Microbial evaluation of the effectiveness of different methods for cleansing clear orthodontic retainers: A randomized clinical trial

Effect of Different Cleaning Regimes on Biofilm Formation of Acrylic-Based Removable Orthodontic Appliance: A Randomized Clinical Trial

Objectives

This study aimed to evaluate the effects of different cleaning regimes of acrylic-based removable orthodontic appliances on bacterial biofilm formation and whether the surface modification, i.e., polished acrylic fitting surface, reduces biofilm formation.

Materials and Methods

This double-blind, parallel, randomized clinical trial involved thirty-nine orthodontic patients indicated for removable orthodontic appliances. The patients were allocated into three groups according to the cleaning method: brushing with a denture brush and chlorhexidine (CHX) toothpaste, Lacalut cleaning tablet, and a combination of both cleaning methods. Each patient wore an upper removable appliance containing eight wells fitted with eight detachable acrylic tiles (four polished and four unpolished) for seven days. Five types of oral microbiota were evaluated using selective growth media and biochemical tests. The biofilm cleaning efficacy was assessed using the colony-forming unit (CFU) and scanning electron microscopy (SEM). Statistical Analysis. Data from the CFU using different cleansing regimes were compared, following log transformation, using one-way analysis of variance (ANOVA). The polished and unpolished tiles were compared for biofilm formation on each cleansing method using an independent t-test.

Results

There was no significant difference among the three cleaning methods on the polished or unpolished tiles. However, in polished tiles, streptococci were significantly reduced in all cleaning methods, whereas staphylococci and Staphylococcus aureus were markedly decreased in brushing and combination cleaning methods. However, the total number of anaerobic bacteria was significantly reduced in polished tiles using the combination method only.

Conclusions

Polishing the fitting surface of an acrylic-based orthodontic appliance reduced the tested bacterial biofilm formation and may enhance cleaning efficiency. Brushing and combination methods showed superior cleaning effects compared to cleaning tablets. This trial is registered with NCT05707221.

Investigation of the cleaning performance of commercial orthodontic cleaning tablets regarding biofilm removal on PMMA test specimens : An ex vivo study

PURPOSE

The purpose of this ex vivo study was to compare the cleaning performance of three commercially available orthodontic cleaners on polymethyl methacrylate (PMMA) test specimens covered with biofilm.

METHODS

Twenty subjects wore an individually manufactured vacuum-formed maxillary splint with four integrated PMMA test specimens for 7 days. The four test specimens were located on the buccal surfaces of the maxillary molars. After a 7-day wearing period, the PMMA test specimens colonized by biofilm were divided into two halves. One half was placed in 150 ml of tap water or in 150 ml of cleaning solution of the cleaners Retainer Brite® (Dentsply International Raintree Essix, Sarasota, FL, USA), Kukis® Xpress (Reckitt Benckiser, Heidelberg, Germany) or Dontodent (Propack, Heidelberg, Germany) while the other half remained uncleaned. The modified o‑phthaldialdehyde (OPA) method was used to determine the amount of protein on both halves of the test specimens. The difference was tested for significance as a measure of the cleaning effect using a paired sample t‑test.

RESULTS

The cleaning performance of the three orthodontic cleaners was higher than the cleaning performance of tap water (mean 25.9 ± 6.5%). While Retainer Brite® (mean 54.5 ± 7.1%) removed significantly more biofilm than Dontodent (mean 41.5 ± 9.2%, p < 0.001) and Kukis® Xpress (mean 39.9 ± 11.5%, p < 0.001), there was no significant difference in the cleaning performance between Kukis® Xpress and Dontodent (p = 1).

CONCLUSION

Seven-day-old biofilm is only removed partially by the investigated orthodontic cleaners, so that they are not suitable as the only measure for removing established biofilms.

