Although sports mouthguards provide protection against
trauma, dentoalveolar
injuries can still occur with the mouthguards in place. This study examined the effect of mouthguard protection in an in vitro model. A simulated maxilla, out of a
polymethylmethacrylate (
PMMA) arch, containing replaceable resin teeth, was used to assess the performance of different mouthguard designs. "Boil and
bite" and custom-fitted mouthguards (
ethylene vinyl acetate [EVA]) laminated with hard (poly-
vinyl chloride [
PVC]) or soft labial intermediate EVA layers were fabricated according to manufacturers' instructions. A steel ram was dropped onto the mouthguards at the maxillary incisor region. Changes in voltage, which were induced by a strain gauge at the back of the upper left incisor, were measured with an amplified voltmeter. Data were analysed by ANOVA at a significance level of 0.05. "Boil and
bite" and mouthguards layered with
silicone or with small hard
PVC inserts of 1.5 mm thickness demonstrated less absorption and differed significantly from the other mouthguard systems (p < 0.05). Bilaminated mouthguards with hard
PVC inserts of 0.8 mm, 1.5 mm or 2 mm thickness showed no significant differences to those with 1.5 mm thick (EVA) inserts. The absorption rates amounted to 33 % compared with the unprotected tooth.