The long observation in vitro of prevention effect of novel self-etching orthodontic adhesive modified with 2-methacryloxyethyl phosphorylcholine in enamel demineralization

New Generation of Orthodontic Elastomeric Ligature to Prevent Enamel Demineralization In Vivo

This study aimed to synthesize a novel elastomeric ligature with dimethylaminohexadecyl methacrylate (DMAHDM) grafted, providing a new strategy for improving the issue of enamel demineralization during fixed orthodontics. DMAHDM was incorporated into elastomeric ligatures at different mass fractions using ultraviolet photochemical grafting. The antibacterial properties were evaluated and the optimal DMAHDM amount was determined based on cytotoxicity assays. Moreover, tests were conducted to evaluate the in vivo changes in the mechanical properties of the elastomeric ligatures. To assess the actual in vivo effectiveness in preventing enamel demineralization, a rat demineralization model was established, with analyses focusing on changes in surface microstructure, elemental composition, and nanomechanical properties. Elastomeric ligatures with 2% DMAHDM showed excellent biocompatibility and the best antibacterial properties, reducing lactic acid production by 65.3% and biofilm bacteria by 50.0% within 24 h, without significant mechanical property differences from the control group (p > 0.05). Most importantly, they effectively prevented enamel demineralization in vivo, enhancing elastic modulus by 73.2% and hardness by 204.8%. Elastomeric ligatures incorporating DMAHDM have shown great potential for application in preventing enamel demineralization, providing a new strategy to solve this issue during fixed orthodontics.

New generation of orthodontic devices and materials with bioactive capacities to improve enamel demineralization

OBJECTIVE

The article reviewed novel orthodontic devices and materials with bioactive capacities in recent years and elaborated on their properties, aiming to provide guidance and reference for future scientific research and clinical applications.

DATA, SOURCES AND STUDY SELECTION

Researches on remineralization, protein repellent, antimicrobial activity and multifunctional novel bioactive orthodontic devices and materials were included. The search of articles was carried out in Web of Science, PubMed, Medline and Scopus.

CONCLUSIONS

The new generation of orthodontic devices and materials with bioactive capacities has broad application prospects. However, most of the current studies are limited to in vitro studies and cannot explore the true effects of various bioactive devices and materials applied in oral environments. More research, especially in vivo researches, is needed to assist in clinical application.

CLINICAL SIGNIFICANCE

Enamel demineralization (ED) is a common complication in orthodontic treatments. Prolonged ED can lead to dental caries, impacting both the aesthetics and health of teeth. It is of great significance to develop antibacterial orthodontic devices and materials that can inhibit bacterial accumulation and prevent ED. However, materials with only preventive effect may fall short of addressing actual needs. Hence, the development of novel bioactive orthodontic materials with remineralizing abilities is imperative. The article reviewed the recent advancements in bioactive orthodontic devices and materials, offering guidance and serving as a reference for future scientific research and clinical applications.

Polymethyl methacrylate resin containing ε-poly-L-lysine and 2-methacryloyloxyethyl phosphorylcholine with antimicrobial effects

STATEMENT OF PROBLEM

Polymethyl methacrylate (PMMA) is commonly used in dentistry, including as a denture base material. However, the colonization of a PMMA surface by microbial microorganisms could increase the risk of oral diseases such as denture stomatitis and gingivitis. The development of PMMA with antibacterial properties should improve its clinical application, but whether adding ε-poly-L-lysine (ε-PL) and 2-methacryloyloxyethyl phosphorylcholine (MPC) provides antimicrobial effects is unclear.

PURPOSE

This in vitro study aimed to develop a novel antibacterial PMMA resin containing the natural nontoxic antibacterial agent ε-PL and the protein repellent agent MPC. The mechanical properties, protein repellency, and antimicrobial activities of the resin were then evaluated.

MATERIAL AND METHODS

Different mass fractions of ε-PL and MPC were mixed into PMMA as the experimental groups, with unaltered PMMA as the control group. The flexural strength (n=10) and surface roughness (n=6) of the resulting mixtures were measured to determine their mechanical properties. The antiprotein properties were measured by using the micro bicinchoninic acid method (n=6). The antimicrobial effect of the resin was assessed using live/dead staining (n=6) and methyltransferase (MTT) assays (n=10). According to the variance homogeneity and normal distribution results, 1-way analysis of variance followed by the Tukey honestly significant difference test or the Welch test and the Games-Howell test were used (α=.05 for all tests).

RESULTS

No significant differences were found in the flexural strength values and surface roughness of the specimens containing 1.5% MPC and 1.5% ε-PL compared with those of the control (P>.05). The addition of ε-PL to the PMMA resin alone significantly increased its bactericidal properties (P<.05). Adding both ε-PL and MPC further increased the antibacterial activity of the PMMA resin without increasing protein adhesion more than in the control group.

CONCLUSIONS

The incorporation of both ε-PL and MPC into PMMA improved its antibacterial capacity without affecting its mechanical properties and did not increase protein adhesion. Therefore, the novel PMMA fabricated in this study shows promise for dental applications.

Shear bond strength of different bonding agents to orthodontic metal bracket and zirconia

This study aimed to evaluate the shear bond strength (SBS) of four bonding agents used to bond metal brackets to zirconia under different storage conditions. Four bonding agents were used [FLC: (Fuji ORTHO LC), XT: (Transbond^TM XT), RUC-SBU: (Rely X^TM Ultimate Clicker Adhesive Resin Cement+Single Bond Universal), and RUC-GBU: (Rely X^TM Ultimate Clicker Adhesive Resin Cement+Gluma Bond Universal)] to bond two types of metal brackets (PT/3M) to zirconia surfaces, and they were stored in water at 37ºC for 24 h or thermocycling for 3,000 cycles. The SBS data of RUC-SBU and RUC-GBU using PT brackets were significantly higher than those of 3M brackets before and after thermocycling. It could be concluded that RUC-SBU and RUC-GBU could offer sufficient bond strength between metal brackets and zirconia for the short term compared with FLC and XT. The design of brackets can significantly affect the bond strength to zirconia.