Appropriate fabrication method for pressure-formed mouthguards using polyolefin sheets.

BACKGROUND/AIM: Polyolefin sheet mouthguards are usually formed in the same manner as ethylene-vinyl acetate sheet mouthguards. However, the heating condition of the polyolefin sheet for the pressure-forming process has not been determined. The aim of this study was to examine the appropriate heating condition for polyolefin sheet mouthguards when fabricated with the pressure-formed technique. MATERIALS AND METHODS: Mouthguard sheets of 3.0 mm polyolefin were pressure formed on working models at three heating temperatures: 90°C, 105°C, and 120°C. 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 central incisor and the first molar by measuring the distance between the mouthguard and the cervical margin of the working model. Differences in the thickness and fit of the mouthguards according to the heating conditions and the measured regions were analyzed using 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 with the heating temperature of 90°C (p < .01). The greatest thickness was found in mouthguards fabricated with the heating temperature of 105°C at the buccal surface of the first molar (p < .01), and 105°C or 120°C at the occlusal surface of the first molar (p < .01). The fit was not significantly different among the three heating conditions both at the central incisor and the first molar. CONCLUSIONS: The appropriate heating condition for pressure-formed mouthguards using polyolefin sheets was 90°C to maintain the mouthguard thickness at the anterior teeth area with proper fit.

Basic research to propose a new design of laminated mouthguard-Effect of lamination order on thickness.

BACKGROUND/AIM: Mouthguard thickness influences the protection ability from orofacial trauma. The aim of this study was to propose a new design for mouthguards and to evaluate the effect of the lamination order on the thicknesses of mouthguards. MATERIALS AND METHODS: Mouthguard sheets of 2.0-mm and 4.0-mm ethylene vinyl acetate were used. The sheets were pressure formed using a pressure former. Two lamination conditions were examined: The condition 24P used the 2.0-mm sheet as the first layer and 4.0-mm sheet as the second layer. The condition 42P used the 4.0-mm sheet as the first layer and 2.0-mm sheet as the second layer. The first layer was trimmed to cover only the anterior region, and then the second layer was formed over the first layer. Mouthguard thickness was measured using a measuring device at the labial surface of the central incisor, plus the buccal and occlusal surfaces of the first molar. Differences in thickness by measurement region of mouthguards formed under different lamination conditions were analyzed by two-way analysis of variance. RESULTS: Mouthguard thickness differed among the regions at the central incisors and the first molars (p < .01). The thickness at the labial surface of the central incisor became statistically significantly larger with the 42P condition (3.38 mm) than with the 24P condition (3.30 mm) (p < .05). The thickness at the buccal and occlusal surfaces of the first molar became statistically significantly larger with the 24P condition (2.25 mm and 2.72 mm, respectively) than with the 42P condition (1.23 mm and 1.44 mm, respectively) (p < .01). CONCLUSIONS: The results suggest that the combination of the 2.0-mm and 4.0-mm sheets could obtain the necessary thickness for the prevention at the labial surface of the central incisor and buccal surface of the first molar.

Difference in laminated mouthguard thickness according to the laminate order.

BACKGROUND/AIM: Mouthguard thickness should be maintained to prevent oral trauma by protecting the teeth and the surrounding soft tissue. The aim of this study was to examine the difference in laminated mouthguard thickness according to the laminate order. MATERIALS AND METHODS: The mouthguard sheets used in this study were 2.0 mm and 3.0 mm ethylene-vinyl acetate. The sheets were pressure-formed using a pressure former, and the laminated mouthguard was fabricated. Two laminate conditions were examined. One condition used the 2.0-mm sheet for the first layer and the 3.0-mm sheet for the second layer (condition 2F3S) and the other condition used the 3.0-mm sheet for the first layer and 2.0-mm sheet for the second layer (condition 3F2S). The first layer was trimmed to cover the labial surface and incisal edge of the anterior teeth and the buccal and occlusal surfaces of the posterior teeth. The second layer was formed over the first layer. The mouthguard thickness was measured at the labial surface of the central incisor and the buccal and occlusal surfaces of the first molar. Differences in thickness by measurement region of mouthguards formed under different laminate conditions were analyzed by two-way analysis of variance. RESULTS: The mouthguard thickness was significantly different at the measured regions of the central incisors and the first molars (p < .01). The thickness at the labial surface of the central incisor and at the buccal and occlusal surfaces of the first molar became statistically significantly larger with the 3F2S condition than that for the 2F3S condition (p < .05 or p < .01). CONCLUSIONS: The thickness of the laminated mouthguard became larger when the sheet thickness of the first layer was greater. It is recommended to use the thicker mouthguard sheet as the first layer when fabricating a laminated mouthguard.

