Effect of pigmentation on force degradation in orthodontic elastomeric chains: an experimental study

Introduction: Elastomeric chains are widely used in orthodontics but struggle to maintain consistent force over time, with significant force reduction occurring shortly after application. This study aimed to compare force degradation, morphology, and chemical composition between pigmented and non-pigmented continuous elastomeric chains. Material and Methods: Three groups (grey, red, transparent) were subjected to 150 g initial tension and immersed in artificial saliva for varying durations (30 minutes, 24 hours, 28 days), then tested using a universal machine. Structural analysis via scanning electron microscopy (SEM) and chemical analysis via Fourier transform infrared spectroscopy (FTIR) were conducted. Results: Significant strength loss in pigmented chains compared to transparent ones occurred. After 24 hours and 28 days, grey chains showed the highest loss (25.2% and 28.1%), followed by red chains (17.9% and 21.2%), with transparent chains exhibiting the least (10.6% and 14.6%) (p<0.05). Grey chains also displayed pronounced surface changes as assessed by SEM, while FTIR revealed characteristic polyurethane bands. Despite their higher strength retention, non-pigmented chains are less popular due to patient preference. Conclusions: Pigmented orthodontic chains exhibit significantly greater mechanical degradation and surface alterations after artificial saliva exposure than transparent chains, indicating that pigmentation adversely affects long-term strength.