The Effects of Dietary and Oral Conditions on the Discoloration of Orthodontic Elastomeric O-Ties: A Prospective Cohort Study

Abstract

This study was conducted to determine the incidence of significant orthodontic O-tie discoloration and identify the dietary and oral hygiene risk factors that predict its development in a cohort of orthodontic patients over one month. The design of this study was a prospective cohort study. We recruited 200 orthodontic patients for this study. All patients completed baseline dietary assessments using a Food Frequency Questionnaire (FFQ) and an evaluation of their oral health status using the Plaque Index (PI) and salivary pH levels. All patients were provided with clear O-ties from the same batch. After four weeks (T1), O-ties were evaluated using a spectrophotometer for discoloration (the ΔE value). Patients were grouped based on the ΔE value into two cohorts: the "Discoloration Cohort" (ΔE ≥ 5.5, n=102) and the "No-Discoloration Cohort" (ΔE < 5.5, n=98). We identified risk factors by comparing baseline exposure characteristics between the two cohorts. Fifty-four percent of orthodontic patients whose O-ties discolored had significant discoloration (54.4%). The Discoloration Cohort had a statistically significantly higher PI score and consumed more foods high in chromogenic properties than those in the No-Discoloration Cohort. A Multivariable Cox regression model demonstrated that a high baseline PI (HR=3.2, 95% CI: 2.1-4.9); daily coffee consumption (HR=2.8, 95% CI: 1.8-4.3); and frequent consumption of curry (≥3 times/week) were independent risk factors predicting O-tie discoloration (HR=2.5, 95% CI: 1.6-3.9). This study found that poor oral hygiene and specific dietary habits are significant risk factors for the development of O-tie discoloration. Patients presenting with high plaque levels and high consumption of coffee or curry are at a substantially increased risk and should be targeted for preemptive counseling.