Effectiveness of oral moisturizing gel and flavor on oral moisture and saliva volume: A clinical study.

STATEMENT OF PROBLEM: Oral dryness leads to problems in the oral cavity and pharynx and problems with dental prostheses. Although some moisturizing agents relieve the symptoms of oral dryness, the influence of the flavor of the moisturizing agent on the symptoms of oral dryness has not been clarified. PURPOSE: The purpose of this clinical study was to examine the effectiveness of moisturizing gels with different flavors. MATERIAL AND METHODS: Participants in this study consisted of 36 healthy adults and 20 individuals with oral dryness. They were randomly divided into 6 groups, and moisturizing gels with 5 different flavors (tasteless and odorless, sweet taste, acid taste with citric acid, acid taste with Japanese apricot extract, and Japanese apricot scent) were tested in 5 of the groups with 1 group acting as the control (no gel administered). Oral moisture and saliva volume were measured before applying the moisturizing gel, just after applying the moisturizing gel, and 10, 20, and 30 minutes after applying the moisturizing gel. Differences in oral moisture and saliva volume according to the gel flavor and duration of contact were analyzed by using 2-way analysis of variance (α=.05). RESULTS: Oral moisture did not differ among the gel flavors and the duration of contact. Saliva volume in the control (no gel administered) reported no statistically significant differences among any of the contact durations in both healthy adults and participants with oral dryness. The saliva volume in healthy adults increased after using the sweet taste (P=.012), acid taste with Japanese apricot extract (P=.006), and Japanese apricot scent (P=.005) moisturizing gels. The saliva volume in participants with oral dryness increased rapidly just after using the acid taste with Japanese apricot extract gel (P=.008) and increased slowly after applying the tasteless and odorless (P=.046), sweet taste (P=.048), and acid taste with citric acid moisturizing gels (P=.010). CONCLUSIONS: The effectiveness of moisturizing gel for increasing saliva secretion differed according to the flavor of the moisturizing gel. This suggests that the moisturizing gel's effect on increasing saliva secretion is related to the flavor of the gel in addition to the moisturizing agent.

Appropriate fabrication method for vacuum-formed mouthguards using polyolefin sheets.

BACKGROUND/AIMS: The appropriate heating conditions for polyolefin sheets have not yet been determined and polyolefin sheets are usually formed in the same manner as ethylene vinyl acetate sheets. The aim of this study was to examine the appropriate heating conditions for polyolefin sheets when fabricating vacuum-formed mouthguards. MATERIALS AND METHODS: Mouthguard sheets of 3.0 mm polyolefin were vacuum formed on working models at three heating temperatures: 90°C, 105°C, and 120°C. 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 central incisor and the first molar by measuring the distance between the mouthguard and the cervical margin of the working model. Differences in the thickness and fit of the mouthguards according to the heating conditions and the measured regions were analyzed by two-way analysis of variance. RESULTS: Mouthguard thickness varied among the measured regions of the central incisors and first molars (P < .01). The smallest thickness was found at the labial surface of the central incisor in mouthguards fabricated at 90°C (P < .01). The smallest thickness was found at the buccal and occlusal surface of the first molar in mouthguards fabricated at 120°C (P < .01). The worst fit was obtained with the heating temperature of 90°C (P < .01). CONCLUSIONS: The appropriate heating temperature for polyolefin sheets was 105°C to maintain mouthguard thickness and to obtain proper fit.

