Experimental comparative study of various mouthguards

Abstract— The aim of this study was to evaluate the mechanical and physical properties of several standard size commercially available mouthguards. For the purpose of objective testing, a special study model, which the various gum shield devices could be fitted onto, was developed to record tooth deflection caused by impact forces induced by a pendulum ram impact testing machine. The data measured on teeth provided with various gum shield devices were correlated with those of unprotected teeth; this enabled the individual cushioning effects of the respective devices and their specific force conduction to be evaluated. Using mouthguards considerably diminishes the deflection of the teeth subjected to stress in comparison with the row of unprotected teeth. In addition, force is transmitted to the adjacent teeth all the way to the distal regions of the row of teeth. The individual cushioning effects are directly correlated to the thickness of the material; the force distribution is determined by the rigidity of the gum shield device. The devices examined showed considerable differences with regard to force distribution and dimensioning. The study showed that this was due to the thickness of the materials, the manufacturing process and the composition of the materials of the devices examined. In comparison to laboratory-produced devices of similar material thickness, the devices that were designed to be fitted by the user achieved significantly poorer results as regards both cushioning properties and dissipation of exerted forces.     

防护牙托的性能评价

目的 研究标准型定制类牙托对于外力打击的缓冲能力。方法 利用一个特殊的工作模型。将外力打击时,单个中切牙所受的力通过舌侧金属导杆传递到压力传感器上,记录数据。比较戴防护牙托和无防护时的相对值。结果 获得了不同厚度牙托的缓冲率,各组间差异有显著性。结论 牙托的缓冲效果与材料厚度呈正相关。建议在高对抗性、高风险性的体育活动中,参加者应使用适宜的防护牙托以防止牙外伤的发生。     

运动牙套的缓冲及能量吸收特性分析

目的:利用冲击试验测试不同厚度和材料的运动牙套缓冲及能量吸收特性.方法 :按照运动牙套的厚度和材料,将牙套分为5 组,每组6个试件.采用钟摆与力锤结合装置(摆锤)对牙套及牙列模型施加冲击能量,通过改变摆锤的释放高度而改变冲击能量的大小.应用力传感器与激光测振仪分别与数据采集和信号分析仪连接,获得锤头的人射速度、反弹速度...     

EVA mouthguards: how thick should they be?

Abstract – A major consideration in the performance of mouthguards is their ability to absorb energy and reduce transmitted forces when impacted. This is especially important to participants in contact sports such as hockey or football. The thickness of mouthguard materials is directly related to energy absorption and inversely related to transmitted forces when impacted. However, wearer comfort is also an important factor in their use. Thicker mouthguards are not user‐friendly. While thickness of material over incisal edges and cusps of teeth is critical, just how thick should a mouthguard be and especially in these two areas? Transmitted forces through different thicknesses of the most commonly used mouthguard material, ethylene vinyl acetate (EVA) (Shore A Hardness of 80) were compared when impacted with identical forces which were capable of damaging the oro‐facial complex. The constant impact force used in the tests was produced by a pendulum and had an energy of 4.4 joules and a velocity of 3 meters per second. Improvements in energy absorption and reductions in transmitted forces were observed with increasing thickness. However, these improvements lessened when the mouthguard material thickness was greater than 4 mm. The results show that the optimal thickness for EVA mouthguard material with a Shore A Hardness of 80 is around 4 mm. Increased thickness, while improving performance marginally, results in less wearer comfort and acceptance.     

