Efficacy of antimicrobial agents incorporated in orthodontic bonding systems: a systematic review and meta-analysis

Effect of the addition of silver nanoparticles on the mechanical properties of an orthodontic adhesive

Objectives

This study evaluated the effects of adding silver nanoparticles on the shear bond strength, microhardness, and surface roughness of orthodontic adhesives.

Material and Methods

Fifty upper premolars were randomly allocated to five groups (n = 10). Orthodontic brackets were bonded with silver nanoparticle (AgNP)-modified adhesives (1 %, 0.5 %, 0.1 %, 0.05 %), and conventional adhesive was used as a control. The shear bond strength was recorded using a universal testing machine, and the adhesive remnant index was evaluated using a stereomicroscope. Ten discs of each adhesive were subjected to the microhardness and surface roughness tests. The Vickers microhardness values were measured under a constant load of 100 g for 30 s using a microhardness tester. The samples were analyzed using a surface profilometer, and the arithmetic average roughness was used as the measurement parameter. Data were analyzed using one-way analysis of variance and chi-square tests. A significance level of 5 % was considered significant.

Results

AgNP concentration > 0.1 % significantly reduced the shear bond strength (p < 0.05). At higher AgNP concentration, the bonding failure pattern occurred mainly at the bracket-resin interface. The Vickers microhardness increased with increasing concentration, and significant differences were observed between the group with 1 % AgNP and the other groups (p < 0.05). The average roughness values were similar between the groups with AgNP concentrations > 0.1 % (p > 0.05).

Conclusion

The incorporation of AgNP into an orthodontic adhesive has the potential to decrease the shear bond strength while increasing the microhardness and surface roughness.

Long term remineralizing effect of casein phosphopeptide amorphous calcium phosphate in white spot lesions: A systematic review and meta-analysis

BACKGROUND

White spot lesions (WSLs) appear as white, opaque areas on the teeth and are caused by a demineralization of the enamel.

OBJECTIVE

The purpose of this systematic review and meta-analysis was to determine whether casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has beneficial effects on WSLs and provides remineralizing benefits that are superior to those of placebo or no treatment.

METHODS

Following a thorough analysis of the literature across major online sources, 103 papers - 54 of which underwent in-depth evaluation - were found. We used inclusion and exclusion criteria to choose research articles that were appropriate for our review.

RESULTS

10 papers met this review's requirements and were subsequently included. As compared to the controls, CPP-ACP demonstrated increased efficacy in treatment of WSLs in terms of remineralisation and other parameters which included microhardness tests and enamel surface roughness. The forest plots present the results of meta-analyses comparing the effect of CPP-ACP versus control/other agents on white spot lesions (WSLs). In terms of odds ratios (OR), CPP-ACP showed a small increase in the odds of WSLs compared to control/other agents. In-vitro studies showed no significant difference in relative risk (RR) between CPP-ACP and control/other agents. Randomized control trials indicated a small increase in the risk of WSLs with CPP-ACP treatment, but the overall effect was not statistically significant.

CONCLUSION

There was evidence to support the use of CPP-ACP over other agents for WSL prevention or treatment, but further research is needed to confirm these findings.

Effect of Orthodontic Appliances on the Oral Environment and Microbiome

Orthodontic treatment is an appliance-intensive endeavor, where an array of mechanical devices is used to bring about tooth movement. By virtue of remaining in close proximity to the enamel, gingiva and periodontal ligament intra-orally over a prolonged period of time, orthodontic appliances have a significant impact on the paradental tissues, oral environment and oral microbiome. Orthodontic appliances by acting as anchors for biofilm and plaque formation, accumulate bacteria and other micro-organisms in amounts unfavorable for maintenance of healthy equilibrium. The resulting loss of balance in the oral microbiome causes dysbiosis which manifests clinically as increased enamel demineralization, dental caries and periodontal disease. Mechanical removal of the accumulated plaque by maintaining rigorous oral hygiene has been proven to be the single most important factor to mitigate the harmful effects of dysbiosis. This review investigates how each of the various components of the orthodontic appliances, different types of appliances and unique surface properties of biomaterials have contributory effects at the interface of orthodontic biomaterials and oral biology. The information thus obtained will be critical in instituting the best diagnostic and therapeutic measures at the clinical level. It will also be instrumental in devising improvements and providing new directions for future research in general and precision orthodontics in particular.