Difference in pressure-formed mouthguard thickness according to the laminate procedure.

AIM: Mouthguard thickness influences the preventive effects against dental and oral injury. The aim of this study was to examine the difference in pressure-formed mouthguard thickness according to the laminate procedure used. MATERIALS AND METHODS: The materials used were mouthguard sheets of 2.0-mm and 3.0-mm ethylene vinyl acetate, and pressure formed using a pressure former. Two forming conditions for laminated mouthguards were examined: the condition 23P used the 2.0-mm sheet as the first layer and 3.0-mm sheet as the second layer. The condition 32P used the 3.0-mm sheet as the first layer and 2.0-mm sheet as the second layer. The first layer was trimmed to cover only the anterior region; then, the second layer was formed over the first layer. Mouthguard thickness was measured at the labial surface of the central incisor, buccal surface of the first molar, and occlusal surface of the first molar. Statistical analysis was performed by two-way analysis of variance and Bonferroni method to analyze the differences in thickness by measurement region of mouthguards and forming conditions. RESULTS: Mouthguard thickness differed in different regions of the central incisors and the first molars (P < .01). The thickness at the labial surface of the central incisor became statistically significantly larger on the 32P condition than that on the 23P condition (P < .01). The thickness at the buccal surface and the occlusal surface of the first molar became statistically significantly larger on the 23P condition than that on the 32P condition (P < .01). CONCLUSIONS: The thicknesses of the labial surface of the central incisor became larger when the sheet thickness of the first layer was larger.

Vacuum-formed mouthguard fabrication to obtain proper fit using notched sheet.

BACKGROUND/AIM: Mouthguards should be provided with appropriate thickness and proper fit to exert their effects. However, mouthguard thickness becomes thinner after forming. The aim of this study was to examine the effect of using a notched mouthguard sheet and forming as the heated surface of the sheet contacts the surface of the working model. MATERIALS AND METHODS: The material used was a 3.8-mm-thick Sports Mouthguard. Notches with a length of 90 and 80 mm were cut into an ethylene vinyl acetate sheet 20 mm from the anterior and posterior margins and 15 mm from the right and left margins, respectively, and the sheet was compared with the original. The sheets were then formed using a vacuum former. Original and notched sheets were heated until the temperature of the sheet reached 80°C, and the non-heated surface of the sheet was sucked down over the model. Both sheets were also heated at first until the sheet temperature reached 80°C, then turned upside down, and the heated surface of the sheet was sucked down over the model. The thickness and fit of the mouthguard were measured at the central incisor and first molar. Differences in thickness and fit according to the measurement parts and the sheet conditions were analyzed by two-way ANOVA. RESULTS: The thickness of the mouthguard significantly differed by the measurement parts and the sheet conditions (P < 0.01), and the notched sheet maintained the required thickness. Fit differed between the measurement parts and the sheet conditions (P < 0.01), and the sheets formed as the heated surface contacted the working model showed better fit. CONCLUSIONS: These results suggest that the ideal mouthguard with appropriate thickness and proper fit can be fabricated by notching a sheet and contacting the heated surface of the sheet to the working model.

Mouthguard sheet temperature after heating under pressure former.

