Force delivery properties of thermoplastic orthodontic materials

Jae Sung Kwon, Yong Keun Lee, Bum Soon Lim, Yong Kyu Lim

Research output: Contribution to journalArticlepeer-review

84 Citations (Scopus)


Introduction: Our objectives were to evaluate the force and energy (resilience) delivery properties of thermoplastic overlay orthodontic materials and to determine the changes in force delivery properties after thermocycling or repeated load cycling. Methods: Three types and 3 thicknesses of materials were investigated. Three-point bending-recovery tests were performed at baseline and after cycling procedures. For cycling, the specimens were thermocycled for 1000 cycles or repeatedly deflected by 1 mm for 100 cycles. Vickers hardness was measured to determine the changes after thermocycling or repeated load cycling. Results: The amount of deflection for optimal force delivery was 0.2 to 0.5 mm. Thin material exerted high energy in the deflection range of optimal force delivery. In the deflection ranges of optimal force delivery (0.2-0.5 mm), the force delivery properties after thermocycling were not different from those at the baseline (P >.01) but were different after repeated load cycling (P <.01). Thermocycling and repeated load cycling influenced Vickers hardness significantly. Conclusions: Thin material (0.508 mm) can deliver higher energy than thick materials (0.762 or 1.016 mm, P <.01) of the same brand. Therefore, thin material should be selected in the same brand of material. The effect of repeated deflection during service should be considered.

Original languageEnglish
Pages (from-to)228-234
Number of pages7
JournalAmerican Journal of Orthodontics and Dentofacial Orthopedics
Issue number2
Publication statusPublished - 2008 Feb

Bibliographical note

Funding Information:
Supported by a grant of the Korea Health 21 R&D Project, Ministry of Health and Welfare, Republic of Korea (03-PJ1-PG1-CH09-0001).

All Science Journal Classification (ASJC) codes

  • Orthodontics


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