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.

Antibacterial Effect of Experimental Orthodontic Adhesives Containing Gold Nanoparticles against Streptococcus mutans and Streptococcus sobrinus

Enamel decalcification usually can be found around orthodontic bracket after debonding. Orthodontic adhesives resistant to bacterial colonization were used to prevent white spot lesion and dental caries in orthodontic treatment with fixed appliance. The objectives of this study were to evaluate the antibacterial properties of expeimental orthodontic adhesive containing gold nanoparticles (AuNPs). 108 orthodontic adhesive discs containing 1.0 wt%, 0.5 wt%, 0.25 wt% AuNPs and without AuNPs were prepared from in-house orthodontic adhesive (27 discs per group). The antibcterial properties of adhesive discs were evaluated by direct contact test. Streptococcus mutans and Streptococcus sobrinus suspensions were placed on the discs and incubated at 37 °C for 1 hour. The adhesive discs were transferred to BHI broth and were incubated at 37°C for 16, 20 and 24 h. Bacterial growth was evaluated by optical density (OD) measurement at 590nm. The results showed that experimental orthodontic adhesives with 1.0 wt% and 0.5 wt% AuNPs exhibited higher antibacterial activity compared to the control group (p < 0.05). At 24 h of incubation, the median OD of 1.0 wt%, 0.5 wt%, 0.25 wt% and control in S. mutans were 0.109, 0.006, 0.007 and 0.372, rescpectively. In S. sobrinus, the median OD were 0.173, 0.012 , 0.007 and 0.328. The incorporation of gold nanoparticles into orthodontic adhesives exhibited antibacterial activity against cariogenic microorganism. At a concentration of 0.5 wt% and 1.0 wt% AuNPs, experimental orthodontic adhesive could reduce bacterial growth of both S. mutans and S. sobrinus.

Comparative Evaluation of Effect of Excessive Adhesive Flash Formed from Two Orthodontic Adhesives on Clinical Periodontal Status of Patients Undergoing Fixed Orthodontic Appliance Therapy

BACKGROUND Increased accumulation of dental plaque and inflammatory response during treatment is due to the appearance of new retentive places around the components of fixed appliances attached to the teeth. During bonding procedures, there is certain amount of adhesive left on the tooth surface invariably around the margins between bracket and enamel interface called excessive adhesive flash (EAF), which may act as a plaque retentive area. We wanted to evaluate and compare the effect of EAF formed from two different orthodontic bonding adhesives on clinical periodontal status of patients undergoing fixed orthodontic appliance therapy. METHODS 20 patients indicated for treatment with fixed stainless steel preadjusted edgewise appliance were selected for the study. A split mouth design was followed where each patient’s teeth were divided into 2 groups; Group A: Teeth of right side bonded with non-tooth coloured orthodontic adhesive resin (Transbond XT Plus) – 1st and 4th quadrants; Group B: Teeth of left side bonded with tooth-coloured orthodontic adhesive resin (Transbond XT) - 2nd and 3rd quadrants. Clinical periodontal status was assessed by measuring Muhlemann modified papillary bleeding index, Turesky Gilmore Glickman modification of Quigley Hein Plaque Index, and a modification of the Orthodontic Plaque Index, before bonding (T0) and 1 week after bonding the appliance (T1). RESULTS Readings at T1 had significantly increased compared to T0 indicating increased plaque retention. However, difference between the indices for both groups at T1 was not statistically significant. CONCLUSIONS The excessive adhesive flash is a site for increased plaque accumulation, irrespective of the composite being tooth coloured or non-tooth coloured. KEY WORDS EAF, Adhesives, Split Mouth

Surface Characteristics, Fluoride Release and Bond Strength Evaluation of Four Orthodontic Adhesives

Orthodontic adhesives have similar properties in terms of fluoride release, roughness, shear bond strength or cement debris for specific clinical conditions. Three commercial consecrated orthodontic adhesives (Opal Seal®, Blugloo®, Light Bond®) were compared with an experimental orthodontic material (C1). Brackets were bonded to enamel using a self-etch technique followed by adhesive application and then de-bonded 60 days later. Share bond strength evaluation, scanning electron microscopy, atomic force microscopy and fluoride release analysis were performed. The highest amount of daily and cumulative fluoride release was obtained for the experimental material, while the lowest value was observed for Opal Seal®. The materials evaluated in the current study presented adequate shear bond strength, with the experimental material having a mean value higher than Opal Seal and Blugloo. The atomic force microscopy measurements indicated that the smoothest initial sample is Opal Seal® followed by Light Bond®. Scanning electron microscopy evaluation indicated different aspects of cement debris on the enamel and/or bracket surface, according to the type of adhesive. The experimental material C1 presented adequate properties in terms of shear bond strength, fluoride release, roughness and enamel characteristics after de-bonding, compared to the commercial materials. Under these circumstances, it can be considered for clinical testing.

Antimicrobial properties, anti-virulence activities, and physico-mechanical characteristics of orthodontic adhesive containing C-phycocyanin: a promising application of natural products

Introduction: Antimicrobial orthodontic adhesives aim to reduce enamel demineralization, white spot lesions, and incipient tooth decay around bonded orthodontic brackets, but they should not imperil its mechanical properties.&nbsp; Aim: To evaluate the antimicrobial and physico-mechanical properties of acrylic containing different concentrations of C-phycocyanin on Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans. Materials and methods: The mechanical properties of acrylic resins were measured by flexural strength test after preparation of acrylic resin samples with concentrations of 1%, 2%, 5%, 7.5%, and 10% of C-phycocyanin. Then we evaluated the antimicrobial effects of acrylic resin containing the maximum concentration of C-phycocyanin with clinically acceptable flexural strength and the changes in expression of virulence factors. Results: The highest and lowest means of flexural strength were obtained in acrylic resins containing 0% and 10% concentrations of C-phycocyanin at 50.2&plusmn;4.5 and 30.1&plusmn;3.3 MPa, respectively. Adding 1%, 2%, and 5% of C-phycocyanin showed no significant decrease in flexural strength (p>0.05). The maximum mean diameter of the growth inhibition zone was observed around discs containing 5% of C-phycocyanin. Until day 30 of the study, no microbial biofilms were formed on any acrylic disc. Only microbial biofilms of C. albicans were able to form on discs containing 5% of C-phycocyanin at 90 days. 5% C-phycocyanin could significantly decrease the expression levels of gtfB, hsp16, and ALS9 6.1-, 7.3-, and 3.9-fold, respectively. Conclusions: It can be concluded that the most acceptable concentration of C-phycocyanin in acrylic resin is 5% based on the results of flexural strength tests and antimicrobial activities of acrylic resin containing various concentrations of C-phycocyanin.