Evaluating the Agreement between the Twin-Block Appliance and a New Low-Cost Arch Development Appliance in Changing the Mandibular Length

Aim: The main objective of this study is to compare the development of mandibular length by comparing the effectiveness of a new low-cost arch development appliance in increasing the length of the mandible with the twin block appliance (Twin-B).

Methodology: This analysis was performed on patients who attended the clinic in the Division of Orthodontics, Faculty of Dental Sciences, University of Peradeniya. The sample included 60 subjects treated with Twin-B (n=30) and new low-cost arch development (n=30) appliances and each appliance comprised 15 males and females. Intraclass Correlation Coefficient (ICC) and the Concordance Correlation Coefficient (CCC) were calculated to check the agreement between the two methods. A mixed-effects model was fitted to predict mandibular length, and Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), and log-likelihood were used for selecting the best model.

Results: It was observed that the Concordance Correlation Coefficient (CCC) for after treatment as 0.9172 with a (0.8488, 0.9555) 95% confidence interval. Furthermore, it gives a Pearson correlation of 0.9609 and bias correlation factor of 0.9545. ICC values after treatment for both single measures and average measures are 0.9499 and 0.9743 with the 95% confidence intervals (0.8976, 0.9758) and (0.9460, 0.9878) respectively.

Conclusion: Besides, both Twin-B and new low-cost arch development appliances have a better agreement and can be used interchangeably. Therefore, the new low-cost arch development appliance is more suitable as a treatment for malocclusion for Sri Lankan patients as it is less expensive, simpler and, less invasive.