Comparison of Various Antimicrobial Agents for Thermoplastic Polymeric Retainers

The thermoplastic retainers indicated a rising incidence of cariogenic bacteria such as Streptococcus mutans. A report suggested the case of a patient with severe gingival inflammation and dental caries as a result of inadequate appliance cleaning. This study aims to compare the various antimicrobial agents for thermoplastic polymeric retainers. A minimum bactericidal concentration (MBC) of acetic acid was determined. Streptococcus mutans biofilm was formed on punched 4-mm copolyester (Essix ACE®) and polyurethane (Vivera®) retainers after they were submerged in 0.12% chlorhexidine (CHX group), acetic acid (AA group), Polident Denture Cleanser® (PD group), and Polident Pro Guard & Retainer® (PR group). A crystal violet (CV) test was performed. The biofilm imaging was assessed by confocal laser scanning microscopy (CLSM). The results showed that all chemical disinfectants exhibited statistically significant differences (p < 0.05) compared to the positive control. This novel finding elucidated that 0.625% acetic acid is effective for antimicrobial in both copolyester and polyurethane retainers. However, only the CHX, PD, and PR groups could reduce biofilm mass. In addition, the CV assay cannot provide information about the actual number of living and dead bacteria. Furthermore, the LIVE/DEAD BacLight assay was able to show the bacterial viability.

Oral Microbiome in Orthodontic Acrylic Retainer

The oral microbiome can be shifted if the patients wear the acrylic retainers for a lengthy period. It is essential to understand the components of the plaque in order to forestall the development of dental caries and gingivitis. The aim of this study is to report the bacterial communities that adhere to the acrylic retainers by full-length nanopore 16S sequencing. Six healthy participants were allocated into 2 groups (chemical tablet and brushing groups). Plaque samples were collected from the acrylic retainer surfaces before and after cleaning. The bacterial communities were reported using full-length nanopore 16S sequencing. The results showed that 7 distinct phyla were identified by sequencing. The most prevalent of these was the Firmicutes. We found a total of 72 genera. The most common microorganism across all samples was Streptococcus, followed by Neisseria, Rothia, and Gemella. The beta diversity showed a significant difference between before and after cleaning (p < 0.05). This study revealed the novel finding that a combination of chemical and mechanical cleaning methods was the most effective method of eliminating retainer biofilms. Moreover, retainer cleaning tablets did not alter the homeostatic balance of the bacterial communities adhering to the acrylic retainers.

Antimicrobial efficacy, optical properties and flexural strength following antimicrobial photodynamic therapy over vacuum-formed orthodontic retainers

BACKGROUND AND AIMS

Vacuum-formed retainers (VFRs) are widely used in dental practices because of their superior esthetics. However, simultaneous maintenance of their hygiene, mechanical and optical properties is challenging. This study aimed to evaluate and compare the disinfection efficacy of antimicrobial photodynamic therapy (aPDT), chlorhexidine (CHX), sodium hypochlorite (NaOCl) and water over VFRs specimens, along with their effect on flexural strength and color stability.

MATERIALS AND METHODS

Fabricated VFRs of thicknesses 1 mm and 2 mm were contaminated with S. mutans and C. albicans. Brain Heart Infusion agar was used to seed Streptococcus Mutans whereas Candida Albicans was seeded in Sabourand Dextrose Agar. The contaminated retainers were divided into four groups and decontaminated using four different treatment protocols: aPDT, CHX, NaOCl and water, with 10 specimens per group. Microbial viability following decontamination, was assayed using MTT. To assess the color stability, pre and post decontamination color difference of 10 specimens was recorded using a spectrophotometer by blinding technique. The flexural strength of 10 specimens was measured using a universal testing machine by a standardized 3-point flexural strength (FS) test.

RESULT

aPDT showed the highest reduction in the viability of S. mutans (28%) and C. albicans (20%) species in 1 mm thickness group while the second highest reduction following disinfection with CHX (40%) in followed by NaOCl disinfection (50%). On comparison between 1 mm and 2 mm, a statistically significant difference was noted for S. mutans in aPDT (p = 0.033) and NaOCl (p = 0.028) groups, and for C. albicans, a significant difference was noted within NaOCl (p = 0.001) and CHX (p = 0.043) groups. For FS, a statistically significant difference (p < 0.05) was observed between aPDT and the rest of the groups, whereas there was no statistically significant difference in the flexural strength between the CHX, NaOCl and water groups (p > 0.05) in both 1 mm and 2 mm specimens. Between 1 mm and 2 mm specimens, no statistically significant difference in the mean color difference was noted after any disinfection protocol (p > 0.05).

CONCLUSION

Antimicrobial photodynamic therapy showed a remarkable reduction in candidal and bacterial viability over VFRs. aPDT treated VFR specimens showed increased flexural strength and a higher color difference post treatment compared to other reagents.

