Time series analysis of patients seeking orthodontic treatment at Seoul National University Dental Hospital over the past decade

Abstract

Introduction: This paper describes changes in the patients seeking orthodontic treatment over the past decade and the treatment they received to identify any seasonal variation or trend. Material and methods: This single-center retrospective cohort study included all patients who presented to the Seoul National University Dental Hospital for orthodontic diagnosis and treatment from January 1, 2005, to December 31, 2015. The study variables included a set of heterogeneous variables in the following categories: demographic (age, gender, and address)

clinical (Angles classification, anomaly, mode of orthodontic treatment, removable appliances for Phase 1 treatment, fixed appliances for Phase 2 treatment, orthognathic surgery, extraction, mini-plate, mini-implant, and patient transfer)

and time related (date of first visit and orthodontic treatment time). Time series analysis was applied to each variable. Results: The sample included 14,510 patients with a median age of 19.5 years. The number of patients and their ages demonstrated clear seasonal variation, with peaks in summer and winter. Increasing trends were observed for the proportion of male patients, the use of non-extraction treatment methods, the use of ceramic brackets, patients from provinces outside the Seoul region at large, patients transferred from private practitioners, and patients who underwent orthognathic surgery by the university surgeons. Decreasing trends included the use of metal brackets and orthodontic treatment time. Conclusions: Time series analysis revealed seasonal variation in some characteristics, and several variables showed changing trends over the past decade.