Evaluation of Wear Characteristics of Nano-Hybrid Denture Teeth

The majority of teeth utilized in the fabrication of conventional complete dentures are made of acrylic resins. These acrylic teeth provide increased bond strength to the denture base and are much easier to adjust for correct denture occlusion compared to teeth made of harder materials, such as porcelain. However, the acrylic teeth will wear faster than the porcelain teeth, leading to alterations in how the teeth contact each other if the denture is not replaced periodically (typically every 5-8 years). With the increase in biting and chewing forces that can be achieved during function with dentures supported by dental implants, the rate of tooth wear may be increased, leading to more frequent need for replacement of the prosthesis. Acrylic teeth made of nano hybrid composite material (NHC) potentially offer greater wear resistance and aesthetic characteristics. The NHC teeth employ a wide range of fillers, including highly cross-linked organic macrofillers, high-density inorganic microfillers and silanized silica based nanofillers. The macrofillers are, to a large part, responsible for the adequate strength and color-stability of the teeth, whereas the microfillers improve the wear resistance. The nanofillers offer fundamentally different optical behaviour from those of larger fillers, improving light reflection without lowering the translucency. This offers additional opportunities in the development of composite teeth, which have to exhibit lifelike aesthetics and translucency. These teeth made of nano-particles and hybrid composites can be made with two different techniques, one where the materials are pressed together and another using an injection technique. The injection method has been found to have better aesthetic results, but resistance to wear in clinical use has not been established.

The purpose of this study is to evaluate the wear characteristics of new resin denture teeth (nano particles - hybrid composite) made by an injection technique. Twenty-four edentulous subjects will be enrolled who have completed implant placement for mandibular implant overdentures opposing a maxillary complete denture or implant overdenture, or patients that have previously received these dentures and are interested in having new dentures. Both maxillary and mandibular dentures will be fabricated using injection molded nano-hybrid composite denture teeth. The wear of denture teeth will be evaluated using stereophotographic recordings at baseline, 6, 12, 18 and 24 months after denture treatment.