An in vitro study of the efficacy of mouthguard protection for dentoalveolar injuries in deciduous and mixed dentitions

Abstract Sports-related dental trauma remains a risk for children and adolescents. Although mouthguards provide protection, up to 25% of dentoalveolar injuries can occur with a mouthguard in place. This study examined the effect of mouthguard protection in an in vitro model. A total of 97 sheep mandibular segments with incisors at four developmental stages (early deciduous, ED, 11 = 37; middle deciduous, MD, n = 20; late deciduous, LD, n=18; mixed dentition, PD, 11 = 22) was used. Customised pressure formed mouthguards (MG) provided protection from trauma produced by a servohyclraulic materials testing machine to test incisors. Injuries were examined clinically, radiographically and by dissection. Mean forces required to produce dentoalveolar injury were significantly greater in test (with MG) teetli than control (no MG) teeth. Mean forces to produce injury in test teeth decreased with resorbing root lengths. Deciduous incisors differed in injury type: subluxalions and horizontal root fractures predominated in test teeth; lateral luxations and horizontal root fractures in control teeth. Predominant injuries in test and control permanent incisors were enamel infractions and snblnxations. The magnitude of lateral luxation measurements of individual teeth was reduced significantly by mouthguard protection in both deciduous and permanent dentitions. The mouthguard tended to increase the mobility of the teeth it encompassed and, in some instances, promoted dentoalveolar injury of adjacent teeth.     

Techniques for mouthguard fabrication

The use and efficacy of mouthguards for the prevention of traumatic athletic injuries to the teeth and oral soft tissues as well as in the prevention of concussions should indicate to the athletic community the importance of this piece of protective equipment. By comparison to other athletic equipment, mouthguards are quite inexpensive. The underlying theme is to emphasize that for maximum comfort and protection, every athlete should possess a properly fitted mouthguard fabricated exclusively for the individual by a dentist. The materials and standard techniques used for the fabrication of stock, mouth-formed, and custom-made protectors are described. The characteristics that an ideal mouthguard should possess suggest that custom-formed mouthguards are superior in quality to either the stock or mouth-formed types, although the custom-formed types are more expensive and require the services of a dentist. The development of new dental materials has provided dentists with the opportunity to explore new techniques for the fabrication of custom-made mouthguards. New techniques for photopolymerized urethane diacrylate lipguards and mouthguards have been developed as have adaptations for those athletes who wear fixed orthodontic appliances and those who are partially edentulous. Proper cleaning and storage of all types of mouthguards can prolong the length of service of these protective appliances.     

Relationship between temporomandibular joint dynamics and mouthguards: feasibility of a test method

Abstract – A test system was developed establishing the feasibility of collecting biomechanical data as they relate to the use of mouthguards. Previous experimental studies have examined the physical and mechanical properties of mouthguard materials. This information has been used as a guide for establishing material standards and specifications for the fabrication of mouthguards, but it lacks the key biomechanical parameters required for a thorough mouthguard evaluation. The current study was designed to assess whether the impact force, condylar deflection, and strain superior to the temporomandibular joint region could be measured. A drop test was conducted on a cadaveric specimen to simulate loading at the chin point. To measure the force of impact, an accelerometer was attached to an impactor of known mass. High‐speed biplanar (1000 frames per second) radiographs were used to determine condylar displacement. Radio‐opaque markers were inserted into the bone at predetermined locations. Total displacement of these markers was determined in reference to anatomical landmarks. Strain gauges were attached to the mandible and skull to monitor the effects of the condyle impacting the base of the skull. Based on the data collected, forces were calculated by determining the product of the time‐based acceleration and known mass. A measurable change in force between the mouthguards and the control (no mouthguard) was demonstrated. The average condylar displacement was successfully measured and indicated as an increase in total deflection for impacts conducted with mouthguards. Quantifiable strain was measured in the region above the mandibular fossa with and without the insertion of a mouthguard at all impact conditions. However, it was determined that additional gauges would provide critical data. Key biomechanical parameters for chin‐point impacts were determined in the current study. The technique demonstrated that both displacement within the mandibular fossa and loading of the condyles occur during the impact event. Although the current study established a technique that can be used to examine the relationship between mouthguards and jaw‐joint injuries, the role, if any, mouthguards play in the reduction of injuries cannot be established until a thorough analysis is completed.     

