Shear Bonding Strength and Thermal Cycling Effect of Fluoride Releasable/Rechargeable Orthodontic Adhesive Resins Containing LiAl-F Layered Double Hydroxide (LDH) Filler.

Chih-Ying Hung,Yin-Chia Chen,Jun-Yen Uan,Liang-Wei Su,Jian-Hong Yu,Dan-Jae Lin

doi:10.3390/ma12193204

Chih-Ying Hung, Yin-Chia Chen + Show 4 more

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https://doi.org/10.3390/ma12193204

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Abstract

This study aims to investigate the shear bonding strength (SBS) and thermal cycling effect of orthodontic brackets bonded with fluoride release/rechargeable LiAl-F layered double hydroxide (LDH-F) contained dental orthodontic resin. 3% and 5% of LDH-F nanopowder were gently mixed to commercial resin-based adhesives Orthomite LC (LC, LC3, LC5) and Transbond XT (XT, XT3). A fluoroaluminosilicate modified resin adhesive Transbond color change (TC) was selected as a positive control. Fifteen brackets each group were bonded to bovine enamel and the SBS was tested with/without thermal cycling. The adhesive remnant index (ARI) was evaluated at 20× magnification. The fluoride-releasing/rechargeability and cytocompatibility were also evaluated. The SBS of LC, LC3, and LC5 were significantly higher than XT and TC. After thermal cycling, the SBS of LC, LC3, and LC5 did not decrease and was significantly higher than TC. The changes of ARI scores indicate that failure occurred not only cohesive but also semi-cohesive fracture. The 30 days accumulated daily fluoride release of LC3, LC5, and TC without recharge are higher than 300 μg/cm2. The LDH-F contained resin adhesive possesses higher SBS compared to positive control TC. Fluoride release and the rechargeable feature can be achieved for preventing enamel demineralization without cytotoxicity.

Highlights

Wearing a brace leads to difficulty in cleaning the mouth, food debris and plaque often accumulate around the structurally complex brackets in orthodontic patient [1,2]
analysis of variance (ANOVA) shows that the adhesive remnant index (ARI) scores are significant different (Table 2, P = 1.8 × 10−8 )
The bracket must be firmly adhered to the teeth through the During orthodontic treatment, the bracket must be firmly adhered to the teeth through the adhesive to withstand the forces generated by the orthodontic devices

Summary

Introduction

Wearing a brace leads to difficulty in cleaning the mouth, food debris and plaque often accumulate around the structurally complex brackets in orthodontic patient [1,2]. The number and proportion of Streptococcus mutans in dental plaque will increase during orthodontic treatment [3,4] It will metabolize food to produce organic acids, causing 60.9% of enamel demineralization (white spots) in just one month [5]. Systemic review showed that application of fluoride releasing orthodontic adhesives apparently reduce demineralization of enamel around brackets during orthodontic treatment [14,15]. Traditional glass ionomer cements (GICs) release fluoride and prevent enamel demineralization, they have limited adhesive strength and are not recommended for clinical use [14,16]. The resin adhesive is often selected for its higher adhesive strength than the GIC adhesives, it does not release fluoride

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