An investigation into the relationship between thickness variations and manufacturing techniques of mouthguards

Dimensions of Hybrid and Nanohybrid Mouthguards for Mixed Martial Arts Fighters-Evaluation of a New Method of Fabrication

Ethylene vinyl acetate mouthguards are the most often used custom protective intraoral appliances by combat sports practitioners. However, due to the difficulties in maintaining the hygiene of such mouthguards and thinning during fabrication, resulting in difficulty in predicting final dimensions, they may not be the optimal solution. The aim of this research was to evaluate an innovative method of mouthguard formation using intraoral modeling of the mouthguard pattern, hybrid acrylic material, and the addition of ZnO nanoparticles. Seventeen mouthguards patterns and 34 custom mouthguards were evaluated: 17 hybrid and 17 nanohybrid. A total of 1122 measurements were performed: each mouthguard and pattern was measured at 22 points. Statistical analyses were performed with the use of IBM^® SPSS^® Statistics 27.0.0 software (IBM, Armonk, NY USA). The mean thickness of the patterns and mouthguards at all labial areas of central incisors were between 4.65 and 4.80 mm. The thickness at the buccal surface of the first molar was between 3.71 and 4 mm, and at the occlusal surface between 3.40 and 3.56 mm in the cusp area. All measurements of hybrid and nanohybrid mouthguards were strongly and highly correlated with the measurements of the mouthguard patterns. Hybrid and nanohybrid mouthguards are an advantageous alternative to thermoformed custom appliances.

Examination of thermoforming techniques to secure mouthguard thickness of the labial and buccal sides with a single sheet: An in vitro study

BACKGROUND/AIM

Mouthguards must have an appropriate thickness to prevent oral trauma during sports. The aim of this study was to establish a thermoforming technique to secure the labial and buccal thicknesses of the mouthguard with a single sheet.

MATERIALS AND METHODS

Mouthguards were thermoformed using 4.0-mm thick sheets manufactured by extrusion molding, a plaster model, and a vacuum forming machine. Two sheet installation conditions were compared: the sheet extrusion direction was either parallel (P) or vertical (V) to the model's centerline. In each extrusion direction, two forming conditions were compared: (1) the sheet was formed when it sagged 15-mm below the sheet frame at the top of the post (control group; C-P, C-V); and (2) the sheet frame was lowered 50-mm below the ordinary level and heated, the frame was lowered when it sagged 15-mm, and the model was moved forward 20-mm before formation (experimental group; E-P, E-V). Difference in thickness (incisal edge, labial surface, cusp, and buccal surface) due to sheet extrusion direction and forming conditions were analyzed by two-way ANOVA and the Bonferroni method.

RESULTS

At all measurement sites, a significant difference in thickness depending on the sheet extrusion direction was observed in the experimental group (p < .01), but not in the control group. Difference in thickness depending on the forming condition was observed at all measurement sites, and the thickness was in the order C-P, C-V < E-P < E-V. Thicknesses of E-P and E-V were 3.01 ± 0.03 mm and 3.25 ± 0.02 mm on the labial surface, and 2.81 ± 0.02 mm and 3.02 ± 0.02 mm on the buccal surface.

CONCLUSIONS

It was possible to obtain 3 mm or more thickness on the labial and buccal sides with a single sheet by adjusting the sheet extrusion direction and the heating method of the sheet, and by applying the thermoforming method where the model is moved forward just before formation.

A new composite made from Luffa Cylindrica and ethylene vinyl acetate (EVA): Mechanical and structural characterization for its use as Mouthguard (MG)

The use of Mouthguards (MGs) in contact sports is an interesting biomedical topic. MGs are protective personal equipment made principally from the copolymer ethylene vinyl acetate (EVA). EVA is a thermoplastic whose thickness and rigidity are variables of concern for a good shock energy absorption capability in an MG. A natural fiber polymer composite is an interesting attempt for tackling these variables. Luffa cylindrica (luffa) is a sponge gourd that grows in 3D structure, which is used mainly as an ornament, a filling, or is trimmed for its use as a bathing product. In this work, a new EVA-luffa composite (EVLc) was made from commercial EVA sheets and luffa mat acting as reinforcement. FTIR, DSC, and TGA tests of EVA revealed its nature compared to literature data. A mechanical testing was applied to eight EVLc ASTM D-638 type V dumbbells (D1-D8) that showed low tensile strength values compared to EVA resistance ranges in literature. SEM images of EVLc's D1-D8 confirmed good adhesion between the reinforcement and matrix without surface treatment, and a descriptive statistical analysis indicated an intrinsic variation.

