The influence of the sensor type on the measured impact absorption of mouthguard material

Abstract –  Mouthguards have been tested for impact energy absorption using drop-ball and/or pendulum devices. While all reports show efficiency of the mouthguard, the impact absorption abilities reported differ considerably. This difference has been attributed to differences of mouthguard material, design, and the impact force used. However, it is also possibly because of the difference in the sensors used in the experiments. The purpose of this study was to test three types of sensors and to assess which type was most appropriate for measurement of the impact absorption ability of mouthguards. A pendulum-type testing equipment and steel ball, wooden bat, baseball, field-hockey ball were used as the impact object. For all sensors or impact objects, the mouthguard decreased the impact forces. However, the absorption ability of the mouthguard varied according to the sensor or impact object. The absorbency values became smaller with the strain gauge, the accelerometer, and the load cell, respectively. With the steel ball as the impact object, 80.3% of impact absorption was measured with the strain gauge and the accelerometer but, only 62.1% with the load cell sensor. With the wooden bat, impact absorption was 76.3% with the strain gauge and 38.8% for the load cell. For the baseball ball, the absorption measurement decreased from 46.3% with the strain gauge to 4.36 with the load cell and for the field-hockey ball, the decrease in measurement values were similar (23.6% with the strain gauge and 2.43% with the load cell). It is clear that the sensor plays an important role in the measurement values reported for absorbency of mouthguard materials and a standard sensor should be used for all experiments.     

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.     

Does hard insertion and space improve shock absorption ability of mouthguard?

Abstract – Mouthguards are expected to reduce sports‐related orofacial injuries. Numerous studies have been conduced to improve the shock absorption ability of mouthguards using air cells, sorbothane, metal wire, or hard material insertion. Most of these were shown to be effective; however, the result of each study has not been applied to clinical use. The aim of this study was to develop mouthguards that have sufficient prevention ability and ease of clinical application with focus on a hard insertion and space. Ethylene vinyl acetate (EVA) mouthguard blank used was Drufosoft and the acrylic resin was Biolon (Dreve‐Dentamid GMBH, Unna, Germany). Three types of mouthguard samples tested were constructed by means of a Dreve Drufomat (Type SO, Dreve‐Dentamid) air pressure machine: the first was a conventional laminated type of EVA mouthguard material; the second was a three layer type with acrylic resin inner layer (hard‐insertion); the third was the same as the second but with space that does not come into contact with tooth surfaces (hard + space). As a control, without any mouthguard condition (NOMG) was measured. A pendulum type impact testing machine with interchangeable impact object (steel ball and baseball) and dental study model (D17FE‐NC.7PS, Nissin, Tokyo, Japan) with the strain gages (KFG‐1‐120‐D171‐11N30C2: Kyowa, Tokyo, Japan) applied to teeth and the accelerometer to the dentition (AS‐A YG‐2768 100G, Kyowa) were used to measure transmitted forces. Statistical analysis (anova , P < 0.01) showed significant differences among four conditions of NOMG and three different mouthguards in both objects and sensor. About acceleration: in a steel ball which was a harder impact object, shock absorption ability of about 40% was shown with conventional EVA and hard‐insertion and about 50% with hard + space. In a baseball that was softer compared with steel ball, a decrease rate is smaller, reduction (EVA = ～4%, hard‐insertion = ～12%, hard + space = ～25%) was admitted in the similar order. A significant difference was found with all the combinations except for between EVA and hard‐insertion with steel ball (Tukey test). About distortion: both buccal and lingual, distortions had become small in order of EVA, hard‐insertion, and hard + space, too. The decrease rate is larger than acceleration, EVA = ～47%, hard‐insertion = 80% or more, and hard +space = ～98%, in steel ball. EVA = ～30%, hard‐insertion =～75%, and hard + space = ～98% in baseball. And a significant difference was found with all the combinations (Tukey test). Especially, hard + space has decreased the distortion of teeth up to several percentages. Acceleration of the maxilla and distortions of the tooth became significantly smaller when wearing any type of mouthguard, in both impact objects. But the effect of mouthguard was clearer in the distortion of the tooth and with steel ball. Considering the differences of mouthguards, the hard‐insertion and the hard + space had significantly greater buffer capacity than conventional EVA. Furthermore, hard + space shows quite high shock absorption ability in the tooth distortion. Namely, hard + space has decreased the distortion of teeth up to several percentages in both impact objects.     

