Wear Resistance Under High Load Forces of Four Different Polyethylene Terephthalate Glycol Vacuum-Formed Orthodontic Retainers

Bratu, Dana Cristina; Vinatu, Vlad Florin; Pop, S.; Petrescu, Pompiliu Horatiu; Simon, Catalin Petru; Popa, George

doi:10.37358/mp.19.3.5218

Cited by 7 publications

(7 citation statements)

References 9 publications

(12 reference statements)

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“…[ 12 ] tested PP and PETG in a thermoformed state using a stone block (76 × 50 × 38 mm) followed by use of a two-body wear machine with steatite balls under a load of 25 kg for 1000 cycles of wear. Bratu et al [ 13 ] used a custom jig, and upper and lower stone study models with retainers in place fixated on a metal plate with screws under a load of 61.2 kg for 10,000 cycles. The steatite ball possesses a hardness similar to tooth enamel (Mohs scale, 7.5) and is therefore more likely to induce a representative amount of wear on the thermoplastic material better simulating the intra-oral environment and related cycling.…”

Section: Discussionmentioning

confidence: 99%

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Assessment of wear characteristics, longevity and stiffness of Essix-type retainers

Alfadil,

Patel,

Pandis

et al. 2024

Clin Oral Invest

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Objective To compare four commercially available Essix-type retainers in terms of longevity, wear characteristics, stiffness and their range of rigidity. Materials and methods An in vitro study was conducted at Queen Mary University of London. Four groups of thermoplastic materials were included: Duran (PETG), Essix C + (Polypropylene), Vivera and Zendura (Polyurethane). A working typodont was fabricated to evaluate surface wear characteristics using a wear machine with a customized jig. Retainers were measured for tensile test, and water absorption was measured at five different time points up to 6 months after initial immersion in two different physical states and two different solutions. Hydrolytic degradation was also evaluated using FTIR spectroscopy. Results Essix C + was the most flexible retainer with Vivera the stiffest material. Zendura and Essix C + had the most surface wear (413 μm ± 80 and 652 μm ± 12, respectively) with absorption rates of up to 15 wt% in artificial saliva occurring with Zendura. Only Essix C + displayed signs of degradation following water absorption. Conclusions All materials had characteristic levels of flexibility and were susceptible to water absorption. Duran 1.5 mm performed similarly to Vivera in relation to stiffness and wear properties. While Zendura and Vivera have similar chemical structures, they exhibited differences concerning wear resistance and water absorption. Further clinical research evaluating the clinical relevance of these laboratory findings is required. Clinical relevance Characteristic patterns of wear and rigidity of four commercially available Essix-type retainers were observed. This information should help in the tailoring of retainer material on a case-by-case basis considering treatment-related factors and patient characteristics including parafunctional habits.

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Section: Discussionmentioning

confidence: 99%

“…Moreover, Bratu et al . [ 13 ] found Duran to have 549-μm median wear in the lower arch. More significant wear levels in the latter study may relate to the increase in the load used (61.2 kg) and a higher number of cycles (10,000).…”

Section: Discussionmentioning

confidence: 99%

Assessment of wear characteristics, longevity and stiffness of Essix-type retainers

Alfadil,

Patel,

Pandis

et al. 2024

Clin Oral Invest

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“…The removable retainers are efficient in the orthodontic practice in terms of maintaining the stability of the result of the active orthodontic treatment. They have many advantages related to the possibility of maintaining proper oral hygiene [ 37 ], are easy to perform [ 38 ], are acceptable in terms of aesthetics (especially the VFRs), and have a satisfactory resistance [ 39 ]. Their main disadvantage is related to the need for optimal collaboration of the patient.…”

Section: Discussionmentioning

confidence: 99%

The Behavior of Two Types of Upper Removable Retainers—Our Clinical Experience

et al. 2020

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The Hawley retainer (HR) and the vacuum-formed retainer (VFR) are the most common removable retainers in orthodontic treatments. The aim of this retrospective study was to comparatively analyze the behavior of two types of removable retainers—HRs and VFRs—in terms of retainer damage, loss, and the rate of installation of mild or severe relapse that required recourse to certain therapeutic interventions. The study was performed on 618 orthodontic patients aged 11–17 years, average age 13.98 ± 1.51, out of which 57% were patients having VFRs and the remaining 43% having HRs in the upper arch. We performed an analysis of the two groups of patients—HRs group and VFRs group—at 6 months (T1) and at 12 months (T2) after the application of the retainer. The results showed that 6% of all the retainers were damaged, mostly at T2 (54.1%). Seven percent of all the retainers were lost, mostly at T1 (58.1%). Of all the patients, 9.1% presented mild relapse, mostly at T1 (58.9%), while 2.6% presented severe relapse. The VFRs were significantly more frequently associated with the occurrence of damage than the HRs (p < 0.001). Severe relapse was more frequently associated with the HRs rather than with VFRs (p < 0.05).

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“…Another FDM-compatible material, polyethylene terephthalate glycol (PETG), is gaining popularity in recent times. PETG is a glycol-modified version of polyethylene terephthalate (PET) [ 35 ] having high toughness, chemical resistance, durability, low forming temperature and, hence, proving to be a good material for thermoforming [ 36 ], extrusion, injection molding and FDM [ 36 , 37 , 38 , 39 , 40 ]. In recent times, PETG has found applications in medical industries, food packaging industries, electronics, etc.…”

Section: Introductionmentioning

confidence: 99%

Parametric Modeling and Optimization of Dimensional Error and Surface Roughness of Fused Deposition Modeling Printed Polyethylene Terephthalate Glycol Parts

et al. 2023

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Polyethylene Terephthalate Glycol (PETG) is a fused deposition modeling (FDM)-compatible material gaining popularity due to its high strength and durability, lower shrinkage with less warping, better recyclability and safer and easier printing. FDM, however, suffers from the drawbacks of limited dimensional accuracy and a poor surface finish. This study describes a first effort to identify printing settings that will overcome these limitations for PETG printing. It aims to understand the influence of print speed, layer thickness, extrusion temperature and raster width on the dimensional errors and surface finish of FDM-printed PETG parts and perform multi-objective parametric optimization to identify optimal settings for high-quality printing. The experiments were performed as per the central composite rotatable design and statistical models were developed using response surface methodology (RSM), whose adequacy was verified using the analysis of variance (ANOVA) technique. Adaptive neuro fuzzy inference system (ANFIS) models were also developed for response prediction, having a root mean square error of not more than 0.83. For the minimization of surface roughness and dimensional errors, multi-objective optimization using a hybrid RSM and NSGA-II algorithm suggested the following optimal input parameters: print speed = 50 mm/s, layer thickness = 0.1 mm, extrusion temperature = 230 °C and raster width = 0.6 mm. After experimental validation, the predictive performance of the ANFIS (mean percentage error of 9.33%) was found to be superior to that of RSM (mean percentage error of 12.31%).

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Wear Resistance Under High Load Forces of Four Different Polyethylene Terephthalate Glycol Vacuum-Formed Orthodontic Retainers

Cited by 7 publications

References 9 publications

Assessment of wear characteristics, longevity and stiffness of Essix-type retainers

Assessment of wear characteristics, longevity and stiffness of Essix-type retainers

The Behavior of Two Types of Upper Removable Retainers—Our Clinical Experience

Parametric Modeling and Optimization of Dimensional Error and Surface Roughness of Fused Deposition Modeling Printed Polyethylene Terephthalate Glycol Parts

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