemangioma's in children are also treated by radiation. Radiation therapy, whether direct or indirect, frequently results in stunted undeveloped roots, retarded eruption, and anodontia (missing teeth). The oral radiation protector appliance will aid in preventing this condition. 4. The alveolar bone which holds the teeth has been seen to resorb and become porous as a result of direct and indirect radiation. The teeth loosen and the patient becomes susceptible to periodontitis (pyohorrea). 5. Alveolar bone that has been exposed to radiation has a reduced blood supply and infected teeth are much more severe and dangerous due to this limited blood supply. 6. It has in many instances been the accepted principle to extract the teeth that are in an area to be radiated, as noted in the above mentioned articles. The oral radiation protector appliance in some cases make this procedure unnecessary, since the radiation would not severely damage the teeth and alveolar bone. 7. The oral radiation protector appliance also minimizes a condition known as osteoradionecrosis. The chronic pathosis in this condition is characterized by infection, pain and necrosis. Sequestrae of bone and overlying mucosa are common and in some cases deformity results. This infection can last from months to years, and has also been known to be fatal. The above listed articles discuss in greater detail some of these problems and it is to be noted that the application of the radiation rays discussed therein is to areas removed from direct impingement on teeth and areas proximate thereto. The direct impingement is understandably more devastating.