Effects on the thickness of single-layer mouthguards with different model positions on the forming table and different sheet frame shapes for the forming device

BACKGROUND/AIM

Effectiveness and safety of mouthguards are greatly affected by their thickness. The aim of this study was to clarify the influence of the frame shape of the forming device on how the model position on the forming table affects the anterior and posterior mouthguard thickness.

MATERIALS AND METHODS

Mouthguards were thermoformed using 4.0-mm-thick ethylene-vinyl-acetate sheets and a vacuum forming device. Square sheets were fixed with the square frame of the forming device. Circular sheets were fixed to the forming device with a circular frame. The model was placed with its anterior rim positioned 40, 30, 20, or 10 mm from the front of the forming table. The model position was marked on the forming table so that it was constant under each condition. Six mouthguards were fabricated for each condition. Mouthguard thicknesses of the incisal edge, labial and buccal surfaces, and the cusp were measured. Differences in the rate of thickness reduction due to frame shapes and model positions were analyzed by two-way ANOVA.

RESULTS

Difference in the thickness reduction rate depending on the frame shape was observed on the labial and buccal surfaces, and it was significantly greater with the circular frame than with the square frame (p < .01). In the anterior region, the thickness reduction rate tended to increase as the model position was moved toward the front of the forming table. The thickness reduction rate of the posterior portion was lowest when the model's molar was positioned at the center of the forming table.

CONCLUSIONS

The labial thickness of the mouthguard was not affected by the frame shape if the distance from the model to the frame was larger than the model height. However, the buccal thickness was thinner with the circular frame than with the square frame regardless of the model position.

Effect on thickness of a single-layer mouthguard of positional relationship between suction port of the vacuum forming device and the model

BACKGROUND/AIM

Wearing a mouthguard reduces the risk of sport-related injuries, but the thickness has a large effect on its efficacy and safety. The aim of this study was to investigate the effect on the thickness of a single-layer mouthguard of the positional relationship between the suction port of the vacuum forming device and the model.

MATERIALS AND METHODS

Ethylene-vinyl-acetate sheets of 4.0-mm-thickness and a vacuum forming machine were used. Two hard plaster models were prepared: Model A was 25-mm at the anterior teeth and 20-mm at the molar, and model B was trimmed so the bucco-lingual width was half that of model A. Three model positions on the forming table were examined: (a) P20, where the model anterior rim was located in front of the suction port, (b) P30, where the model anterior rim and front edge of the suction port were close, and (c) P43, where the model anterior rim and palatal rim were located on the suction port. Six mouthguards were fabricated for each condition. Thickness differences due to model form and model position were analyzed.

RESULTS

Thickness differences due to model form were observed at the incisal edge and labial surface, and model A was significantly thicker than model B in P43 (P<.01). The thickness of the incisal edge and labial surface was significantly greatest in P43 for model A, but in P30 for model B.

CONCLUSIONS

The effect of the model position on the forming table on suppressing the labial thickness reduction of the mouthguard depended on the bucco-lingual width of the model. It is important to position the model anterior rim away from the sheet frame if the bucco-lingual width of the model is large and to place the model anterior rim in front of the suction port if the width is small.

Fabrication method to maintain mouthguard thickness regardless of the model angle

BACKGROUND/AIM

The safety and effectiveness of mouthguards depend on the sheet material and thickness. The aim of this study was to investigate the fabrication method for a mouthguard with appropriate thickness using a single sheet regardless of the model angle.

MATERIALS AND METHODS

Mouthguards were thermoformed using 4.0 mm thick ethylene vinyl acetate sheets and a vacuum forming machine. The working models were three hard plaster models trimmed so that the angle of the anterior teeth to the model base was 90°, 100°, and 110°. The model position was 40 mm from the front of the forming unit. The sheet was softened until it sagged 15 mm, after which the sheet frame was lowered to cover the model. Next, the vacuum was turned on and held for 30 seconds for the control. Under the forming conditions in which the model position (MP) was moved, after the model was covered with the sheet, a scissors handle was positioned at the rear of the model and used to push it forward 20 mm, and then, the vacuum switch was turned on for 30 seconds. Six specimens were formed for each condition. Mouthguard thickness after formation was measured using a specialized caliper. The differences in mouthguard thickness due to forming conditions and model angle were analyzed.

RESULTS

The MP was significantly thicker than the control in each model (P < .01). The mouthguard thickness tended to decrease as the model angle increased. The average thickness of the labial surface in the MP was 3 mm or more and was not affected by the model angle.

CONCLUSIONS

This study suggested that the fabrication method in which moving the model forward by 20 mm just before formation could produce a mouthguard with approximately 3 mm thickness on the labial side with a single sheet regardless of the model angle.

