Effects of Nail Biting (Onychophagy) on Upper Central Incisors in Children and Young Adolescents

Featured Application: Nail biting is a very common oral disorder whose dental and clinical implication are not well-known. Therefore, this study is a novelty in the field of oral disease since it considers changes on tooth shape caused by nail biting. Nail biting (NB) is a repetitive and uncontrolled parafunctional activity that can affect oral health by altering tooth shape and intraoral position. Nowadays, there is not enough scientific evidence about the impact of NB on teeth; therefore, this study aimed to evaluate the effects of NB on the length, width and inclination of upper central incisors. This retrospective study involved 76 patients, 40 males and 36 females, with a mean age of 10.6 ± 0.3 years. Digital scans of the maxillary arch of each patient were recorded. Next, the length, width and inclination of upper central incisors used and not used for NB were measured. Finally, data were analysed with a paired t-test. Statistical analysis showed statistically significant differences in the length and inclination of upper central incisors used for NB compared with those of upper central incisors not used for NB, while the width did not show a significant difference. There were relevant changes in upper central incisors subjected to NB, demonstrating that NB impairs the shape, morphology and inclination of teeth. Therefore, because of the potentially negative consequences of NB, it is recommended that NB not be underestimated.