[Thickness of mouthguard sheet material after vacuum forming process depending on the thickness of mouthguard sheet].

PURPOSE Mouthguards are available to provide protection from stomatognathic injury during sports. The aim of this study was to examine the thickness of each part of mouthguard sheet depending on the thickness of mouthguard sheet material. METHODS Cross stripes (10 x 10 mm) were printed in mouthguard sheets. We measured the thickness of each cross stripe area using a measuring-device (R). Two mouthguard sheet materials were compared. The thickness of the mouthguard sheet materials were 2 and 4 mm. The difference in the thickness of the two mouthguard sheet materials was analyzed by Wilcoxon signed-rank test and t-test. Additionally, the relationship between the elongation and the thickness of the mouthguard sheets was investigated by regression analysis. RESULTS All parts of the sheet mounted on the cast decreased the thickness. The changes of the thickness in each part of mouthguard sheet were similar in both the 2-mm sheets and 4-mm sheets. In addition, the ratio of changes of the thickness in the part of the sheet fitted to the anterior teeth and palate on the 2-mm sheets was greater than that of the 4-mm sheets (p < 0.01). There was no statistically significant difference between the thicknesses of the sheet on the posterior teeth. The relationship between the elongation and the thickness of mouthguard sheet was modeled by quadratic equation. CONCLUSIONS This study suggests that the ratio of changes of the thickness of the part of the sheet fitted to the anterior teeth and palate on the 2-mm sheets was greater than that of the 4-mm sheets. Furthermore the ratio of changes of the thickness of the part of the sheet fitted to the posterior teeth did not differ between the 2-mm and the 4-mm sheets.