Are all mouthguards the same and safe to use? Part 2. The influence of anterior occlusion against a direct impact on maxillary incisors

Abstract –  The purpose of this study was to clarify the influence anterior occlusion, of mouthguards, has on protecting against a direct collision to the maxillary anterior teeth. In other words, the support mandibular dentition has when wearing a mouthguard. Two types of mouthguards were used for this study, one with an appropriate anterior occlusion or a mouthguard with positive anterior occlusion (MGAO+) and another which was a single-layer mouthguard lacking the same occlusion or a mouthguard with negative anterior occlusion (MGAO−) but with the same thickness on the buccal side. The instruments used for testing were a pendulum-type impact device with two interchangeable impact objects (a steel ball and a baseball), with a plastic jaw model having artificial teeth. Four testing conditions were observed: one with the jaw open without a mouthguard (Open NoMG), the second with the jaw clenching (loaded with 30 kg weight) without a mouthguard (Clench. NoMG), the third with the jaw clenching with MGAO− (Clench. MGAO−) and the last with the jaw clenching with MGAO+ (Clench. MGAO+). The results are as follows: both types of mouthguards showed the effects in reducing the distortion of the teeth. However, the effect was significantly obvious (steel ball = about 57% shock absorption ability, baseball = about 26%) in the mouthguard with anterior occlusion or support by lower dentition through mouthguard (Clench. MGAO+) than Clench. MGAO−. Thus, the influence of anterior occlusion of mouthguards or the support of mandibular dentition through wearing a mouthguard (MGAO+) is indispensable in reducing the impact force and tooth distortion. The results of this research should further contribute to the establishment of guidelines for safer mouthguards.     

The influence of impact object characteristics on impact force and force absorption by mouthguard material

Abstract –  Most impact force and impact energy absorption tests for mouthguards have used a steel ball in a drop-ball or the pendulum device. However, in reality most sports-related trauma is caused by objects other than the steel ball, e.g. various sized balls, hockey puck, or bat or stick. Also, the elasticity, the velocity and the mass of the object could change the degree and the extent of injuries. In this study, we attempted to measure the impact force from actual sports equipment in order to clarify the exact mechanism of dental-related sports injuries and the protective effects of mouthguards. The present study was conducted using the pendulum impact device and load cell. Impact objects were removable. Seven mobile impact objects were selected for testing: a steel ball, baseball, softball, field hockey ball, ice hockey puck, cricket ball, and wooden baseball bat. The mouthguard material used in this study was a 3-mm-thick Drufosoft (Dreve-Dentamid GmbH, Unna, Germany), and test samples were made of the one-layer type. The peak transmitted forces without mouthguard ranged from the smallest (ice hockey stick, 46.9 kgf) to the biggest (steel ball, 481.6 kgf). The peak transmitted forces were smaller when the mouthguard was attached than without it for all impact materials but the effect was significantly influenced by the object type. The steel ball showed the biggest (62.1%) absorption ability while the wooden bat showed the second biggest (38.3%). The other balls or the puck showed from 0.6 to 6.0% absorbency. These results show that it is important to test the effectiveness of mouthguards on specific types of sports equipment. In future, we may select different materials and mouthguard designs suitable for specific sports.     

Comparison of forces transmitted through different EVA mouthguards

Abstract –  Athletic mouthguards have been recommended for decades with varying levels of athlete acceptance. Issues related to compliance center around the ability to breath and speak while wearing the mouthguards. Fabrication techniques have changed over time to a two-layer ethylene vinyl acetate mouthguard fabricated on a high-pressure machine. The reported ideal thickness of these mouthguards has been somewhat variable depending on the sport and anticipated level of risk. Recent research however, has identified 4 mm as the optimal thickness of EVA. In this study an acrylic dental cast was fabricated and mounted to a drop impact fixture. Mouthguards of varying ply, thickness and palatal coverage were fabricated and tested in the fixture. Strain gauges and load cells were used to evaluate the effect of ply, thickness, and palatal coverage on the ability of these mouthguards to minimize transmitted forces. The purpose of this study was to identify those variables of mouthguard construction that will minimize the overall transmitted force of impact to the anterior dentition.     

