Predicting the bracket bond failure rate in orthodontic patients: A retrospective cohort study

Abstract

The aim of this study was to determine the risk factors associated with orthodontic bracket bond failure and to develop a prediction equation for orthodontic bracket bond failure rate using the risk factors. This was a retrospective cohort study conducted on a sample of 690 brackets in orthodontic patients aged 10 to 28 years old (mean age 17.97±5.11 years old) visiting a dental hospital. The effect of various parameters of orthodontic bond strength was assessed on bracket failure rate using survival analysis. Parametric (exponential) regression analysis was used to determine the risk factors associated with bracket failure and a prediction equation was formulated to predict the bracket failure rate. The overall mean survival time for the brackets was 3.04 (2.9-3.17) years. The univariate analysis showed a statistically significant (P<0.05) association of bracket material, site, overjet, overbite, incisor and molar classification and age. The multivariate analysis showed a significant interaction between site and side along with bracket material, jaw, overjet and overbite in the model. The risk of bracket failure on the right posterior region is 7.7 times that in the right anterior region when adjusted for all other variables in the model (HR: 7.7; 95% CI: 4.3-13.6). The model including bracket material, jaw, overjet, overbite and interaction between site and side can be used as a predictor of hazard rate for orthodontic bracket failure. Care should be taken in bonding brackets in the posterior region, as their debonding rate is higher as compared to anterior region.