Sir, working in the A&E department on Halloween brings with it a myriad of unusual clinical presentations. Our maxillofacial team was referred a 55-year-old gentleman after his vampire costume failed, unable to remove his thermoplastic 'boil-and-bite'-type novelty teeth. A&E staff attempted removal of the fake fangs by recommending the patient hold warm water in his mouth. After unsuccessful attempts at pulling the teeth off, he was referred for management by the maxillofacial team.
With a foundation in dental materials and retention, we were able to recognise that the patient would not tolerate orally 80 °C water required to melt the ethylene-vinyl acetate and polycaprolactone material.1 Furthermore, similar to the retentive forces of thermoplastic mouthguards, we theorised that the excessive retention was related to thermal shrinkage, engagement of undercuts and surface tension.2,3
With these foundation dental sciences in mind, we pivoted open the labial and palatal aspects of the teeth with simultaneous flat plastics to help guide the material from engaging the embrasures and allow air to break the surface tension. The appliance was successfully removed using this technique; however, the patient had sustained superficial gingival lacerations (Figures 1 and 2). Following supportive management with salt water mouth rinses, he had a complete recovery and discarded his novelty vampire teeth.
Although this seems like a unique Halloween clinical presentation, thermoplastic materials have a number of uses that may result in similarly unlucky situations. Other applications for thermoplastic oral appliances include mouthguards, whitening trays, mandibular advancement splints and custom scuba diving mouthpieces. An understanding of dental materials is useful when considering methods to remove the appliance.
Vunain E, Mishra A K, Krause R W. Ethylene-vinyl acetate (EVA)/polycaprolactone (PCL)-Fe3O4 composites. J Therm Anal Calorim 2013; doi: 10.1007/s10973-013-3004-8.
Takahashi M, Koide K. Variation in mouthguard thickness according to heating conditions during fabrication Part 2: sheet shape and effect of thermal shrinkage. Dent Traumatol 2016; 32: 185-191.
Maeda Y, Yonehata Y, Satoh H. Mouthguard retention: Is design or accuracy of fit more critical? Quintessence Int 2009; 40: 13-18.
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Wilson, B., Hemm, L. Fake fangs fail. Br Dent J 231, 148 (2021). https://doi.org/10.1038/s41415-021-3342-z