Antimicrobial Activity of Various Disinfectants to Clean Thermoplastic Polymeric Appliances in Orthodontics

There is a lack of research evidence on the risk–benefits of the various disinfectants in cleaning products and cleansing regimens. This systematic review compared the antimicrobial activity of various chemical disinfectants to disinfect the thermoplastic polymeric appliances in orthodontics. The study was carried out using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane Handbook of Systematic Reviews of Interventions. An electronic search was conducted on Pubmed, Google Scholar, Scopus, ScienceDirect, and Springer. Two authors independently investigated the risk of bias in duplication. A total of 225 articles were collected. After removing duplicates, 221 articles remained, and after filtering their titles and abstracts, 11 articles met eligibility qualifications remained. Finally, nine articles that met the criteria were selected. It showed that both over-the-counter orthodontic appliance cleaners and applied-chemical disinfectants were effective against bacteria. The duration and frequency of usage guidelines cannot be concluded.

Evaluation of the time-dependent efficacy of commercial denture or orthodontic appliance cleansers: An in vitro study

The aim of this study was to evaluate the antimicrobial, stain and protein removal efficacy of denture or orthodontic appliance cleansers using in vitro test methods. Experimental cleansers were applied for experimental time in each evaluation method. To evaluate the microorganism removal efficacy, C. albicans and S. mutans removal rate was calculated from the specimen surface. Stain and protein removal rate was calculated using the spectrophotometer. Experimental cleansers significantly affected the microorganism removal rate for both C. albicans and S. mutans, as well as the stain and protein removal rates, at each experimental time (p<0.05). As the application time increased, the stain and protein removal rates of all experimental cleansers significantly increased (p<0.05). The present study provided in vitro evaluation methods to assess the efficacy of denture or orthodontic appliance cleansers. Also, manufacturers and researchers can predict clinical outcomes and ensure proper hygiene management of dentures or orthodontic appliances.

Removable orthodontic retainers: practical considerations

This article provides an overview of removable orthodontic retainers, discussing their history and the different types available, and compares the two most popular removable retainers. Practical information on consent and the clinical steps involved in the provision of removable retainers, as well as suggested wear and care instructions, are also presented.

Surface Characterization, Antimicrobial Activity, and Biocompatibility of Autopolymerizing Acrylic Resins Coated with Reynoutria elliptica Extract

We conducted surface characterization to assess the biocompatibility and investigate the antimicrobial activity against oral pathogens in autopolymerizing acrylic resins, coated with light-curable coating resin, containing various concentrations of Reynoutria elliptica extract (0, 200, 400, and 600 µg/mL). The R. elliptica extract powder was prepared using a freeze-drying technique. Further, a goniometer and microhardness tester were used to determine the water contact angle, and Vickers hardness, respectively; color measurements were performed on the uncoated and coated acrylic resin disks. The polyphenol content of the extracts from the coated acrylic resin disk was analyzed using UV-VIS spectroscopy. The antimicrobial activity of the coated acrylic resin disk against Streptococcus mutans and Candida albicans was observed for 24 and 48 h by measuring the optical density using spectrophotometry. In addition, biocompatibility was confirmed by testing the cell viability according to ISO 10993-5. The water contact angle, Vickers hardness, and color change values of the coated acrylic resin disks were not significantly different from the control. Polyphenol was detected in all experimental groups, with no significant differences between the experimental groups. The experimental groups exhibited significant antimicrobial activity against S. mutans and C. albicans compared to the control group, after 48 h of incubation. The cell viability between the control and experimental groups was not significantly different. The proposed coating resin containing R. elliptica extract is applicable on dental acrylic resins, due to their antimicrobial properties and excellent biocompatibility, with no deterioration of surface characteristics.

Evaluation of the Efficacy of Different Cleaning Methods for Orthodontic Thermoplastic Retainers in terms of Bacterial Colonization

Objective

This study investigated the antimicrobial efficacy of three different cleaning methods on Streptococcus mutans (SM) and Lactobacillus (LB) bacteria colonization in vivo. The three different cleaning methods were applied by volunteers on clear vacuum formed retainers (VFRs).

Methods

In this prospective, cross-over study, a total of 21 volunteers were included. All VFRs used by the volunteers were cleaned using three different cleaning methods in a sequence. These methods were peroxide-based cleanser tablets (PBCTs) plus brushing, control (only brushing), and vinegar plus brushing, respectively. The obtained salivary, VFR material, and periodontal data were statistically compared by factorial design repeated measures analysis of variance.

