Methods: Cross stripes (10×10 mm) were printed in mouthguard sheets. Two shapes of the sheet were compared: square and round shape. The sheet colors were six on each shape of the sheet. A cast was made by taking an impression of a maxillary dental model using silicone rubber replicate impression paste, then gypsum was poured onto the impression. The cast was trimmed to a height of 20 mm at the incisal edge of the upper central incisor and 15 mm at the medial buccal cusp of the upper first molar. The round-shape sheets were stabilized by a disk tray at the top and bottom of the sheet. The sheets were heated until they sagged 15 mm from the baseline used vacuum former. After forming, the thickness of each cross stripe area was measured by measuring device at the parts fitted to the anterior teeth, the palate and the posterior teeth. The difference in the ratio of change of thickness, depending on the shapes and the color of the sheet were analyzed by two- way ANOVA.
Results: The thickness after formation of the round-shape sheet was thinner than that of square. There was significant, that the thickness was found the difference dependent upon few colors of the sheets on the square-shape sheet on the palate and the posterior teeth, and on the round-shape sheet on the posterior teeth.
Conclusions: The present study suggests that the shape of the sheet effected to the thickness of the mouthguard sheet after vacuum formation. Additionally, the thickness reduction was differed from the color of the sheet.