Orofacial/cerebral injuries and the use of mouthguards by professional athletes in Switzerland

Abstract –  The objective of the present study was to measure the occurrence of orofacial and cerebral injuries in different sports and to survey the awareness of athletes and officials concerning the use of mouthguards during sport activities. Two hundred and sixty-seven professional athletes and 63 officials participating in soccer, handball, basketball and ice hockey were interviewed. The frequency of orofacial and cerebral trauma during sport practice was recorded and the reason for using and not using mouthguards was assessed. A great difference in orofacial and cerebral injuries was found when comparing the different kinds of sports and comparing athletes with or without mouthguards. 45% of the players had suffered injuries when not wearing mouthguards. Most injuries were found in ice hockey, (59%), whereas only 24% of the soccer players suffered injuries when not wearing mouthguards. Sixty-eight percentage of the players wearing mouthguards had never suffered any orofacial and cerebral injuries. Two hundred and twenty-four athletes (84%) did not use a mouthguard despite general acceptance by 150 athletes (56%). Although the awareness of mouthguards among officials was very high (59%), only 25% of them would support the funding of mouthguards and 5% would enforce regulations. Athletes as well as coaches should be informed about the high risk of oral injuries when performing contact sports. Doctors and dentists need to recommend a more intensive education of students in sports medicine and sports dentistry, and to increase their willingness to become a team dentist.     

Mouthguard utilization rates during sport activities in Ankara, Turkey

Abstract –  The objective of this study was to determine the attitudes towards mouthguard use in Ankara, Turkey. In the first part of this study, an eight-item questionnaire was distributed to 22 coaches from 15 secondary schools randomly selected from five municipalities of Ankara, Turkey. The questionnaire sought information on how much coaches know regarding mouthguards and how often children and adolescents of the ages 11–18 use mouthguards. The second part of the study was based on the data obtained from direct interviews answered by 121 university athletes of three different sport modalities (football, ice hockey and martial arts). The purpose of this part of the study was to determine the rate of mouthguard use and the frequency and type of oral trauma in these athletes. The result of the coaches' questionnaires revealed that; none of the 11–18 years old children and adolescents used mouthguards while participating in sports. Of the coaches, 77.2% had seen orofacial trauma in this age group during sport activities and 95.5% of the coaches believed that mouthguards prevented oral injuries. Of the coaches, 72.7% reported that children and adolescents should use mouthguards in sport activities. The second part of the study showed that although all of the athletes owned mouth-formed type of mouthguards, the utilization rate was 74.4%. Of all players, 13.2% had suffered from one or more form of oral injury while not wearing mouthguards. The results show that in Turkey, the use of mouthguards has not become widespread in sports. It can be concluded that regular mouthguard use in sports should be encouraged in Turkey.     

Fiber Bragg grating sensor for measurement of impact absorption capability of mouthguards

Abstract – Background: There is no standard technique to monitor impact absorption capability of mouthguards. Earlier investigations have established that strain transferred to the teeth through mouthguard is a good indication of their efficiency. In the present study, a unique experimental scheme utilizing fiber Bragg gratings (FBGs) as distributed strain sensors is proposed and investigated to estimate impact absorption capability of custom‐made mouthguard. The proposed methodology is useful due to advantages such as, very small size and flexibility for ease of bonding, self‐referencing, and multiplexing capability of using FBG sensors. Material and methods: Finite‐element analysis was performed to simulate the stress distribution due to impact on the mouthguard. The FBGs were fabricated by exposing the core of photosensitive fiber to intense Ultra‐Violet light through a ‘phase mask’. One FBG sensor was bonded on the jaw model and another on the mouthguard surface at similar positions, so that both gratings are simultaneously affected by impact. Two different sets of the sensors were used, one for the anterior region and another for posterior region. The impact was produced using customized pendulum device with interchangeable impact objects i.e. cricket ball, hockey ball, and steel ball. Response of gratings was monitored using optical spectrum analyzer and strain induced due to each impact was determined from the Bragg wavelength shifts for each grating. Results and conclusions: Strain induced due to impact was calculated from the Bragg wavelength shifts. Difference in the strain values for the two gratings is interpreted as impact energy absorbed by the mouthguard. The Bragg wavelength shifts (induced strain) for FBG bonded on the jaw model was much lower than the shift for FBG bonded on the mouthguard, indicating that most of the impact energy is absorbed by the mouthguard.     

Dental trauma and mouthguard usage among ice hockey players in Turkey premier league

Abstract –  An epidemiological survey was carried out among the ice hockey players of Turkish Premier Ice Hockey League. The purpose of the present study was to evaluate the prevalence of dental trauma in youth and adult ice hockey players, as well as to check if the players were aware of mouthguards and had used any. The players were interviewed to determine the occurrence of dental trauma during ice hockey and mouthguard usage level. Results revealed that awareness of Turkish ice hockey players to dental trauma is neglected while the majority of players also demonstrated limited utilization of mouthguard.     

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.     

