The Effect of Pigmentation on Thermoplastic and Thermoset Elastomeric Power Chain
Abstract
Aim: The purpose of the study was to determine the effect of pigmentation on force levels and their degradation over time in orthodontic power chain of different chain types and manufactures.
Materials & Methods: Groups consisted of closed power chain from American Orthodontic (AO) thermoplastic (TP) in 5 colors, AO thermoset (TS) in 2 colors, Ormco TP in 4 colors, Ormco TS in 2 colors, and Rocky Mountain Orthodontics (RMO) TS in 5 colors (18 groups total, 10 chain samples in each group). Testing was performed over a period of 6 weeks at intervals of initial (T0), 1 hour (T1), 1 day (T2), 1 week (T3), 2 weeks (T4), 4 weeks (T5), and 6 weeks (T6). At each timepoint, an Instron Universal Testing Machine was utilized to stretch a sample to 25mm and record the force level. After testing, the chain samples were placed on the 3D printed arch model, stretched 25mm from tooth #23 to #26 and stored in distilled water at 370C between time points to simulate canine retraction in the oral environment.
Results: In general, force levels of all chains significantly decreased at each time point, but the decrease was larger for the TP groups early on and leveled off at the later time points. The TS groups exhibited a more gradual and continuous decrease in force values while maintaining overall higher force values. Chain pigmentation had a significant effect on force levels at all time points within each manufacturer and chain material. Chains containing blue pigment, in both TP and TS chain types, degraded faster and delivered significantly lower force values in all colored groups at most time points. In addition, at weeks 4 and 6, AO TS grey had a significantly lower mean force than the corresponding AO TS clear.
Conclusions: Pigmentation played a significant role in force levels and their degradation over time, but the specific pattern is not consistent between manufacturer or chain material.