Occlusal accommodation and mouthguards for prevention of orofacial trauma.

PURPOSE: The aim of this study was to investigate the effect of two types of occlusal accommodation on the arch separation in centric and eccentric arch positions and to assess the opposing tooth contacts in professionally made, thermoformed sports mouthguards. MATERIALS AND METHODS: Maxillary and mandibular alginate impressions, a wax interocclusal record of centric occlusion together with maxillary/condylar face-bow registrations, were recorded clinically for 10 undergraduate dental students who are sports activist volunteers of the School of Medicine and Dentistry, Queen's University Belfast. Two ethylene vinyl acetate thermoformed maxillary mouthguards were made for each player (N = 20) using a standardised procedure. Ten mouthguards served both as the control (i.e. the non-accommodated) group and also the accommodated, occlusally 'imprinted' group. The other 10 mouthguards served as the accommodated, occlusally 'ground' group. Casts were articulated, each non-accommodated and accommodated mouthguard was seated and the extent of the interocclusal opening was recorded in all three arch relationships. The number of mouthguard and mandibular tooth contacts were also recorded in each position. RESULTS: The increased vertical occlusal dimension that was found in the presence of non-accommodated mouthguards equated to the full-sheet thickness of the material that was used to form the mouthguards. Only mouthguards accommodated by grinding retained high levels of occlusal contact in all arch relationships that were tested. CONCLUSIONS: Within the limitations of this study, the modification of the occlusal surface made by flat grinding reduced the arch separation in eccentric movements and increased the opposing tooth contacts in custom-made mouthguards. This may contribute to increased comfort, compliance and the protective effect of these appliances thus resulting in a reduction of injuries to the teeth, arches and soft tissues.

Post thermoforming dimensional changes of ethylene vinyl acetate used in custom-made mouthguards for trauma prevention--a pilot study.

It is important that mouthguards have an adequate thickness of material if they are to be effective in the prevention of trauma. The aim of this study was to quantify dimensional changes that occur on thermoforming ethylene vinyl acetate (EVA) sheets used in the construction of mouthguards. Fourteen batches of 3 mm thick sheet EVA were thermoformed over dental models under a number of common processing conditions including, model height, inclination, shape and model temperature, model position on thermoforming platform, plasticizing time and evacuation method. Thickness of thermoformed material was determined at anterior and posterior sites and measurements were compared to determine the magnitude and patterns of stretching collectively and within each processing condition. Overall, sheets of 3-mm EVA stretched by 52% during the thermoforming conditions tested. Incisal/cuspal sites were found to be significantly thinner when compared with all other locations measured. A number of thermoforming conditions were demonstrated to have a significant effect on the degree to which the EVA material stretched. For the combination of materials and equipment tested in this study, current thermoforming practices may cause excessive thinning of EVA in critical areas including incisal edges and cusp tips, thereby reducing the protective effect for professionally made mouthguards. To optimize protection in vulnerable areas, it is important that clinicians distinguish between EVA sheet thickness and the cross-sectional dimensions achieved in the finished mouthguards. They need to be specific in their prescription of the thickness of material they require especially in critical areas.