BACKGROUND/AIM: Ethylene vinyl acetate and polyolefin sheets have been used commonly for fabricating mouthguards. However, the change of the sheet temperature during heating of the polyolefin has not been clarified. The aim of this study was to examine the effects of changing the sheet temperature during heating, and to examine whether there were any differences between the sheet materials. MATERIALS AND METHODS: The mouthguard materials used were 4.0 mm sheets of ethylene vinyl acetate and polyolefin. The sheet temperature of the two materials was measured when the center of the sheet was displaced by 10, 15, and 20 mm from the baseline after heating. The sheets were pressure-formed when the heating temperatures reached 100°C. Mouthguard thickness and fit were measured at the central incisor and the first molar. Differences in the sheet temperature and the thickness between the sheet materials were analyzed by two-way analysis of variance. RESULTS: The sheet temperature of ethylene vinyl acetate and polyolefin sheets became higher as the hanging distance became larger (P < 0.01), and there were statistically significant differences between ethylene vinyl acetate and polyolefin sheets at the hanging distance of 10 and 15 mm (P < 0.01). The thicknesses of the pressure-formed mouthguard at the central incisor and the first molar were greater in the mouthguards formed by ethylene vinyl acetate sheets than those with polyolefin sheets (P < 0.01 and P < 0.05, respectively). The fit of the mouthguard was not different between mouthguards formed by ethylene vinyl acetate sheets and those formed by polyolefin sheets. CONCLUSIONS: The change of mouthguard sheet temperature during heating was different between ethylene vinyl acetate and polyolefin sheets. The ethylene vinyl acetate sheets maintained the mouthguard thickness in comparison with the polyolefin sheets at the same heating temperature.

Appropriate fabrication method for pressure-formed mouthguards using ethylene vinyl acetate sheets.

BACKGROUND/AIMS: Fabrication of mouthguards should be performed properly. However, the appropriate heating temperature for fabricating a pressure-formed mouthguard has not been determined. The aim of this study was to examine the influence of the heating temperature on the fabrication of a pressure-formed mouthguard. MATERIALS AND METHODS: Mouthguard sheets of 3.8 mm ethylene vinyl acetate were pressure-formed on a working model at three heating temperatures: 80, 100, and 120°C. 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 central incisor and first molar by measuring the distance between the mouthguard and the cervical margin of the working model. Differences in the thickness of the mouthguards according to the heating temperatures were analyzed by two-way analysis of variance, and differences in the fit were analyzed by one-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 and the buccal surface of the first molar in mouthguards fabricated at the heating temperature of 120°C (P < .01). Mouthguard fit varied among the heating temperatures of the central incisors, and the greatest fit was obtained in mouthguards fabricated at the heating temperatures of 100 and 120°C (P < .01). CONCLUSIONS: Heating the ethylene vinyl acetate sheet until the temperature reached 120°C was the best fabrication method to maintain the pressure-formed mouthguard thickness with proper fit.

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.

Mouthguard sheet temperature after heating.

BACKGROUND/AIM: Mouthguard sheet materials such as ethylene vinyl acetate and polyolefin have been used commonly. However, the change of the sheet temperature during heating of the polyolefin has not been determined. The aim of this study was to examine the change of the sheet temperature during heating and to examine the vacuum-formed mouthguard characteristics for the sheet materials. MATERIALS AND METHODS: The mouthguard materials used were 4.0-mm sheets of ethylene vinyl acetate and polyolefin. The sheet temperature of the two materials was measured when the center of the sheet was displaced by 10, 15, and 20 mm from the baseline after heating. Sheet temperature differences by sheet materials were analyzed by two-way analysis of variance. The sheets were vacuum-formed when the heating temperatures reached 100°C using ethylene vinyl acetate sheet and polyolefin sheet. Mouthguard thickness and fit was measured at the central incisor and the first molar. Differences in the thickness and fit between the sheet materials were analyzed by two-way analysis of variance. RESULTS: The sheet temperature of ethylene vinyl acetate sheets became higher as the hanging distance became larger (P < 0.05), but that of polyolefin sheets was not different. The thicknesses of the vacuum-formed mouthguard at the central incisor and the first molar were greater in the mouthguards formed by ethylene vinyl acetate sheets than that with polyolefin sheets (P < 0.01 or P < 0.05). The fit of the mouthguard was not different between mouthguards formed by ethylene vinyl acetate sheets and that formed by polyolefin sheets. CONCLUSIONS: The change of mouthguard sheet temperature during heating was different between ethylene vinyl acetate and polyolefin sheets. The ethylene vinyl acetate sheets maintained the vacuum-formed mouthguard thickness in comparison with the polyolefin sheets with a better fit.