Oro-facial injuries and mouthguard use in elite female field hockey players

Abstract –  The objectives of this study were to assess the prevalence of oro-facial injuries, frequency of mouthguard use and players' attitudes towards the use of mouthguards among elite English female field hockey players. All 140 players of the English Hockey Association female Premiere League were asked to complete a questionnaire. Main outcome measures were prevalence of oro-facial injuries, frequency of wearing of mouthguards and attitudes to mouthguard wearing. One hundred and ten completed questionnaires were returned (79% response rate). Facial injuries were common. Nineteen percent had sustained dental injury. Five percent of the respondents had at least one tooth avulsed. Eighty-eight percent of the players said that they owned a mouthguard. Mouthguards were worn regularly during matches by 69% but were used less frequently during training. Six percent thought that mouthguards were ineffective. Eighteen percent of the subjects refused to play if they did not have their mouthguard. Sixty-nine percent of the subjects felt that the mouthguards should be worn compulsorily at all times during the game. The following were finally concluded from the study: oro-facial injuries were commonly reported; 88% of the players possessed a mouthguard; and mouthguards were worn regularly during matches by 69% but were used less frequently during training.     

Are all mouthguards the same and safe to use? The influence of occlusal supporting mouthguards in decreasing bone distortion and fractures

Abstract –  The safety benefits of mouthguards have been demonstrated in many studies, with many authors and sports dentists strongly recommending the wearing of mouthguards. However, wearing a mouthguard with incorrect occlusion might cause a variety of problems. It comes as no surprise that a traumatic blow to the chin, while wearing an insufficient mouthguard lacking anterior contact, can result in severe distortions to the mandibular bone, and bone fractures. The aim of this study was to clarify how ineffective insufficient occlusal supporting mouthguards are and how dangerous they can be to use. Consequently, in this study, occlusal supportive areas were varied and accelerations of head and distortions of the mandible were measured using an artificial skull model and a pendulum impact device. As a result, the distortions of the mandible tended to increase as the supported area decreased. On the contrary, accelerations of the head decreased as the occlusion part decreased. Thus, a lot of impact energy was consumed in the distortion of the mandible; accordingly, it seemed that only a little destructive energy was transferred to the head. From this study, it would seem that wearing a mouthguard, which is insufficient in the occlusion, has the potential of causing a bone fracture of the mandible. Consequently, mouthguards should have proper occlusion.     

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.     

Mandibular fracture with a mouth formed mouthguard in kickboxing

Abstract –  Reports of injuries caused by kickboxing, one of the contact sports that potentially causes a large number of injuries, are relatively rare. Wearing a mouthguard is obligatory in kickboxing, but the association between maxillofacial injuries and the quality of mouthguards has not been described thus far. In this article, we present a case of mandibular fracture in a 25-year-old male, who was injured during kickboxing despite wearing a mouth formed mouthguard.     

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...     

Influence of pre-laminated material on shock absorption ability in specially designed mouthguard with hard insert and space

Purpose

We have developed a new type of laminated mouthguard, the Hard & Space mouthguard, which incorporates a hard material insert and a space to prevent contact between the mouthguard and the buccal surfaces of the teeth. The purpose of this study was to investigate the effect of this new design on shock absorption.

Methods

Three types of mouthguard (a conventional laminated EVA mouthguard and two 3-layer type “Hard & Space” mouthguards made of 1.8-mm or 3.0-mm thick pre-laminated material (Konbiplast) and EVA with a 1.0-mm space) were impacted. Shock absorption was measured by means of a pendulum type steel ball impact testing machine at impact distances of 10, 20, and 30 cm and a dental study model with strain gauges attached to the lingual surfaces and an accelerometer fixed to the maxilla.

Results

Distortion of the impacted tooth and acceleration of the model were significantly reduced by all types of mouthguard at all 3 impact distances. The effect of the mouthguard was remarkable in terms of tooth distortion: both thicknesses of Hard & Space mouthguard showed more than 90% shock absorption, compared with only approximately 55–78% with an EVA mouthguard. Furthermore, shock absorption with the thicker 3.0-mm Hard & Space mouthguard reached more than 95% at the highest impact power.

Conclusion

Within the limitations of this laboratory study, Hard & Space mouthguards showed significantly greater buffer capacity than a conventional EVA mouthguard in terms of tooth distortion at the 3 impact powers tested.     

