A NEW METHOD OF MEASURING DIMENSIONAL CHANGE

A new method of measuring linear dimensional change in denture base resins is presented and its precision in determining distances between two points was investigated. Chrome steel ball bearings 1.57 mm in diameter were invested in a stone mold and were used to record measurements by a reflection from the surface of the ball bearings. The accuracy of this method was determined by performing repeated measurements between two points in a stone mold. Random measurements were made to an accuracy of 0.002 mm. The dimensional change of light-cured, heat-cured, and self-cured denture base resins was also determined with this method, followed by an analysis of variance of the data. The findings support the accuracy and reproducibility of this new method in recording linear measurements. The dimensional changes of all three resins were different from each other after the specimens were processed and stored in distilled water for 7 days at 37-degrees-C.