Retrieval analysis of lingual fixed retainer adhesives

Abstract

INTRODUCTION:Our objective was to analyze the surface and bulk properties alterations of clinically aged composites used for fixed retention. METHODS: Twenty-six lingual retainers bonded for different time periods (2.2-17.4 years) were retrieved from postorthodontic patients. Fifteen lingual retainers had been cemented by a chemically cured adhesive (Maximum Cure, Reliance Orthodontic Products, Itasca, Ill), and 11 were treated with a photo-cured adhesive (Flow-Tain, Reliance Orthodontic Products). The first group was in service for 2.8 to 17.4 years and the second for 2.2 to 5.4 years. Five specimens from each material were prepared and used as the control (or reference) group. The debonded surfaces from enamel were studied by attenuated total reflectance Fourier transform infrared spectroscopy (n = 3 per material per group), low-vacuum scanning electron microscopy, and energy dispersive x-ray microanalysis (n = 3 per material per group). All specimens were used for the assessment of Vickers hardness, indentation modulus, and elastic index with the instrumented indentation testing method. The values of Vickers hardness, indentation modulus, and elastic index were compared between the retrieved and the reference groups with 1-way analysis of variance and the Student-Newman-Keuls multiple comparison test ( = 0.05). RESULTS: The attenuated total reflectance Fourier transform infrared spectroscopy analysis showed that both retrieved composites demonstrated reduced unsaturation in comparison with the corresponding reference specimens. Some bonded surfaces showed development of organic integuments. All retrieved specimens showed reduced silicon content. Barium was identified only in the photo-cured group. No significant differences were found between the reference and retrieved groups in Vickers hardness, indentation modulus, and elastic index. CONCLUSIONS: Despite the changes in composition, the mechanical properties of the materials tested remained unaffected by intraoral aging.

Creep, Hardness, and Elastic Modulus of Lingual Fixed Retainer Adhesives

“…The results for GA are similar to the data provided by the manufacturer (7.9 GPa) [24] and a previous study after testing in three point bending [19]. The moduli of FT and TL were also found close to previously reported values (FT 5.2 GPa [13]), (TL 17.3 GPa [6,25]) after IIT. The same is true for E IT for TX (15.0 GPa [6]), a value close to one provided by the manufacturer (16.4 GPa [23]) and the value of 14.3 GPa calculated after three point bending [16].…”

“…A small value indicates a ductile material while a high value indicates a brittle one. The results of this study are close to previously reported values for LR (33.6%) [ 6 , 25 ], TX (30.7%) [ 6 ]), and FT (45.0%) [ 13 ], while to the best of our knowledge there are no comparable data available on the creep resistance of orthodontic adhesive apart from one recently published study where only one commercially available product was tested [ 16 ].…”

“…Despite the fact that the mechanical properties of adhesives have been tested by experimental and retrieval analysis studies [ 6 , 10 , 11 , 12 , 13 ], there is currently no information on the time-dependent properties of orthodontic adhesives. However, adhesive resins in both aforementioned applications undergo static forces over the whole time of intraoral service.…”

Enamel Evaluation after Debonding of Fixed Retention and Polishing Treatment with Three Different Methods

“…Many studies have analyzed the retention phase in terms of: stability, retention material, adhesion, clinicians and patients’ preference, and hygiene. Researchers have described the best characteristics for adhesion systems in fixed retainers, considering mechanical properties of the composite and wear resistance [ 2 , 3 ], while other authors focused on long-term stability of the tooth position [ 4 ] and periodontal health in comparison with control groups or removable retentions [ 5 , 6 ], but there is a lack of literature focused on the study of the consequences of retention in the enamel.…”

Fear of the Relapse: Effect of Composite Type on Adhesion Efficacy of Upper and Lower Orthodontic Fixed Retainers: In Vitro Investigation and Randomized Clinical Trial

“…For this reason, retention is considered the final and essential step to maintain, through an adequate appliance, the correct position reached by dental elements at the end of the active orthodontic therapy. Clinicians agree that retention should be maintained as long as a perfect alignment is desired [2]. Several studies investigated the most used retention device in various European and non-European countries, and bonded retainers resulted to be the most widely used device in different countries, especially for the mandibular arch [3][4][5][6][7][8].…”