https://doi.org/10.1177/14653125211042891 Journal of Orthodontics 1–12 DOI: 10.1177/14653125211042891 © The Author(s) 2021 Article reuse guidelines: sagepub.com/journals-permissions journals.sagepub.com/home/joo Introduction Approximately 250,000 people in the UK have a severe enough malocclusion to justify orthognathic surgery (Kumar et al., 2008). When resources are limited, it is important that we consider the financial, social, emotional and functional consequences for those who do not receive an intervention, while recognising the benefits for those that do. Since 2006, access to NHS orthodontic treatment in England and Wales has been primarily based on the Index of Orthodontic Treatment Need (Brook and Shaw, 1989). While the fundamental question remains whether the The consequences of living with a severe malocclusion: A review of the literature Richard Leck , Ninu Paul , Sarah Rolland and David Birnie Abstract Aim: To facilitate the orthognathic shared decision-making process by identifying and applying existing research evi- dence to establish the potential consequences of living with a severe malocclusion. Methods: A comprehensive narrative literature review was conducted to explore the potential complications of severe malocclusion. A systematic electronic literature search of four databases combined with supplementary hand searching identified 1024 articles of interest. A total of 799 articles were included in the narrative literature review, which was divided into 10 themes: Oral Health Related Quality Of Life; Temporomandibular Joint Dysfunction; Masticatory Limita- tion; Sleep Apnoea; Traumatic Dental Injury; Tooth Surface Loss; Change Over Time; Periodontal Injury; Restorative Difficulty; and Functional Shift and Dual Bite. A deductive approach was used to draw conclusions from the evidence available within each theme. Results: The narrative literature review established 27 conclusions, indicating that those living with a severe malocclu- sion may be predisposed to a range of potential consequences. With the exception of Oral Health Related Quality Of Life, which is poorer in adults with severe malocclusion than those with normal occlusions, and the risk of Traumatic Dental Injury, which increases when the overjet is >5 mm in the permanent and 3 mm in the primary dentition, the evidence supporting the remaining conclusions was found to be of low to moderate quality and at high risk of bias. Conclusion: This article summarises the findings of a comprehensive narrative literature review in which all of the rel- evant research evidence within a substantive investigative area is established and evaluated. Notwithstanding limitations regarding the quality of the available evidence; when combined with clinical expertise and an awareness of individual patient preferences, the conclusions presented may facilitate the orthognathic shared decision-making process and fur- thermore, may guide the development of the high-quality longitudinal research required to validate them. Keywords orthognathic surgery, orthognathic treatment, malocclusion, aetiology of malocclusion and growth, occlusal development, restorative-orthodontic interface, interdisciplinary treatment, sleep apnoea, health services and quality of life aspects, quality of life and orthodontics, risk/benefit assessment, craniofacial growth, genetics of malocclusion Date received: 3 June 2021; revised: 26 July 2021; accepted: 12 August 2021 School of Dental Sciences, Newcastle University, Newcastle upon Tyne, UK Corresponding author: Richard Leck, School of Dental Sciences, Newcastle University, Newcastle upon Tyne NE24BW, UK. Email: richard.leck@nhs.net 1042891JOO Journal of OrthodonticsLeck et al. Clinical Section