Can mouthguards prevent mandibular bone fractures and concussions? A laboratory study with an artificial skull model

Abstract –  Some sports' accidents are responsible for inflicting traumatic brain injuries and mandibular bone fractures when impacts occur to the chin. It is often thought that mouthguards can prevent many of these injuries. However, such assertions may be insufficient without adequate research. It is therefore necessary to establish a systematic method of investigation to solve this problem. In the present laboratory study, tests were performed using pendulum impact equipment and an artificial skull model connected to strain gages and accelerometers to simulate and measure the surface distortions related to bone deformation or fractures and the acceleration of the head related to concussions. As impacts, direct blows to the mandibular undersurface were applied. As a result, wearing a mouthguard decreased ( P   < 0.01) the distortion to the mandibular bone and the acceleration of the head significantly compared with not wearing a mouthguard (54.7%: to the mandible – measured at a total of three different points, 18.5%: to the head measured at a total of three different points). Within the limits of this study, the following conclusions were drawn: The present measuring system in this study was able to evaluate the distortion to the mandibular and the acceleration of the head from the direct blow to the mandibular undersurface. Mouthguards can reduce distortion to the mandibular and the acceleration of the head from the same blow. So mouthguards might have the possibility to prevent mandibular bone fractures and concussions. However, further well-designed and exhaustive studies are vital to show that mouthguards reduce the incidence of concussions and mandibular bone fractures.     

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.     

Use of mouthguard rates among university athletes during sport activities in Erzurum, Turkey

Abstract –  The purpose of this study was to determine the attitudes of mouthguard users in Erzurum, Turkey. The participants' appreciation in the use of protective devices, such as mouthguards, during sport activities was also evaluated. In this study, a 10-item questionnaire was distributed to 50 coaches and a 10-item questionnaire was distributed to 768 university athletes of three different sport modalities (basketball, soccer and volleyball) in the Atatürk University Sport Competitions. The Sport Competitions are composed of 20 faculty, except the faculty of dentistry. The result of the coaches' questionnaires indicated that none of the athletes used mouthguards while participating in sports. Of the coaches, 64% had seen orofacial trauma in their athletes during sport activities and 76% believed that mouthguards prevented oral injuries. Of the coaches, 76% reported that university athletes should use mouthguards in sport activities. The result of the university athletes' questionnaires revealed that the mouthguard utilization rate was 0%. Of all players, 78.1% were males (age 17–29) and 21.9% were females (age 18–23). Of all players, 7.31% had suffered from one or more type of oral injury while not wearing mouthguards. The results indicate that in Turkey, the use of mouthguards is rare in sports. It should be a combined duty of dentists, sports physicians, and coaches to encourage the use of mouthguards during training and sport activities. Doctors and dentists need to recommend a more intensive education of students in sports medicine and sports dentistry.     

Nigerian dentists' knowledge and attitudes towards mouthguard protection

Abstract –  The objective of this study was to assess the knowledge and attitudes of Nigerian dentists towards mouthguard protection. A pre-tested 15-item, one-page questionnaire was distributed to 185 dentists practising in different parts of the country with government hospitals or private establishments, by 'hand-delivery' system. Filled and returned forms were 170 (response rate of 92%). The period of the survey was between April and August 2003. Dental graduates from the different dental schools in the country responded to this survey. About 49% of the respondents indicated having only classroom lectures on mouthguards during their undergraduate trainings, 11% said they had some laboratory sessions in addition while no form of education on mouthguards was received by 40%. About 82% had never recommended mouthguard protection for athletic patients, and the major reason was no formal training in the subject. Only 58.5% were familiar with the different types of mouthguards, 75.9% would not be able to supervise or fabricate mouthguards and 50.6% would prefer custom-made mouthguard for their athletic patients. About 84% felt the current training on mouthguards in Nigerian dental schools is inadequate. Over 98% agreed that mouthguard usage in contact sports should be encouraged with the involvement of the dentists. The knowledge and attitudes of the respondents towards mouthguard protection did not vary significantly across years of postqualification from dental schools as well as the professional status of the dentists ( P  > 0.05). Although Nigerian dentists support mouthguard protection in contact sports and want to be involved in the provision of mouthguards for athletes, their knowledge of the protective device is inadequate. There is need for attention to be given to this subject in the undergraduate curricula of our dental schools.     

Easy fabrication of a new type of mouthguard incorporating a hard insert and space and offering improved shock absorption ability

Abstract – The positive effects of wearing a mouthguard have been indicated in various epidemiological surveys and experiments, and their usage appears to be increasing in many sports. However, many preventable sports‐related dental injuries still occur even with the use of a conventional mouthguard. We have developed a mouthguard (the Hard & Space mouthguard) with sufficient injury prevention ability (more than 95% shock absorption ability against impact with a steel ball carrying 15.2 kg m² S^?2 potential energy) and ease of clinical application. This mouthguard consists of an outer and an inner EVA layer and a middle layer of acrylic resin (hard insert), with a space to prevent contact between the inner surface of the mouthguard and the buccal surfaces of the maxillary front teeth or teeth already weakened through prior damage or treatment. The purpose of this article is to describe the method by which the Hard & Space mouthguard may easily be fabricated. We believe that this new type of mouthguard has the potential to reduce sports‐related dental injuries.     

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.