Forces transmitted through EVA mouthguard materials of different types and thickness

Previous studies into sporting mouthguards have been mainly attitudinal or epidemiological. The aim of the present study was to build an impact rig to measure the impact absorbed by mouthguard materials of various thicknesses. The acceleration of the pendulum of the rig was measured and used to calculate the force transmitted to the materials.
Impact tests were also performed on three commercially available mouthguard materials. Tests showed that the force transmitted through mouthguard materials was inversely related to the material thickness.
Mouthguard construction techniques with ethylene vinyl acetate (EVA) plastics should be monitored to avoid occlusal thinning especially on the incisal edges. Thinning results in reduction in the protection offered by the mouthguard.     

A comparison of commercially available mouthguards and a custom mouthguard

Participation in sporting events involves a risk of injury to the teeth and surrounding structures. The purpose of this study was to compare the properties of a custom mouthguard and three commercially available mouthguards. Tests included rebound upon impact as well as incisor thickness and hardness after fabrication. Results revealed that all three commercially available mouthguards exhibited greater rebound than the custom mouthguard. Rebound was related directly to the thickness of the mouthguard in the incisor region. The thickness of a mouthguard may be critical to avoiding injury to the teeth and surrounding structures.     

An improved mouthguard material

a modified mouthguard material which reduces transmitted forces is described. Tests showed that the inclusion of air cells in a 4 mm thick polyvinylacetate-polyethylene (EVA) copolymer reduced the effects of impacts of less than 10 KN when compared with a material of the same EVA composition and thickness. The EVA copolymer with air-inclusions is suitable for the construction of stock, mouth-formed and vacuum-formed mouthguards. The improved elastic properties of the modified mouthguard material properties of the modified mouthguard material reduced transmitted forces by 32 per cent when copared with traditional EVA mouthguard polymers of the same thickness.     

Thickness and stiffness characteristics of custom-made mouthguard materials.

OBJECTIVES: The purpose of this investigation was to determine the thickness of different types of custom-made mouthguards after processing and the deformational changes after simulated occlusal loading. MATERIALS AND METHODS: Ten mouthguards were fabricated for the same dental arch using the following materials and processing techniques: Group I: vacuum-formed (4 mm), Colored Mouthguard; Group II: vacuum-formed (4 mm), Proform; and Group III: pressure-laminated (3 + 3 mm), Drufosoft. After processing, the thickness was measured in three places: lingual cusps of the first molar, distal marginal ridge of the first premolar; and facial of central incisor. The stiffness of each group was determined by applying a simulated clenching force to the first molar lingual cusp areas on an Instron test machine with a blunt probe. The corresponding penetration was measured with a dial gauge. Thickness and force-deflection measurements of the different mouthguard groups were compared using analysis of variance and post hoc tests. RESULTS: The mean thicknesses at the molar for Groups I and II were 1.55 and 1.52 mm, respectively, and were significantly smaller then the corresponding thickness for Group III (3.48 mm). The mean thicknesses at the facial of the incisors for Groups I and II were similar (2.05 and 2.06 mm, respectively), and were significantly smaller than the corresponding thickness for Group III (3.29 mm). Groups I and II demonstrated similar stiffness that was significantly higher than that for Group III. CONCLUSION: These results show that vacuum-formed mouthguards produced smaller thicknesses than the pressure-laminated mouthguards. The pressure-laminated mouthguards produced material thicknesses that were previously shown to be adequate to protect athletes from trauma.     