Casein phosphopeptide amorphous calcium phosphate and universal adhesive resin as a complementary approach for management of white spot lesions: an in-vitro study

Background

White spot lesion (WSL) is the most common consequence during and after orthodontic treatment. This study was conducted to investigate the ability of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) coupled with universal adhesive resin to treat white spot lesions.

Material and methods

Forty-five extracted premolars were sectioned to create 90 specimens. Seventy-five specimens were demineralized to generate artificially created WSLs. Different strategies have been applied for the management of the artificially created WSLs. Six experimental groups were employed: Group I: sound enamel (control), Group II: demineralized enamel (artificially-created WSLs), Group III: ICON resin-treated WSLs, Group IV: CPP-ACP-treated WSLs, Group V: universal adhesive resin-treated WSLs, and Group VI: CPP-ACP followed by universal adhesive resin-treated WSLs. Assessment of color stability using a spectrophotometer, surface microhardness using a Vickers tester, and surface roughness using a profilometer was done. The surface topography of representative specimens from each experimental group was inspected using a scanning electron microscope. Collected data were analyzed using one-way ANOVA followed by Tukey’s post hoc test at p ≤ 0.05.

Results

White spot lesions treated with CPP-ACP and subsequently coated with universal adhesive resin (Group VI) exhibited a significantly lower ΔE than both CPP-ACP (Group IV) and universal adhesive resin-treated (Group V) groups (p ≤ 0.05), but it was not significantly different from the ICON resin-treated group (Group III). For surface microhardness, WSLs treated with CPP-ACP and consequently coated with universal adhesive resin (Group VI) recorded the highest mean that was significantly different from both ICON resin (Group III) and universal adhesive resin-treated (Group V) groups (p ≤ 0.05). All the tested strategies (ICON resin, CPP-ACP, universal adhesive resin, and CPP-ACP followed by universal adhesive resin) significantly lowered the surface roughness of the WSLs (p ≤ 0.05), while no significant difference was detected among them.

Conclusions

Combining a considerable caries remineralizing program using CPP-ACP with subsequent universal adhesive resin infiltration could be a promising approach to manage WSLs efficiently through increasing surface microhardness and restoring esthetic while developing a smoother surface.

Physical/Mechanical and Antibacterial Properties of Orthodontic Adhesives Containing Calcium Phosphate and Nisin

Enamel demineralization around orthodontic adhesive is a common esthetic concern during orthodontic treatment. The aim of this study was to prepare orthodontic adhesives containing monocalcium phosphate monohydrate (MCPM) and nisin to enable mineralizing and antibacterial actions. The physicomechanical properties and the inhibition of S. mutans growth of the adhesives with added MCPM (5, 10 wt %) and nisin (5, 10 wt %) were examined. Transbond XT (Trans) was used as the commercial comparison. The adhesive containing a low level of MCPM showed significantly higher monomer conversion (42–62%) than Trans (38%) (p < 0.05). Materials with additives showed lower monomer conversion (p < 0.05), biaxial flexural strength (p < 0.05), and shear bond strength to enamel than those of a control. Additives increased water sorption and solubility of the experimental materials. The addition of MCPM encouraged Ca and P ion release, and the precipitation of calcium phosphate at the bonding interface. The growth of S. mutans in all the groups was comparable (p > 0.05). In conclusion, experimental orthodontic adhesives with additives showed comparable conversion but lesser mechanical properties than the commercial material. The materials showed no antibacterial action, but exhibited ion release and calcium phosphate precipitation. These properties may promote remineralization of the demineralized enamel.