Experience with mouthguards and prevalence of orofacial injuries among field hockey players in Catalonia

BACKGROUND/AIM

Orofacial injuries are a serious problem in field hockey. The aim of this study was to determine the prevalence of orofacial injuries in field hockey players in Catalonia, the frequency of mouthguard use, the types of mouthguards used and the degree of interference with oral function.

MATERIAL AND METHODS

In this cross-sectional study, 325 field hockey players (28% women) from all age categories completed a questionnaire about orofacial injuries occurring during their sporting lives, including dental injuries, oral lacerations and episodes of acute temporomandibular disorder (TMD) pain. The questionnaire also asked about the experience of using a mouthguard, the type of mouthguard used and any adverse effects of use. The degree of interference with oral function was compared by type of mouthguard (mouth-formed, custom-made and pre-fabricated mouthguards) using the Kruskal-Wallis test.

RESULTS

Half of the players (50.2%) reported at least one orofacial injury during their sporting lives. The mean number of oral lacerations, TMD pain episodes and dental injuries were 1.59, 0.24 and 0.18, respectively. In total, 310 players (95.7%) had tried a mouthguard, and of these 269 (86.8%) and 283 (91.3%) still used a mouthguard habitually during training and competition, respectively. Only 11 players (3.5%) had tried all three types of mouthguards, and 71 players (22.9%) had tried two types of mouthguard. By type, 217 players (70.0%) had tried mouth-formed (boil-and-bite) mouthguards, 156 (50.3%) had tried custom-made mouthguards and 30 (9.7%) had tried pre-fabricated mouthguards. Custom-made mouthguards were rated as more comfortable than the mouth-formed type (P < .05).

CONCLUSIONS

The prevalence of orofacial injuries among field hockey players is relatively high. Most players habitually use a mouthguard during training and competition, typically preferring custom-made or a mouth-formed types. Custom-made mouthguards were considered the most comfortable.

Risk of orofacial injuries and mouthguard use in water polo players

BACKGROUND/AIM

The incidence of orofacial injuries and the use of mouthguards in water polo players have not been well established. The aim of this study was to determine the incidence of orofacial injuries in water polo players. Frequency of mouthguard use, the types of mouthguards used and the degree of interference with oral functions were also assessed.

MATERIAL AND METHODS

In this cross-sectional study, 347 water polo players completed a questionnaire about the orofacial injuries suffered in the 2015-2016 season and the experience of using a mouthguard, such as the type of mouthguard used and the degree of interference with oral functions.

RESULTS

In the 2015-2016 season, 57.9% of the players reported at least one orofacial injury, with mean numbers of 2.7 oral lacerations, 0.4 episodes of temporomandibular pain and 0.06 dental injuries. Among the 35 players (10.1%) who had tried a mouthguard, only four (1.2%) used it habitually. Some players had tried more than one type of mouthguard; 26 had tried the mouth-formed type; 11 the custom-made type; and 7 the prefabricated mouthguard. Custom-made mouthguards were rated as more comfortable than the mouth-formed type (P < 0.05). The main disadvantages of mouth-formed mouthguards were interferences with speaking, breathing and swallowing.

CONCLUSIONS

The incidence of orofacial injuries in water polo players is high. Although some players had tried a mouthguard, mainly the mouth-formed type, most of them do not wear them routinely for training and competition.

The Role of Mouthguards in Preventing and Reducing Sports-related Trauma

a mouthguard, also known as a gumshield, mouth protector or sports guard is an appliance that covers the teeth and surrounding mucosa with the aim of preventing or reducing trauma to the teeth, gingival tissue, lips and jaws. The device is usually worn on the maxillary arch and works by separating the maxillary and mandibular dentition, protecting the teeth from the surrounding soft tissue, absorbing or redistributing shock and/or stabilising the mandible during traumatic jaw closure. They may also play a role in preventing and reducing concussion by absorbing impact forces that would otherwise be transmitted through the base of the skull to the brain, although the evidence for this is less conclusive. A mouthguard will usually fall into one of three categories: stock mouthguards (which are made ready to use and are believed to give the least protection), the mouth-formed or 'boil and bite' type (which are heated in hot water, placed in the mouth and moulded to the teeth) and custom-made mouthguards (which are usually made on a stone model of the maxillary teeth and surrounding tissue and are thought to give the most protection). These devices can be made from various materials but ethylene-vinyl acetate is by far the most popular material, probably because of the ease with which it can be used for the production of custom-made mouthguards. This paper gives a review of the role of mouthguards in preventing and reducing sports-related trauma and examines the materials that are used to fabricate them.