scholarly journals The Effect of Material Type and Location of an Orthodontic Retainer in Resisting Axial or Buccal Forces

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2319
Author(s):  
Jaana Ohtonen ◽  
Lippo Lassila ◽  
Eija Säilynoja ◽  
Pekka K. Vallittu

The purpose of this study was to investigate the effect of retainer material and retainer position on a tooth to resist movement of the tooth in a simulation model. Bidirectional continuous glass fiber-reinforced composite (FRC) retainers and control retainers of steel wires were tested. The FRC retainers had a polymer matrix of bisphenol-A-glycidyldimethacrylate (bis-GMA) and poly(methylmethacrylate) (PMMA), and it was cured with a photoinitiator system. The retainers were adhered to a lower jaw Frasaco model in two different positions. Resistance against the movement of one tooth was measured from two directions. The average load values within the FRC retainer groups were higher than within the metal retainer groups. The load values for the groups loaded from the axial direction were higher than those loaded from the buccal direction. FRC retainers, which were located 1–2 mm from the incisal edge, showed higher load values than those located 4–5 mm from the incisal edge. There was a significant difference in load values between FRC retainers and metal retainers (p < 0.01). The wire position and the direction of force also had significant effects (p < 0.01). There were no significant differences between metal retainer groups. The results of this study suggest that metal retainers are more flexible, allowing for tooth movements of larger magnitude than with FRC retainers.

2017 ◽  
Vol 25 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Jiuqiang Song ◽  
Yan Qin ◽  
Jia Chen ◽  
Siwen Qin

In this paper, a continuous glass fiber-reinforced polypropylene prepreg was prepared by fiber treatment with a silane coupling agent and MAH-g-PP resin. Continuous glass fiber-reinforced polypropylene sheets were made from prepreg and PP mats by hot-pressing; they displayed exceptional performance. This paper studies the effects of maleic anhydride grafting on the polypropylene crystallinity and MAH-g-PP content in the prepreg, and the mechanical properties of the composites. The results showed that modifying PP with maleic anhydride decreased the tacticity of the polypropylene molecular chain, which reduced the crystallinity and melting point. An excellent interface formed between the polypropylene and fiber after the glass fiber was treated with a silane coupling agent and MAH-g-PP resin. The mechanical properties of the polymer materials displayed more favorable properties as MAH-g-PP content increased; the ideal MAH-g-PP content was 50%.


2020 ◽  
Vol 54 (27) ◽  
pp. 4231-4239
Author(s):  
Vishal Gavande ◽  
Anoop Anand

Continuous glass fiber reinforced thermoplastic composites have been manufactured and their mechanical properties have been evaluated. A catalyzed monomer is infused through a stack of compacted dry reinforcement under vacuum. The monomer undergoes radical polymerization with a peroxide catalyst. Viscosity and reactivity profile have been characterized to determine the catalyst concentration and temperature of infusion. Glass fiber reinforced thermoplastic composites realized through this method have mechanical properties that are comparable with that of epoxy with an added advantage of excellent toughness and repairability. For example, the residual compressive strength of thermoplastic composites after low-velocity impact is found to be over 140% more than that of epoxy-based composites using the same reinforcement and realized under identical manufacturing methods.


2017 ◽  
Vol 30 (4) ◽  
pp. 489-499 ◽  
Author(s):  
Zhiping Xu ◽  
Guibin Wang ◽  
Jiazhuo Hu ◽  
Mei Zhang ◽  
Shuling Zhang ◽  
...  

This study focused on the effect of processing conditions on the tensile properties of continuous glass fiber–reinforced polyether ether ketone composites, fabricated by co-wrapped yarn method, under different conditions. Their tensile properties were investigated in terms of thermal and fracture characterizations. The cooling rate significantly affected only the tensile modulus. However, both holding temperature and holding time had a significant effect on the tensile strengths and modulus. Although the effects of both were the same, the optimal increase of the holding time was found to be more beneficial.


Sign in / Sign up

Export Citation Format

Share Document