Novel Orthodontic Cement Comprising Unique Imidazolium-Based Polymerizable Antibacterial Monomers

White spot lesions (WSLs) can develop quickly and compromise the successful outcome of the orthodontic treatment. Orthodontic bonding cement with the capability to prevent or mitigate WSLs could be beneficial, especially for patients with high risk of caries. This study explored novel mono- and di-imidazolium-based polymerizable antibacterial monomers and evaluated orthodontic cement compositions comprising such novel monomers. Their antibacterial potentials, mechanical properties, and shear bond strength (SBS) to bovine enamel were investigated. Statistical tests were applied to SBS and mechanical tests (one-way ANOVA and Tukey’s test). For antibacterial resins C (ABR-C) and E (ABR-E), their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against cariogenic Streptococcus mutans bacterial strain UA159 were found to be 4 μg/mL and 8 μg /mL, respectively. The loss of dry mass from completely demineralized dentin beams in buffer solutions pre-dipped into ABR-C and ABR-E resins is much less than that in control buffer (artificial saliva) only. For unfilled resins comprising up to 12 wt % ABR-C, no significant decreases in flexural strength or modulus were observed. For experimental cements incorporating 1–4 wt % ABR-C, there was no drastic compromise to the SBS to enamel except for 3 wt % ABR-C. Furthermore, their SBS was all comparable to the commercially available orthodontic cements. The ISO-22196 antimicrobial test against S. aureus showed significant levels of antibacterial effects—up to over 5 logs of microorganism reduction exhibited by ABR-C-containing experimental cements. The imidazolium-based polymerizable monomers could be utilized to functionalize orthodontic bonding cement with steady antibacterial activity and develop a potential strategy to counteract WSLs.

Evaluation of the Shear Bond Strength and Antibacterial Activity of Orthodontic Adhesive Containing Silver Nanoparticle, an In-Vitro Study

This study evaluated the effect of incorporating silver nanoparticles (AgNPs) into conventional orthodontic adhesive on its antibacterial activity and the shear bond strength (SBS) to stainless steel orthodontic brackets. Thirty-four extracted premolars were randomly allocated into two groups (n = 17). Orthodontic adhesive (Transbond XT, 3M Unitek) was blended with AgNPs (50 nm, 0.3% w/w) to form a nano-adhesive. In order to bond stainless steel twin brackets (0.022-inch, American Orthodontics), Transbond XT (n = 17) and nano-adhesive (n = 17) were used in each group, respectively, after acid etching (37% phosphoric acid, 30 s) and rinsing with water (15 s). SBS and the adhesive remnant index (ARI) scores were recorded. Antibacterial activity against Streptococcus mutans in both groups after 24 h and 30 days was assessed (Disc agar diffusion test) and the inhibition zone diameter around each specimen was measured and recorded. Adding AgNPs significantly (p = 0.009) reduced the mean (SD) SBS in the nano-adhesive group [10.51(7.15) MPa] compared to Transbond XT [17.72(10.55) MPa]. The ARI scores on the Transbond XT and nano-adhesive showed no statistically significant difference (p = 0.322). Nano-adhesive with AgNPs showed significant antibacterial activity against Streptococcus mutans at 24 h and 30 days (p < 0.001). In both groups, no significant decline in the zones of inhibition was detected after 30 days (p = 0.907). The findings suggest that SBS decreased after incorporation of AgNPs [0.3% (w/w)], but was still above the recommended SBS of 5.9–7.8 MPa. The nano-adhesive showed significant antibacterial activity which did not change much after 30 days.

The effect of incorporation Nano Cinnamon powder on the shear bond of the orthodontic composite (an in vitro study)

Objectives

One of the causes of dental caries that occurs due to orthodontic treatment is the lack of antibacterial properties in orthodontic adhesive. This study was designated to investigate the effect of orthodontic resin modified by incorporating Nano Cinnamon powder on the shear bond strength of orthodontic brackets.

Materials and methods

Heliosit Orthodontic Resin, a photo-activated light cure resin was modified by the addition of Cinnamon in the form of Nano particle powder. Twenty uniform disks were made, 5 as a control and 5 for each concentration of the 1%, 3% and 5% wt/wt Cinnamon modified resin. Their antimicrobial activity against Streptococcus Mutans was tested using the disk diffusion method. Then, the most effective concentration of the modified resin was used to bond metal orthodontic brackets to human extracted premolars. The universal testing machine was used to record the shear bond strength of the control and the modified resin. Also, the adhesive remnant index was measured.

Results

Disc diffusion method showed that the 3% wt/wt Cinnamon powder modified resin was more effective than 1% with a larger bacterial inhibition zone. Shear bond strengths of the control were 8.50 MPa and 7.20 MPa for the 3% Cinnamon modified resin with no significant difference between them. Also, no significant difference was recorded in the adhesive remnant index scores between the control and the modified resin groups.

