Effect of Commercial Acrylic Resins on Dimensional Accuracy of the Maxillary Denture Base
Acrylic resin is one of the components of a denture base and other dental construction which is prone to polymerization shrinkage and distortion during flask cooling. On the other hand, the difference in curing technique may not considerably alter the outline of dimensional acrylic resin actions due to the decline in molecular weight of the polymer chains.
The polymerization shrinkage of the acrylic resin in the denture base is not the same; the palate of the maxillary denture is more obvious and will poorly compensate after resin base processing. The base thickness may differ at different site inside the flask, changes the denture base adaptation and stability.
Some processing technique has been suggested as a substitute to the conventional heat water bath in order to reduce the variables that change the base stability. In the demonstration in some of the studies, base adaptation to the stone cast is substandard, because it manipulates the base thickness, palate geometry and the method in processing, with no control of different curing cycles.
Dimensional change in denture base is found together with commercial thermocured acrylic resins. Scientist conducts a study why the denture base has dimensional changes during the polymerization. Different products were tested and it was prepared according to the manufacturer instructions. After the last acrylic resin pressing, the flasks were put in strain clamps and submitted to polymerization cycles in heat water. The base of the resin was set permanently on the cast with a direct adhesive and position laterally sectioned in the corresponding area of the tooth. The gap between the stone cast and resin base was demonstrated with a tool microscope at different location for every type of cut.
A tool maker microscope is most widely use in dental laboratories. Uses of a tool maker microscope include measurement of tooth shapes and angles of the tooth. Like the gap between the stone cast and resin, it is hard to measure if we just use ordinary measuring tools. A tool maker microscope is the best measuring instrument to be use to have an accurate fitting of the denture to the patient. Not all denture after processing and polishing fits easily to the patient because as mentioned while ago during the polymerization there is a dimensional changes in the denture base which affect the accurate fitting of the denture to the patient.
Not only in dental laboratories can the tool maker microscope be used. Another use of tool maker microscope is for examining the facet or outline of different shaped parts, like templates, cutters, punching dies and cams. Tool maker microscope also measures different restriction of the tread, like the roundness, the flatness and the straightness of the thread profile. A video monitor is usually attached to a tool maker microscope. Videography allows laboratory and doctor to create a record and profile of the patient’s teeth. An advantage of this system is it allow the laboratory and doctor to have reference of the cast in question and minimize laboratory downtime and at the same time cost. Read more
