Thickness and fit of mouthguards according to a vacuum‐forming process

The purpose of this study was to examine the difference in the thickness and the fit of mouthguards fabricated with a vacuum‐forming method of the mouthguard sheet material. The material used in this study was Sports Mouthguard (3.8 mm thickness). Two forming conditions were performed. In the first condition, the sheet was lowered over the working model after the vacuum was applied, and in the other trial, the sheet was lowered over the working model before the vacuum was applied. The sheets were formed using a vacuum former when the heated sheets hung 1.5 cm from the baseline. We measured the thickness and the fit of the mouthguard at the areas of the central incisor and first molar in both conditions. The difference of the thickness at the areas of the central incisor and first molar and the forming condition was analyzed by Two‐way anova . The difference of the fit according to the forming conditions was analyzed by the Mann–Whitney U test. The results showed that the thickness of the mouthguard differed at the areas of the central incisor and first molar, but the thickness of the mouthguard did not differ according to the forming conditions. The fit of the mouthguard at the central incisor and first molar was significantly different between the forming conditions (P < 0.01 and P < 0.05). These results suggested that the fit of the mouthguard was the best without any deficiency of thickness when the vacuum was applied first and then the sheet was pressed onto the working model. These results may be useful in fabricating proper mouthguards.     

Thinning factors influence on custom‐made mouthguards thermoforming

The aim of this study was to clarify and quantify factors influencing thinning during a thermoforming using a special simulation model that has three different flat surfaces such as 0 degree, 45 degree and 90 degree against a pressurizing force. Air pressure type samples were made by EVA and acrylic resin blank. Vacuum type samples were also made by EVA. Thickness gauge was employed to measure the thickness. As results, pressure forming showed significantly larger thinning at 45 and 90 degree surfaces and smaller thinning at 0 degree surface, 36% in thinning rate by vacuum forming and 66% by the pressure forming at 90 degree surface, and 17% and 20% at 45 degree surface, and 11% and 2% at 0 degree surfaces. Thinning was increased with the increase in distance from the centre in 0 degree surface and increased with the decrease in height in the vertical surface significantly. The air pressure, the material thickness in EVA (Drufosoft) and difference in material colour did not affect thinning rate. An acrylic resin material showed approximately 10% smaller thinning than EVA (Drufosoft). To retain enough thickness of 3 mm on 90 degree surface corresponding to an incisal labial aspect for pressure laminate type, over 55% reduction is taken into consideration and at least two 3‐mm‐thickness materials should be laminated. 0 degree surface showed at most 2 % reduction in pressure lamination; post thermoforming occlusal thickness became almost 6 mm with a usual 3 mm plus 3 mm lamination. Therefore, careful occlusal adjustment in an actual mouthguard fabrication to achieve an appropriate 2 mm thickness on this surface should be requested.     

Thickness and fit of mouthguards according to heating methods

The purpose of this study was to examine the difference in the thickness and fit of mouthguards made by four different heating methods of the mouthguard sheet material. A Sports Mouthguard^® of 3.8‐mm thickness was used in this study. Four heating methods were performed. In one method, the sheet was heated only one side. In the other methods, one side of the sheet was heated first until the center of the sheet was displaced by 0.5 cm, 1.0 cm, and 1.5 cm from the baseline, and then turned upside down and heated. The sheets were adapted using a vacuum former when the heated sheets hung 1.5 cm from the baseline. We measured the thickness and fit of the mouthguard at the areas of the central incisor and first molar. The difference in thickness at the central incisor and first molar regions was analyzed by two‐way anova . The difference in fit with different heating methods was analyzed by one‐way anova . The results showed that the thickness of the mouthguard differed in the central incisor and first molar areas (P < 0.01 or P < 0.05), but not with the heating methods. The fit of the mouthguard at the central incisor and first molar areas was significantly different among the heating methods (P < 0.01 and P < 0.05). These results suggested that the fit of the mouthguard was superior when the heated surface of the sheet contacted the surface of the working model. This finding may help to fabricate accurate mouthguards.     

Pressure‐forming method using a single‐mouthguard sheet

Background/Aim

Mouthguard thickness is important for the prevention of orofacial trauma during sports. However, it is difficult to maintain the necessary thickness after forming the mouthguard. The aim of this study was to evaluate a pressure‐forming method using a single‐mouthguard sheet.

Materials and Methods

A mouthguard sheet of 3.8 mm ethylene vinyl acetate was prepared by cutting 3 mm from the anterior margin of the sheet holder with a length of 7 mm and with the width being from the buccal cusp of the upper right first premolar to the buccal cusp of the upper left first premolar and compared with the original sheet. The sheets were pressure‐formed when the sheet was heated until the centre was displaced by 15 mm from baseline. The thickness of the mouthguard was measured at the labial surface of the central incisor, and the buccal and occlusal surfaces of the first molar. The fit of the mouthguard was examined at the right central incisor and right first molar by measuring the distance between the mouthguard and the cervical margin of the working model. Differences in the thickness and the fit of the mouthguards between the sheet conditions and the measured regions were analysed by two‐way analysis of variance.

Results

Mouthguard thickness varied among the measured regions of the central incisors and first molars (P < .01). The greatest thickness was found at the labial surface of the central incisor in mouthguards fabricated using the cut sheet (P < .01). Mouthguard fit did not differ between the two sheets.

Conclusions

The results suggest that a useful mouthguard with proper thickness and fit can be produced with the pressure‐forming method using a single‐mouthguard sheet by cutting the anterior part of the sheet.