Results

The SM and LB bacteria counts on VFRs after using both PBCTs and vinegar were statistically similar (p>0.05), but bacteria counts were statistically lower than the control method (p<0.01). There were no statistically significant differences between the SM and LB bacteria counts in saliva samples taken before and after the application of the cleaning methods (p>0.05). Similarly, there were no significant differences between periodontal data obtained from plaque and bleeding indices at all study times. The periodontal pocket depth gradually decreased in the successively performed cleaning applications (p<0.05).

Conclusion

The application of PBCTs and vinegar to VFRs at sequential time intervals resulted in similar bacteria counts. The higher LB counts and similarly higher SM counts on the VFR samples indicate that mechanical cleaning only (control method) is not adequate to obtain hygiene. Salivary flora was not correlated with bacteria counts of VFRs.

Colorimetric and spectrophotometric measurements of orthodontic thermoplastic aligners exposed to various staining sources and cleaning methods

Background

Manufacturers of orthodontic aligners suggest that users remove appliances every time they consume solid foods or any drink (except water). This is to avoid a color change within the clear thermoplastic material of which they are made. However, limited quantitative evidence exists to guide users and practitioners in this regard. Herein, we evaluated the color stability of the polymer forming three different American brands of aligners and the stain-removal potential of two cleansers to provide such guidelines.

Methods

The removable appliances (300 specimens, 100 per brand) were exposed to different staining agents common in a regular diet (coffee, black tea, red wine, cola) or to a control solution in vitro over 12 h or 7 days. The three brands evaluated were Invisalign®, ClearCorrect® and Minor Tooth Movement®. These were then cleaned by using either Invisalign® cleaning crystals or the Cordless Sonic Cleaner combined with a Retainer Brite® tablet. The CIELAB color space approach was used to compare color changes (ΔE) in aligners before immersion (T0), after a 12-h exposure (T1), after a 7-day exposure (T2) and after cleaning (T3). Statistical methods (Levene’s test, ANOVA, Brunner-Langer model, Tukey’s range test and t-test) were used to identify interactions between the brands themselves or between the brands and the cleaning methods. Statistical analyses were performed at the .05 significance level.

Results

A 12-h or 7-day exposure to instant coffee or red wine significantly colored the Invisalign® aligners compared to the two other brands. Black tea created an important extrinsic color change for all three brands after 7 days. Clinically, both cleaning methods showed a better efficacy in removing stains from black tea compared to other staining agents.

Conclusions

The Invisalign® aligners were more prone to pigmentation than the ClearCorrect® or the Minor Tooth Movement® devices after an exposure to coffee or red wine. Black tea caused important stains on the surface of the three tested brands. Both cleansing methods performed similarly.

Long-term effects of different cleaning methods on copolyester retainer properties

OBJECTIVE

To evaluate light transmittance, surface roughness, and flexural modulus of copolyester retainer material after long-term exposure to different cleaning methods.

MATERIALS AND METHODS

Standardized copolyester retainer specimens (ACE) were subjected to seven chemical cleaning solutions for 6 months: Invisalign cleaning crystals, Retainer Brite, Polident, Listerine mouthwash, 2.5% acetic acid, 0.6% NaClO, and 3% H₂O₂. Seventy specimens (n = 10 per method, 50.8 mm × 12.7 mm × 1.0 mm) were exposed to the different solutions twice a week for 2 minutes or according to manufacturer's instructions and stored in artificial saliva at 37°C. Another group of specimens (n = 10) was brushed with a standardized toothbrushing machine for 2 minutes twice a week. At baseline and 6 months, light transmittance, surface roughness and flexural modulus of the specimens were quantified using spectrophotometry, profilometry, and three-point bend testing, respectively. Qualitative assessment was performed using scanning electron microscopy (SEM). Statistical analyses were accomplished at a significance level of .05.

RESULTS

The results indicated that light transmittance through the specimens decreased significantly from baseline for all cleaning methods at 6 months. Flexural modulus of the specimens decreased significantly for all cleaning methods except Invisalign crystals and Retainer Brite ( P > .05). The Listerine group demonstrated the worst light transmittance change while H₂O₂ demonstrated the greatest change in flexural modulus of the specimens compared with other cleaning methods; however, no qualitative difference was observed using SEM analysis.

CONCLUSIONS

The results suggest that different cleaning methods affect long-term physical properties of the ACE retainer material. At the present time, none of these cleaning methods is ideal for copolyester retainer material.