In situ evaluation of orthodontic elastomeric chains

Area of Science:

• Orthodontics
• Biomaterials Science
• Dental Materials

Background:

• Elastomeric chains are crucial in orthodontic treatment for applying continuous force.
• Their long-term stability and force degradation in the oral environment are critical for treatment efficacy.
• Understanding material behavior in situ is essential for selecting optimal orthodontic appliances.

Purpose of the Study:

• To investigate the in situ tensile strength changes of different elastomeric chains over a 3-week period.
• To compare the force degradation rates of conventional plastic chains (PC) with enhanced memory (MC) and super slick (SSC) chains.
• To determine the influence of intraoral exposure duration and material type on elastomeric chain force maintenance.

Main Methods:

• Three types of elastomeric chains (PC, MC, SSC) were tested.
• Chains were stretched to a fixed distance (16 mm) with an initial force (180 g) in 13 patients.
• Tensile testing was conducted at intervals: initial, 1 hour, 24 hours, 1 week, 2 weeks, and 3 weeks.
• Statistical analysis included two-way ANOVA and Tukey's post hoc test to assess material and time effects.

Main Results:

• Both material type and time significantly affected force degradation.
• All chains exhibited significant force decrease within the first hour (PC: 23%, MC & SSC: 14%).
• After 3 weeks, remaining forces were: PC 57% (96 g), MC 67% (129 g), and SSC 71% (125 g).
• Enhanced chains (MC, SSC) maintained significantly higher forces than PC throughout the study.
• Only enhanced chains sustained over 100 g of force after 3 weeks.

Conclusions:

• Intraoral exposure significantly alters the tensile strength of elastomeric chains.
• Force degradation is most pronounced in the initial hour.
• Enhanced elastomeric chains demonstrate superior force retention compared to conventional plastic chains.
• These findings suggest enhanced chains may offer more consistent force delivery in orthodontic applications.