Appropriate fabrication method for vacuum-formed mouthguards.

AIM: The aim was to examine the influence of the heating temperature on the fabrication of vacuum-formed mouthguards. MATERIALS AND METHODS: Mouthguard sheets of 3.8 mm ethylene vinyl acetate were vacuum-formed on working models at three heating temperatures: 80, 100, and 120°C. 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. Differences in the thickness of the mouthguards were analyzed by two-way analysis of variance. The fit of the mouthguard was examined at the central incisor and the first molar by measuring the distance between the mouthguard and the cervical margin of the working model. Differences in the distance between the mouthguard and the cervical margin according to the heating temperatures were analyzed by one-way analysis of variance. RESULTS: Mouthguard thickness varied among the measured regions of the central incisors and first molars (P < 0.01). The greatest thickness was found at the labial surface of the central incisor and the buccal surface of the first molar in mouthguards fabricated with heating temperature of 120°C (P < 0.05). The best fit was obtained in mouthguards fabricated with heating temperature of 120°C (P < 0.05). CONCLUSIONS: Heating the mouthguard sheet until the temperature reached 120°C was the best fabrication method to maintain the thickness and to obtain proper fit. It is important to control the heating temperature when fabricating vacuum-formed mouthguards.

Formation of vacuum-formed and pressure-formed mouthguards.

BACKGROUND/AIM: The method used to form mouthguards should be carefully selected in order to obtain their full preventive benefits. The aim of this study was to examine the differences of mouthguard characteristics according to the forming methods. MATERIALS AND METHODS: Mouthguard sheets of 3.8-mm ethylene vinyl acetate were vacuum-formed and pressure-formed on a working model. The sheets were formed when heating causing them to displace 15 mm from baseline. Mouthguard thickness was measured at the labial surface of the central incisor, the buccal surface of the first molar, and the occlusal surface of the first molar. The fit of the mouthguard was measured at the central incisor and the first molar. Differences in the thickness and fit between the vacuum-formed and pressure-formed mouthguards were analyzed by two-way analysis of variance and the Bonferroni method. RESULTS: Mouthguard thickness varied between the central incisors and first molars (P<.01). The thicknesses at the labial surface of the central incisor and the buccal surface of the first molar were greater in the vacuum-formed mouthguards than in the pressure-formed mouthguards (P<.01). The fit was better in the pressure-formed mouthguards than that in the vacuum-formed mouthguards (P<.01). CONCLUSIONS: The vacuum-forming method maintained the mouthguard thickness, while the pressure-forming method obtained better fit.

Influence of working model angle on the formation of a pressure-formed mouthguard.

BACKGROUND/AIM: Custom-made mouthguards are fabricated on working models. However, the influence of the working model to the mouthguard characteristics has not been clearly established. The aim of this study was to examine the influence of the angle of the working model on the formation of a pressure-formed mouthguard. MATERIALS AND METHODS: Mouthguard sheets of 3.8 mm ethylene vinyl acetate were pressure-formed onto working models. The angle of the working model formed by the labial surface of the central incisor and the base of the working model was set at 85°, 90°, and 95°. 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. Differences in the thickness of the mouthguards were analyzed by two-way analysis of variance. RESULTS: Mouthguard thickness varied among the measured regions of the central incisors and first molars (P < 0.01). The thickness at the labial surface of the central incisor and buccal surface of the first molar was greatest for mouthguards formed using the working model with the angle set at 85° (P < 0.01). CONCLUSIONS: The angle of the working model at the labial surface of the central incisor and the base of the working model should be maintained at an acute angle (e.g., 85°) to control the thickness at the central incisors and the first molars of pressure-formed mouthguards.

Optimal heating condition of mouthguard sheet in vacuum-pressure formation: part 2 Olefin-based thermoplastic elastomer.

