The dental practitioner is familiar with a host of cosmetically unacceptable facial aspects of anterior teeth. These aspects include discoloration due to pharmaceuticals, diet, metabolic disease or bacteria; and can also include enamel defects or hypoplasia.
Until recent years, cosmetic restoration of such discolored teeth could be effected only by application of crowns. These crowns are composed of expensive metal materials, such as gold, or of plastic materials and necessitate a considerable amount of dental chair time for their application. Moreover, because crown application frequently requires drastic reduction or reshaping of an affected tooth, it is contraindicated in many situations, especially for patients of young age.
A more recently utilized cosmetic restoration technique has been to apply a layer of acrylic or composite resin directly to the etched enamel surface of the tooth and then light cure the resin to bond it to the tooth. The resulting laminate can be shaped, contoured and given its appropriate anatomy with composite finishing burs, stones and discs. Application of direct composite resin laminates is time consuming and has been found ineffective in cases of severe tooth discoloration where it has not been possible to mask completely.
It is also known to use preformed acrylic laminates which are prepared in a laboratory or to commercial specifications, and are then fitted to the affected teeth in the dental chair. One such restoration system involves fabricating an acrylic laminate in a laboratory, in much the same manner as described above, on a mold of the affected teeth. Because the laminates can not be fitted to adjacent teeth on the mold, this process requires that two separate molds be provided to the lab technician. Additionally, the process is time consuming. Discoloration of the tooth is masked by mixing shade resin with the bonding material.
A second type of preformed laminate is provided by the L.D. Caulk Company in its Mastique kit. Each kit contains a full selection of pre-sized plastic laminates and accessories, including bonding resins. The Mastique laminates are bonded to acid-etched enamel tooth surfaces using light cured bonding resins. They may be prepared in the dentist's office or in advance on a model in the laboratory. A disadvantage of the Mastique system is that the laminates themselves have little color or shade; thus, all shading must be effected through the shade and bonding resins. Such shades have been known to change over a short period of time. It is also more difficult to control the shade of the restoration at various areas of the labial surface. It is known, for example, that dark tooth discoloration is often most intense in the gingival area of the tooth.
While the aforementioned restorative techniques have achieved some satisfactory results, they are not altogether desirable. Because of the porosity of the plastic materials from which these laminates are made, their long-term color stability and wear resistance are low. The thickness of these laminates has also been a source of periodontal pathology development such as inflammation of the gingival tissue. Additionally, the plastic materials have been found to be toxic to the mouth. Other problems reported with respect to these techniques have included extended dental chair time, inadequate marginal finish and contour and lack of cosmetic customizing and transparency. It is desirable, therefore, to provide a long-lasting, non-pathogenic custom-made veneer of specified color, shading and shape, which is easily suited for inexpensive and effective adaptation to a dental patient's cosmetically defective teeth.
USPTO Backgrounds
USPTO Backgrounds