Risk of failure at the cement-enamel junction of a human premolar tooth

Non-carious cervical lesions (NCCL) are characterized by the loss of dental hard tissue at the cement-enamel junction (CEJ). This type of cervical tooth loss, the so-called abfraction, can be associated with cuspal flexure, due to malocclusal loads causing the tooth to laterally bend. Exceeding stresses are therefore generated in the cervical region of the tooth that cause disruption of the bonds between the hydroxyapatite crystals, leading to crack formation and eventual loss of enamel and the underlying dentine. The aim of this study was to perform stress analyses of the first maxillary human premolar. An accurate model based on CT images of both the tooth and the periodontal ligament was employed. The threedimensional finite element model was used to investigate the stress distributions and to compare the changes occurring between normal and malocclusion. The risk of failure at the CEJ and to crack initiation at the dentin-enamel junction was also estimated.