The purposes of this study were to clarify the suitable heating conditions during vacuum-pressure formation of olefin copolymer sheets and to examine the sheet temperature at molding and the thickness of the molded mouthguard. Mouthguards were fabricated using 4.0-mm-thick olefin copolymer sheets utilizing a vacuum-pressure forming device, and then, 10 s of vacuum forming and 2 min of compression molding were applied. Three heating conditions were investigated. They were, defined by the degree of sagging observed at the center of the softened sheet (10, 15, or 20 mm lower than the clamp (H-10, H-15, or H-20, respectively)). The working model was trimmed to the height of 20 mm at the maxillary central incisor and 15 mm at the mesiobuccal cusp of the maxillary first molar. The temperature on both the directly heated and the non-heated surfaces of the mouthguard sheet was measured by the radiation thermometer for each condition. The thickness of mouthguard sheets after fabrication was determined for the incisal portion (incisal edge and labial surface) and molar portion (cusp and buccal surface), and dimensional measurements were obtained using a measuring device. Differences in the thickness due to the heating condition of the sheets were analyzed by one-way analysis of variance and Bonferroni's multiple comparison tests. The temperature difference between the heated and non-heated surfaces was highest under H-10. Sheet temperature under H-15 and H-20 was almost the same. The thickness differences were noted at incisal edge, cusp, and buccal surface, and H-15 was the greatest. This study demonstrated that heating of the sheet resulting in sag of 15 mm or more was necessary for sufficient softening of the sheet and that the mouthguard thickness decreased with increased sag. In conclusion, sag of 15 mm can be recommended as a good indicator of appropriate molding timing for this material.

Variation in mouthguard thickness according to heating conditions during fabrication Part 2: sheet shape and effect of thermal shrinkage.

The aim of this study was to investigate the influence of the thermal shrinkage to thickness of the mouthguard with the heating method by the setting position of a sheet and the working model using an ethylene vinyl acetate sheet prepared by extrusion. Mouthguards were fabricated with EVA sheets (4.0 mm thick) using a vacuum-forming machine. Two forming conditions were compared: the square sheet was pinched by the clamping frame attached to the forming machine (S); and the round sheet was pinched at the top and bottom and stabilized by the circle tray (R). The sheet was aligned to make the sheet's extrusion direction vertical (V) or parallel (P) to the midline of the working model. The following two heating conditions were compared: (i) the sheet was molded when it sagged 15 mm below the level of the sheet frame measured at the top of the post in condition S (S-0), or that sagged 10 mm in condition R (R-0) in the usual position; (ii) the sheet frame was lowered by 50 mm from the ordinary height (S-50, R-50). Postmolding thickness was determined using a measuring device. Measurement points were the incisal and molar portion. Differences in the change of thickness of mouthguards molded under different heating conditions and extrusion directions for each sheet shape were analyzed by two-way analysis of variance (anova). The results of this study showed that by lowering the height of the sheet frame, the difference of the sheet temperature of each part was reduced. Among all sheets, condition V produced under S-50 and R-50 had the largest thickness independently of shape sheet. Furthermore, thickness reduction is effectively suppressed by aligning the direction of the extruded sheet to be vertical to the midline of the model.

Influence of working model position on the formation of a pressure-formed mouthguard.

AIM: The aim of this study was to examine the influence of the position of the working model on the formation of a pressure-formed mouthguard. MATERIALS AND METHODS: Mouthguard sheets of 3.8 mm ethylene vinyl acetate were pressure-formed on working models in three positions: anterior, central, and posterior. 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. Differences in the thickness of the mouthguards were analyzed by two-way analysis of variance. RESULTS: Mouthguard thickness varied among the measured regions of the central incisors and first molars (P < 0.01). The thickness at the labial surface of the central incisor was greatest for mouthguards formed with the working model in the posterior position (P < 0.01). CONCLUSIONS: The results of this study suggest that pressure-formed mouthguards could be fabricated effectively by positioning the center of the working model 15 mm posteriorly from the center of the pressure former. The position of the working model should be considered carefully when forming a mouthguard.

