title: Impact absorption and force dissipation of protective mouth guards with or without titanium reinforcement.
abstract: BACKGROUND
  Mouth guards are used to reduce the risk of experiencing dental injuries. Various individual and commercial designs are available.
  
  
  METHODS
  The authors prepared 20 artificial maxillae from a polyether-resin to simulate teeth, jaw bone and gingiva. They customized two designs of mouth guards by using stone models from impressions of the artificial maxillae; one (n = 10) was constructed of four layers of ethylene vinyl acetate (EVA) (total thickness = 4.0 millimeters) (group EVA), and the other (n = 10) was constructed of EVA with an intermediate layer of 1.0-mm-thick sheet titanium from the left maxillary canine to the right maxillary canine (total thickness = 4.0 mm) (group EVA-Ti). They used a drop-weight impact testing machine (DTM 1000-S, Omnipotent Instruments, Seremban, Negeri Sembilan Darui Khusus, West Malaysia) for a frontal impact with 1.7 kilograms of mass dropped at 0.34 meter per second. The force of the drop was verified by means of a laser Doppler vibrometer (laser model OFV-323 and controller model OFV-3020, Polytec, Irvine, Calif.) to calculate the absorbed energy. They used a high-speed camera (FastCam APX-RS, Photron, San Diego) to obtain images of energy dissipation over the length of the mouth guard.
  
  
  RESULTS
  The mean effective total impact energy that reached the maxillae-mouth guard models was 5.66 (standard deviation [SD], 0.035) joules. The mean absorbed energy in group EVA was 4.39 (0.023) J (77.8 percent of total impact energy). The mean (SD) absorbed energy in group EVA-Ti was 4.28 (0.013) J (75.9 percent of total impact energy). The mean (SD) total dissipated energy was 1.26 (0.21) J in group EVA and 1.36 (0.11) J in group EVA-Ti. The mean (SD) transmitted energy for the mouth guards was 1.08 (0.19) J in group EVA and 0.99 (0.05) J in group EVA-Ti. There was no statistically significant difference between the groups in terms of any energy transmission or absorption.
  
  
  CONCLUSIONS
  The results of this study suggest that an additional intermediate titanium layer in the anterior area of a mouth guard may not have a beneficial effect on impact absorption and dissipation.
  
  
  CONCLUSIONS
  The use of mouth guards is a general requirement for physical sports activities, and it should be strongly encouraged for people playing contact sports in particular. However, the authors' results indicate that the total thickness of a mouth guard is more important than is the use of an additional intermediate layer (in this case, titanium).
authors.affiliation: Dr. Kataoka is an assistant professor and a doctoral candidate, Department of Esthetic Dentistry, Faculty of Dentistry, University of São Paulo.
authors.forename: Simony H H
authors.initials: SH
authors.lastname: Kataoka
authors.affiliation: Dr. Setzer is an assistant professor and the clinic director, Department of Endodontics, Penn Dental Medicine, University of Pennsylvania, 240 S. 40th St., Philadelphia, Pa. 19104-6030, e-mail fsetzer@exchange.upenn.edu. Address correspondence to Dr. Setzer.
authors.forename: Frank C
authors.initials: FC
authors.lastname: Setzer
authors.affiliation: Dr. Gondim is an assistant professor, Department of Endodontics, Penn Dental Medicine, University of Pennsylvania, Philadelphia.
authors.forename: Eudes
authors.initials: E
authors.lastname: Gondim
authors.affiliation: Dr. Caldeira is a professor, Department of Esthetic Dentistry, Faculty of Dentistry, University of São Paulo.
authors.forename: Celso L
authors.initials: CL
authors.lastname: Caldeira
mesh_terms: D004735:Energy Transfer; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D055595:Mechanical Phenomena; D003765:Models, Dental; D009064:Mouth Protectors; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium
chemical_list: D014025:Titanium
keywords: Mouth guards; mouth injuries; mouth protectors