Conclusion

Findings of this study revealed that the incorporation of 3% Cinnamon Nano particles in orthodontic resin produced an antibacterial effect against Streptococcus mutans without compromising the shear bond strength.

Clinical relevance

Incorporation of Cinnamon Nano particles in orthodontic resin may reduce caries formation around brackets during treatment course.

Polymeric and inorganic nanoscopical antimicrobial fillers in dentistry

Failure of dental treatments is mainly due to the biofilm accumulated on the dental materials. Many investigations have been conducted on the advancements of antimicrobial dental materials. Polymeric and inorganic nanoscopical agents are capable of inhibiting microorganism proliferation. Applying them as fillers in dental materials can achieve enhanced microbicidal ability. The present review provides a broad overview on the state-of-the-art research in the field of antimicrobial fillers which have been adopted for incorporation into dental materials over the last 5 years. The antibacterial agents and applications are described, with the aim of providing information for future investigations. STATEMENT OF SIGNIFICANCE: Microbial infection is the primary cause of dental treatment failure. The present review provides an overview on the state-of-art in the field of antimicrobial nanoscopical or polymeric fillers that have been applied in dental materials. Trends in the biotechnological development of these antimicrobial fillers over the last 5 years are reviewed to provide a backdrop for further advancement in this field of research.

Surface morphologic evaluation of orthodontic bonding systems under conditions of cariogenic challenge

Orthodontic bonding systems are submitted to demineralization and remineralization dynamics that might compromise their surface smoothness, and favor biofilm aggregation and caries development. The aim of the present study was to evaluate the effects of a cariogenic challenge model (in vitro pH-cycling model) on the surface roughness and topography of 3 bonding materials: Transbond™ XT (XT), Transbond™ Plus Color Change (PLUS) and Fuji Ortho™ LC (FUJI), by means of Atomic Force Microscopy (AFM). Six specimens with standardized dimensions and surface smoothness were fabricated per group, and the materials were manipulated in accordance with the manufacturers' instructions. No polishing was necessary. AFM tests were performed before and after pH-cycling, taking 3 readouts per specimen. The roughness results (Ra) were obtained at nanometric levels (nm) and surface records were acquired in two- and three-dimensional images of height and lock-in phase of the material components. The surfaces of all groups analyzed in the study were morphologically altered, presenting images suggestive of matrix degradation and loss of matrix-load integrity. FUJI presented the greatest increase in surface roughness, followed by XT and PLUS, respectively (p≤0.001). Nevertheless, the roughness values found did not present sufficient degradation to harbor bacteria. The surface roughness of all tested materials was increased by pH-cycling. The use of materials capable of resisting degradation in the oral environment is recommended, in order to conserve their integrity and of the surrounding tissues.

Antibacterial Activity of Orthodontic Cement Containing Quaternary Ammonium Polyethylenimine Nanoparticles Adjacent to Orthodontic Brackets

Enamel demineralization is a common problem found in patients using orthodontic devices, such as orthodontic braces. It was found that Streptoccocus mutans growth increases adjacent to orthodontic devices, which may result in caries development. Incorporated antibacterial quaternary ammonium polyethylenimine (QPEI) nanoparticles were previously shown to be highly efficacious against various bacteria. Combining antibacterial materials in orthodontic cement may be advantageous to prevent bacterial outgrowth adjacent to orthodontic brackets. The aim was to evaluate the efficiency of orthodontic cement containing QPEI nanoparticles in reducing S. mutans and Lactobacillus casei outgrowth adjacent to orthodontic brackets. Orthodontic brackets were bonded to the buccal surfaces of extracted lower incisors. The antibacterial effect on S. mutans and L. casei outgrowth of Neobond bracket adhesive orthodontic cement with and without QPEI nanoparticles was compared. The antibacterial effect was evaluated using crystal violet staining and bacterial count (CFU/mL). The teeth in the experimental group, with the QPEI nanoparticles cement, showed significantly lower optical density (OD) values and CFU counts of S. mutans and L. casei than the teeth in the control group (p < 0.05). Based on the results, it can be concluded that orthodontic cement containing QPEI nanoparticles significantly inhibits S. mutans and L. casei growth around orthodontic brackets.