Difference in vacuum-formed mouthguard thickness according to timing of vacuum application.

AIM: The purpose of this study was to examine the differences of the vacuum-formed mouthguard thickness by the timing of vacuum application. MATERIALS AND METHODS: The material used in this study was a mouthguard sheet of 3.8-mm ethylene vinyl acetate. Three conditions of the timing of vacuum application were examined: the vacuum was applied immediately, 5 s after, and 10 s after the sheet holder was lowered over the vacuum-forming stand. We measured mouthguard thickness at the labial surface of the central incisor, buccal surface of the first molar, and occlusal surface of the first molar. Differences in thickness in different regions of mouthguards formed under different timing of vacuum application were analyzed by two-way analysis of variance and Bonferroni method. RESULTS: We found that mouthguard thickness differed in different regions of the central incisors and the first molars (P < 0.01). The mouthguard thickness at the labial surface of the central incisor and buccal surface of the first molar became thinner when the vacuum was applied immediately after the sheet holder was lowered over the forming stand. The thickness at the occlusal surface of the first molar did not vary with the timing of vacuum application. CONCLUSIONS: Our results suggest that the thicknesses of the labial surface of the central incisor and buccal surface of the first molar became larger when the vacuum was applied several seconds after the sheet holder was lowered over the forming stand. This finding is necessary knowledge when forming a mouthguard sheet.

New fabrication method to maintain proper mouthguard thickness.

AIM: The aim of this study was to examine the effectiveness of layering a second piece of ethylene vinyl acetate on the original sheet before fabrication to maintain the thickness of vacuum-formed mouthguards. MATERIALS AND METHODS: Two methods were used to form mouthguards. In the first, a 3.8-mm ethylene vinyl acetate sheet was laminated after 3.0-mm ethylene vinyl acetate sheet was formed at the anterior teeth area. In the second, a second piece of 3.0-mm sheet was layered on the original 3.8-mm sheet in the region mounted on the anterior teeth. Mouthguard thickness at specific sites on the central incisors and first molars was measured. The differences in mouthguard thickness according to measurement regions and forming methods were analyzed by two-way analysis of variance and a post hoc test (Bonferroni method). RESULTS: Mouthguard thickness differed significantly among the measurement regions (P < 0.01). Mean thickness at the central incisors was significantly greater with the sheet-layering method (5.5 mm) than with the laminate method (3.9 mm) (P < 0.01). CONCLUSIONS: The results of this study indicate that adding a second layer of ethylene vinyl acetate to the original sheet effectively maintained the thickness of the mouthguard. This method is effective to maintain the mouthguard thickness and cost-effective method.

Difference in pressure-formed mouthguard thickness according to heating condition.

PURPOSE: The purpose of this study was to investigate the differences of pressure-formed mouthguard thickness by varying the heating conditions within the proper heating temperature. MATERIALS AND METHODS: The material used in this study was a mouthguard sheet of 3.8-mm ethylene vinyl acetate. The sheets were formed by pressure forming using a vacuum-pressure former. Three heating conditions were varied as follows: the sheet was heated until the center was displaced by 10, 15, and 20 mm from baseline. We measured the mouthguard thickness at the labial surface of the central incisor, buccal surface of the first molar, and occlusal surface of the first molar. Differences in thickness by measurement region of the mouthguards formed under different heating conditions were analyzed by two-way analysis of variance and Bonferroni's method. RESULTS: We found that mouthguard thickness varied in different regions of the central incisors and the first molars (P < 0.01). The incisal (cusp) region was thinner than the cervical region. There were statistically significant differences among the heating conditions at the labial surface of the central incisor (P < 0.05), and the thickness became larger as the sheet was heated. Mouthguard thickness at the buccal surface and occlusal surface of the first molar did not differ among the three heating conditions. CONCLUSIONS: Our results suggest that the best heating condition of the pressure-forming method was the condition that the sheet was heated until its center displaced by 20 mm. This finding is an important fact when fabricating a mouthguard.