CAD/CAM supported production process of standardized enamel and dentin tooth discs with different thicknesses for in vitro material testing

ObjectiveThe production of similar specimens for material testing is very difficult and crucial. This has much influence on the results of an experiment. With CAD design and new printing technologies it is possible to create individual devices to produce specimens for different testing situations. In this study different devices were designed for the standardized production of tooth discs for testing with bonded materials.MethodsThe different devices were designed using optimized CAD for 3D printing. After the design, the different parts of the devices were printed using a desktop SLA 3D printer with high precision. Three different tools were needed for the generation of a standardized disc. After the production, the different devices were tested on natural teeth.ResultsIt is possible to generate very precise tools for the creation of round tooth discs. 40 tooth discs divided into 4 groups with a thickness of 2.0 mm, 2.5 mm, 3.0 mm and 3.5 mm and a constant diameter of 5 mm were produced. For all groups the median of the diameter and thickness was under +/−0.05 mm and the lower and the upper quartile were all under +/−0.06 mm.SignificanceWith this new approach the creation of very precise and uniform tooth discs is possible. The whole process for the creation of the tooth discs was standardized.     

Dental Care with Manual Toothbrushes during Fixed Orthodontic Treatment—a New Testing Procedure

AbstractAim: The aim of this investigation was to employ a new in-vitro testing system for manual toothbrushes in order to distinguish the more effective from those less so for dental care during fixed appliance treatment.Materials and Methods: The testing apparatus consisted of a sliding carriage able to execute a horizontal brushing movement, and a row of artificial teeth upon which the various toothbrushes were manipulated. The artificial row of teeth was fixed on a sensor that recorded in all three dimensions the forces and moments caused by the toothbrushes on the toothbrush field. All the tests were executed with a weight of 110 g on a tooth field with a multibracket appliance. Tests were also carried out with five toothbrushes having weights of 200 g, 250 g and 300 g. Here, the decisive target values were 1) the degree of exertion necessary in the brushing direction to move a brush over the artificial teeth, and 2) the maximum force occurring in the brushing direction. High target values indicated high interaction between toothbrush bristles and the surfaces being brushed.Results: From testing five toothbrushes with four different weights, we have established profiles confirming the beneficial and less beneficial properties of certain toothbrushes involving various high contact forces.     

Fabricating a better mouthguard. Part II: The effect of color on adaptation and fit

Abstract –  The thermoforming process involves the heating of plastic sheets to a critical temperature followed by the shaping of the heated material into a three-dimensional structure. Given that custom-fabricated mouthguards are produced using the thermoforming process, the adaptation of plastic sheets to a stone model of the dentition is likely to be affected by the ability of the mouthguard material to be heated. The purpose of this study was to establish if material color affected the adaptation and fit of custom-made mouthguards. Twelve stone models were used in this investigation. Five mouthguards were produced using each model. These mouthguards were made using clear-, white-, black-, blue- and green-colored ethyl vinyl acetate. The force required to remove the various colored mouthguards from the corresponding stone models was determined using a strain gauge housed within a specially designed apparatus. Each of the mouthguards were tested three times at two different angles of pull −45° and 90°. Statistical tests performed using the average amount of force required for mouthguard removal revealed an angle by color interaction. Post hoc analyses revealed that the mean force required to remove the clear-colored mouthguards from their respective stone models was significantly less than the force required to pull away blue-, black- and green-colored mouthguards. This difference between clear- and dark-colored mouthguards was observed at both angles tested with the exception of the black mouthguard which differed from the clear-colored mouthguard only when removed at an angle of 90°. The results of the present study indicate that by using dark-colored mouthguard material, one can achieve superior adaptation and thus produce a more firmly fitting mouthguard.     

A new technique for the custom fabrication of mouthguards with photopolymerized urethane diacrylate.

The use of protective mouthguards in athletes has proven to be an effective and inexpensive means of preventing traumatic injuries to the teeth and supporting structures. Of the three general types of mouthguards available currently, the custom-fabricated type is considered superior to stock and mouth-formed protectors. A new technique is introduced for the fabrication of custom-made mouthguards with light-curing urethane diacrylate material.